bluuebunny/crossref_metadata_2025 huggingface dataset:
Machine interpretation of CAD data for manufacturing applications
Authors: Ji Qiang , Marefat Michael M.
Published: July 2002

Machine interpretation of the shape of a component for CAD databases is an important problem in CAD/CAM, computer vision, and intelligent manufacturing. It can be used in CAD/CAM for evaluation of designs, in computer vision for machine recognition and machine inspection of objects, and in intelligent manufacturing for automating and integrating the link between design and manufacturing. This topic has been an active area of research since the late '70s, and a significant number of computational methods have been proposed to identify portions of the geometry of a part having engineering significance (here called “features”). However, each proposed mechanism has been able to solve the problem only for components within a restricted geometric domain (such as polyhedral components), or only for components whose features interact with each other in a restricted manner. The purposes of this article are to review and summarize the development of research on machine recognition of features from CAD data, to discuss the advantages and potential problems of each approach, and to point out some of the promising directions future investigations may take. Since most work in this field has focused on machining features, the article primarily covers those features associated with the manufacturing domain. In order to better understand the state of the art, methods of automated feature recognition are divided into the following categories of methods based on their approach: graph-based, syntactic pattern recognition, rule-based, and volumetric. Within each category we have studied issues such as the definition of features, mechanisms developed for recognition of features, the application scope, and the assumptions made. In addition, the problem is addressed from the perspective of information input requirements and the advantages and disadvantages of boundary representation, constructive solid geometry (CSG), and 2D drawings with respect to machine recognition of features are examined. Emphasis is placed on the mechanisms for attacking problems associated with interacting features.
Geometric compression through topological surgery
Authors: Taubin Gabriel , Rossignac Jarek
Published: July 2002

The abundance and importance of complex 3-D data bases in major industry segments, the affordability of interactive 3-D rendering for office and consumer use, and the exploitation of the Internet to distribute and share 3-D data have intensified the need for an effective 3-D geometric compression technique that would significantly reduce the time required to transmit 3-D models over digital communication channels, and the amount of memory or disk space required to store the models. Because the prevalent representation of 3-D models for graphics purposes is polyhedral and because polyhedral models are in general triangulated for rendering, this article introduces a new compressed representation for complex triangulated models and simple, yet efficient, compression and decompression algorithms. In this scheme, vertex positions are quantized within the desired accuracy, a vertex spanning tree is used to predict the position of each vertex from 2,3, or 4 of its ancestors in the tree, and the correction vectors are entropy encoded. Properties, such as normals, colors, and texture coordinates, are compressed in a similar manner. The connectivity is encoded with no loss of information to an average of less than two bits per triangle. The vertex spanning tree and a small set of jump edges are used to split the model into a simple polygon. A triangle spanning tree and a sequence of marching bits are used to encode the triangulation of the polygon. Our approach improves on Michael Deering's pioneering results by exploiting the geometric coherence of several ancestors in the vertex spanning tree, preserving the connectivity with no loss of information, avoiding vertex repetitions, and using about three fewer bits for the connectivity. However, since decompression requires random access to all vertices, this method must be modified for hardware rendering with limited onboard memory. Finally, we demonstrate implementation results for a variety of VRML models with up to two orders of magnitude compression.
Algorithm 778: L-BFGS-B
Authors: Zhu Ciyou , Byrd Richard H. , Lu Peihuang , Nocedal Jorge
Published: July 2002

L-BFGS-B is a limited-memory algorithm for solving large nonlinear optimization problems subject to simple bounds on the variables. It is intended for problems in which information on the Hessian matrix is difficult to obtain, or for large dense problems. L-BFGS-B can also be used for unconstrained problems and in this case performs similarly to its predessor, algorithm L-BFGS (Harwell routine VA15). The algorithm is implemented in Fortran 77.
Polynomial time approximation schemes for Euclidean traveling salesman and other geometric problems
Authors: Arora Sanjeev
Published: July 2002

We present a polynomial time approximation scheme for Euclidean TSP in fixed dimensions. For every fixed
c
> 1 and given any
n
nodes in ℛ
2
, a randomized version of the scheme finds a (1 + 1/
c
)-approximation to the optimum traveling salesman tour in
O(n
(log
n
)

O(c)
)

time. When the nodes are in ℛ
d
, the running time increases to
O(n
(log
n
)
(O(√
c))
d-1
). For every fixed
c, d
the running time is
n
· poly(log
n
), that is
nearly linear
in
n
. The algorithmm can be derandomized, but this increases the running time by a factor

O(n
d

). The previous best approximation algorithm for the problem (due to Christofides) achieves a 3/2-aproximation in polynomial time.

We also give similar approximation schemes for some other NP-hard Euclidean problems: Minimum Steiner Tree,
k
-TSP, and
k
-MST. (The running times of the algorithm for
k
-TSP and
k
-MST involve an additional multiplicative factor
k
.) The previous best approximation algorithms for all these problems achieved a constant-factor approximation. We also give efficient approximation schemes for Euclidean Min-Cost Matching, a problem that can be solved exactly in polynomial time.

All our algorithms also work, with almost no modification, when distance is measured using any geometric norm (such as ℓ

p

for
p
≥ 1 or other Minkowski norms). They also have simple parallel (i.e., NC) implementations.
An optimal algorithm for approximate nearest neighbor searching fixed dimensions
Authors: Arya Sunil , Mount David M. , Netanyahu Nathan S. , Silverman Ruth , Wu Angela Y.
Published: July 2002

Consider a set of
S
of
n
data points in real
d
-dimensional space, R
d
, where distances are measured using any Minkowski metric. In nearest neighbor searching, we preprocess
S
into a data structure, so that given any query point
q
∈ R
d
, is the closest point of S to
q
can be reported quickly. Given any positive real ϵ, data point
p
is a (1 +ϵ)-
approximate nearest neighbor
of
q
if its distance from
q
is within a factor of (1 + ϵ) of the distance to the true nearest neighbor. We show that it is possible to preprocess a set of
n
points in R
d
in
O(dn
log
n
) time and
O(dn)
space, so that given a query point
q
∈ R
d
, and ϵ > 0, a (1 + ϵ)-approximate nearest neighbor of
q
can be computed in
O
(
c

d
, ϵ

log
n
) time, where

c
d,ϵ

≤
d
⌈1 + 6d/ϵ⌉
d
is a factor depending only on dimension and ϵ. In general, we show that given an integer
k
≥ 1, (1 + ϵ)-approximations to the
k
nearest neighbors of
q
can be computed in additional
O(kd
log
n
) time.
Profiles in computing: Allan L. Scherr
Authors: Frenkel Karen A.
Published: July 2002

"Most of the work I've done has been done to break things into existence that didn't exist before. . . . In a sense, my whole career's been about building organizations that didn't exist before, creating processes to do things that have never been done before, and solving technical problems that hadn't been solved before. The work I did at MIT was that way as well. There was no real foundation to build on, and I had to make it up as I went along. That's characterized, if not my whole career, at least the parts of my career that I consider the most rewarding."

"Pioneers are also the people that get arrows shot through them. That's the downside, and I've had my share of arrows pulled out of my hide."
Impossibility of distributed consensus with one faulty process
Authors: Fischer Michael J. , Lynch Nancy A. , Paterson Michael S.
Published: July 2002

The consensus problem involves an asynchronous system of processes, some of which may be unreliable. The problem is for the reliable processes to agree on a binary value. In this paper, it is shown that every protocol for this problem has the possibility of nontermination, even with only one faulty process. By way of contrast, solutions are known for the synchronous case, the “Byzantine Generals” problem.
A fast bit-vector algorithm for approximate string matching based on dynamic programming
Authors: Myers Gene
Published: July 2002

The approximate string matching problem is to find all locations at which a query of length
m
matches a substring of a text of length
n
with
k
-or-fewer differences. Simple and practical bit-vector algorithms have been designed for this problem, most notably the one used in
agrep
. These algorithms compute a bit representation of the current state-set of the
k
-difference automaton for the query, and asymptotically run in either
O
(
nm/w
) or
O
(
nm
log σ/
w
) time where
w
is the word size of the machine (e.g., 32 or 64 in practice), and σ is the size of the pattern alphabet. Here we present an algorithm of comparable simplicity that requires only
O
(
nm/w)
time by virtue of computing a bit representation of the
relocatable
dynamic programming matrix for the problem. Thus, the algorithm's performance is independent of
k
, and it is found to be more efficient than the previous results for many choices of
k
and
small
m
.

Moreover, because the algorithm is not
dependent on
k
, it can be used to rapidly compute blocks of the dynamic programming matrix as in the 4-Russians algorithm of Wu et al.(1996). This gives rise to an
O(kn/w)
expected-time algorithm for the case where
m
may be arbitrarily large. In practice this new algorithm, that computes a region of the dynamic progr amming (d.p.) matrx
w
entries at a time using the basic algorithm as a subroutine is significantly faster than our previous 4-Russians algorithm, that computes the same region 4 or 5 entries at a time using table lookup. This performance improvement yields a code that is either superior or competitive with
all
existing algorithms except for some filtration algorithms that are superior when
k/m
is sufficiently small.
The tracker
Authors: Denning Dorothy E. , Denning Peter J.
Published: July 2002

The query programs of certain databases report raw statistics for query sets, which are groups of records specified implicitly by a characteristic formula. The raw statistics include query set size and sums of powers of values in the query set. Many users and designers believe that the individual records will remain confidential as long as query programs refuse to report the statistics of query sets which are too small. It is shown that the compromise of small query sets can in fact almost always be accomplished with the help of characteristic formulas called trackers. Schlörer's individual tracker is reviewed; it is derived from known characteristics of a given individual and permits deducing additional characteristics he may have. The general tracker is introduced: It permits calculating statistics for arbitrary query sets, without requiring preknowledge of anything in the database. General trackers always exist if there are enough distinguishable classes of individuals in the database, in which case the trackers have a simple form. Almost all databases have a general tracker, and general trackers are almost always easy to find. Security is not guaranteed by the lack of a general tracker.
Two Complete Axiom Systems for the Algebra of Regular Events
Authors: Salomaa Arto
Published: July 2002

The theory of finite automata is closely linked with the theory of Kleene's regular expressions. In this paper, two formal systems for the algebraic transformation of regular expressions are developed. Both systems are consistent and complete; i.e., the set of equations derivable within the system equals the set of equations between two regular expressions denoting the same event. One of the systems is based upon the uniqueness of the solution of certain regular expression equations, whereas some facts concerning the representation theory of regular events are used in connection with the other.
Code Generation for Expressions with Common Subexpressions
Authors: Aho A. V. , Johnson S. C. , Ullman J. D.
Published: July 2002

This paper shows the problem of generating optimal code for expressions containing common subexpressions is computationally difficult, even for simple expressions and simple machines. Some heuristics for code generation are given and their worst-case behavior is analyzed. For one register machines, an optimal code generation algorithm is given whose time complexity is linear in the size of an expression and exponential only in the amount of sharing.
ELIZA — a computer program for the study of natural language communication between man and machine
Authors: Weizenbaum Joseph
Published: July 2002

ELIZA is a program operating within the MAC time-sharing system of MIT which makes certain kinds of natural language conversation between man and computer possible. Input sentences are analyzed on the basis of decomposition rules which are triggered by key words appearing in the input text. Responses are generated by reassembly rules associated with selected decomposition rules. The fundamental technical problems with which ELIZA is concerned are: (1) the identification of key words, (2) the discovery of minimal context, (3) the choice of appropriate transformations, (4) generation of responses in the absence of key words, and (5) the provision of an editing capability for ELIZA “scripts”. A discussion of some psychological issues relevant to the ELIZA approach as well as of future developments concludes the paper.
Certification of programs for secure information flow
Authors: Denning Dorothy E. , Denning Peter J.
Published: July 2002

ertification mechanism for verifying the secure flow of information through a program. Because it exploits the properties of a lattice structure among security classes, the procedure is sufficiently simple that it can easily be included in the analysis phase of most existing compilers. Appropriate semantics are presented and proved correct. An important application is the confinement problem: The mechanism can prove that a program cannot cause supposedly nonconfidential results to depend on confidential input data.
A program data flow analysis procedure
Authors: Allen F. E. , Cocke J.
Published: July 2002

The global data relationships in a program can be exposed and codified by the static analysis methods described in this paper. A procedure is given which determines all the definitions which can possibly “reach” each node of the control flow graph of the program and all the definitions that are “live” on each edge of the graph. The procedure uses an “interval” ordered edge listing data structure and handles reducible and irreducible graphs indistinguishably.
Determining the minimum-area encasing rectangle for an arbitrary closed curve
Authors: Freeman H. , Shapira R.
Published: July 2002

This paper describes a method for finding the rectangle of minimum area in which a given arbitrary plane curve can be contained. The method is of interest in certain packing and optimum layout problems. It consists of first determining the minimal-perimeter convex polygon that encloses the given curve and then selecting the rectangle of minimum area capable of containing this polygon. Three theorems are introduced to show that one side of the minimum-area rectangle must be collinear with an edge of the enclosed polygon and that the minimum-area encasing rectangle for the convex polygon is also the minimum-area rectangle for the curve.
Interactive consulting via natural language
Authors: Shapiro Stuart C. , Kwasny Stanley C.
Published: July 2002

Interactive programming systems often contain help commands to give the programmer on-line instruction regarding the use of the various systems commands. It is argued that it would be relatively easy to make these help commands significantly more helpful by having them accept requests in natural language. As a demonstration, Weizenbaum's ELIZA program has been provided with a script that turns it into a natural language system consultant.
Representation of contours and regions for efficient computer search
Authors: Merrill R. D.
Published: July 2002

A novel computer-searchable representation for the three basic pictorial features, contour maps, region coverage, and line structures, is described. The representation, which has practical storage requirements, provides a rapid means of searching large files for data associated with geometric position as well as with attribute value. An application of this representation to handling terrain information illustrates its utility. The algebraic properties of the data structure make it computationally easy to determine whether a point lies within a closed boundary; compute the area contained by a closed boundary; generate the closed boundary representing the union or intersection of two closed boundaries; and determine the neighboring boundaries to a point and the minimum distances between them and the point.
Proof of a program
Authors: Hoare C. A. R.
Published: July 2002

A proof is given of the correctness of the algorithm “Find.” First, an informal description is given of the purpose of the program and the method used. A systematic technique is described for constructing the program proof during the process of coding it, in such a way as to prevent the intrusion of logical errors. The proof of termination is treated as a separate exercise. Finally, some conclusions relating to general programming methodology are drawn.
Lattice computers for approximating Euclidean space
Authors: Case John , Rajan Dayanand S. , Shende Anil M.
Published: July 2002

In the context of mesh-like, parallel processing computers for (i) approximating continuous space and (ii)
analog
simulation of the motion of objects and waves in continuous space, the present paper is concerned with
which
mesh-like interconnection of processors might be particularly suitable for the task and why.

Processor interconnection schemes based on nearest neighbor connections in geometric lattices are presented along with motivation. Then two major threads are exploded regarding which lattices would be good: the
regular lattices
, for their symmetry and other properties in common with continuous space, and the well-known
root lattices
, for being, in a sense, the lattices required for physically natural basic algorithms for motion.

The main theorem of the present paper implies that the well-known lattice A

n

is the regular lattice having the maximum number of nearest neighbors among the
n
-dimensional regular lattices. It is noted that the only
n
-dimensional lattices that are both regular and root are A

n

and Z

n

(Z

n

is the lattice of
n
-cubes. The remainder of the paper specifies other desirable properties of A

n

including other ways it is superior to Z

n

for our purposes.
Storage and retrieval of aspects of meaning in directed graph structures
Authors: Simmons R. F.
Published: July 2002

An experimental system that uses LISP to make a conceptual dictionary is described. The dictionary associates with each English word the syntactic information, definitional material, and references to the contexts in which it has been used to define other words. Such relations as class inclusion, possession, and active or passive actions are used as definitional material. The resulting structure serves as a powerful vehicle for research on the logic of question answering. Examples of methods of inputting information and answering simple English questions are given. An important conclusion is that, although LISP and other list processing languages are ideally suited for producing complex associative structures, they are inadequate vehicles for language processing on any large scale—at least until they can use auxiliary memory as a continuous extension of core memory.
A programmer's description of L
6
Authors: Knowlton Kenneth C.
Published: July 2002

Bell Telephone Laboratories' Low-Level Linked List Language
L
6
(pronounced “
L
-six”) is a new programming language for list structure manipulations. It contains many of the facilities which underlie such list processors as IPL, LISP, COMIT and SNOBOL, but permits the user to get much closer to machine code in order to write faster-running programs, to use storage more efficiently and to build a wider variety of linked data structures.
Problems of storage allocation in a multiprocessor multiprogrammed system
Authors: Maher R. J.
Published: July 2002

Multiprogramming
is defined here as the use of a buffered processor by time-sharing its central control and its memory between two or more object programs under control of an executive system.
Program organization and record keeping for dynamic storage allocation
Authors: Holt Anatol W.
Published: July 2002

The material presented in this paper is part of the design plan of the core allocation portion of the ACSI-MATIC Programming System. Project ACSI-MATIC is concerned with the application of computer techniques to the activities of certain headquarters military intelligence operations of the U.S. Army.

In describing features of organization and record keeping there has been no attempt at completeness, but rather an exploration of the salient aspects of the system to some reasonable level of technical detail.
1
Dynamic storage allocation for an information retrieval system
Authors: Sams Burnett H.
Published: July 2002

This paper presents an information retrieval problem whose programming solution included dynamic storage allocation. Allocatable machine code is defined, and an assembly program to produce allocatable machine code is described. The work reported on was done as part of Project ACSI-MATIC
1
which is concerned with the application of computer techniques to the activities of certain headquarters military intelligence operations of the U.S. Army [1, 2].
The international impact of computers
Authors: Auerbach Isaac L.
Published: July 2002

Just one year ago, I had the pleasure of surveying over 40 laboratories, factories and universities throughout Western Europe that were actively engaged in the computer field. Since then, many visitors from Europe have visited me and updated my information on the status of developments abroad.
Unconditional security in quantum cryptography
Authors: Mayers Dominic
Published: July 2002

Basic techniques to prove the unconditional security of quantum crypto graphy are described. They are applied to a quantum key distribution protocol proposed by Bennett and Brassard [1984]. The proof considers a practical variation on the protocol in which the channel is noisy and photos may be lost during the transmission. Each individual signal sent into the channel must contain a single photon or any two-dimensional system in the exact state described in the protocol. No restriction is imposed on the detector used at the receiving side of the channel, except that whether or not the received system is detected must be independent of the basis used to measure this system.
A new approach to the maximum-flow problem
Authors: Goldberg Andrew V. , Tarjan Robert E.
Published: July 2002

All previously known efficient maximum-flow algorithms work by finding augmenting paths, either one path at a time (as in the original Ford and Fulkerson algorithm) or all shortest-length augmenting paths at once (using the layered network approach of Dinic). An alternative method based on the
preflow
concept of Karzanov is introduced. A preflow is like a flow, except that the total amount flowing into a vertex is allowed to exceed the total amount flowing out. The method maintains a preflow in the original network and pushes local flow excess toward the sink along what are estimated to be shortest paths. The algorithm and its analysis are simple and intuitive, yet the algorithm runs as fast as any other known method on dense graphs, achieving an
O
(
n
3
) time bound on an
n
-vertex graph. By incorporating the dynamic tree data structure of Sleator and Tarjan, we obtain a version of the algorithm running in
O
(
nm
log(
n
2
/
m
)) time on an
n
-vertex,
m
-edge graph. This is as fast as any known method for any graph density and faster on graphs of moderate density. The algorithm also admits efficient distributed and parallel implementations. A parallel implementation running in
O
(
n
2
log
n
) time using
n
processors and
O
(
m
) space is obtained. This time bound matches that of the Shiloach-Vishkin algorithm, which also uses
n
processors but requires
O
(
n
2
) space.
Program verification: the very idea
Authors: Fetzer James H.
Published: July 2002

The notion of program verification appears to trade upon an equivocation. Algorithms, as logical structures, are appropriate subjects for deductive verification. Programs, as causal models of those structures, are not. The success of program verification as a generally applicable and completely reliable method for guaranteeing program performance is not even a theoretical possibility.
Proposed NIST standard for role-based access control
Authors: Ferraiolo David F. , Sandhu Ravi , Gavrila Serban , Kuhn D. Richard , Chandramouli Ramaswamy
Published: July 2002

In this article we propose a standard for role-based access control (RBAC). Although RBAC models have received broad support as a generalized approach to access control, and are well recognized for their many advantages in performing large-scale authorization management, no single authoritative definition of RBAC exists today. This lack of a widely accepted model results in uncertainty and confusion about RBAC's utility and meaning. The standard proposed here seeks to resolve this situation by unifying ideas from a base of frequently referenced RBAC models, commercial products, and research prototypes. It is intended to serve as a foundation for product development, evaluation, and procurement specification. Although RBAC continues to evolve as users, researchers, and vendors gain experience with its application, we feel the features and components proposed in this standard represent a fundamental and stable set of mechanisms that may be enhanced by developers in further meeting the needs of their customers. As such, this document does not attempt to standardize RBAC features beyond those that have achieved acceptance in the commercial marketplace and research community, but instead focuses on defining a fundamental and stable set of RBAC components. This standard is organized into the RBAC Reference Model and the RBAC System and Administrative Functional Specification. The reference model defines the scope of features that comprise the standard and provides a consistent vocabulary in support of the specification. The RBAC System and Administrative Functional Specification defines functional requirements for administrative operations and queries for the creation, maintenance, and review of RBAC sets and relations, as well as for specifying system level functionality in support of session attribute management and an access control decision process.
A BVP solver based on residual control and the Maltab PSE
Authors: Kierzenka Jacek , Shampine Lawrence F.
Published: July 2002

Our goal was to make it as easy as possible to solve a large class of boundary value problems (BVPs) for ordinary differential equations in the Matlab problem solving environment (PSE). We present here theoretical and software developments resulting in bvp4c, a capable BVP solver that is exceptionally easy to use.
GAMS: a framework for the management of scientific software
Authors: Boisvert Ronald F. , Howe Sally E. , Kahaner David K.
Published: July 2002

The Guide to Available Mathematical Software (GAMS) provides a framework for both a scientist-end-user and a librarian-maintainer to deal with large quantities of mathematical and statistical software. This framework includes a classification scheme for mathematical and statistical software, a database system to manage information about this software, and both an on-line interactive consulting system and a printed catalog for providing users with access to this information. A description is given of GAMS and its use at the National Bureau of Standards.
Convex separable optimization is not much harder than linear optimization
Authors: Hochbaum D. S. , Shanthikumar J. George
Published: July 2002

The polynomiality of nonlinear separable convex (concave) optimization problems, on linear constraints with a matrix with “small” subdeterminants, and the polynomiality of such integer problems, provided the inteter linear version of such problems ins polynomial, is proven. This paper presents a general-purpose algorithm for converting procedures that solves linear programming problems. The conversion is polynomial for constraint matrices with polynomially bounded subdeterminants. Among the important corollaries of the algorithm is the extension of the polynomial solvability of integer linear programming problems with totally unimodular constraint matrix, to integer-separable convex programming. An algorithm for finding a ε-accurate optimal continuous solution to the nonlinear problem that is polynomial in log(1/ε) and the input size and the largest subdeterminant of the constraint matrix is also presented. These developments are based on proximity results between the continuous and integral optimal solutions for problems with any nonlinear separable convex objective function. The practical feature of our algorithm is that is does not demand an explicit representation of the nonlinear function, only a polynomial number of function evaluations on a prespecified grid.
NARRATING THE SELF
Authors: Ochs Elinor , Capps Lisa
Published: July 2002

▪ Abstract  Across cultures, narrative emerges early in communicative development and is a fundamental means of making sense of experience. Narrative and self are inseparable in that narrative is simultaneously born out of experience and gives shape to experience. Narrative activity provides tellers with an opportunity to impose order on otherwise disconnected events, and to create continuity between past, present, and imagined worlds. Narrative also interfaces self and society, constituting a crucial resource for socializing emotions, attitudes, and identities, developing interpersonal relationships, and constituting membership in a community. Through various genres and modes; through discourse, grammar, lexicon, and prosody; and through the dynamics of collaborative authorship, narratives bring multiple, partial selves to life.
THE ARCHAEOLOGY OF SYMBOLS
Authors: Robb John E.
Published: July 2002

▪ Abstract  Why should archaeologists deal with symbols and how can they do so? This article outlines three major traditions archaeologists have followed in conceptualizing symbols, each with its own preferred topics of study, understanding of power and social relations, and epistemology. These include the processual view of symbols as tokens that represent reality, the structuralist view of symbols as mental girders framing a cultural reality, and the postmodern view of symbols as arbitrary fragments incorporated into phenomenological experience. The primary conclusions are that (a) any serious consideration of ancient society requires us to deal with its symbols; (b) human symbolism is so diverse (it includes cognitive structures; ritual icons; identities such as gender, prestige, and ethnicity; technological knowledge; and political ideologies) that multiple approaches are needed to deal adequately with it; and (c) a major problem in the archaeology of symbols is understanding how varied kinds of symbols relate to each other.
Moving Bodies, Acting Selves
Authors: Farnell B.
Published: July 2002

▪ Abstract  This review describes a paradigmatic shift in anthropological studies of human movement, from an observationist view of behavior to a conception of body movement as dynamically embodied action. After outlining the scope of such study, historical and cultural reasons for the relative neglect of body movement in anthropological enquiry are examined critically and placed in the wider context of recent social and cultural theorizing about the body and the problem of dynamic embodiment. A historical overview situates earlier approaches, such as kinesics and proxemics, in relation to more recent developments in theory and method, such as those offered by semasiology and the concept of the “action sign.” Overlapping interests with linguistic and cognitive anthropology are described. The emergence of a holistic “anthropology of human movement” has raised new research questions that require new resources. Theoretical insights have challenged researchers to devise new methods and to adopt or devise new technologies, such as videotape and an adequate transcription system. An example of the latter illustrates the analytic advantages of literacy in the medium.
Anthropology of Tourism: Forging New Ground for Ecotourism and Other Alternatives
Authors: Stronza Amanda
Published: July 2002

▪ Abstract  Tourism is relevant to many theoretical and real-world issues in anthropology. The major themes anthropologists have covered in the study of tourism may be divided conceptually into two halves: One half seeks to understand the origins of tourism, and the other reveals tourism's impacts. Even when taken together, these two approaches seem to produce only a partial analysis of tourism. The problem is that most studies aimed at understanding the origins of tourism tend to focus on tourists, and most research concerning the impacts of tourism tend to focus on locals. The goal of future research should be to explore incentives and impacts for both tourists and locals throughout all stages of tourism. This more holistic perspective will be important as we explore the ways in which ecotourism and other alternative forms of tourism can generate social, economic, and environmental benefits for local communities while also creating truly transformative experiences for tourists.

Tourism has some aspects of showbiz, some of international trade in commodities; it is part innocent fun, part a devastating modernizing force. Being all these things simultaneously, it tends to induce partial analysis only.

     Victor Turner, 1974
World Englishes
Authors: Bhatt Rakesh M.
Published: July 2002

▪ Abstract  This essay is an overview of the theoretical, methodological, pedagogical, ideological, and power-related issues of world Englishes: varieties of English used in diverse sociolinguistic contexts. The scholars in this field have critically examined theoretical and methodological frameworks of language use based on western, essentially monolingual and monocultural, frameworks of linguistic science and replaced them with frameworks that are faithful to multilingualism and language variation. This conceptual shift affords a “pluricentric” view of English, which represents diverse sociolinguistic histories, multicultural identities, multiple norms of use and acquisition, and distinct contexts of function. The implications of this shift for learning and teaching world Englishes are critically reviewed in the final sections of this essay.
CHILLING SENSITIVITY IN PLANTS AND CYANOBACTERIA: The Crucial Contribution of Membrane Lipids
Authors: Nishida I. , Murata N.
Published: July 2002

▪ Abstract  The contribution of membrane lipids, particularly the level of unsaturation of fatty acids, to chilling sensitivity of plants has been intensively discussed for many years. We have demonstrated that the chilling sensitivity can be manipulated by modulating levels of unsaturation of fatty acids of membrane lipids by the action of acyl-lipid desaturases and glycerol-3-phosphate acyltransferase. This review covers recent studies on genetic manipulation of these enzymes in transgenic tobacco and cyanobacteria with special emphasis on the crucial importance of the unsaturation of membrane lipids in protecting the photosynthetic machinery from photoinhibition under cold conditions. Furthermore, we review the molecular mechanism of temperature-induced desaturation of fatty acids and introduce our hypothesis that changes in the membrane fluidity is the initial event of the expression of desaturase genes.
PHLOEM UNLOADING: Sieve Element Unloading and Post-Sieve Element Transport
Authors: Patrick J. W.
Published: July 2002

▪ Abstract  The transport events from the sieve elements to the sites of utilization within the recipient sink cells contribute to phloem unloading. The phenomenon links sink metabolism and/or compartmentation with phloem transport to, and partitioning between, sinks. The nature of the linkage depends upon the cellular pathway and mechanism of unloading. The common unloading pathway is symplasmic, with an apoplasmic step at or beyond the sieve element boundary reserved for specialized situations. Plasmodesmal conductivity exerts the primary control over symplasmic transport that occurs by diffusion with bulk flow anticipated to be of increasing significance as import rate rises. In the case of an apoplasmic step, efflux across the plasma membranes of the vascular cells occurs by simple diffusion, whereas efflux from nonvascular cells of developing seeds is facilitated and, in some cases, energy coupled. Accumulation of sugars from the sink apoplasm universally occurs by a plasma membrane–bound sugar/proton symport mechanism.
ALTERNATIVE OXIDASE: From Gene to Function
Authors: Vanlerberghe Greg C. , McIntosh Lee
Published: July 2002

▪ Abstract  Plants, some fungi, and protists contain a cyanide-resistant, alternative mitochondrial respiratory pathway. This pathway branches at the ubiquinone pool and consists of an alternative oxidase encoded by the nuclear gene Aox1. Alternative pathway respiration is only linked to proton translocation at Complex 1 (NADH dehydrogenase). Alternative oxidase expression is influenced by stress stimuli—cold, oxidative stress, pathogen attack—and by factors constricting electron flow through the cytochrome pathway of respiration. Control is exerted at the levels of gene expression and in response to the availability of carbon and reducing potential. Posttranslational control involves reversible covalent modification of the alternative oxidase and activation by specific carbon metabolites. This dynamic system of coarse and fine control may function to balance upstream respiratory carbon metabolism and downstream electron transport when these coupled processes become imbalanced as a result of changes in the supply of, or demand for, carbon, reducing power, and ATP.
GENETIC CONTROL OF FLOWERING TIME IN ARABIDOPSIS
Authors: Koornneef Maarten , Alonso-Blanco Carlos , Peeters Anton J. M. , Soppe Wim
Published: July 2002

▪ Abstract  The timing of the transition from vegetative to reproductive development is of great fundamental and applied interest but is still poorly understood. Recently, molecular-genetic approaches have been used to dissect this process in Arabidopsis. The genetic variation present among a large number of mutants with an early- or late-flowering phenotype, affecting the control of both environmental and endogenous factors that influence the transition to flowering, is described. The genetic, molecular, and physiological analyses have led to identification of different components involved, such as elements of photoperception and the circadian rhythm. Furthermore, elements involved in the signal transduction pathways to flowering have been identified by the cloning of some floral induction genes and their target genes.
PHYTOREMEDIATION
Authors: Salt D. E. , Smith R. D. , Raskin I.
Published: July 2002

▪ Abstract  Contaminated soils and waters pose a major environmental and human health problem, which may be partially solved by the emerging phytoremediation technology. This cost-effective plant-based approach to remediation takes advantage of the remarkable ability of plants to concentrate elements and compounds from the environment and to metabolize various molecules in their tissues. Toxic heavy metals and organic pollutants are the major targets for phytoremediation. In recent years, knowledge of the physiological and molecular mechanisms of phytoremediation began to emerge together with biological and engineering strategies designed to optimize and improve phytoremediation. In addition, several field trials confirmed the feasibility of using plants for environmental cleanup. This review concentrates on the most developed subsets of phytoremediation technology and on the biological mechanisms that make phytoremediation work.
MOLECULAR AND CELLULAR ASPECTS OF THE ARBUSCULAR MYCORRHIZAL SYMBIOSIS
Authors: Harrison Maria J.
Published: July 2002

▪ Abstract  Arbuscular mycorrhizae are symbiotic associations formed between a wide range of plant species including angiosperms, gymnosperms, pteridophytes, and some bryophytes, and a limited range of fungi belonging to a single order, the Glomales. The symbiosis develops in the plant roots where the fungus colonizes the apoplast and cells of the cortex to access carbon supplied by the plant. The fungal contribution to the symbiosis is complex, but a major aspect includes the transfer of mineral nutrients, particularly phosphate from the soil to the plant. Development of this highly compatible association requires the coordinate molecular and cellular differentiation of both symbionts to form specialized interfaces over which bi-directional nutrient transfer occurs. Recent insights into the molecular events underlying these aspects of the symbiosis are discussed.
HOWGIBBERELLINREGULATESPLANTGROWTH ANDDEVELOPMENT: A Molecular Genetic Analysis of Gibberellin Signaling
Authors: Richards Donald E , King Kathryn E , Ait-ali Tahar , Harberd Nicholas P
Published: July 2002

▪ Abstract  Gibberellins are hormones that control growth and a wide variety of other plant developmental processes. In recent years, significant progress has been made on the biochemistry of gibberellin biosynthesis and on the mechanisms by which gibberellin levels are regulated in plants. There have also been major advances in the understanding of gibberellin signaling, with several key genes being cloned. This review discusses our current understanding of gibberellin signaling, as seen from the perspective of molecular genetic analysis, and relates these observations to previous biochemical studies. In particular, we highlight an important conclusion of recent years: that GAI/RGA and orthologs play major roles in gibberellin signaling in diverse plant species, and that gibberellin probably stimulates growth by derepression of GAI/RGA.
THECOHESION-TENSIONMECHANISM AND THEACQUISITION OFWATER BYPLANTROOTS
Authors: Steudle Ernst
Published: July 2002

▪ Abstract  The physical basis and evidence in support of the cohesion-tension theory of the ascent of sap in plants are reviewed. The focus is on the recent discussion of challenges to the cohesion-tension mechanism based on measurements with the pressure probe. Limitations of pressure probes to measure tensions (negative pressures) in intact transpiring plants are critically assessed. The possible role of the cohesion-tension mechanism during the acquisition of water and solutes by plant roots is discussed.
CYTOKININMETABOLISM ANDACTION
Authors: Mok David WS , Mok Machteld C
Published: July 2002

▪ Abstract  Cytokinins are structurally diverse and biologically versatile. The chemistry and physiology of cytokinin have been studied extensively, but the regulation of cytokinin biosynthesis, metabolism, and signal transduction is still largely undefined. Recent advances in cloning metabolic genes and identifying putative receptors portend more rapid progress based on molecular techniques. This review centers on cytokinin metabolism with connecting discussions on biosynthesis and signal transduction. Important findings are summarized with emphasis on metabolic enzymes and genes. Based on the information generated to date, implications and future research directions are presented.
GALACTIC MAGNETISM: Recent Developments and Perspectives
Authors: Beck Rainer , Brandenburg Axel , Moss David , Shukurov Anvar , Sokoloff Dmitry
Published: July 2002

▪ Abstract  We discuss current observational and theoretical knowledge of magnetic fields, especially the large-scale structure in the disks and halos of spiral galaxies. Among other topics, we consider the enhancement of global magnetic fields in the interarm regions, magnetic spiral arms, and representations as superpositions of azimuthal modes, emphasizing a number of unresolved questions. It is argued that a turbulent hydromagnetic dynamo of some kind and an inverse cascade of magnetic energy gives the most plausible explanation for the regular galactic magnetic fields. Primordial theory is found to be unsatisfactory, and fields of cosmological origin may not even be able to provide a seed field for a dynamo. Although dynamo theory has its own problems, the general form of the dynamo equations appears quite robust. Finally, detailed models of magnetic field generation in galaxies, allowing for factors such as spiral structure, starbursts, galactic winds, and fountains, are discussed and confronted with observations.
The Evolution of Rotating Stars
Authors: Maeder André , Meynet Georges
Published: July 2002

▪ Abstract  In this article we first review the main physical effects to be considered in the building of evolutionary models of rotating stars on the Upper Main-Sequence (MS). The internal rotation law evolves as a result of contraction and expansion, meridional circulation, diffusion processes, and mass loss. In turn, differential rotation and mixing exert a feedback on circulation and diffusion, so that a consistent treatment is necessary.

We review recent results on the evolution of internal rotation and the surface rotational velocities for stars on the Upper MS, for red giants, supergiants, and W-R stars. A fast rotation enhances the mass loss by stellar winds and, conversely, high mass loss removes a lot of angular momentum. The problem of the breakup or Ω-limit is critically examined in connection with the origin of Be and LBV stars. The effects of rotation on the tracks in the HR diagram, the lifetimes, the isochrones, the blue-to-red supergiant ratios, the formation of Wolf-Rayet stars, and the chemical abundances in massive stars as well as in red giants and AGB stars are reviewed in relation to recent observations for stars in the Galaxy and Magellanic Clouds. The effects of rotation on the final stages and on the chemical yields are examined, along with the constraints placed by the periods of pulsars. On the whole, this review points out that stellar evolution is not only a function of mass M and metallicity Z, but of angular velocity Ω as well.
Millisecond Oscillations in X-Ray Binaries
Authors: Klis M. van der
Published: July 2002

▪ Abstract  The first millisecond X-ray variability phenomena from accreting compact objects have recently been discovered with the Rossi X-ray Timing Explorer. Three new phenomena are observed from low-mass X-ray binaries containing low-magnetic-field neutron stars: millisecond pulsations, burst oscillations, and kilohertz quasi-periodic oscillations. Models for these new phenomena involve the neutron star spin and orbital motion close around the neutron star, and rely explicitly on our understanding of strong gravity and dense matter. I review the observations of these new neutron-star phenomena and some possibly related phenomena in black-hole candidates, and describe the attempts to use these observations to perform measurements of fundamental physical interest in these systems.