bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of an organizational interface: the new business department at a largeinsurance firm
Authors: Clement Andrew , Gotlieb C. C.
Published: July 2002

This paper describes how the work organization and computer system of the New Business Department at a large life insurance firm have interacted and evolved over time. The dynamics of interaction are explained largely in terms of the economic incentive to reduce the length of transaction-processing chains and the more political goal of extending managerial control. It is argued that examining the interaction of organizations and computer systems can contribute to a better theoretical understanding of the development of large computer systems and offer guidance to designers of user-computer interfaces. A graphical technique for depicting organizational interfaces is presented.
Practical in-place merging
Authors: Huang Bing-Chao , Langston Michael A.
Published: July 2002

We present a novel, yet straightforward linear-time algorithm for merging two sorted lists in a fixed amount of additional space. Constant of proportionality estimates and empirical testing reveal that this procedure is reasonably competitive with merge routines free to squander unbounded additional memory, making it particularly attractive whenever space is a critical resource.
Cost/benefit analysis for incorporating human factors in the software lifecycle
Authors: Mantei Marilyn M. , Teorey Toby J.
Published: July 2002

New software engineering techniques and the necessity to improve the user interface in increasingly interactive software environments have led to a change in traditional software development methods. Methodologies for improvement of the interface design, an overview of the human factors element, and cost/benefit aspects are explored.
Stating security requirements with tolerable sets
Authors: Johnson Dale M. , Thayer F. Javier
Published: July 2002

This paper introduces and develops the concept of tolerable sets for analyzing general security requirements. Tolerable sets, and corresponding purging functions and invisibility based on the sets, are used to state and test such requirements. The approach used in this paper resulted from our attempt to apply the noninterference ideas of Goguen and Meseguer to the problem of stating special security requirements in the case of so-called trusted subjects. It turns out that the conditional purging function defined by Goguen and Meseguer is only one example, though an important one, of a conditional purging function. This paper provides a definition and characterization of a general class of purging functions similar to the purging function of Goguen and Meseguer. Furthermore, it relates purging and invisibility to security requirements. Some particular applications are described toward the end of the paper. At the end there are some critical remarks about purging functions.
Discovering the secrets of DNA
Authors: Friedland Peter , Kedes Laurence H.
Published: July 2002

Sophisticated software tools are becoming increasingly important in helping biologists understand how nature operates. Symbolic pattern-recognition and artificial-intelligence methodologies are contributing to the development of such software.
Internet Publishing and Transformation of Knowledge Processes
Authors: Zhao J. Leon , Resh Vincent H.
Published: July 2002

Surveying the transition from conventional to Internet-based publishing mechanisms.
Collaborative Shape Conceptualization in Virtual Design Environments
Authors: Horváth Imre , Rusák Zoltán
Published: July 2002

Vague discrete modeling is a flexible and adaptable means for designers to express and shape ideas in a collaborative environment.
Constructive approaches to internet recreation in the workplace
Authors: Oravec Jo Ann
Published: July 2002

"Banana Time" takes on new dimensions when it comes to the Internet.
Monitoring for pornography and sexual harassment
Authors: Panko Raymond R. , Beh Hazel Glenn
Published: July 2002

The legal basis for workplace surveillance when dealing with two particular Internet abuses.
Is AI abstract and impractical? isn't the answer obvious?
Authors: Kaczmarczyk Lisa C.
Published: July 2002

Musings Inspired by Sun, Lemonade, and Lost Students
Optimal time borrowing analysis and timing budgeting optimization for latch-based designs
Authors: Lin Shi-Zheng Eric , Changfan Chieh , Hsu Yu-Chin , Tsai Fur-Shing
Published: July 2002

An interesting property of a latch-based design is that the combinational path delay is allowed to be longer than the clock cycle as long as it can "borrow" time from the shorter paths in the subsequent logic stages. This gives designers a lot of flexibility in designing circuits, especially high performance ones. However, it also increases the complexity in timing analysis. Finding the best clock period or determining how much time to borrow from the subsequent logic stages is difficult especially for designs containing multiple clocks, mixed-clock paths, user-specified multicycle paths, and false paths. In this article, we formulate the time borrowing problem as a linear programming problem. An optimal time borrowing solution can be found by solving the formulation. Based on this time borrowing solver, algorithms are proposed for timing optimization to achieve the optimal clock period. Experimental results show our algorithm is efficient and yields very good results.
University of British Columbia
Authors: Fisher Brian
Published: July 2002

The University of British Columbia
is the largest university in western Canada, with an enrollment of 35,000 students and offerings of both undergraduate and graduate degrees. An interdisciplinary HCI institute supports HCI teaching and research and is coordinating a proposed interdisciplinary master of science degree in HCI. A new downtown campus will offer a range of educational options in HCI, from executive certificates through master's-level programs.
Wichita State University
Authors: Halcomb Charles G. , Chaparro Barbara S.
Published: July 2002

The WSU Human Factors doctoral program is one of two graduate programs offered by the Department of Psychology at
Wichita State University
. Although the program is offered through the psychology department in the College of Liberal Arts and Sciences, students take elective courses from departments as diverse as Industrial Engineering, Management Information Systems, Computer Science, Exercise Science, and Marketing, contributing an interdisciplinary flavor to the program.
Lycos Europe
Authors: Jonason Jens
Published: July 2002

Spray Labs is one of three software development organizations within Lycos Europe, a major European network of Web portals. Spray Labs is located in Stockholm, Sweden, and specializes in building communities, mobile services, and games.
Oracle
Authors: Ashley Jeremy , Desmond Kristin
Published: July 2002

Oracle
is the market leader in database sales and the world's second largest software maker. In addition, Oracle creates industry award-winning, Web-based corporate applications, business intelligence tools, server management tools, and development tools.
Siemens AG
Authors: Schoen Stefan , Degen Helmut , Aykin Nuray , Rudorfer Arnold , Yuan Xiaowei
Published: July 2002

SIEMENS
is one of the leading global electrical- and electronic-engineering companies. It has offices in more than 190 countries and has 460,000 employees worldwide. SIEMENS's products and services range from information and communications, automation and control, power, transportation, medical, and lighting to semiconductors.
Moving beyond market-speak
Authors: Gerwig Kate
Published: July 2002

"Big hat, no cattle." It took a French global telecom analyst speaking American cowboy to perfectly sum up how imperfect service providers are at giving business customers telecommunications services and solutions that help improve their businesses. Unfortunately, I couldn't agree more---lots of talk, but where's the beef?
User interface design from a real time perspective
Authors: Kuo Feng-Yang , Karimi Jahangir
Published: July 2002

Using a data flow diagram (DFD) to represent the functional requirements of a system to be developed, an analysis of a real-time perspective is augmented to generate user interface specifications. By applying a set of heuristics, these specifications facilitate the design of three user interface styles: question/answer, menu/form, and command language.
Exact solution of general integer systems of linear equations
Authors: Springer Jörn
Published: July 2002

Methods are known for the exact computation of the solution of integer systems of linear equations
AX
=
B
with a nonsingular coefficient matrix
A
by congruence techniques. These methods are now generalized for systems with an arbitrary integer coefficient matrix
A
. To make congruence techniques applicable, a common denominator of all elements of the solution
X
=
A
+
B
must be computed. This is achieved by defining the natural denominator CODE of
A
+
and describing it by some formulas. Methods for the exact computation of additional results (consistency, null space, solution of at most
R
nonzero elements), a recursive test to save computing time, and a comparison with some results from the literature are presented.
The human aspects of computing
Authors: Ledgard Henry
Published: July 2002

What makes computer users happy? Can systems help humans to use them? Does programming sharpen other thinking skills? Is computer anxiety important? Will programmers use Ada packages? How do students learn programming concepts? Are spelling correctors at their limits? When does the work load on a terminal get too heavy? Are instruction sets too large?

These nine questions define some important issues for those of us who study human factors—the ways hardware and software affect, and are affected by, their users. Although the major accomplishments in the field will always rest on careful inspiration, to some degree these questions can be resolved empirically.

Generally, empirical work falls into three broad categories:

Although not at all by choice, only the first two of these categories are represented in this collection.

As with most papers that are accepted and appear in print, the reviewers or editors have some special reason for liking a paper in the first place. This reason may not appear in the reviews of the paper, but it does capture some underlying point or principle deemed to be important.

Each of the articles in this special section is a short description of a study addressing one of the nine questions. The results of these studies do not always reinforce conventional wisdom. Some of the conclusions are provocative. I invite you to read the articles and to see whether you agree with their conclusions.
Data replicas in distributed information services
Authors: Gladney H. M.
Published: July 2002

In an information distribution network in which records are repeatedly read, it is cost-effective to keep read-only copies in work locations. This paper presents a method of updating replicas that need not be immediately synchronized with the source data or with each other. The method allows an arbitrary mapping from source records to replica records. It is fail-safe, maximizes workstation autonomy, and is well suited to a network with slow, unreliable, and/or expensive communications links.

The algorithm is a manipulation of queries, which are represented as short encodings. When a response is generated, we record which portion of the source database was used. Later, when the source data are updated, this information is used to identify obsolete replicas. For each workstation, the identity of obsolete replicas is saved until a workstation process asks for this information. This workstation process deletes each obsolete replica, and replaces it by an up-to-date version either promptly or the next time the application asks for this particular item. Throughout, queries are grouped so that the impact of each source update transaction takes effect atomically at each workstation.

Optimizations of the basic algorithm are outlined. These overlap change dissemination with user service, allow the mechanism to be hidden within the data delivery subsystem, and permit very large networks.
Rasterizing curves of constant width
Authors: Hobby John D.
Published: July 2002

This paper gives a fast, linear-time algorithm for generating high-quality pixel representations of curved lines. The results are similar to what is achieved by selecting a circle whose diameter is the desired line width, and turning on all pixels covered by the circle as it moves along the desired curve. However, the circle is replaced by a carefully chosen polygon whose deviations from the circle represent subpixel corrections designed to improve the aesthetic qualities of the rasterized curve. For nonsquare pixels, equally good results are obtained when an ellipse is used in place of the circle. The class of polygons involved is introduced, an algorithm for generating them is given, and how to construct the set of pixels covered when such a polygon moves along a curve is shown. The results are analyzed in terms of a mathematical model for the uniformity and accuracy of line width in the rasterized image.
An empirical study of computer capacity planning in Japan
Authors: Lam S. F.
Published: July 2002

Capacity planners in Japan rely heavily on intuitive and judgmental approaches in their computer capacity planning functions, even more so than their U.S. counterparts, according to the following survey. The emphasis in large Japanese firms on job rotations, lifetime employment, and extensive social and informal interaction among employees helps contribute to the effectiveness of these judgmental methods.
Variable precision exponential function
Authors: Hull T. E. , Abrham A.
Published: July 2002

The exponential function presented here returns a result which differs from

e
x

by less than one unit in the last place, for any representable value of
x
which is not too close to values for which

e
x

would overflow or underflow. (For values of
x
which are not within this range, an error condition is raised.)

It is a “variable precision” function in that it returns a
p
-digit approximation for a
p
-digit argument, for any
p
= 0 (
p
-digit means
p
-decimal-digit). The program and analysis are valid for all
p
= 0, but current implementations place a restriction on
p
.

The program is presented in a Pascal-like programming language called Numerical Turing which has special facilities for scientific computing, including precision control, directed roundings, and built-in functions for getting and setting exponents.
Using an architectural knowledge base to generate code for parallel computers
Authors: Terrano Anthony E. , Dunn Stanley M. , Peters Joseph E.
Published: July 2002

The authors present a reconfigurable compiler for distributed memory parallel computers that performs automatic program partitioning, mapping, and communication code generation under the guidance of directives supplied by the programmer.
Remark on algorithm 587
Authors: Dadurkevicius V.
Published: July 2002

The subroutine WNNLS of Algorithm 587 has exposed some shortcomings, especially in solving rank-deficient problems. They may lead to fatal errors and (or) false results. Five improvements are proposed. The effect of the changes is tested on four rank-deficient test problems. It is emphasized that the WNNLS still remains vulnerable to bad scaling of the problem.
Self-assessment procedure XVI: a self-assessment procedure dealing with computer organization and logic design
Authors: Langdon Glen G.
Published: July 2002

A self-assessment procedure dealing with computer organization and logic design
A unified analysis of batched searching of sequential and tree-structured files
Authors: Lang Sheau-Dong , Driscoll James R. , Jou Jiann H.
Published: July 2002

A direct and unified approach is used to analyze the efficiency of batched searching of sequential and tree-structured files. The analysis is applicable to arbitrary search distributions, and closed-form expressions are obtained for the expected batched searching cost and savings. In particular, we consider a search distribution satisfying Zipf's law for sequential files and four types of uniform (random) search distribution for sequential and tree-structured files. These results unify and extend earlier research on batched searching and estimating block accesses for database systems.
On local implicit approximation and its applications
Authors: Chuang J. H. , Hoffmann C. M.
Published: July 2002

A method is proposed for computing an implicit approximant at a point to a parametric curve or surface. The method works for both polynomially and rationally parameterized curves and surfaces and achieves an order of contact that can be prescribed. In the case of nonsingular curve points, the approximant must be irreducible, but in the surface case additional safeguards are incorporated into the algorithm to ensure irreducibility. The method also yields meaningful results at most singularities. In principle, the method is capable of exact implicitization and has a theoretical relationship with certain resultant-based elimination methods.
Council decision of July 26, 1988
Authors: Council of the European Communities CORPORATE
Published: July 2002

concerning the establishment of a plan of action for setting up an information services market (88/524/EEC)
Knot insertion for Beta-spline curves and surfaces
Authors: Joe Barry
Published: July 2002

Discrete Beta-splines arise when a Beta-spline curve is subdivided; that is, extra knots are inserted so that the curve is expressed in terms of a larger number of control vertices and Beta-splines. Their properties and an algorithm for their computation are given in “Discrete Beta-Splines” by Joe (
Computer Graphics
, vol.
21
, pp. 137-144). We prove a stronger version of one of these properties, from which a new algorithm for computing discrete Beta-splines is obtained. This algorithm can also be used to compute discrete B-splines. We give a comparison of operation counts for this algorithm versus other algorithms, and for two methods to compute the new control vertices of Beta-spline and B-spline curves and surfaces.
A two-dimensional view controller
Authors: Glassner Andrew S.
Published: July 2002

Description: Many two-dimensional graphics programs provide a user with a rectangular screen window for viewing a two-dimensional image. Common examples of this underlying “world” image include text, line, or shaded pictures, and plots of one- or two-dimensional functions. Typically the screen image cannot display the world image with a 1:1 ratio between screen units (pixels) and the smallest resolvable world units. Thus the screen image is typically scaled and panned across the world image. The scaling is often differential, i.e., different scaling factors are applied in X and Y. Suppose a user is viewing a function y = f(x) at a ratio of 1:1. Increasing the scale factor in X will bring more data into view, while retaining vertical amplitude; increasing the scale factor in Y will provide a finer view of the values of the function, while retaining the range plotted.

We have developed a compact control device which allows a user to continuously adjust the
aspect ratio
of the world data presented to the window. Our model is based on the projection of the window on the untouched world data. If the screen window is narrow and tall in the world data, then the world data will be expanded horizontally and compressed vertically when displayed on the screen (note that the window itself never changes size on the screen). Accompanying the aspect ratio selection is a zoom multiplier, which can uniformly grow or shrink the screen window's image in the world. We also include variable-speed scrolling controls. Scrolling and uniform zooming are decoupled from differential scaling. The advantage of our technique is that the user need not independently scale X and Y while searching for the proper scaling of data; although both may be adjusted individually, and may also be adjusted simultaneously in a coupled, single-position device. Thus a single-button input device (such as a mouse) is all that is needed to control any aspect of the display. The technique has the additional advantage of being nonmodal, so the user need not remember any state during operation.
Completeness of rewrite rules and rewrite strategies for FP
Authors: Halpern Joseph Y. , Williams John H. , Wimmers Edward L.
Published: July 2002

This paper treats languages whose operational semantics is given by a set of rewrite rules. For such languages, it is important to be able to determine that there are enough rules to be able to compute the correct meaning of all expressions, but not so many that the system of rules is inconsistent. A formal framework is developed in which to give a precise treatment of these completeness and soundness issues, which are then investigated in the context of an extended version of the functional programming language FP. The rewrite rules of FP are shown to be sound and complete with respect to three different notions of completeness. The latter half of the paper considers rewrite strategies. In order to implement a language based on rewrite rules, it does not suffice to know that there are “enough” rules in the language; a good strategy for determining the order in which to apply them is also needed. But what is “good”? Corresponding to each notion of completeness, there is a notion of a good rewrite strategy. These notions of goodness are examined and characterized, and examples of a number of natural good strategies are given. Although these results are presented in the context of FP, the techniques (some of which are nontrivial extensions of techniques first used in the context of λ-calculus) should apply well beyond the realm of FP rewriting systems.
Object subclass hierarchy in SQL: a simple approach
Authors: Kung Chenho
Published: July 2002

The object subclass hierarchy is a useful way of modeling property and behavior inheritance. It can be implemented on a relational DBMS using views.
The mutual exclusion problem has been solved
Authors: Lamport Leslie
Published: July 2002

“A common assumption underlying mutual exclusion algorithms in shared memory systems is that: b. A memory reference to an individual word is mutually exclusive.”
14-3-3 PROTEINS AND SIGNAL TRANSDUCTION
Authors: Ferl Robert J.
Published: July 2002

▪ Abstract  Perhaps in keeping with their enigmatic name, 14-3-3 proteins offer a seemingly bewildering array of opportunities for interaction with signal transduction pathways. In each organism there are many isoforms that can form both homo- and heterodimers, and many biochemical activities have been attributed to the 14-3-3 group. The potential for diversity—and also confusion—is high. The mammalian literature on 14-3-3 proteins provides an appropriate context to appreciate the potential roles of 14-3-3s in plant signal transduction pathways. In addition, functional and structural themes emerge when 14-3-3s are examined and compiled in ways that draw attention to their participation in protein phosphorylation and protein-protein interactions. These themes allow examination of plant 14-3-3s from two perspectives: the ways in which plant 14-3- 3s contribute to and extend ideas already described in animals, and the ways that plant 14-3-3s present unique contributions to the field. The crystal structure of an animal 14-3- 3 has been solved. When considered with the evolutionary stability of large segments of the 14-3-3 protein, the structure illuminates several aspects of 14-3-3 function. However, diversity in other regions of the 14-3-3s and their presence as multigene families offer many opportunities for cell-specific specialization of individual functions.
Control of Carpel and Fruit Development in Arabidopsis
Authors: Ferrándiz Cristina , Pelaz Soraya , Yanofsky Martin F.
Published: July 2002

▪ Abstract  The fruit is a highly specialized plant organ that occurs in diverse forms among the angiosperms. Fruits of Arabidopsis thaliana, which are typical of the >3000 species of Brassicaceae, develop from a gynoecium that consists of two fused carpels. The mature gynoecium of Arabidopsis is composed of an apical stigma, a short style, and a basal ovary that contains the developing ovules. After the ovules are fertilized, the fruit elongates and differentiates a number of distinct cell types, allowing for the successful maturation and the eventual dispersal of the seeds. Although the processes involved in carpel and fruit morphogenesis are not well understood, recent studies have identified a large number of mutants that display abnormal gynoecium and fruit development. The detailed phenotypic description of these mutants together with recent cloning of many of these genes has begun to shed light on this interesting and complex developmental process. Here we review the growing collection of Arabidopsis genes known to control the initiation and development of the gynoecium and resulting fruit.
The Process and Development of Image-Guided Procedures
Authors: Galloway Robert L.
Published: July 2002

▪ Abstract  Medical imaging has been used primarily for diagnosis. In the past 15 years there has been an emergence of the use of images for the guidance of therapy. This process requires three-dimensional localization devices, the ability to register medical images to physical space, and the ability to display position and trajectory on those images. This paper examines the development and state of the art in those processes.
SPATIO-TEMPORAL RESOLUTION OF EXOCYTOSIS FROM INDIVIDUAL CELLS
Authors: Travis Eric R. , Wightman R. Mark
Published: July 2002

▪ Abstract  Biophysical events involved in late stages of exocytosis occur at highly localized areas of cells on millisecond and submillisecond time scales. Thus, methodologies with high spatio-temporal resolution are required to achieve measurements at individual secretory cells. Much has been learned about the mechanisms and kinetics of vesicular release through analysis with the carbon fiber microelectrode techniques amperometry and cyclic voltammetry. Coupling of these techniques with other methods such as patch-clamp continues to reveal details of the secretion process. It is now clear that extrusion of the vesicular contents is a more complex process than previously believed. Vesicle-cell fusion, revealed by cell capacitance measurements, is temporally dissociated from secretion measured amperometrically. The stability imparted by interaction and association of vesicle contents at rest results in a rate-limiting extrusion process after full fusion. Furthermore, the presence of partial fusion events and the occurrence of nonquantized release have been revealed with electrochemical tools.
THERMODYNAMIC MODELS OF IGNEOUS PROCESSES
Authors: Ghiorso Mark S.
Published: July 2002

▪ Abstract  Thermodynamic modeling alone cannot uniquely characterize the evolution path (T-P-t path) of a magmatic system, because the assumption of reaction reversibility precludes recovery of the history of that evolution from the final state that is preserved in the rock record. Nevertheless, as a tool for discriminating possible scenarios for magma evolution, such models are informative. This point is illustrated with two examples: The first involves modeling equilibrium and fractional crystallization of midocean ridge basalts. Attention is focused on the variation of intensive parameters (like oxygen fugacity) and heat output with crystallization, and how the latter can impact fluid dynamical modeling. The second example illustrates modeling mantle metling during closed-system adiabatic ascent. Here thermodynamic modeling leads to quantitative predictions of melt productivity, which may be used to interpret melt generation rates and chemical characteristics of lavas produced from volcanic centers.
Dating the Time of Origin of Major Clades: Molecular Clocks and the Fossil Record
Authors: Smith Andrew B. , Peterson Kevin J.
Published: July 2002

▪ Abstract  Molecular and paleontological data provide independent means of estimating when groups of organisms evolved in the geological past, but neither approach can be considered straightforward. The single most fundamental obstacle to developing an accurate estimate of times of origination from gene sequence data is variation in rates of molecular evolution, both through time and among lineages. Although various techniques have been proposed to circumvent this problem, none unambiguously allow the components of time and rate to be separated. Furthermore, problems of establishing accurate calibration points, correctly rooted phylogenies, and accurate estimates of branch length remain formidable. Conversely, paleontological dates fix only the latest possible time of divergence, and so probabilistic methods are required to set a lower boundary on origination dates. Realistic confidence intervals that take preservational biases into account are only just becoming available.

Although molecular and paleontological approaches to dating often agree reasonably well, there are two notable areas of disagreement; when mammal and bird orders originated and when the major phyla originated. The discrepancy in dating bird/mammal ordinal origins probably reflects a global rock-record bias. Paleontological sampling in the Late Cretaceous is still too restricted geographically to draw any firm conclusions about the existence of a pre-Tertiary record for modern orders of bird or mammal from anywhere other than North America. Dating the time of origin of phyla is more complicated, and is confounded by both preservational biases and problems of molecular clock estimation.
DEMOGRAPHIC AND GENETIC MODELS IN CONSERVATION BIOLOGY: Applications and Perspectives for Tropical Rain Forest Tree Species
Authors: Alvarez-Buylla E. R. , García-Barrios R. , Lara-Moreno C. , Martínez-Ramos M.
Published: July 2002

▪ Abstract  We review deterministic and stochastic demographic models as well as classical population genetic models that have been applied to tropical rain forest tree species. We discuss their implications for conservation. The main conclusions of deterministic demographic models are the key importance of species' longevity in determining susceptibility of population growth rate to harvesting of individuals at different life-stages, the critical effect of patch dynamics, and the importance of density-dependent mechanisms at least for abundant species. Population viability analysis to predict extinction times of tropical rain forest tree species has only been performed for four tropical rain forest tree species using the simplest Lefkovitch matrix linear model. Results obtained are in accordance with results of simple stochastic models for nonstructured populations that have been solved analytically. Population genetic models have shown that tropical rain forest trees: (a) possess high levels of genetic diversity, (b) maintain greater proportions of genetic variation within than among populations, (c) are predominantly outcrossed, and (d) have high levels of gene flow. These results suggest that tropical tree species may not be in immediate danger of extinction from genetic factors if actual conditions are maintained. However, the impact of forest fragmentation is expected to be particularly strong for most tropical rain forest tree species due mainly to the high genetic load kept by their present population genetic structures. Recent theoretical demographic-genetic models for simple systems suggest that the fixation of new mildly detrimental mutations may be comparable in importance to environmental stochasticity, implying minimum viable populations as large as a few thousands. It is urgent to develop a model that integrates genetic and demographic factors, that enables evaluations of their relative importance in long-term persistence of tropical rain forest tree species.
OVERVIEW AND EVALUATION OF FUEL ETHANOL FROM CELLULOSIC BIOMASS: Technology, Economics, the Environment, and Policy
Authors: Lynd Lee R.
Published: July 2002

▪ Abstract  Ethanol is a high performance fuel in internal combustion engines. It is a liquid, which is advantageous in terms of storage, delivery, and infrastructural compatability. Ethanol burns relatively cleanly, especially as the amount of gasoline with which it is blended decreases. Evaporative and toxicity-weighted air toxics emissions are consistently lower for ethanol than for gasoline. It is likely that vehicles can be configured so that exhaust emissions of priority pollutants are very low for ethanol-burning engines, although the same can probably be said for most other fuels under consideration. Recent work suggests that ethanol may be more compatible with fuel cell—powered vehicles than has generally been assumed. Research and development—driven advances have clear potential to lower the price of cellulosic ethanol to a level competitive with bulk fuels. Process areas with particular potential for large cost reductions include biological processing (with consolidated bioprocessing particularly notable in this context), pretreatment, and incorporation of an advanced power cycle for cogeneration of electricity from process residues. The cellulosic ethanol fuel cycle has a high thermodynamic efficiency (useful energy/high heating value = from 50% to over 65% on a first law basis, depending on the configuration), and a decidedly positive net energy balance (ratio of useful energy output to energy input). Cellulosic ethanol is one of the most promising technogical options available to reduce transportation sector greenhouse gas emissions. It may well be possible to develop biomass-based energy on a very large scale in the United States with acceptable and in some cases positive environmental impacts. To do so will however require responsible management and increased understanding of relevant technological and natural systems. The potential biomass resource is large, but so is demand for transportation fuels as well as other uses. The following hypotheses are offered as tentative hypotheses pertaining to biomass supply and demand in the United States: There will probably not be enough suitable land available to meet transportation demand if total vehicle miles traveled increase relative to current levels, and vehicle efficiency and animal protein utilization are unchanged. There probably is enough suitable land to meet transportation demand, even given some increase in vehicle miles traveled, given large but probably possible increases in vehicle efficiency, or large but probably possible decreases in reliance on animal protein, or a combination of less aggressive changes in both of these factors. The policy debate concerning fuel ethanol has tended to ignore cellulosic ethanol. It is suggested that an appropriate policy objective is to foster a transition to cellulosic feedstocks at a pace such that opportunities for ethanol producers and the farmers that supply them are expanded rather than contracted.
COLONYDISPERSAL AND THEEVOLUTION OFQUEENMORPHOLOGY INSOCIALHYMENOPTERA
Authors: Peeters Christian , Ito Fuminori
Published: July 2002

▪ Abstract  Social Hymenoptera show two contrasting strategies of colony reproduction. A reproductive female can raise the first generation of brood alone (independent foundation), or a colony can divide into autonomous parts in which the reproductive female is helped by sterile relatives (fission, budding, swarming). In independent-founding ants, queens can histolize their flight muscles after dispersal; in many species, large flight muscles and metabolic reserves reduce or eliminate the need for risky foraging trips during the vulnerable solitary stage. Colony division is a derived strategy, and we review the selective pressures leading to its occurrence in the different social taxa. In various ants, fission coexists with independent foundation, and alate queens are retained. However, in ants exhibiting obligate fission (e.g. all army ants and many Ponerinae), queens are permanently wingless (ergatoid), or the queen caste is missing altogether. When reproductive females are flightless, dispersal distances and colonization ability are reduced, and there are extensive modifications in mating behavior and resource allocation. We focus on the characteristics of fission in the phylogenetically primitive ants Ponerinae in which both ergatoid queens and gamergates occur. The ground-living habits of ants have permitted extensive changes in the phenotypes of their reproductive females, unlike in wasps and bees.
QUANTITATIVE FLOW VISUALIZATION IN UNSEEDED FLOWS
Authors: Miles and Richard B. , Lempert Walter R.
Published: July 2002

▪ Abstract  The various tools for flow visualization have been significantly expanded over the past several years through the use of molecular scattering and molecular laser-induced fluorescence. These approaches have added the capability of sampling individual small volume elements within a flow, and by using cameras for detection, they are easily extended to sample lines and cross-sectional planes. This localized measurement capability means that these approaches can be made quantitative even in complex and/or unsteady flow fields. If the molecular species is naturally occurring, such as oxygen or nitrogen in air, then no seeding is required.

Furthermore, in these applications, images of the flow can be frozen in time by using a short pulse laser for illumination. The distribution of the molecules reflects the true physics of the flow, so even raw images taken in this manner give an immediate understanding of flow field properties. With proper calibration, the images can be further analyzed to yield quantitative information about the flow. In the case of flow tagging, the analysis gives velocity profiles when lines are written, and deformation, vorticity, and dilation with grid patterns. Molecular scattering can be used to give quantitative values of density, temperature, and two-dimensional velocity.

This paper presents three such molecular-based approaches: laser-induced fluorescence from oxygen, flow tagging by oxygen excitation, and Rayleigh scattering. These three approaches are chosen because all three can be used in naturally occurring air with no seeding. The raw data from each of these approaches gives an immediate appreciation of the flow structure and further analysis yields accurate values of velocity, temperature, and density. These approaches use readily available laser sources; however, they will be greatly enhanced with new source technologies that are currently under development.
MATURE T LYMPHOCYTE APOPTOSIS—Immune Regulation in a Dynamic and Unpredictable Antigenic Environment
Authors: Lenardo Michael , Chan Francis Ka-Ming , Hornung Felicita , McFarland Hugh , Siegel Richard , Wang Jin , Zheng Lixin
Published: July 2002

▪ Abstract  Apoptosis of mature T lymphocytes preserves peripheral homeostasis and tolerance by countering the profound changes in the number and types of T cells stimulated by diverse antigens. T cell apoptosis occurs in at least two major forms: antigen-driven and lymphokine withdrawal. These forms of death are controlled in response to local levels of IL-2 and antigen in a feedback mechanism termed propriocidal regulation. Active antigen-driven death is mediated by the expression of death cytokines such as FasL and TNF. These death cytokines engage specific receptors that assemble caspase-activating protein complexes. These signaling complexes tightly regulate cell death but are vulnerable to inherited defects. Passive lymphokine withdrawal death may result from the cytoplasmic activation of caspases that is regulated by mitochondria and the Bcl-2 protein. The human disease, Autoimmune Lymphoproliferative Syndrome (ALPS) is due to dominant-interfering mutations in the Fas/APO-1/CD95 receptor and other components of the death pathway. The study of ALPS patients reveals the necessity of apoptosis for preventing autoimmunity and allows the genetic investigation of apoptosis in humans. Immunological, cellular, and molecular evidence indicates that throughout the life of a T cell, apoptosis may be evoked in excessive, harmful, or useless clonotypes to preserve a healthy and balanced immune system.
THE CENTRAL EFFECTORS OF CELL DEATH IN THE IMMUNE SYSTEM
Authors: Rathmell Jeffrey C. , Thompson Craig B.
Published: July 2002

▪ Abstract  The immune system relies on cell death to maintain lymphoid homeostasis and avoid disease. Recent evidence has indicated that the caspase family of cysteine proteases is a central effector in apoptotic cell death and is absolutely responsible for many of the morphological features of apoptosis. Cell death, however, can occur through caspase-independent and caspase-dependent pathways. In the case of cells that are irreversibly neglected or damaged, death occurs even in the absence of caspase activity. In contrast, healthy cells require caspase activation to undergo cell death induced by surface receptors. This review summarizes the current understanding of these two pathways of cell death in the immune system.
MOLECULAR GENETICS OF HYPERTROPHIC CARDIOMYOPATHY
Authors: Marian, M.D A. J. , Roberts, M.D R.
Published: July 2002

▪ Abstract  Hypertrophic cardiomyopathy (HCM) is genetically and phenotypically a heterogeneous disease. Genes identified include the β myosin heavy chain gene (βMHC) on chromosome 14q1, the troponin T gene on chromosome 1q, and the α tropomyosin gene on chromosome 15q. In addition, a fourth locus is present on chromosome 11q11, but the gene remains to be identified. More than 35 missense mutations in the βMHC, 3 mutations in troponin T, and 2 mutations in α tropomyosin gene in HCM patients have been identified. Functional studies have shown that the mutant βMHC protein has impaired acto-myosin interaction and that expression of the mutant myosin disrupts the assembly of sarcomere in feline cardiocytes. Genotype-phenotype correlations of βMHC mutations have shown that mutations such as Arg403Gln, Arg453Cys, and Arg719Trp are associated with a high incidence of sudden cardiac death and a significantly decreased life expectancy, whereas mutations Gly256Glu and Leu908Val have a near-normal life span. Preclinical genetic diagnosis should help in genetic counseling and therapeutic stratification.
Circadian Programs in Cyanobacteria: Adaptiveness and Mechanism
Authors: Johnson Carl Hirschie , Golden Susan S.
Published: July 2002

▪ Abstract  At least one group of prokaryotes is known to have circadian regulation of cellular activities—the cyanobacteria. Their “biological clock” orchestrates cellular events to occur in an optimal temporal program, and it can keep track of circadian time even when the cells are dividing more rapidly than once per day. Growth competition experiments demonstrate that the fitness of cyanobacteria is enhanced when the circadian period matches the period of the environmental cycle. Three genes have been identified that specifically affect circadian phenotypes. These genes, kaiA, kaiB, and kaiC, are adjacent to each other on the chromosome, thus forming a clock gene cluster. The clock gene products appear to interact with each other and form an autoregulatory feedback loop.
STRUCTURE AND FUNCTION OF PANCREATIC LIPASE AND COLIPASE
Authors: Lowe Mark E.
Published: July 2002

▪ Abstract  Dietary fats are essential for life and good health. Efficient absorption of dietary fats is dependent on the action of pancreatic triglyceride lipase. In the last few years, large advances have been made in describing the structure and lipolytic mechanism of human pancreatic triglyceride lipase and of colipase, another pancreatic protein that interacts with pancreatic triglyceride lipase and that is required for lipase activity in the duodenum. This review discusses the advances made in protein structure and in understanding the relationships of structure to function of pancreatic triglyceride lipase and colipase.
Novel Effects of Nitric Oxide
Authors: Davis Karen L , Martin Emil , Turko Illarion V , Murad Ferid
Published: July 2002

Nitric oxide (NO), a simple free radical gas, elicits a surprisingly wide range of physiological and pathophysiological effects. NO interacts with soluble guanylate cyclase to evoke many of these effects. However, NO can also interact with molecular oxygen and superoxide radicals to produce reactive nitrogen species that can modify a number of macromolecules including proteins, lipids, and nucleic acids. NO can also interact directly with transition metals. Here, we have reviewed the non–3′,5′-cyclic-guanosine-monophosphate–mediated effects of NO including modifications of proteins, lipids, and nucleic acids.
ASPIRIN IN THE TREATMENT AND PREVENTION OF CARDIOVASCULAR DISEASE
Authors: Hennekens Charles H.
Published: July 2002

▪ Abstract  Aspirin irreversibly inhibits cyclooxygenase in platelets for their entire lifespan, raising the possibility of clinical benefits by decreasing risks of occlusive vascular events. In secondary prevention among patients with a wide range of prior occlusive vascular events, including myocardial infarction (MI), stroke, transient ischemic attacks (TIAs), as well as unstable and chronic stable angina, aspirin therapy is associated with a reduction in risks of subsequent MI, stroke, and vascular deaths. In acute MI, aspirin also confers clear benefits on subsequent MI, stroke, and vascular deaths. In primary prevention, the available randomized trial data, which to date are limited to men, indicate a clear reduction in risk of a first MI; the current data are inconclusive concerning aspirin's effect on stroke and total vascular mortality. A currently ongoing trial among 40,000 apparently healthy women will provide reliable data concerning the balance of benefits and risks of aspirin in primary prevention.
Internal Cardioversion of Chronic Atrial Fibrillation During Percutaneous Mitral Commissurotomy
Authors: Fan Katherine , Lee Kathy L. , Chow Wing-Hing , Chau Elaine , Lau Chu-Pak
Published: July 2002

Background

—

Mechanoelectrical feedback caused by atrial dilatation plays an important role in atrial fibrillation (AF). To test the hypothesis that remodeling is reversible by reducing atrial stretch, we investigated electrophysiological changes after a reduction of left atrial (LA) pressure in patients undergoing percutaneous balloon mitral commissurotomy (PBMC).

Methods and Results

—

In 22 patients with chronic AF who were undergoing PBMC for mitral stenosis, internal cardioversion was successful in 19 patients (86%). Twelve patients with sinus rhythm acted as controls. Mean LA pressure was significantly reduced after PBMC (18.5±5.9 mm Hg versus 10.2±4.1 mm Hg;
P
<0.001). The effective refractory period (ERP), conduction delay (CD), and the index of heterogeneity (CoV) of the ERP and CD were compared. Changes in LA pressure were only significantly correlated with AF vulnerability (
r
=0.7;
P
=0.02) and CoV of CD (
r
=0.3;
P
=0.03). There were no significant changes in ERP and CD immediately after PBMC in the AF group. However, the overall CoV of ERP was reduced in the AF group after PBMC. There were homogenous, although not significant, increases in regional ERP in the control group immediately after PBMC. Atrial CD and CoV of CD were significantly reduced after PBMC in the control group; this was most prominent within the regions of the LA.

Conclusions

—

AF vulnerability and CoV of CD correlated significantly with LA pressure. A homogenous increase in regional ERPs could be demonstrated in the control group after an immediate reduction of atrial stretch, whereas the recovery course of electrical remodeling was prolonged and heterogenous in the AF group. Regional conductions were irreversible in patients with preexisting AF.