bluuebunny/crossref_metadata_2025 huggingface dataset:
From Noosphere to Theosphere: Cyclotrons, Cyberspace, and Teilhard's Vision of Cosmic Love
Authors: Shafer Ingrid H.
Published: March 2003

Two theme–setting quotations introduce this essay—that of Yeats's falcon, deaf to the falconer's call, adrift in space above the blood–dimmed tide, counterpoised to Pierre Teilhard de Chardin's call to abandon old nationalistic prejudices and build the earth. With primary references to the thought of Teilhard, along with, among others, to Ewert Cousins, Andrew M. Greeley, Karl Jaspers, Marshall McLuhan, Ilya Prigogine, Karl Rahner, Leonard Swidler, David Tracy, and Alfred North Whitehead, I argue that the most crucial intellectual paradigm shift of the twenty–first century will challenge humanity to take the turn from uncritical attachment to rigid absolutism or atomistic fragmentation toward a sense of open–ended, off–centered centeredness and fluid connections—from a static to a dynamic model of reality. Central to my argument is the Teilhardian reinterpretation of the Christian metaphors of creation, fall, incarnation, salvation, and the eschaton in the evolutionary terms of the emergence of cosmic consciousness from the chrysalis of the world of the past—from chaos to order, from biosphere via noosphere to theosphere. Facilitated by the exponential growth of populations, collaborative research, science, technology, and global communication (most dramatically manifested by the Internet), this emergent understanding of what it means to be human can, first, foster the awareness that in humanity evolution has become conscious of itself, and then, gradually, precipitate the formation of “the global village” (the mystical body of Christ), as respectful dialogue replaces diatribe and the dualistic pugilism of Samuel Huntington's “Clash of Civilizations” is gradually transformed into a nonadversarial mentality that values shared humanity and a common purpose. Thus, eons hence, empowered by love–energy, the transmutation of the human into the ultra–human can take the ultimate quantum leap into a yet higher dimension where spirit/energy is no longer in need of flesh/mass, and Earth can be safely left behind.
Albert Einstein and Bernard Lonergan on Empirical Method
Authors: Teevan Donna
Published: March 2003

In the science–and–theology dialogue, it becomes imperative that theologians develop sophistication in empirical method. Albert Einstein stated that to understand what physicists do we should not listen to what they say but watch what they do. Still, he wrote incisively about method in physics. Theologian and philosopher Bernard Lonergan developed a methodical approach to theology that was influenced by the natural sciences. I present Einstein's thought on epistemology and the relationship between sense experience and theory. I then turn to Lonergan's understanding of empirical method in the natural sciences, generalized empirical method, and his treatment of Einstein's work.
Laboratory Ritual: Experimentation and the Advancement of Science
Authors: Geraci Robert M.
Published: March 2003

Technical achievement in laboratories requires millennia–old ritual formulations; the methodological expectations and presuppositions of scientists stem not only from investigations of the last three centuries but also from the ritual knowledge making that has governed human religion. Laboratory research is a form of human ritual open to interpretation in the manner of religious ritual. The experiments of the laboratory are fact–gathering ventures, but the integration of that knowledge into our general understanding of a universe of information networks is the process of knowledge making, and it is the highest achievement of all rituals, be they religious or scientific. Ritual theory offers insight into the nature of scientific experimentation.
The Anthropic Principle: Life in the Universe
Authors: Sharpe Kevin , Walgate Jonathan
Published: March 2003

The anthropic principle, that the universe exists in some sense for life, has persisted in recent religious and scientific thought because it derives from cosmological fact. It has been unsuccessful in furthering our understanding of the world because its advocates tend to impose final metaphysical solutions onto what is a physical problem. We begin by outlining the weak and strong versions of the anthropic principle and reviewing the discoveries that have led to their formulation. We present the reasons some have given for ignoring the anthropic implications of these discoveries and find these reasons wanting—a real phenomenon demands real investigation. Theological and scientific solutions of the problem are then considered and criticized; these solutions provide dead ends for explanation. Finally, we pursue the path that explanation must follow and look at the physical details of the problem. It seems clear that the anthropic principle has been poorly framed. Removing the ambiguities surrounding the meaning of “life” may lead to more profitable investigations.
The Body as the Ground of Religion, Science, and Self
Authors: Kovach Judith
Published: March 2003

The human body is both religious subject and scientific object, the manifest locus of both religious gnosis and secular cognition. Embodiment provides the basis for a rich cross–fertilization between cognitive science and comparative religion, but cognitive studies must return to their empiricist scientific roots by reembodying subjectivity, thus spanning the natural bridge between the two fields. Referencing the ritual centrality and cognitive content of the body, I suggest a materialist but nonreductionist construct of the self as a substantial cognitive embodiment that embraces not just perception and cognition, mind and spirit, but the forceful physicality of the moving body. Proprioception of the body's moving mass constitutes a mode of knowing that resonates strongly with the experience of self, not only across religious traditions but also within the physical sciences. By way of illustration, two directions are suggested in which a construct of the self as a substantial cognitive embodiment might lead us: first, a body–based interpretation of the Islamic myth of Adam and Iblis that reveals an internal substantiality as constitutive of the divinely imaged Self, and second, a new, religious direction for human evolutionary theory based on the implications of an embodied intentionality.
Quantum Mechanics and “Song of Myself”: Getting a Grip on Reality
Authors: Schaible Robert M.
Published: March 2003

Most recent writing linking science and literature has concerned itself with challenges to the epistemological status of scientific knowledge in an attempt to demonstrate its contingency, arguing in the more radical efforts that the structures of science are no more than useful fictions. This essay also includes an epistemological comparison between science and literature, but instead of making grand or meta–statements about the nature of knowing generally in the two fields, mine is a much narrower aim. My exploration entails two tasks. First, I provide a close–up look at a particular type of experiment, called the delayed–choice experiment, which clearly reveals the strangeness of the quantum world. In connection with this experiment, I discuss wave functions—mathematical expressions used by physicists to describe quantum behavior and predict the outcome of experiments involving quanta. Second, I look at Walt Whitman's “Song of Myself” focusing on the meaning of the “self” in the poem. My aim is to treat the object of study in each field as a “text” and to assert and demonstrate a parallel in the strategies of thought and response between physicists (“readers”) pondering the meaning and status of a wave function and poem readers pondering the meaning and status of the poem's self. In Whitman's “Song” we find an attempt to understand complex aspects of human experience that are said to transcend ordinary reality, an effort for which I believe there are parallels in the attempts of modern physicists to understand complex, nonintuitive aspects of the subatomic world. While not making the kind of broad claims eschewed above, I do suggest that this focused study has interesting implications since both the wave function and the poem's self force their respective sets of “readers” to confront questions of ultimacy—to consider, that is, epistemological and ontological issues of more than passing interest to students of science as well as those of metaphysics and theology.
Negotiating The Boundaries of Science and Religion: The Conversion of Allan Sandage
Authors: Durbin William A.
Published: March 2003

In the early 1950s, astronomer Allan Sandage inherited from Edwin Hubble the task of determining whether expansion was real. In the succeeding forty years, Sandage “established the discipline of observational cosmology” (Overbye 1991, 188). At the same time, he encountered the limits of science to address the full mystery of existence. In seeking an answer to the question of purpose, in particular, Sandage came to the “abyss of reason” and made the “leap of faith.” This conversion, however, involved, and continues to involve, an ongoing process of balancing two avenues to the truth, drawing upon resources from both scientific and religious traditions. Reason and faith seem reconcilable in life lived as an experiment and in “bowing before the mystery” (Sandage 1990). Ultimately, Sandage suggests that religious conversion comes not so much through reasoned pursuit as in the realization of being pursued.
Biohistorical Naturalism and The Symbol “God”
Authors: Kaufman Gordon D.
Published: March 2003

This article has two parts, as the title suggests. The first sketches what I call biohistorical naturalism, a naturalistic position in which it is emphasized that the historicocultural development of our humanity, particularly our becoming linguistic/symbolical beings, is as central to our humanness as the biological evolutionary development that preceded (and continues to accompany) it. Apart from such a biohistorical emphasis (or its equivalent), naturalistic positions cannot give adequate accounts of human religiousness. The second part suggests that, although it would not be consistent with biohistorical naturalism to continue thinking of God in the traditional supernaturalistic way as “the Creator,” it would be quite appropriate to understand God as the ongoing creativity (of truly novel realities) manifest in the long history of the universe, particularly in the evolution of life on Earth.
Religious Naturalism and Naturalizing Morality
Authors: Goodenough Ursula
Published: March 2003

I first offer some reflections on the term religious naturalism. I then outline how moral thought might be configured in the context of religious naturalism. It is proposed that the goal of morality is to generate a flourishing community and that humans negotiate their social interactions using moral capacities that are cultivated in the context of culture. Six such capacities are considered: strategic reciprocity, humaneness, fair–mindedness, courage, reverence, and mindfulness. Moral capacities are contrasted with moral susceptibilities, fueled by self–interest, and brought to the fore in times of stress and humiliation. The essay is in two parts. I first respond to Jerome Stone's query as to the nature of religious naturalism. This is followed by the text of my presentation at the 2001 AAR meeting.
Naturism as a Form of Religious Naturalism
Authors: Crosby Donald A.
Published: March 2003

The version of religious naturalism sketched here is called naturism to distinguish it from conceptions of religious naturalism that make fundamental appeal to some idea of deity, deities, or the divine, however immanental, functional, nonontological, or purely valuational or existential such notions may be claimed to be. The focus of naturism is on nature itself as both metaphysically and religiously ultimate. Nature is sacred in its own right, not because of its derivation from some more–ultimate religious principle, state, being, beings, or order of being. Humans, their cultures, and their histories are conceived as integral parts of nature, manifestations of potentialities that lie within it and have been actualized by biological evolution. While there is no purpose of nature, the natural order contains beings capable of purposive behavior. With this purposive behavior, and the goals and ideals implicit in it, humans have the capacity to give significant direction to their ongoing cultural evolution and to discover and maintain their appropriate place within the community of creatures.
The Prospect of a Global Ethic on HIV/AIDS: The Religions and the Science–and–Religion Dialogue
Authors: Moore James F.
Published: March 2003

This article introduces essays from a 2001 symposium on a global ethic and the issue of the spread of HIV/AIDS. The symposium began with the assumption that we can determine the possibility for such a global ethic if we both explore the potential of an interreligious dialogue and do so in the context of a science–and–religion dialogue. I argue that while the possibilities for a global ethic, in particular addressing the issue of HIV/AIDS, may be debated, the results of this symposium suggest that the dialogue ought to be continued and that there is significant potential in the interfaith dialogue for creating models for both an ethic and specific strategies for action.
Ethics of Globalization and the AIDS Crisis from a Jewish Perspective
Authors: Samuelson Norbert M.
Published: March 2003

This essay explores what Jewish ethics has to say about globalization in relation to the AIDS crisis. Special attention is paid to the consequences in affirming current intellectual trends to transcend traditional limits in both society and thought for rethinking traditional Jewish values. The discussion proceeds from two presuppositions. The first is that there is an intimate connection between ethics, science, and politics. The second is that the history of Jewish ethics involves three distinct forms that are generally correlated but rarely identical in content and moral judgment. These three forms are law, wisdom or virtue, and covenant. The discussion considers related issues of accidental connections in time between the bubonic plague and Zionism and between AIDS and homosexuality in relation to moral–theological issues related to divine providence and distributive justice.
Some Hindu Insights on a Global Ethic in the Context of Diseases and Epidemics
Authors: Raman Varadaraja V.
Published: March 2003

As we develop a global ethic in the context of diseases, we need to reconsider the wisdom of the religious traditions, for there is more to ailments than their material causes. In the Hindu framework, aside from the Ayurvedic system, which is based on herbal medicines and a philosophical framework, there is the insight that much of what we experience is a direct consequence of our karma (consequential actions). Therefore, here one emphasizes self–restraint and self–discipline in contexts that are conducive to self–hurting behavior.
Adaptive Tracking Control of Linear Uncertain Mechanical Systems Subjected to Unknown Sinusoidal Disturbances
Authors: Xian B. , Jalili N. , Dawson and D. M. , Fang Y.
Published: March 2003

The design and implementation of an adaptive disturbance rejection approach is presented for single-input-single-output linear-time-invariant uncertain mechanical systems subject to sinusoidal disturbances with unknown amplitudes and frequencies. The proposed technique suggests construction of a set of stabilizing tuning functions via a state estimate observer in a backstepping fashion to achieve asymptotic disturbance rejection. The tuning functions design is based on a single Lyapunov function incorporating both the error states and update law, and hence, global stability and improved transient performance are readily achieved. Utilizing only the system output, a virtual control input is used in place of non-measurable and unknown signals. The performance of the adaptation algorithm is demonstrated through both simulations and experiments for a single-degree-of-freedom system with unknown parameters and subject to an unknown sinusoidal disturbance. Significant matching between the simulation and experimental results is observed.
Combined Synthesis of State Estimator and Perturbation Observer
Authors: Kwon SangJoo , Chung Wan Kyun
Published: March 2003

A combined observer is synthesized by unifying the conventional linear state estimator and the perturbation observer to estimate plant uncertainties and disturbances. It enables robust state estimation for uncertain dynamical systems and simultaneously, provides full-state to the perturbation observer under output feedback conditions. The proposed combined observer is very practical since it is given as a recursive discrete-time form with minimal tuning parameters, and it requires no knowledge of the plant uncertainty. A coupled estimation error dynamics is derived, and the related technical issues such as stability and noise sensitivity are addressed. The combined observer setting is also extended to stochastic systems, and the discrete Kalman filter is reformulated by including the perturbation estimate update process. Numerical examples and experimental results validate the proposed schemes.
Robust Tracking Control of a Piezoactuator Using a New Approximate Hysteresis Model
Authors: Tsai Meng-Shiun , Chen Jin-Shin
Published: March 2003

A new approximate model, which consists of a variable gain and a variable time-delay, is proposed to describe the hysteresis behavior of a piezoactuator. The variable gain is assumed to be a function of the magnitude of the input command, while the time-delay is assumed to be a function of the frequency of the input command. The ranges of these two variable parameters are determined through open loop tests. According to the proposed approximate model, a Smith predictor-based robust H∞ controller is developed to achieve high-precision tracking control of a piezoactuator. Analytical simulation and experimental results on tracking several types of reference inputs demonstrate that the maximum tracking error can be reduced to be less than 2% of the traveling path by utilizing the proposed controller design.
Fuzzy Controller Design via the Inverse Solution of Lyapunov Equations
Authors: Chang Wen-Jer
Published: March 2003

In this paper, a fuzzy control design method is be developed for the plant model whose structure is represented by the Takagi-Sugeno fuzzy model. In each rule of the Takagi-Sugeno fuzzy model, the system is characterized by linear dynamics given in the controllability canonical form. Replacing the Lyapunov inequality with a Lyapunov equation for stability analysis, the proposed method will make use of the inverse solution of Lyapunov equations to obtain a common Lyapunov function for all the subsystems. Based on this solution, the fuzzy controller can be constructed by using the parallel distributed compensation technique.
A Simple Novel Approach to Active Vibration Isolation With Electrohydraulic Actuation*
Authors: Zhang Yisheng , Alleyne Andrew
Published: March 2003

This paper describes a novel reformulation of a classical active vibration isolation problem, explicitly accounting for the dynamics of the actuator. By utilizing a clever reformulation of the problem rather than the traditional approaches, a very difficult problem can be transformed into a relatively easy one. Subsequently, any reasonable loop closure methodology can be used to achieve the necessary performance. The traditional approaches usually consider a regulation problem, whereas the focus here will be on generating a tracking problem to achieve the same results: reduced transmission of vibration. Experimental results are included to demonstrate the effectiveness and advantages of the proposed problem representation.
Vibration Control of an ER Seat Suspension for a Commercial Vehicle
Authors: Choi S. B. , Choi J. H. , Lee Y. S. , Han M. S.
Published: March 2003

This paper presents a semi-active seat suspension with an electrorheological (ER) fluid damper. A cylindrical ER seat damper is devised on the basis of a Bingham model of an arabic gum-based ER fluid and its field-dependent damping characteristics are empirically evaluated. A semi-active seat suspension is then constructed, and the governing equations of motion are derived by treating the driver mass as a parameter uncertainty. A sliding mode controller, which has inherent robustness to system uncertainties, is formulated to attenuate seat vibration due to external excitations. The controller is then experimentally realized, and controlled responses are presented in both time and frequency domains. In addition, a full-car model consisting of primary, cabin, and seat suspensions is established, and a hardware-in-the-loop simulation is undertaken to demonstrate a practical feasibility of the proposed seat suspension system showing ride comfort quality under various road conditions.
Fuzzy-Chip-Based Control and Its Application to Adaptive Machining
Authors: Yao Xifan
Published: March 2003

The use of fuzzy chip to implement the control of machining processes is investigated. The hardware solution can process rules in fuzzy controllers at high speed. In this paper, fuzzy-chip-based regular and self-tuning controllers are developed to maintain a constant cutting force during machining processes under time-varying cutting conditions. In the fuzzy-chip-based self-tuning controller, two knowledge bases are employed. One base is used to implement the inference of control rules and the other to execute tuning rules for adjusting the output scaling factor on line. The structure makes the proposed fuzzy-chip-based self-tuning controller different from those fuzzy adaptive controllers developed in machining. Those fuzzy-chip-based controllers are characterized by the simple structure and practical applicability for real-time implementation. Both simulation and experimental results on machining processes show that the fuzzy-chip-based controllers demonstrate feasibility, applicability, and adaptability.
Nonfragile H∞ Output Feedback Controller Design for Linear Systems*
Authors: Yang Guang-Hong , Wang Jian Liang
Published: March 2003

This paper is concerned with the nonfragile H∞ controller design problem for linear time-invariant systems. The controller to be designed is assumed to have norm-bounded uncertainties. Design methods are presented for dynamic output (measurement) feedback. The designed controllers with uncertainty (i.e. nonfragile controllers) are such that the closed-loop system is quadratically stable and has an H∞ disturbance attenuation bound. Furthermore, these robust controllers degenerate to the standard H∞ output feedback control designs, when the controller uncertainties are set to zero.
On Optimal Filtering for Polynomial System States
Authors: Basin Michael V.
Published: March 2003

The paper presents the optimal nonlinear filter for quadratic state and linear observation equations confused with white Gaussian disturbances. The general scheme for obtaining the optimal filter in case of polynomial state and linear observation equations is announced.
Harmonic Disturbance Observer for Nonlinear Systems
Authors: Chen Wen-Hua
Published: March 2003

A nonlinear harmonic disturbance observer for nonlinear systems subject to harmonics is designed and stability of the proposed observer is established using passivity approach. A systematic procedure to choose the nonlinear gain function in the observer is proposed. The proposed nonlinear disturbance observer can be integrated with a linear/nonlinear controller to improve its disturbance attenuation ability for nonlinear systems under harmonics.
Jerk Limited Time Optimal Control of Flexible Structures
Authors: Muenchhof Marco , Singh Tarunraj
Published: March 2003

This paper addresses the problem of designing jerk limited time-optimal control profiles for rest-to-rest maneuvers of flexible structures. The variation of the structure of the jerk profile as a function of the permissible jerk is studied. An optimal control problem is formulated which includes constraints to cancel the poles corresponding to the rigid body and flexible modes of the system and to satisfy the boundary conditions of the rest-to-rest maneuver. The proposed technique is illustrated on the benchmark Floating Oscillator problem where the jerk profile is parameterized as a bang-off-bang or bang-bang profile.
Analysis of Trans-Permanent Magnetic Systems
Authors: Silverberg Larry , Duval Luis
Published: March 2003

This paper develops a method of switching the states of permanent magnets through an on-board magnetization process. The resulting dynamic systems are referred to as trans-permanent magnetic systems. This paper first describes the governing equations needed for the analysis of trans-permanent magnetic systems. Then, the paper demonstrates their feasibility in an experiment. In doing so, this paper presents a method that has the potential of leading to new ultra-low-power designs for electromechanical devices.
On Feynman’s analysis of the geometry of Keplerian orbits
Authors: Kowen Michael , Mathur H.
Published: March 2003

A geometrical construction, introduced by Maxwell and Feynman to demonstrate that closed Keplerian orbits are elliptical, is adapted to show that open Keplerian orbits are hyperbolic or parabolic.
A comprehensive treatment of classical nucleation in a supercooled or superheated fluid
Authors: Gunther Leon
Published: March 2003

The transition of the metastable phase of a supercooled or a superheated fluid to the stable phase occurs by the nucleation of a small droplet or nucleus of the stable phase. The most likely shape of the nucleus is a sphere. Once the nucleus reaches a critical size, it is overwhelmingly probable for it to grow indefinitely, thus converting the entire metastable phase to the stable phase. Nucleation involves fluctuations of both the radius of the droplet as well as the internal pressure within the droplet. Previous treatments have taken into account one or the other, but not both of these fluctuations. We present a comprehensive treatment that includes both types of fluctuations simultaneously, and find that the barrier lies at a saddle point of the free energy of the nucleus in the two-dimensional space of the internal pressure and nucleus radius. Although previous treatments result in a barrier of the free energy with respect to the nuclear radius, with the barrier lying at the critical radius, we find a saddle point on a surface plot of the free energy with respect to the nuclear radius and the internal pressure. The saddle point lies at the critical radius and the pressure corresponding to mechanical equilibrium. Our results clarify the relation between the two types of fluctuations.
An introduction to signal extraction in interferometric gravitational wave detectors
Authors: Black Eric D. , Gutenkunst Ryan N.
Published: March 2003

In the very near future gravitational wave astronomy is expected to become a reality, giving us a completely new tool for exploring the universe around us. We provide an introduction to how interferometric gravitational wave detectors work, suitable for students entering the field and teachers who wish to cover the subject matter in an advanced undergraduate or beginning graduate level course.
Total time derivatives of operators in elementary quantum mechanics
Authors: Andrews Mark
Published: March 2003

The use of a total time derivative of operators, that depends on the time evolution of the wave function as well as on any intrinsic time dependence in the operators, simplifies the formal development of quantum mechanics and allows its development to more closely follow the corresponding development of classical mechanics. We illustrate the use of the total time derivative for a free particle, the linear potential, the harmonic oscillator, and the repulsive inverse square potential. In these cases, operators whose total time derivative is zero can be found and yield general properties of wave packets and several useful time-dependent solutions of Schrödinger’s equation, including the propagator.
Quantum interference experiments with large molecules
Authors: Nairz Olaf , Arndt Markus , Zeilinger Anton
Published: March 2003

Wave–particle duality is frequently the first topic students encounter in elementary quantum physics. Although this phenomenon has been demonstrated with photons, electrons, neutrons, and atoms, the dual quantum character of the famous double-slit experiment can be best explained with the largest and most classical objects, which are currently the fullerene molecules. The soccer-ball-shaped carbon cages C60 are large, massive, and appealing objects for which it is clear that they must behave like particles under ordinary circumstances. We present the results of a multislit diffraction experiment with such objects to demonstrate their wave nature. The experiment serves as the basis for a discussion of several quantum concepts such as coherence, randomness, complementarity, and wave–particle duality. In particular, the effect of longitudinal (spectral) coherence can be demonstrated by a direct comparison of interferograms obtained with a thermal beam and a velocity selected beam in close analogy to the usual two-slit experiments using light.
Heat loss and hypothermia in free diving: Estimation of survival time under water
Authors: Aguilella-Arzo Marcel , Alcaraz Antonio , Aguilella Vicente M.
Published: March 2003

The heat exchange between a diver and the colder surrounding water is analyzed on the basis of the fundamental equations of thermal transport. To estimate the decrease in the diver’s body temperature as a function of time, we discuss the complex interplay of several factors including the body heat production rate, the role of the diver’s wet suit, and the way different heat exchange mechanisms (conduction, convection, and radiation) contribute to thermal transport. This knowledge could be useful to prevent physiological disorders that occur when the human body temperature drops below 35 °C.
N
-coupled masses with resistive forces linear in velocity: Exact expression for the final system position
Authors: West J.
Published: March 2003

A system of N-coupled masses constrained to move in one dimension, where each mass is subject to dissipative forces linear in velocity, is investigated. A simple analytical expression is obtained for the final positions of those masses subject to the dissipative forces. The positions of these masses are determined by the initial momentum of the system, the initial positions of only those masses subject to dissipative forces, and the relative strengths of the dissipative forces. However, it is found that the final positions are independent of the details of the interaction forces, the initial energy of the system, and the initial position of any mass that is not subject to a linear resistive force. Furthermore, if the initial momentum of the system is zero, the results also are independent of the masses of the particles, and hence the mass of the system as a whole. The results obtained are analytic and simple in form, yet they apply to model systems involving components of fundamental interest in physics.
Flatness of the setting Sun
Authors: Néda Z. , Volkán-Kacsó S.
Published: March 2003

The flattened rim of the setting or rising Sun is a consequence of atmospheric refraction. We study the flatness as a function of the Sun’s inclination angle, the observation height, and the meteorological conditions characterized by pressure, temperature, and lapse rate using a standard model of the atmosphere. Numerical calculations are compared with simple observations. Extreme and unusual situations are revealed.
Dynamics of spear throwing
Authors: Baugh Richard A.
Published: March 2003

The spear thrower (atlatl) is a hunting weapon with very ancient origins. It is a lever that enables wrist rotation to make a substantial increase in the velocity of a thrown spear. A model for throwing a projectile with an atlatl is presented. This model is used to analyze the projectile velocity as a function of the dimensions, rigidity, and mass distribution of the atlatl and mass of the projectile. The model assumes that the throwing force and wrist torque are functions only of the horizontal position of the throwing hand and that the spear is sufficiently long that the atlatl applies only a horizontal force to the proximal end of the spear. The applied force and torque were derived from a high-speed video digitizer plus the known physical dimensions of the atlatl and spear.
Recent Trends in Arctic Surface, Cloud, and Radiation Properties from Space
Authors: Wang Xuanji , Key Jeffrey R.
Published: March 2003

Trends in satellite-derived cloud and surface properties for 1982 to 1999 show that the Arctic has warmed and become cloudier in spring and summer but has cooled and become less cloudy in winter. The increase in spring cloud amount radiatively balances changes in surface temperature and albedo, but during summer, fall, and winter, cloud forcing has tended toward increased cooling. This implies that, if seasonal cloud amounts were not changing, surface warming would be even greater than that observed. Strong correlations with the Arctic Oscillation indicate that the rise in surface temperature and changes in cloud amount are related to large-scale circulation rather than to local processes.
Timing of Atmospheric CO
2
and Antarctic Temperature Changes Across Termination III
Authors: Caillon Nicolas , Severinghaus Jeffrey P. , Jouzel Jean , Barnola Jean-Marc , Kang Jiancheng , Lipenkov Volodya Y.
Published: March 2003

The analysis of air bubbles from ice cores has yielded a precise record of atmospheric greenhouse gas concentrations, but the timing of changes in these gases with respect to temperature is not accurately known because of uncertainty in the gas age–ice age difference. We have measured the isotopic composition of argon in air bubbles in the Vostok core during Termination III (∼240,000 years before the present). This record most likely reflects the temperature and accumulation change, although the mechanism remains unclear. The sequence of events during Termination III suggests that the CO
2
increase lagged Antarctic deglacial warming by 800 ± 200 years and preceded the Northern Hemisphere deglaciation.
Dispelling the Myths--Biocatalysis in Industrial Synthesis
Authors: Schoemaker Hans E. , Mink Daniel , Wubbolts Marcel G.
Published: March 2003

Biocatalysis has emerged as an important tool in the industrial synthesis of bulk chemicals, pharmaceutical and agrochemical intermediates, active pharmaceuticals, and food ingredients. However, the number and diversity of the applications are modest, perhaps in part because of perceived or real limitations of biocatalysts, such as limited enzyme availability, substrate scope, and operational stability. Recent scientific breakthroughs in genomics, directed enzyme evolution, and the exploitation of biodiversity should help to overcome these limitations. As a result, we expect many new industrial applications of biocatalysis to be realized, from single-step enzymatic conversions to customized multistep microbial synthesis by means of metabolic pathway engineering.
Rapid Evolution of Egg Size in Captive Salmon
Authors: Heath Daniel D. , Heath John W. , Bryden Colleen A. , Johnson Rachel M. , Fox Charles W.
Published: March 2003

Captive breeding and release programs, widely used to supplement populations of declining species, minimize juvenile mortality to achieve rapid population growth. However, raising animals in benign environments may promote traits that are adaptive in captivity but maladaptive in nature. In chinook salmon, hatchery rearing relaxes natural selection favoring large eggs, allowing fecundity selection to drive exceptionally rapid evolution of small eggs. Trends toward small eggs are also evident in natural populations heavily supplemented by hatcheries, but not in minimally supplemented populations. Unintentional selection in captivity can lead to rapid changes in critical life-history traits that may reduce the success of supplementation or reintroduction programs.
Spread of HTLV-I Between Lymphocytes by Virus-Induced Polarization of the Cytoskeleton
Authors: Igakura Tadahiko , Stinchcombe Jane C. , Goon Peter K. C. , Taylor Graham P. , Weber Jonathan N. , Griffiths Gillian M. , Tanaka Yuetsu , Osame Mitsuhiro , Bangham Charles R. M.
Published: March 2003

Cell contact is required for efficient transmission of human T cell leukemia virus– type 1 (HTLV-I) between cells and between individuals, because naturally infected lymphocytes produce virtually no cell-free infectious HTLV-I particles. However, the mechanism of cell-to-cell spread of HTLV-I is not understood. We show here that cell contact rapidly induces polarization of the cytoskeleton of the infected cell to the cell-cell junction. HTLV-I core (Gag protein) complexes and the HTLV-I genome accumulate at the cell-cell junction and are then transferred to the uninfected cell. Other lymphotropic viruses, such as HIV-1, may similarly subvert normal T cell physiology to allow efficient propagation between cells.
Fielding Biology
Authors: Smocovitis Vassiliki Betty
Published: March 2003

Landscapes and Labscapes
Exploring the Lab-Field Border in Biology. Robert E. Kohler. University of Chicago Press, Chicago, 2002. 342 pp. $58, £41. ISBN 0-226-45009-0. Paper, $22, £15.50. ISBN 0-226-45010-4.

Kohler explores how researchers developed studies in fields and forests that allowed them to go beyond the simplifications required in laboratory work-practices that contributed to the creation of the disciplines of ecology and evolutionary biology.
Loss of
IGF2
Imprinting: A Potential Marker of Colorectal Cancer Risk
Authors: Cui Hengmi , Cruz-Correa Marcia , Giardiello Francis M. , Hutcheon David F. , Kafonek David R. , Brandenburg Sheri , Wu Yiqian , He Xiaobing , Powe Neil R. , Feinberg Andrew P.
Published: March 2003

Loss of imprinting (LOI), an epigenetic alteration affecting the insulin-like growth factor II gene (
IGF2
), is found in normal colonic mucosa of about 30% of colorectal cancer (CRC) patients, but it is found in only 10% of healthy individuals. In a pilot study to investigate the utility of LOI as a marker of CRC risk, we evaluated 172 patients at a colonoscopy clinic. The adjusted odds ratio for LOI in lymphocytes was 5.15 for patients with a positive family history [95% confidence interval (95% CI), 1.70 to 16.96; probability
P
= 0.002], 3.46 for patients with adenomas (95% CI, 1.14 to 11.37;
P
= 0.026), and 21.7 for patients with CRC (95% CI, 3.48 to 153.6;
P
= 0.0005). LOI can be assayed with a DNA-based blood test, and it may be a valuable predictive marker of an individual's risk for CRC.
Protein Insertion into the Mitochondrial Inner Membrane by a Twin-Pore Translocase
Authors: Rehling Peter , Model Kirstin , Brandner Katrin , Kovermann Peter , Sickmann Albert , Meyer Helmut E. , Kühlbrandt Werner , Wagner Richard , Truscott Kaye N. , Pfanner Nikolaus
Published: March 2003

The mitochondrial inner membrane imports numerous proteins that span it multiple times using the membrane potential Δψ as the only external energy source. We purified the protein insertion complex (TIM22 complex), a twin-pore translocase that mediated the insertion of precursor proteins in a three-step process. After the precursor is tethered to the translocase without losing energy from the Δψ, two energy-requiring steps were needed. First, Δψ acted on the precursor protein and promoted its docking in the translocase complex. Then, Δψ and an internal signal peptide together induced rapid gating transitions in one pore and closing of the other pore and drove membrane insertion to completion. Thus, protein insertion was driven by the coordinated action of a twin-pore complex in two voltage-dependent steps.
Meltwater Pulse 1A from Antarctica as a Trigger of the Bølling-Allerød Warm Interval
Authors: Weaver Andrew J. , Saenko Oleg A. , Clark Peter U. , Mitrovica Jerry X.
Published: March 2003

Meltwater pulse 1A (mwp-1A) was a prominent feature of the last deglaciation, which led to a sea-level rise of ∼20 meters in less than 500 years. Concurrent with mwp-1A was the onset of the Bølling-Allerød interstadial event (14,600 years before the present), which marked the termination of the last glacial period. Previous studies have been unable to reconcile a warm Northern Hemisphere with mwp-1A originating from the Laurentide or Fennoscandian ice sheets. With the use of a climate model of intermediate complexity, we demonstrate that with mwp-1A originating from the Antarctic Ice Sheet, consistent with recent sea-level fingerprinting inferences, the strength of North Atlantic Deep Water (NADW) formation increases, thereby warming the North Atlantic region and providing an explanation for the onset of the Bølling-Allerød warm interval. The established mode of active NADW formation is then able to respond to subsequent freshwater forcing from the Laurentide and Fennoscandian ice sheets, setting the stage for the Younger Dryas cold period.
Dissecting Temporal and Spatial Control of Cytokinesis with a Myosin II Inhibitor
Authors: Straight Aaron F. , Cheung Amy , Limouze John , Chen Irene , Westwood Nick J. , Sellers James R. , Mitchison Timothy J.
Published: March 2003

Completion of cell division during cytokinesis requires temporally and spatially regulated communication from the microtubule cytoskeleton to the actin cytoskeleton and the cell membrane. We identified a specific inhibitor of nonmuscle myosin II, blebbistatin, that inhibited contraction of the cleavage furrow without disrupting mitosis or contractile ring assembly. Using blebbistatin and other drugs, we showed that exit from the cytokinetic phase of the cell cycle depends on ubiquitin-mediated proteolysis. Continuous signals from microtubules are required to maintain the position of the cleavage furrow, and these signals control the localization of myosin II independently of other furrow components.
Homogeneous Catalysis--New Approaches to Catalyst Separation, Recovery, and Recycling
Authors: Cole-Hamilton David J.
Published: March 2003

Homogeneous catalysts have many attractive properties, such as high selectivities. However, many homogeneous catalytic systems cannot be commercialized because of difficulties associated with separating the products from the catalyst. Recent approaches to tackling this problem are reviewed and compared.
Catalytic Nanoarchitectures--the Importance of Nothing and the Unimportance of Periodicity
Authors: Rolison Debra R.
Published: March 2003

Heterogeneous catalysis has always been an inherently nanoscopic phenomenon with important technological and societal consequences for energy conversion and the production of chemicals. New opportunities for improved performance arise when the multifunctionality inherent in catalytic processes, including molecular transport of reactants and products, is rethought in light of architectures designed and fabricated from the appropriate nanoscale building blocks, including the use of “nothing” (void space) and deliberate disorder as design components. Architectures with all of the appropriate electrochemical and catalytic requirements, including large surface areas readily accessible to molecules, may now be assembled on the benchtop. Designing catalytic nanoarchitectures that depart from the hegemony of periodicity and order offers the promise of even higher activity.
Privileged Chiral Catalysts
Authors: Yoon Tehshik P. , Jacobsen Eric N.
Published: March 2003

One of the most active current areas of chemical research is centered on how to synthesize handed (chiral) compounds in a selective manner, rather than as mixtures of mirror-image forms (enantiomers) with different three-dimensional structures (stereochemistries). Nature points the way in this endeavor: different enantiomers of a given biomolecule can exhibit dramatically different biological activities, and enzymes have therefore evolved to catalyze reactions with exquisite selectivity for the formation of one enantiomeric form over the other. Drawing inspiration from these natural catalysts, chemists have developed a variety of synthetic small-molecule catalysts that can achieve levels of selectivity approaching, and in some cases matching, those observed in enzymatic reactions.
Tectonic evolution and significance of Silurian  Early Devonian hinterland-directed deformation in the internal Humber zone of the southern Quebec Appalachians
Authors: Castonguay Sébastien , Tremblay Alain
Published: March 2003

In the southern Quebec Appalachians, the early tectonic history of the Laurentian margin (Humber zone) comprises foreland-propagating, northwest-directed thrust faulting, nappe emplacement, and regional prograde metamorphism in response to the obduction of large ophiolitic nappes during the Taconian orogeny. In the internal Humber zone, this event is dated at 462 ± 3 Ma (late Middle Ordovician), which is interpreted to represent the timing of near-peak Taconian metamorphism. Superimposed hinterland-directed structures are accompanied by retrograde metamorphism and consist of back thrusts and normal faults, which respectively delimit the northwestern and southeastern limbs of the Sutton and Notre-Dame mountains anticlinoria, both salient structures of the internal Humber zone of southern Quebec. Geochronologic data on the timing of hinterland-directed deformation vary from 431 to 411 Ma. Two tectonic models are presented and discussed, which may account for the Silurian  Early Devonian evolution of the Laurentian margin: (1) back thrusting and syn- to post-compressional crustal extension in response to the tectonic wedging of basement-cored duplexes inducing delamination of supracrustal rocks; (2) tectonic exhumation of the internal Humber zone by extensional collapse. Evidence for Silurian  Early Devonian extensional tectonism in the Humber zone provides the basement infrastructures necessary for the creation and the onset of sedimentation in the Gaspé Belt basins (e.g., Connecticut Valley  Gaspé synclinorium). Several structural, metamorphic features in the internal Humber zone of the northwestern New England Appalachians yield analogous characteristics with those of southern Quebec and may have shared a similar Silurian  Early Devonian tectonic evolution.
Structural analysis of supracrustal faults in the Charlevoix area, Quebec: relation to impact cratering and the St-Laurent fault system
Authors: Lemieux Yvon , Tremblay Alain , Lavoie Denis
Published: March 2003

The Charlevoix area, which is host to an impact structure of Devonian age, straddles the boundaries among crystalline rocks of the Grenville Province, the CambrianOrdovician sedimentary succession of the St. Lawrence Platform, and accreted units of the Appalachian orogen. The area features well-developed supracrustal fault systems attributed to impact cratering. A major fault system oriented from northeast to northwest consists of normal faults marked by cataclastic and gouge breccias and, less frequently, by pseudotachylyte. Detailed mapping of faults both within and outside the Charlevoix impact crater suggests that brittle faulting occurred both before and after impact cratering. Polymictic fault breccias occurring along some supracrustal faults are the clearest evidence of impact-related fault rocks in the Charlevoix area. The St-Laurent fault, trending to the northeast, represents a major structure interpreted as being related to Late Proterozoic  early Paleozoic rifting of the Iapetus Ocean. However, the St-Laurent fault crosses the Charlevoix impact crater without major deflection, suggesting post-impact reactivation. The fault systems in the Charlevoix area are interpreted to be pre-impact structures related to the opening of the Iapetus Ocean, most of which have also been reactivated during the Devonian cratering event and in post-impact time, the latter most likely coeval with the Atlantic Ocean rifting in Mesozoic time.