bluuebunny/crossref_metadata_2025 huggingface dataset:
Offering Odds on Impact
Authors: Verschuur Gerrit L.
Published: November 2020

There is no doubt that the earth continues to be struck by objects from space. Most of the impactors are very tiny, such as those that produce common meteor trails, and major collisions no longer happen very often. But if a large object, a half kilometer across say, were to strike our planet, the consequences would be devastating. In 1989 an asteroid large enough to bring civilization to the brink of total destruction missed earth by 6 hours and this close encounter in itself should be enough to give us food for thought. There will be other close shaves in the years to come, but no one can predict just when or how close. Only time will tell. Fortunately there are several dedicated groups of astronomers around the world searching for near-earth asteroids (NEAs) in order to catalog their existence and figure orbits lest any should be on a collision course. As a result of their efforts, crucial data are being obtained that will allow the probability of impact to be more accurately estimated, even if only in a statistical sense. The best anyone can do, or will ever be able to do, is to offer odds on the chance of collisions. Odds on comet impact, in the form of estimates of the period between such events, have been published for two centuries. Each generation no doubt felt that the latest estimates were superior to those that went before. For example, in 1861 James Watson, in A Popular Treatise on Comets, said that “it has been found by actual calculation, from the theory of probabilities, that if the nucleus of a comet having a diameter equal to only one fourth part of that of the earth...the probability of receiving a shock from it, is only one in two hundred and eighty-one millions.” This estimate was also quoted by Thomas Dick in 1840 who, in turn, credited it to Francois Arago for calculating this around 1800.
The Search
Authors: Verschuur Gerrit L.
Published: November 2020

The earth orbits the sun in a veritable swarm of asteroids that have the nasty habit of occasionally slamming into the planet. To add to the potential danger, comets sometimes wander into the vicinity of the sun, break up, change course, and hang about posing a threat for up to tens of thousands of years. We don’t really want to be hit by any of these, so what can we do to avoid the blows? Most important, we have to keep our collective, astronomical eyes open and try to spot the dangerous ones before they get here. With almost religious fervor some planetary scientists have been seeking near-earth asteroids in recent years to determine how many may be out there that might yet pose a threat to our planet. These scientists have met on many different occasions in the past five years to discuss search strategies and what to do next. The first major meeting of this type, open to more than those in the inner circle that grew from the discovery of the iridium layer in the K/T clays, was held at San Juan Capistrano in 1991. It was billed as the First International Symposium on Near-Earth Asteroids and brought together interested scientists from all over the world. Eugene Shoemaker was there and he urged caution about describing what a civilization-destroying asteroid is. After all, two out of three will hit water, he said, ignoring the point raised in chapter 12, that a water impact is almost certain to produce a greater catastrophe than a land strike, especially if several fragments should be involved. He estimated a civilization-threatening impact once every few million years. Tom Gehrels of Spacewatch at the University of Arizona did not take well to this caution and pointed out that “Humanity is ill-advised to say the probabilities are so low as to ignore them. I will not take that point of view.” As I listened to the talks and arguments, a sobering thought crossed my mind. Resting upon the efforts of this group of searchers might be the future of humankind. All of them realized that estimating probabilities of that magnitude was nit-picking.
Words and Pictures : Using Visual Aids
Authors: Wiener Harvey S.
Published: November 2020

I want you to expand your definition of reading. Most people define the word literally: Reading is determining meaning from printed words and sentences. But I believe that that's too limited a definition. We're always trying to "read" meanings from our physical environments, even when no print is involved. (It's interesting to note the legitimate, though certainly metaphorical, use of the word read for actions beyond a page of text.) The point to remember here is that the same skills that we use for a printed page we often apply to nonprint experiences as well. Thus when you try to "read" any situation, you aim to extract meaning from it. However, the connection between reading print and reading the surrounding world is more than a metaphorical one. The roster of skills in the table of contents for this book, Any Child Can Read Better—figuring out the main point, inferring, predicting outcomes, generalizing— are the intellectual processes we use almost everywhere to decipher meanings throughout the day. As I explain those skills and how to help your son or daughter use them, I'll be showing you the connections you can make between print and nonprint situations. You'll be able to help your child apply to words on a page some of the same mental activities that she draws on to interpret her daily life. When your child sees a group of youngsters waiting at the school bus, or when she watches an episode of Captain Kangaroo, or when she looks at a photograph or a cartoon or an advertisement—as soon as she tries to figure out what's going on, she's reading. Shakespeare reminds us that all the world's a stage; but it's also a book. As you know, I've been making frequent connections all along between the print world and the world of nonprint experiences that your child tries to read (that word again!) each day. In this chapter I want to concentrate on some of the representational forms that youngsters meet regularly in their lives. By representational I mean all those elements that stand for, or represent, experience.
The Crystal Ball: Predicting Outcomes And Drawing Conclusions
Authors: Wiener Harvey S.
Published: November 2020

Mature readers always reach beyond the text they are reading. They know unconsciously how to interact with print, regularly uncovering new meanings and making inferential leaps that connect with other thoughts, id s, or experiences. As you saw in the last chapter's discussion of inference, a piece of writing almost always means more than it says, and the awake reader constantly fleshes out suggestions, nuances, and implications to enrich the reading experience. In this and the next chapter, I want to talk with you about some high-order inference skills: predicting outcomes, drawing conclusions, and generalizing. These three skills work together because they involve the reader's ability to follow a trail begun but not completed by the words on the page. The three skills all relate to inferential reasoning in that they require readers to evolve meanings derived from the prose. Remember our definition of inference? When we infer, we uncover information that is unstated—hidden, if you will. The information expands upon the writer's words. Using what the writer tells us, we plug into the complex circuitry of ideas by adducing what's not exactly stated in what we're reading. We dig out meanings, shaping and expanding the writers ideas. Predicting, concluding, and generalizing move us toward wider and deeper meanings in what we read. Let's take them up one at a time. An engaged reader regularly looks ahead to what will happen next—what will be the next event in a chronological sequence, what will be the next point in a logical progression, what will be the next thread in the analytic fabric the writer is weaving. We base our predictions on prior events or issues in the narrative or analytical sequence. Making correct predictions involves our ability to see causes and effects, stimuli and results, actions and consequences. Your child already knows how to predict outcomes. Right from her earliest days in the crib, she has used important analytical skills instinctively.
Conservation, Management, and Rehabilitation
Authors: Moll Don , Moll Edward O.
Published: November 2020

It is interesting to note in Swettenham’s account that the Malays were already practicing conservation methods for the river terrapins in the nineteenth century. By protecting the beaches from poachers and leaving the third laying to hatch, they maintained moderate recruitment to offset the egg harvest. Similar conservation measures existed on the Amazon River in the nineteenth century to protect the heavily exploited giant South American river turtle, including the protection of females and leaving a third of the eggs laid on the beaches to hatch (Goeldi, 1906 in Parsons, 1962; see also a brief history of exploitation patterns of this species in chapter 5, this volume.). Unfortunately, conservation actions such as these have been the exception rather than the rule in human interactions with river turtles. As emphasized in earlier chapters, populations of most riverine turtle species have seriously declined from nineteenth century levels, but unlike the general declines reported for amphibians, most of the causes are obvious. The burgeoning commercial exploitation for food, traditional medicines, and pets, expanding populations of traditional and introduced predators, and extensive habitat destruction exemplified by such practices as sand mining, damming, channelizing, and pollution of flowing waterways have been key factors. We know far better how we reached this state of decline than how we can reverse the trend. Since the early beginnings of river turtle conservation chronicled by Swettenham and Goeldi, a variety of conservation techniques have been tried world-wide. As there are few proven methods, most actions have been based on what seemed logical or was simply cloned from the methods being used in sea turtle conservation programs. The latter may not have been the best approach for as Pritchard warned in a 1980 paper (Pritchard, 1980b) “sea turtle conservation remains without a theoretical framework, and almost all techniques that have been used remain unproven and riddled with paradox.” Conservation methodology is generally divisible into two divergent approaches, one emphasizing in-situ (on site) techniques and the other ex-situ (off site) techniques. The former aim at protecting animals and their habitat while minimizing intrusion into the life history of the target species.
VR 101
Authors: Heim Michael
Published: November 2020

Today we call many things “virtual.” Virtual corporations connect teams of workers located across the country. In leisure time, people form clubs based on shared interests in politics or music, without ever meeting face-to-face. Even virtual romances flourish through electronic mail. All sorts of hybrid social realities have sprung up on fax machines and computers, cellular telephones and communication satellites. Yet most of these “virtual realities” are not, in the strict sense of the term, virtual reality. They are pale ghosts of virtual reality, invoking “virtual” to mean anything based on computers. A strong meaning of virtual reality, however, ties together these looser meanings. A certain kind of technology—“VR” for short—has become the model for a pervasive way of seeing things. Contemporary culture increasingly depends on information systems, so that we find virtual reality in the weak sense popping up everywhere, while virtual reality in the strong sense stands behind the scenes as a paradigm or special model for many things. The first step in virtual realism is to become clear about the meaning of virtual reality in the strong sense of the term. We need to be clear about using virtual reality as a model because the loose or weak sense of virtual reality grows increasingly fuzzy as the face value of the term wears down in the marketplace, where virtual reality sells automobiles and soap. Car manufacturers use virtual reality in television commercials: “Climb out of that virtual reality and test drive the real road car that stimulates all five senses!” Newspaper cartoons and entertainment parks pump the popularity of virtual reality. Products on CD-ROM bill their 3-D (three dimensional) graphics as “true virtual reality.” AT&T welcomes you into its “virtual world.” The term now belongs to the universal vocabulary. But movies and seasonal television shows should not stretch VR to a thin vapor. Because virtual reality belongs to an important part of the future, we need to understand it not only as an undercurrent affecting cultural developments but also as a powerful technology in its own right.
Virtual Realism
Authors: Heim Michael
Published: November 2020

His words hovered in my mind for months, then boomeranged with painful irony. What he said over lunch held the future in a horrible way that neither of us could grasp at the time. His words foreshadowed a tragedy that would injure him and implicate our schizophrenic culture. At the time, the prophetic words were innocent of the shadowy terrorist the FBI calls “the Unabomber.” Lunch was at a Sheraton Hotel on the second day of a national conference on virtual reality held in Washington, D.C., December 1-2, 1992. I had organized the conference for the Education Foundation of the Data Processing Management Association, and Professor David Gelernter was the keynote speaker. I had been looking forward to talking with him, and lunch seemed a perfect opportunity. The Yale computer scientist had invented the Linda programming language and had also written eloquently about the human side of computing. I knew him not only as a writer but also as a friendly reader of my books. I looked forward to an exchange of ideas. Our conversation moved from pleasantries to questions about how to humanize the computer. Several of David Gelernter’s sentences imprinted themselves on my memory and later played back to me in ways I could not—would not—have imagined: “We are on a social collision course,” he warned. “One portion of our population is building computer systems—the software cathedrals of this era — while another portion grows increasingly alienated from computers. This situation holds the greatest danger of a cultural collision.” Here was a premonition about the cyberspace backlash. Seven months later, on June 24, 1993, David Gelernter opened a mail package on the fifth floor of the Watson computer science building at Yale, and the package blew up in his face. The office was in flames, and David barely escaped. He staggered to the campus clinic, arriving just in time to save his life. The permanent injuries he suffered from the mail bomb included a partially blinded right eye, damage in one ear, and a maimed right hand.
The Art of Virtual Reality
Authors: Heim Michael
Published: November 2020

The snow hits your windshield without mercy. The car’s headlights reveal nothing about the highway. You can only guess where the lanes are, where the shoulder begins, where the exit ramps might be. The blizzard has so iced the road that you crawl along at five miles an hour. Other travelers sit stranded in their cars off the road, lights dimming in the dark. Hours later, you flop exhausted on the bed. Tension tightens your shoulders and forehead. You close your eyes. On the back of your eyelids, everything appears again in startling detail: the swirling snowflakes, the headlights, the windshield wipers fighting the moisture — all in slow motion this very minute. . . . > Modern art objects had aesthetic appeal when the viewer could stand apart from them to appreciate their sensory richness, their expressive emotion, or their provocative attitude. Today, detached contemplation still holds antique charm, as the contemporary scene presents quite different circumstances. . . . Flashbacks, a kind of waking nightmare, often belong to your first experiences with virtual reality. Subtract the terror and sore muscles and you get an idea of how I felt after two and a half hours in the exhibit Dancing as the Virtual Dervish (Banff, Alberta). Even the next day, my optical nerves held the imprint of the brightly colored transhuman structures. I could summon them with the slightest effort—or see them sometimes in unexpected flashes of cyberspace. . . . > Art is coming to terms with interactivity, immersion, and information intensity. Aesthetics—the delighted play of the senses—cannot preserve its traditional detachment. The modern museum with its bright spaces and airy lighting is giving way to darkened rooms glowing with computer screens and hands-on buttons. . . . For hours, you feel a touch of perceptual nausea, a forewarning of the relativity sickness called AWS (Alternate World Syndrome) in my book The Metaphysics of Virtual Reality. Everything seems brighter, even slightly illusory. Reality afterwards seems hidden underneath a thin film of appearance. Your perceptions seem to float over a darker, unknowable truth. The world vibrates with the finest of tensions, as if something big were imminent, as if you were about to break through the film of illusion.
Interactive Design : Tunnel or Spiral
Authors: Heim Michael
Published: November 2020

Interactivity pounds at the doors of all broadcast media. Newspapers publish daily reports about cyberspace, then invite readers to subscribe to their online news services. Television programs encourage on-air feedback via email. Movies and popular television shows maintain viewer newsgroups and offer World Wide Web sites with click-on audio and video. As the era of one-way messages fades, the tone of unilateral broadcasting sinks to the trashy low-end of media culture. Quality switches from the TV remote controls to the computer console. Programming ceases to be unilateral when interactivity arrives. Digital switching is, of course, under the hood of interactivity. The computer establishes a reciprocal relationship between sender and receiver, viewer and producer. Because computers handle high-speed transmission to-and-fro, the separating line between sender and receiver, viewer and producer, begins to blur. The digital switch converts text, sounds, and video to transmissible bits. And bits produce incoherent fragments that are hardly distinguishable from cultural noise. The blast of information shatters what remains of cultural coherence in the wobbling worlds of print and film distribution. The digital era splatters attention spans till the shared sensibility dribbles into fragmentary, disintegrative de-construction. Interactivity signals a process of reconstruction. The digital Humpty-Dumpty needs mending. Reconstruction is a process of designing wholes, virtual worlds, that are both received and actively assembled —full, rich experiential places fit for human habitation. From the bits of the digital era arises the holism of virtual design. Virtual design means building worlds from digital fragments, engineering usable software environments from disparate information sources. Worlds are not simply re-packaged fragments. Nor do virtual worlds re-present the primary physical world. What emerges are new functional wholes, habitats that emulate the engagement of real worlds. Software engineering and software architecture support these virtual worlds, but artists with traditional skills must play a pivotal role in their construction. Virtual architecture must go well beyond wire-frame models set in clean Cartesian coordinates. Polygons in Renaissance perspective are only the first steps of interactive design. Worlds require mood-tuned scenarios that draw on traditional artistic insights.
The Hodgkin-Huxley Model of Action Potential Generation
Authors: Koch Christof
Published: November 2020

The vast majority of nerve cells generate a series of brief voltage pulses in response to vigorous input. These pulses, also referred to as action potentials or spikes, originate at or close to the cell body, and propagate down the axon at constant velocity and amplitude. Fig. 6.1 shows the shape of the action potential from a number of different neuronal and nonneuronal preparations. Action potentials come in a variety of shapes; common to all is the all-or-none depolarization of the membrane beyond 0. That is, if the voltage fails to exceed a particular threshold value, no spike is initiated and the potential returns to its baseline level. If the voltage threshold is exceeded, the membrane executes a stereotyped voltage trajectory that reflects membrane properties and not the input. As evident in Fig. 6.1, the shape of the action potential can vary enormously from cell type to cell type. When inserting an electrode into a brain, the small all-or-none electrical events one observes extracellularly are usually due to spikes that are initiated close to the cell body and that propagate along the axons. When measuring the electrical potential across the membrane, these spikes peak between +10 and +30 mV and are over (depending on the temperature) within 1 or 2 msec. Other all-or-none events, such as the complex spikes in cerebellar Purkinje cells or bursting pyramidal cells in cortex, show a more complex wave form with one or more fast spikes superimposed onto an underlying, much slower depolarization. Finally, under certain conditions, the dendritic membrane can also generate all-or-none events that are much slower than somatic spikes, usually on the order to 50-100 msec or longer. We will treat these events and their possible significance in Chap. 19. Only a small fraction of all neurons is unable—under physiological conditions—to generate action potentials, making exclusive use of graded signals. Examples of such nonspiking cells, usually spatially compact, can be found in the distal retina (e.g., bipolar, horizontal, and certain types of amacrine cells) and many neurons in the sensory-motor pathway of invertebrates (Roberts and Bush, 1981).
Diffusion, Buffering, and Binding
Authors: Koch Christof
Published: November 2020

In Chap. 9 we introduced calcium ions and alluded to their crucial role in regulating the day-to-day life of neurons. The dynamics of the free intracellular calcium is controlled by a number of physical and chemical processes, foremost among them diffusion and binding to a host of different proteins, which serve as calcium buffers and as calcium sensors or triggers. Whereas buffers simply bind Ca2+ above some critical concentration, releasing it back into the cytoplasm when [Ca2+]i has been reduced below this level, certain proteins— such as calmodulin—change their conformation when they bind with Ca2+ ions, thereby activating or modulating enzymes, ionic channels, or other proteins. The calcium concentration inside the cell not only determines the degree of activation of calcium-dependent potassium currents but—much more importantly—is relevant for determining the changes in structure expressed in synaptic plasticity. As discussed in Chap. 13, it is these changes that are thought to underlie learning. Given the relevance of second messenger molecules, such as Ca2+, IP3, cyclic AMP and others, for the processes underlying growth, sensory adaptation, and the establishment and maintenance of synaptic plasticity, it is crucial that we have some understanding of the role that diffusion and chemical kinetics play in governing the behavior of these substances. Today, we have unprecedented access to the spatio-temporal dynamics of intracellular calcium in individual neurons using fluorescent calcium dyes, such as fura-2 or fluo-3, in combination with confocal or two-photon microscopy in the visible or in the infrared spectrum (Tsien, 1988; Tank et al., 1988; Hernández-Cruz, Sala, and Adams, 1990; Ghosh and Greenberg, 1995).
Origins
Authors: Yung Yuk L. , DeMore William B.
Published: November 2020

Cosmology is a subject that borders on and sometimes merges with philosophy and religion. Since antiquity, the deep mysteries of the universe have intrigued mankind. Who are we? Where do we come from? What are we made of? Is the development of advanced intelligence capable of comprehending the grand design of the cosmos, the ultimate purpose of the universe? Is there life elsewhere in the universe? Is ours the only advanced intelligence or the most advanced intelligence in the universe? These questions have motivated great thinkers to pursue what Einstein called "the highest wisdom and the most radiant beauty." In the fourth century B.C., the essence of the cosmological question was formulated by the philosopher Chuang Tzu:… If there was a beginning, then there was a time before that beginning. And a time before the time which was before the time of that beginning. If there is existence, there must have been non-existence. And if there was a time when nothing existed, then there must be a time before that—when even nothing did not exist. Suddenly, when nothing came into existence, could one really say whether it belonged to the category of existence or of nonexistence? Even the very words I have just uttered, I cannot say whether they have really been uttered or not. There is nothing under the canopy of heaven greater than the tip of an autumn hair. A vast mountain is a small thing. Neither is there any age greater than that of a child cut off in infancy. P'eng Tsu [a Chinese Methuselah] himself died young. The universe and I came into being together; and I, and everything therein, are one. … Fortunately, our subject matter, solar system chemistry, is less esoteric than the questions asked by Chuang Tzu. A schematic diagram showing the principal pathways by which our solar system is formed is given in figure 4.1. The great triumphs of modern science have been summarized in this figure as fundamental contributions to the five "origins": (a) origin of the universe, (b) origin of the elements, (c) origin of the solar system, (d) origin of life, and (e) origin of advanced intelligence.
Jovian Planets
Authors: Yung Yuk L. , DeMore William B.
Published: November 2020

The four giant planets in the outer solar system, Jupiter, Saturn, Uranus, and Neptune, are a distinct group by themselves. The essential astronomical and atmospheric aspects of these planets are summarized in table 5.1. The significance of this group in the chemistry of the solar system is briefly pointed out in chapter 4. These planets are composed primarily of the lightest elements, hydrogen and helium, which were captured from the solar nebula during formation. The planets have rocky cores made of heavier elements. In the case of Jupiter and Saturn the mass of the gas greatly exceeds that of the core, whereas for Uranus and Neptune the masses of gas and core are comparable. Due to the enormous gravity of the giant planets, little mass has escaped from their atmospheres. Hence, the bulk composition of these planets provides a good measure of the initial composition of the solar nebula from which they were derived. Of all planetary bodies in the solar system, the constituents of giant planets are the closest to the cosmic abundances of the elements. The chemistry of the atmospheres of the giant planets is interesting for the following reasons:… 1. chemistry in a dominantly reducing atmosphere 2. interplay between photochemistry and equilibrium chemistry 3. ion chemistry in polar auroral regions 4. heterogeneous chemistry of aerosols 5. chemistry of meteoritic debris 6. lack of a planetary "surface"… We briefly comment on these reasons in this section. Each topic will receive a more detailed treatment in later sections. First of all, the atmospheres of the Jovian planets are more than 90% hydrogen and helium. Since helium is inert, the atmospheric chemistry is dominated by hydrogen. Therefore, we would expect the most stable compounds of carbon, oxygen, nitrogen, and phosphorus to be CH4, H2O, NHa, and PHs. This is in fact confirmed by the available observed composition of the bulk atmospheres of these planets. However, in the upper atmospheres of these planets, the composition is controlled by photochemistry.
Mars
Authors: Yung Yuk L. , DeMore William B.
Published: November 2020

Mars has been extensively studied by a series of spacecraft since the dawn of the space age: by Mariners 4, 6, 7, and 9 (1965-1972), Mars 2 through 6 (1971-1974), and the two Viking Landers and Orbiters in 1976. The knowledge from spacecraft is supplemented by ground-based observations. The essential aspects of Mars are summarized in table 7.1. It is a smaller planet than Earth; the radius and mass are, respectively, 53% and 11% of Earth. The surface gravity is 3.71 m s~2, compared with the terrestrial value of 9.82 m s~2. The physical properties and composition of the Martian atmosphere are summarized in tables 7.1 and 7.2; isotopic composition is given in table 7.3. An example of how this knowledge is obtained is illustrated in figure 7.1, showing the mass spectrum obtained by the mass spectrometer experiment on Viking. The bulk atmosphere is composed of CO2, with small amounts of N2 and Ar and a trace amount of water vapor. Located at 1.52 AU from the sun, the mean insolation at Mars is about half that of Earth. As a result, it is a colder planet, with mean surface temperature of 220 K, too cold for water to flow on the surface in the current epoch. The lack of an ocean results in an arid and dusty climate. The obliquity of Mars is 25.2°, close to the terrestrial value of 23.5°; however, Mars has an eccentric orbit, with eccentricity of 0.093. The ratio of incident solar radiation at perihelion to aphelion is 1.45. The large seasonal variation in heating is believed to be responsible for the spectacular global dust storms that can be observed from Earth and have inspired imaginative but erroneous theories about their origin. The polar regions of Mars can be as cold as 125 K, so CO2 will condense as frost on the surface. In fact, according to the Leighton-Murray model, this is what determines the pressure of the atmosphere. Figure 7.2 shows the seasonal pressure variations at the Viking lander sites for 3.3 Mars years from 1976. Note that the magnitude of the pressure changes is of the order of 20%, compared to the maximum change of 1% on the surface of Earth.
Earth: Human Impact
Authors: Yung Yuk L. , DeMore William B.
Published: November 2020

For eons the global environment of the planet has shaped the biosphere, and has been in turn shaped by the biosphere. According to the Gaia hypothesis, the overall impact of the biosphere on the global environment has been beneficial for the development and sustenance of life. However, this harmonious relationship between the biosphere and the environment has been disturbed with the emergence of one species, Homo sapiens, in the biosphere in the last million years. Our species has the potential to cause major disruptions in the global environment, thus threatening the integrity of the biosphere and its own survival. Some of these adverse effects are already known. The crucial challenge facing the future of humanity is to achieve a fundamental understanding of the global environment and to arrive at a new harmony between ourselves and nature. The adverse impact of humans on the local environment has been known for some time in human history. Urban pollution is an ancient problem. Land degradation and destruction of natural habitats were the probable causes of the earliest recorded migration of the Chinese people during the Shang Dynasty around 1500 B.C. (about the time of Moses) in the valleys of the Yellow River. However, until recently there has been relatively little anthropogenic impact on the global environment. There are at least two major global environmental problems that have been identified to date: the CO2 greenhouse effect and the global ozone depletion. These problems lie at the heart of what makes Earth a habitable planet. As discussed in chapter 9, Earth's atmosphere is responsible for a greenhouse effect of about 30°C, without which the surface of the planet would be too cold to allow water to flow. A doubling of atmospheric CO2 would increase the mean surface temperature of the planet by 2-3 °C. There would also be major shifts in the patterns of precipitation. Although the anticipated climatic changes caused by CO2 are small compared to the variations in climate in the geological history of the planet, the rate of change is unprecedented and could result in major social and economical disruptions. As discussed in chapter 9, life on land became possible only after an ozone shield had developed. As far as we know, no advanced living organism can survive the harsh radiation environment on Earth's surface in the absence of this ultraviolet screen.
Yellowstone Tour
Authors: Smith Robert B. , Siegel Lee J.
Published: November 2020

This tour of Yellowstone National Park and the Hebgen Lake earthquake area begins at Yellowstone’s south entrance, just north of Grand Teton National Park. Those entering Yellowstone from other directions may start this tour at any stop that is convenient. For that reason, we have not shown cumulative mileage for this trip from start to finish. Instead, we provide cumulative mileage only from one stop to the next, and for points of interest between them. (Figure 9.1. See also Figure 1.4 for a view of the region’s topography.) Two long days or three less hectic days are required for this 251-mile tour. For those with limited time, some time-saving options are included, such as skipping West Yellowstone, Montana, and the Hebgen Lake earthquake area (Stops 7—12) or omitting Mammoth Hot Springs and other stops on the northern end of the park (Stops 14—16). If you want to spend only two days in Yellowstone and its environs, start early the first day (136 miles) and continue to Stop 12, West Yellowstone, Montana, where overnight accommodations are available. During the second day, visit Stops 13—20 (115 miles). If you wish to divide this chapter’s tour into three days, begin at Stop 1 and proceed through Stop 7, also West Yellowstone (79 miles). Spend the night there. Tour the Hebgen Lake area, Stops 8—11, the second day and return to West Yellowstone, Stop 12, the second night (57 miles). Cover Stops 13—20 the third day (115 miles). The tour ends inside Yellowstone, so you may want to spend the night in the area if you have a long drive home. The driving tour of Yellowstone is passable only from late spring to fall, when park roads are open. West Yellowstone, Montana, and the Hebgen Lake area, Stops 7—12, are accessible year-round, although winter snow covers most geological features. Vehicle odometers vary, sometimes significantly, so mileages should be taken as approximate. Some visitors may choose to drive part or all of these tours in a direction opposite to the one we use.
Fundamental Aspects Of Incompressible And Compressible Turbulent Flows
Authors: Lumley John L. , Berkooz Gal
Published: November 2020

Turbulence generally can be characterized by a number of length scales: at least one for the energy containing range, and one from the dissipative range; there may be others, but they can be expressed in terms of these. Whether a turbulence is simple or not depends on how many scales are necessary to describe the energy containing range. Certainly, if a turbulence involves more than one production mechanism (such as shear and buoyancy, for example, or shear and density differences in a centripetal field) there will be more than one length scale. Even if there is only one physical mechanism, say shear, a turbulence which was produced under one set of circumstances may be subjected to another set of circumstances. For example, a turbulence may be produced in a boundary layer, which is then subjected to a strain rate. For a while, such turbulence will have two length scales, one corresponding to the initial boundary layer turbulence, and the other associated with the strain rate to which the flow is subjected. Or, a turbulence may have different length scales in different directions. Ordinary turbulence modeling is restricted to situations that can be approximated as having a single scale of length and velocity. Turbulence with multiple scales is much more complicated to predict. Some progress can be made by applying rapid distortion theory, or one or another kind of stability theory, to the initial turbulence, and predicting the kinds of structures that are induced by the applied distortion. We will talk more about this later. For now, we will restrict ourselves to a turbulence that has a single scale of length in the energy containing range.
The Power of Ideas
Authors: Pool Robert
Published: November 2020

When Edison introduced his new-fangled electric-lighting system, he found a receptive audience. The public, the press, and even his competitors— with the possible exception of the gaslight industry—recognized that here was a technology of the future. Alexander Graham Bell, on the other hand, had a tougher time. In 1876, just three years before Edison would create a practical light bulb, Bell’s invention of the telephone fell flat. “A toy,” his detractors huffed. What good was it? The telegraph already handled communications quite nicely, thank you, and sensible inventors should be trying to lower the cost and improve the quality of telegraphy. Indeed, that’s just what one of Bell’s rivals, Elisha Gray, did—to his everlasting regret. Gray had come up with a nearly identical telephone some months before Bell, but he had not patented it. Instead, he had turned his attention back to the telegraph, searching for a way to carry multiple signals over one line. When Gray eventually did make it to the patent office with his telephone application, he was two hours behind Bell. Those two hours would cost him a place in the history books and one of the most lucrative patents of all time. Some months later, Bell offered his patent to the telegraph giant Western Union for a pittance—$100,000—but company officials turned him down. The telephone, they thought, had no future. It wasn’t until the next year, when Bell had gotten financing to develop his creation on his own, that Western Union began to have second thoughts. Then the company approached Thomas Edison to come up with a similar machine that worked on a different principle so that it could sidestep the Bell patent and create its own telephone. Eventually, the competitors combined their patents to create the first truly adequate telephones, and the phone industry took off. By 1880 there were 48,000 phones in use, and a decade later nearly five times that. More recently, when high-temperature superconductors were first created in 1986, the experts seemed to be competing among themselves to forecast the brightest future for the superconductor industry.
Risk
Authors: Pool Robert
Published: November 2020

In June 1995, speaking to an audience of 250 fellow doctors and medical researchers, Steven Decks described what he hoped would be a breakthrough treatment for AIDS. The human immunodeficiency virus, which causes AIDS, attacks key components of a person’s immune system and gradually destroys the body’s ability to fight off infection. Consequently, an AIDS patient generally succumbs to what doctors call “opportunistic infections”— invasions by viruses, bacteria, and other microorganisms that take advantage of the body’s weakened defenses. If some way could be found to rebuild a patient’s devastated immune system, Deeks said, it could be lifesaving news for the 100,000 or so Americans in the advanced stages of AIDS. It might even make it possible for people with AIDS to live relatively normal lives. The treatment Deeks advocated was dramatic. He proposed extracting bone marrow from a baboon, separating out a special portion of it, then injecting that bit into a patient with an advanced case of AIDS. Because bone marrow contains the special cells that produce the immune system, Deeks hoped that the bone-marrow extract would create a baboonlike immune system in the patient. And because baboons are immune to AIDS, Deeks surmised that the patient’s new immune system could survive and do the job that the old, AIDS-wracked system no longer could perform—fight off disease-causing invaders. The AIDS virus would still be present, lurking in the remnants of the patient’s own immune system, but its main threat to the patient would have been deflected. For Deeks, a San Francisco physician who treats many AIDS patients, it was a gamble that had to be taken. Deeks spoke at a conference on xenograft transplantation, the medical term for the transplant of organs or tissue from one species into another—particularly, from animals into humans. The audience, most of whom were xenotransplant researchers, generally approved of Deeks’s proposal, but there were dissenters. The most vocal was Jonathan Allan, a virologist at the Southwest Foundation for Biomedical Research in San Antonio.
Lectures on Geophysical Fluid Dynamics
Authors: Salmon Rick
Published: November 2020

Lectures on Geophysical Fluid Dynamics offers an introduction to several topics in geophysical fluid dynamics, including the theory of large-scale ocean circulation, geostrophic turbulence, and Hamiltonian fluid dynamics. Since each chapter is a self-contained introduction to its particular topic, the book will be useful to students and researchers in diverse scientific fields.
Noninertial Theory of Ocean Circulation
Authors: Salmon Rick
Published: November 2020

This third chapter represents both a change in topic and a change in viewpoint. In chapter 2, we mainly considered the free (that is, unforced) motions of an ideal, horizontally unbounded fluid in which the inertia was always important. In this chapter, we examine the response of a horizontally bounded fluid to an external forcing. The presence of coastal boundaries is a complicating but indispensable feature of ocean circulation models. To compensate somewhat for the extra complications of the boundaries, we now simplify our dynamical equations by entirely neglecting the advection of momentum, or, more precisely, by replacing the inertia terms in the momentum equations with a large eddy viscosity of the kind discussed in chapter 1. Although this drastic step might be easier to justify for the ocean than tor the atmosphere—the ocean is in some sense more sluggish—our real motivation is a desire for tractable equations. Throughout most of this chapter, we also neglect the advection of buoyancy, and thus consider the linear theory of ocean circulation, which is relatively easy and reasonably complete. However, in the final two sections, we return to the much more challenging problem of properly incorporating nonlinear buoyancy advection.
The Effect of Medium and Interaction
Authors: Kukulska-Hulme Agnes
Published: November 2020

• Why are electronic texts suspect? • Can you tear out a page on a screen? • How does chopping up sentences make them coherent? • When do actions speak louder than words? • How can we use questions to map out knowledge needs? . . . We begin this chapter by looking at what is to be gained from understanding the relationship between written and spoken language. The consequences of putting words on the screen are explored, in terms of changes in the meaning of terms, pronunciation, and the effect of spatial proximity on meanings. We then move on to consider aspects of verbal interaction, such as politeness and fluency, and conclude with an overview of users’ knowledge needs identified by analyzing their language. Written texts all have to be related somehow, directly or indirectly, to the world of sound, the natural habitat of language, to yield their meanings. The world of sound as “the natural habitat of language.” Historically, and in an individual’s development, speech comes before writing. For a small child, language is all speech. This is obviously not so for older children and adults, and for some, language is nearly all reading and writing. Still, for most people, language is strongly associated with sound, in a concrete way through hearing and producing language as well as through mental association. In a situation where computers are used, spoken and written language are both present in some way (not necessarily at the same time), not least of all because it is most unusual for someone to use an application without ever speaking about its use! In general, indirect reference from written language to sound through a reader’s prior experience of spoken language or through a special notation is acceptable in many different circumstances, such as in books and newspapers. The question is, What, if anything, do we lose when real sound is missing? Physical demands on the reader (user) are now focused on visual processing.
Vadose Zone Hydrology
Authors: Parlange Marc B. , Hopmans Jan W.
Published: November 2020

The vadose zone is the region between ground level and the upper limits of soil fully saturated with water. Hydrology in the zone is complex: nonlinear physical, chemical, and biological interactions all affect the transfer of heat, mass, and momentum between the atmosphere and the water table. This book takes an interdisciplinary approach to vadose zone hydrology, bringing together insights from soil science, hydrology, biology, chemistry, physics, and instrumentation design. The chapters present state-of-the-art research, focusing on new frontiers in theory, experiment, and management of soils. The collection addresses the full range of processes, from the pore-scale to field and landscape scales.
Non ideal Transport of Reactive Solutes in Porous Media : Cutting Across History and Disciplines
Authors: Brusseau Mark L.
Published: November 2020

The potential for human activities to adversely affect the environment has become of increasing concern during the past three decades. As a result, the transport and fate of contaminants in subsurface systems has become one of the major research areas in the environmental/hydrological/earth sciences. An understanding of how contaminants move in the subsurface is required to address problems of characterizing and remediating soil and groundwater contaminated by chemicals associated with industrial and commercial operations, waste-disposal facilities, and agricultural production. Furthermore, such knowledge is needed for accurate risk assessments; for example, to evaluate the probability that contaminants associated with a chemical spill will reach an aquifer. Just as importantly, knowledge of contaminant transport and fate is necessary to design “pollution-prevention” strategies. A tremendous amount of research on the transport of solutes in porous media has been generated by several disciplines, including analytical chemistry (chromatography), chemical engineering, civil/environmental engineering, geology, hydrology, petroleum engineering, and soil science. This research includes the results of theoretical studies designed to pose and evaluate hypotheses, the results of experiments designed to test hypotheses and investigate processes, and the development and application of mathematical models useful for integrating theoretical and experimental results and for evaluating complex systems. While much of the previous research has focused on transport of nonreactive solutes, it is the transport of “reactive” solutes that is currently receiving increased attention. Reactive solutes are those subject to phase-transfer processes (e.g., sorption, precipitation/dissolution) and transformation reactions (e.g., biodegradalion). Of special interest in the field of contaminant transport is so-called nonideal transport. In the most general sense, nonideal transport can be described as transport behavior that deviates from the behavior that is predicted using a given set of assumptions. A homogeneous porous medium and linear, instantaneous phase transfers and transformation reactions are the most basic set of assumptions for ideal solute transport in porous media. As discussed in a recent review, transport of reactive contaminants is often nonideal (Brusseau, 1994). The potential causes of nonideal transport include rate-limited and nonlinear mass transfer and transformation reactions, as well as spatial (and temporal) variability of material properties.