bluuebunny/crossref_metadata_2025 huggingface dataset:
Bursting Cells
Authors: Koch Christof
Published: November 2020

Some neurons throughout the animal kingdom respond to an intracellular current injection or to an appropriate sensory stimulus with a stereotypical sequence of two to five fast spikes riding upon a slow depolarizing envelope. The entire event, termed a burst, is over within 10-40 msec and is usually terminated by a profound afterhyperpolarization (ΑΗΡ). Such bursting cells are not a random feature of a certain fraction of all cells but can be identified with specific neuronal subpopulations. What are the mechanisms generating this intrinsic firing pattern and what is its meaning? Bursting cells can easily be distinguished from a cell firing at a high maintained frequency by the fact that bursts will persist even at a low firing frequency. As illustrated by the thalamic relay cell of Fig. 9.4, some cells can switch between a mode in which they predominantly respond to stimuli via single, isolated spikes and one in which bursts are common. Because we believe that bursting constitutes a special manner of signaling important information, we devote a single, albeit small chapter to this topic. In the following, we describe a unique class of cells that frequently signal with bursts, and we touch upon the possible biophysical mechanisms that give rise to bursting. We finish this excursion by focussing on a functional study of bursting cells in the electric fish and speculate about the functional relevance of burst firing. Neocortical cells are frequently classified according to their response to sustained current injections. While these distinctions are not all or none, there is broad agreement for three classes: regular spiking, fast spiking, and intrinsically bursting neurons (Connors, Gutnick, and Prince, 1982; McCormick et al., 1985; Connors and Gutnick, 1990; Agmon and Connors, 1992; Baranyi, Szente, and Woody, 1993; Nuńez, Amzica, and Steriade, 1993; Gutnick and Crill, 1995; Gray and McCormick, 1996). Additional cell classes have been identified (e.g., the chattering cells that fire bursts of spikes with interburst intervals ranging from 15 to 50 msec; Gray and McCormick, 1996), but whether or not they occur widely has not yet been settled. The cells of interest to us are the intrinsically bursting cells.
A Land of Scenery and Violence
Authors: Smith Robert B. , Siegel Lee J.
Published: November 2020

It was the busy summer season in Yellowstone National Park, a beautiful moonlit night with 18,000 people in the park’s campgrounds and hotels and thousands more in surrounding towns and recreation areas. At 23 minutes before midnight, a talent contest was wrapping up at the Old Faithful recreation hall. A beauty queen had just been crowned. As she walked down the aisle to the applause of several hundred people, the log building creaked loudly and began to shake. Within seconds, the earthquake sent people scurrying for the exits. A park ranger dropped the hand of his date—a waitress from Old Faithful Inn—and rushed to open the doors so no one would be trampled. Nearby, frightened guests fled Old Faithful Inn, where a waterline broke and an old stone chimney soon would collapse into a dining room, thankfully closed at that late hour. Out in the darkness, in geyser basins along Yellowstone’s Firehole River, the Earth began belching larger-than-usual volumes of hot water. About 160 geysers erupted, some for the first time, others after decades-long dormant periods. Sapphire Pool, once a gentle spring, became a violent geyser, hurling mineral deposits around Biscuit Basin. Clepsydra, Fountain, and some other geysers in Lower Geyser Basin began erupting more often than usual. Old Faithful’s eruptions became less frequent, although some observers thought it spouted with unusual vigor earlier that evening. Hundreds of hot springs became muddy. Fountain Paint Pot spewed mud violently, spattering tourist walkways. Rocks and landslides tumbled into park highways in several places, blocking roads between Old Faithful and Mammoth and closing the route to the park’s west entrance at West Yellowstone, Montana. Within an hour, thousands of vehicles streamed out of Yellowstone on roads that remained open—a serpentine parade of headlights fleeing the strongest earthquake yet recorded in the Rocky Mountains and the Intermountain West. The panic and damage in Yellowstone were minimal compared with the unimaginable horror that would overtake a popular Montana recreation area just outside the park’s northwest boundary.
How Yellowstone Works
Authors: Smith Robert B. , Siegel Lee J.
Published: November 2020

Most people who visit Yellowstone are blissfully unaware they are standing on top of an active, breathing volcano. They visit geysers and hot springs, and may feel some of the numerous earthquakes that rattle the region. Few realize the seemingly solid ground beneath them is slowly stretching apart and huffing and puffing upward and downward. Nor are many visitors aware of the large chamber of molten and partially molten rock several miles beneath their feet, or of the even deeper plume of hot rock moving up from deep within Earth. Indeed, it is easy to enjoy the national park’s geysers and other scenery without stopping to consider they are merely the uppermost, most visible parts of one of the world’s geological wonders: the Yellowstone hotspot. Even fewer tourists realize the same forces driving Yellowstone’s renowned geysers also reshaped the landscape of 25 percent of the northwestern United States—a broad band stretching from Yellowstone almost 500 miles southwest to the Idaho—Oregon—Nevada border. As North America drifted southwest over the hotspot during the past 16.5 million years, the immense heat and molten rock rising from Earth’s mantle melted, rearranged, and blew apart the overlying crust. Today, the hotspot is beneath Yellowstone, making the national park a field laboratory of active geologic process: volcanism, earthquakes, faulting, and large-scale movement and deformation of Earth’s crust. Let us examine how this system works—how heat and magma, or molten rock, from within the Earth drive small-scale features such as geysers and hot springs, contribute to the most intense earthquake and volcanic activity in the Rocky Mountains, and help mold the topography of the region. The amount of heat flowing from the ground in the Yellowstone caldera is thirty to forty times more than the heat emitted by an average piece of ground elsewhere on Earth’s continents. This enormous heat flow provides the energy that melted rock under the caldera and helped lift Yellowstone to its lofty altitude. Heat powers Yellowstone’s volcanic activity by melting rock in Earth’s mantle and crust. In turn, the molten rock heats groundwater to produce geysers and hot springs.
Beyond Engineering
Authors: Pool Robert
Published: November 2020

We have long recognized technology as a driving force behind much historical and cultural change. The invention of the printing press initiated the Reformation. The development of the compass ushered in the Age of Exploration and the discovery of the New World. The cotton gin created the conditions that led to the Civil War. Now, in Beyond Engineering, science writer Robert Pool turns the question around to examine how society shapes technology. Drawing on such disparate fields as history, economics, risk analysis, management science, sociology, and psychology, Pool illuminates the complex, often fascinating interplay between machines and society, in a book that will revolutionize how we think about technology. We tend to think that reason guides technological development, that engineering expertise alone determines the final form an invention takes. But if you look closely enough at the history of any invention, says Pool, you will find that factors unrelated to engineering seem to have an almost equal impact. In his wide-ranging volume, he traces developments in nuclear energy, automobiles, light bulbs, commercial electricity, and personal computers, to reveal that the ultimate shape of a technology often has as much to do with outside and unforeseen forces. For instance, Pool explores the reasons why steam-powered cars lost out to internal combustion engines. He shows that the Stanley Steamer was in many ways superior to the Model T--it set a land speed record in 1906 of more than 127 miles per hour, it had no transmission (and no transmission headaches), and it was simpler (one Stanley engine had only twenty-two moving parts) and quieter than a gas engine--but the steamers were killed off by factors that had little or nothing to do with their engineering merits, including the Stanley twins' lack of business acumen and an outbreak of hoof-and-mouth disease. Pool illuminates other aspects of technology as well. He traces how seemingly minor decisions made early along the path of development can have profound consequences further down the road, and perhaps most important, he argues that with the increasing complexity of our technological advances--from nuclear reactors to genetic engineering--the number of things that can go wrong multiplies, making it increasingly difficult to engineer risk out of the equation. Citing such catastrophes as Bhopal, Three Mile Island, the Exxon Valdez, the Challenger, and Chernobyl, he argues that is it time to rethink our approach to technology. The days are gone when machines were solely a product of larger-than-life inventors and hard-working engineers. Increasingly, technology will be a joint effort, with its design shaped not only by engineers and executives but also psychologists, political scientists, management theorists, risk specialists, regulators and courts, and the general public. Whether discussing bovine growth hormone, molten-salt reactors, or baboon-to-human transplants, Beyond Engineering is an engaging look at modern technology and an illuminating account of how technology and the modern world shape each other.
Managing the Faustian Bargain
Authors: Pool Robert
Published: November 2020

A quarter of a century ago, Alvin Weinberg offered one of the most insightful— and unsettling—observations anyone has made about modern technology. Speaking of the decision to use nuclear power, the long-time director of Oak Ridge National Laboratory warned that society had made a “Faustian bargain.” On the one hand, he said, the atom offers us a nearly limitless supply of energy which is cheaper than that from oil or coal and which is nearly nonpolluting. But on the other hand, the risk from nuclear power plants and nuclear-waste disposal sites demands “both a vigilance and a longevity of our social institutions that we are quite unaccustomed to.” We cannot afford, he said, to treat nuclear power as casually as we do some of our other technological servants—coal-fired power plants, for instance—but must instead commit ourselves to maintaining a close and steady control over it. Although Weinberg’s predictions about the cost of nuclear power may now seem naive, the larger issue he raised is even more relevant today than twenty-five years ago: Where should society draw the line in making these Faustian technological bargains? With each decade, technology becomes more powerful and more unforgiving of mistakes. Since Weinberg’s speech, we have witnessed major accidents at Three Mile Island, Chernobyl, and Bhopal, as well as the explosion of the Challenger and the wreck of the Exxon Valdez. And looking into the future, it’s easy to see new technological capabilities coming along that hold the potential for far greater disasters. In ten or twenty years, many of our computers and computer-controlled devices may be linked through a widespread network that dwarfs the current telecommunications system. A major breakdown like those that occasionally hit long-distance telephone systems could cost billions of dollars and perhaps kill some people, depending on what types of devices use the network. And if genetic engineering becomes a reality on a large scale, a mistake there could make the thalidomide debacle of the late 1950s and early 1960s look tame.
Fundamentals of Transport Equation Formulation for Two-Phase Flow in Homogeneous and Heterogeneous Porous Media
Authors: Quintard Michel , Whitaker Stephen
Published: November 2020

Most porous media of practical importance are hierarchical in nature; that is, they are characterized by more than one length-scale. When these length-scales are disparate, the hierarchical structure can be analyzed by the method of volume averaging (Anderson and Jackson, 1967; Marie, 1967; Slattery, 1967; Whitaker, 1967). In this approach, macroscopic quantities at a given length-scale are defined in terms of a boundary value problem that describes the phenomena at a smaller length-scale, and information is filtered from one scale to another by a series of volume and area integrals. Other methods, such as ensemble averaging (Matheron, 1965; Dagan, 1989) or homogenization theory (Bensoussan et al, 1978; Sanchez-Palencia, 1980), have been used to study hierarchical systems, and developments specific to the problems under consideration in this chapter can be found in Bourgeat (1984), Auriault (1987), Amaziane and Bourgeat (1988), and Sáez et al. (1989). The transformation from the Darcy scale to the large scale is a recurrent problem in reservoir and aquifer engineering. A detailed description of reservoir properties is available through geostatistical analysis (Journel, 1996) on a fine grid with a length-scale much smaller than the scale of the blocks in the reservoir simulator. “Effective” or “pseudo” properties are assigned to the coarse grid blocks, while the forms of the large-scale equations are required to be the same as those used at the Darcy scale (Coats et al., 1967; Hearn, 1971; Jacks et al., 1972; Kyte and Berry, 1975; Dake, 1978; Killough and Foster, 1979; Yokoyama and Lake, 1981; Kortekaas, 1983; Thomas, 1983; Kossack et al., 1990). A detailed discussion of the comparison between the several approaches is beyond the scope of this chapter; however, one can read Bourgeat et al. (1988) for an introductory comparison between the method of volume averaging and the homogenization theory, and Ahmadi et al. (1993) for a discussion of the various classes of pseudofunction theories.
Emerging Measurement Techniques for Vadose Zone Characterization
Authors: Hopmans Jan W. , Hendrickx Jan M. H.
Published: November 2020

Variables and parameters required to characterize soil water flow and solute transport are often measured at different spatial scales from those for which they are needed. This poses a problem since results from field and laboratory measurements at one spatial scale are not necessarily valid for application at another. Herein lies a challenge that vadose zone hydrologists are faced with. For example, vadose zone studies can include flow at the groundwater-unsaturated zone as well as at the soil surface-atmosphere interface at either one specific location or representing an entire field or landscape unit. Therefore, vadose zone measurements should include techniques that can monitor at large depths and that characterize landsurface processes. On the other end of the space spectrum, microscopic laboratory measurement techniques are needed to better understand fundamental flow and transport mechanisms through observations of pore-scale geometry and fluid flow. The Vadose Zone Hydrology (VZH) Conference made very clear that there is an immediate need for such microscopic information at fluid-fluid and solid-fluid interfaces, as well as for methodologies that yield information at the field/landscape scale. The need for improved instrumentation was discussed at the ASA-sponsored symposium on “Future Directions in Soil Physics” by Hendrickx (1994) and Hopmans (1994). Soil physicists participating in the 1994-1999 Western Regional Research Project W-188 (1994) focused on “improved characterization and quantification of flow and transport processes in soils,” and prioritized the need for development and evaluation of new instrumentation and methods of data anlysis to further improve characterization of water and solute transport. The regional project documents the critical need for quantification of water flow and solute transport in heterogeneous, spatially variable field soils, specifically to address preferential and accelerated contaminant transport. Cassel and Nielsen (1994) describe the contributions in computed tomography (CT) using x-rays or magnetic resonance imaging (MRI) as “an awakening,” and they envision these methodologies to become an integral part of vadose zone research programs. The difference in size between measurement and application scales poses a dilemma for the vadose zone hydrologist.
Pleistocene Herpetological Localities
Authors: Holman J. Alan
Published: November 2020

Localities in countries in the Geographic Divisions below arc numbered to correspond with those in the taxonomic accounts in Chapter 4. Figure 40 is an artists concept of some Pleistocene herpetological species and extinct mammals at the Shropham Pit Locality (Interglacial Component), Norfolk, England (Britain: Upper Pleistocene Site 10). Countries are arranged in divisions from west to cast, and from north to south when possible. Oceanic islands are listed under the country to which they belong. Malta is included with Italy because of its important Pleistocene herpetofauna and proximity to Sicily and Italy…. I. Northwest Division: Ireland and Britain, p. 130 II. French Division: France and Monaco, p. 142 III. Southwest Division: Spain, p. 149 IV. Northcentral Division: Netherlands, Belgium, Luxembourg, Germany, Austria, and Switzerland, p. 157 V. Northeast Division: Poland and the Czech Republic, p. 175 VI. Southeast Division: Italy, Hungary, Yugoslavia: (Croatia, Bosnia, Serbia), and Greece, p. 182… Pleistocene herpetofaunal records in Ireland are rare and consist mainly of records of Rana temporaria. More work needs to be done in this critical area for the study of the fragmentation of ranges of herpetological species in the Pleistocene.
Middle Eocene through Early Miocene North American Vegetational History: 50-16.3 Ma
Authors: Graham Alan
Published: November 2020

During the Middle Eocene through the Early Miocene, erosion of the Appalachian Mountains exceeded uplift and there was a net reduction in elevation. In the Rocky Mountains uplift continued through the Middle Eocene (end of the Laramide orogeny), waned in the Middle Tertiary, and then increased beginning at about 10 Ma. Earlier reconstructions placed paleoelevations in the Rocky Mountains during the Middle Eocene through the Early Miocene at approximately half the present relief. The maximum elevation in the Front Ranges during the latest Eocene was estimated at ~2500 m (~8000 ft; MacGinitie, 1953). Recent approximations are for nearly modern elevations in several areas by the Eocene-Oligocene. Extensive Eocene volcanism deposited ash and blocked drainage systems, augmenting uplift and facilitating the preservation of extensive fossil floras and faunas. In the far west the beginning of Tertiary volcanism in the Sierra Nevada is dated at ~ 33 Ma near the Eocene-Oligocene boundary. A drying trend becomes evident in the Middle Eocene and reduced moisture, along with the waning of volcanic activity in the Oligocene, restricted conditions favorable to fossilization. The number of Oligocene floras in the northern Rocky Mountains is considerably fewer than in younger deposits to the west. In the absence of extensive plate reorganization and orogeny, CO2 concentration decreased, which contributed to a temperature decline that continued through the Cenozoic and intensified in the Late Tertiary. Recall from Chapter 2 (sections on orogeny and volcanism) that uplift plays a role in determining long-term climate by creating rainshadows, altering atmospheric circulation patterns, and increasing the erosion of silicate rocks that causes a drawdown of CO2. This allows heat to escape from the troposphere and results in lower temperatures. Marine benthic temperatures were ~10°C in the early Late Eocene and ~2°C near the Eocene-Oligocene boundary, assuming an essentially ice-free Earth during that time, and increased to ~5-6°Cnear the end of the Early Miocene. Temperatures over land in the midnorthern latitudes are estimated to have dropped by ~12°C between the Late Eocene and Early Oligocene (Wolfe, 1992a).
Middle Miocene through Pliocene North American Vegetational History: 16.3-1.6 Ma
Authors: Graham Alan
Published: November 2020

During the Middle Miocene through the Pliocene the Appalachian Mountains underwent continued erosion and approached modern elevations. The Rocky Mountains had undergone uplift to half or more of their present elevation during the Late Cretaceous to Middle Eocene Laramide Revolution; after a lull during the Middle Eocene through the Early Miocene, there was increased tectonic activity beginning ~12 Ma and especially between 7 and 4 Ma. Locally some highlands may have approached or attained modern elevations. The increasingly high mountains and plateaus of Asia and North America deflected the major air streams southward, bringing colder polar air into the middle latitudes of North America. An extensive Antarctic ice sheet further cooled ocean waters and contributed to the spread of seasonally dry climates. The elimination of most of the Asian exotics from the North American flora dates to the Late Miocene-Pliocene as a result of a decline in summer rainfall. The Sierra Nevada attained about two-thirds of their present elevation within the past 10 Ma. They were appreciably elevated at ~5 Ma, stood at ~2100 m at 3 Ma, and have risen ~950 m since 3 Ma (Huber, 1981). The California Coast Ranges and Cascade Mountains attained significant heights by 3 Ma, and there was a rapid rise of the Alaska Range at ~6 Ma. Temperatures increased between ~18 and 16 Ma. In the absence of major plate reorganization and intense volcanic activity and with increased erosion from continued replacement of the dense evergreen forest by deciduous forest and shrubland (increasing albedo), atmospheric CO2 concentration decreased and a sharp lowering of temperature occurred in the Middle Miocene between 15 and 10 Ma. Eolian dust deposits increased in the Late Cenozoic, suggesting greater aridity (Rea et al., 1985). This is supported by kaolinite records from North Atlantic deep sea sediments (Chamley, 1979). At ~4.8~4.9 Ma global cooling and a marine regression of ~40~50 m combined to isolate the Mediterranean Basin from the ocean and to concentrate large volumes of salt as water evaporated. The biota was destroyed, giving rise to the term Messinian salinity crisis.
Soil versus Biological Controls on Nutrient Cycling in Terra Firme Forests
Authors: Cuevas Elvira
Published: November 2020

Terra firme forests are those that by definition are not permanently or seasonally flooded (terra firme meaning “firm terrain”). This type of forest encompasses the Amazon and Orinoco basins, stretching from the lower slopes of the Andes, east to the Guianas, and south to about 15°S in western Brazil and northern Bolivia (Richards 1996). Structural and compositional variability in these forests in the Amazon basin is very wide as a result of climate differences and geomorphological position. The region is not climatically uniform; the central and much of the southern parts have less and more seasonal rainfall than the eastern and western parts (Walsh 1996). These differences have direct and indirect ecological significance, as phenology and biological processes related to nutrient availability will be strongly influenced by both factors (Cuevas and Medina 1986, 1988, 1990, Medina and Cuevas 1989). Periods of two or more consecutive dry days are ecologically significant in a humid area such as San Carlos de Río Negro, in the northern part of the Amazon, because of low water retention capacity in the widespread sandy soils. In lower geomorphological positions, dry spells of 5-10 days may result in fluctuations of the water table from 0.4-1.0 m (Herrera 1977, Bongers et al. 1985). In areas with a more strongly seasonal climate, roots have been found extending to 18 m depth (Nepstad et al. 1995). This may explain the presence of evergreen forest in the seasonally dry eastern Amazon. Structure and physiognomy of terra firme forests is very similar throughout Amazonia, but floristically it is quite variable due to different compositions in the subbasins of the Amazon’s major tributaries. These subbasins are located within geochemical regions that can be differentiated based on the physicochemical properties of drainage waters (Sioli 1975, Fittkau 1971, Fittkau et al. 1975). Blackwater rivers, such as the Río Negro, drain mostly sandy podsolized soils low in most essential nutrients for plant growth. They are characterized by a high content of humic acids, which remain dissolved because of the predominant low concentrations of polyvalent cations, mainly Ca2+ and Mg2+.
Properties and Management of Kaolinitic Soils
Authors: Juo Anthony S. R. , Franzluebbers Kathrin
Published: November 2020

Kaolinitic soils are the most widely occurring soils in the tropics, especially in tropical Africa. They comprise about 70% of the soils in the low-altitude tropics. Typically, these soils have a sandy, loamy sand, or sandy loam surface soil and sandy clay to clayey subsoil containing approximately 20-60% clay in the lower B horizons. Silt content is usually low throughout the profile (< 20%) with the exception of soils derived from loess materials. Soil erosion, compaction, and low nutrient- and water-holding capacities are the major constraints under intensive cropping. Ideally, kaolinitic soils in the humid and subhumid regions should be used for natural forest reserves and tree farms. In drier regions, sustainable land use includes natural grasslands and managed pastures with low stocking rates. When kaolinitic soils are used for annual crop production, crop rotation and managed fallow must be included in the farming system after a short cropping cycle to restore soil physical, chemical, and biological fertility and to sustain crop yield in the long term. Kaolinitic soils may be further distinguished into two subgroups based on inherent chemical fertility, namely, high-base-status and low-base-status kaolinitic soils. High-base-status kaolinitic soils usually have pH values of 5.3 or higher (measured in soil-water suspension), and a base saturation (BS) of 70% or higher throughout the soil profile calculated on the basis of effective cation exchange capacity (ECEC). Low-base-status kaolinitic soils generally have a pH value of 5.2 or lower, and a base saturation below 70%. The properties of high-base-status and low-base-status kaolinitic soils are given in tables 10-1 and 10-2, respectively. The common properties of these two soils are the dominance of kaolinite in the clay fraction, a low CEC, and a high bulk density in the subsoil horizon. The differences are the degree of base saturation, soil pH, degree of exchangeable Al saturation, and the quality of soil organic matter. In other words, the cation exchange sites of soil organic matter in the low-base-status soil are dominated by Al3+, whereas Ca++ and Mg++ are the dominating ions in the high base-status soil.
The Framework
Authors: Rostow W. W.
Published: November 2020

The title of this book, The Great Population Spike and After: Reflections on the 21st Century, requires some explanation. The Great Spike is illustrated in the figure that serves as the book's frontispiece.1 The figure plots the rate of growth of global population from 8000 B.C. to 8000 A.D. In highly stylized form, it exhibits an average growth rate of zero except for the period between 1776 and 2176. In that interval, the spike occurs: the growth rate rises to a bit over 2% per annum in 1976, and then falls to zero again in the next century. Falling growth rates for the global population, the downward part of the spike, are already upon us. I should emphasize the word "stylized." The world's population growth rate was evidently not static at zero from 8OOOB.C. to the middle of the eighteenth century, nor will it remain static for the 8,000 years after the spike. It will fluctuate with the vicissitudes of history. But despite the illustration's oversimplicity, its message is significant. Figure 1.1 shows, in absolute terms, the leveling off of the global population, which will take place gradually. Global population will attain, according to present estimates, an absolute level of about 10 billion people as opposed to about 790 million in the mid-18th century. This rise, along with the rise in income per capita, is a rough measure of what the Industrial Revolution has achieved since the 18th century, but the industrialization of the globe also set in motion forces that will bring about a decline in the rate of increase in population. The demographic transition decrees that after a certain point the birth rate will fall as income per capita rises. These negative forces will come to dominate the 21st century. Thus, this book concentrates on the period from the 1990s to around 2050, set against the background of the past several centuries. It deals, in effect, with both sides of the Great Spike. It is suffused, however, with the proposition that the 21st century, if it proves relatively peaceful, will soon face a period in which a rising population and effective demand in the presently developing nations will strain technologies and existing resources, followed by a long period in which the Industrial Revolution will have been largely diffused around the world.
The Critical Margin and America's Inner Cities
Authors: Rostow W. W.
Published: November 2020

I agree with British economist Alfred Marshall about the high costs of "wasteful negligence" of the poor and with the Economist that the slums in our cities constitute "America's main domestic challenge." But those judgments alone would not justify making the urban problem the subject of the final substantive chapter of this book. What argues for coming to rest here on the contemporary urban problem is the view that it will be impossible, over a period of time, for the United States to play the role of critical margin on the world scene if we do not solve the urban problem. By "solve," I do not mean a reduction of the social pathology within the inner cities to the level of the more affluent counties that surround them. That will take time, perhaps a generation or more. Indeed, it might never happen. In any case, there is no quick fix. By "solve," I mean the bringing about of a systematic and substantive process of decline in the social pathology of the inner city. That demonstration will convince those who live there and the community as a whole that the job is doable. Right now, the greatest obstacle to a solution of the problem is the belief both in the inner city and the community at large that the job is not doable. As I said on another occasion:… When i am asked how I would rate the urban problem on the agenda of national-security problems, I reply it is our number one nationalsecurity problem. If we succeed in mastering the current urban problem of our country, we shall strengthen our hand on the world scene. We shall demonstrate that we can he a truly multiracial society, which is at the same time true to the international ideals to which we as a nation have long been committed. Nothing constructive can be accomplished in this dynamic, contentious, aspiring world without the active participation of the United States. But, ii we fail to master the urban problem, we shall, I fear, turn inward, away from the world. We shall he unable to play our part at the critical margin. And we shall risk a world environment of chaos.
Climate
Authors: Greenland David , Losleben Mark
Published: November 2020

Climate is one of the most important determinants of biotic structure and function in the alpine. High winds and low temperatures are defining elements of this ecosystem, requiring adaptations of the alpine biota. Interaction between topography and snowcover strongly influences spatial heterogeneity of microclimate, which in turn influences and is influenced by the distribution of vegetation. For nearly 50 years investigators have used Niwot Ridge to examine and document the climate and its interaction with the biota of the alpine tundra. This chapter reviews some of the many findings of these ongoing bioclimatic investigations. Climate studies started on Niwot Ridge in October 1952 when Professor John W. Marr and his students set up a transect of climate stations across the Front Range between Boulder and the Continental Divide (Marr 1961). There were originally 16 stations in groups of four representing different slope exposures in what he defined as the Lower and Upper Montane Forest, the Subalpine Forest, and the Alpine Tundra ecosystems of the Front Range. After 1 year, the network was reduced to four stations, called Al, Bl, Cl, and Dl, which all had ridge-top locations and ranged from lower montane (Al) to high alpine (Dl). From time to time, these stations were supplemented by other stations that supported particular studies. This was especially true during the International Biological Programme years in the early 1970s when focus on work on the Saddle research site of the Ridge began. Following the establishment of Niwot Ridge and Green Lakes Valley as a Long-Term Ecological Research (LTER) site in 1980, even more intensive climatological work has been conducted. The construction of the Tundra Laboratory in August 1990 facilitated intensive winter climatological studies. Geographical locations and elevational data on most of the stations has been provided by Greenland (1989) and is also found in the LTER electronic database (http://culter.colorado.edu/). The climate of Niwot Ridge is characterized by large seasonal and annual variability with very windy and cold winters, wet springs, mild summers, and cool, dry autumns.
Soils
Authors: Seastedt Timothy R.
Published: November 2020

This chapter examines alpine soils from a traditional soil science and ecological perspective, with a bias toward the latter. Soil physical and chemical properties are presented, but the soils as a resource for the biota as well as the feedbacks between abiotic and biotic processes are emphasized. Over half a century ago, Hans Jenny (1941) developed a conceptual model of the factors responsible for soil development. Jenny recognized that parent material, climate, topography, and geological and ecological disturbance factors could be viewed as independent phenomena that interact to produce soils. Jenny (1980) subsequently expanded this model to one that was also useful to describe entire ecosystems. To date, I've found no better framework with which to explain soils as true ecosystem characteristics—an entity generated by the interaction of biota with the abiotic environment. Accordingly, the roles that parent materials, topography, climate, biota, and disturbance frequencies have in controlling the structural and functional aspects of alpine soils are discussed. Because each of these five factors of soil formation has the potential to interact with various combinations of the other four factors, the number of possible combinations—and soil types—is surprisingly large, especially when one or more of the five factors exhibits tremendous within-site variability. Certainly the alpine must rank “most heterogeneous” among terrestrial ecosystem types in terms of topography, making this variable particularly important in any discussion of soil characteristics. As will be demonstrated, however, the other four factors also exhibit significant variation that contributes to the complexity of the alpine soil landscape. Soil characteristics emphasized here include those variables that affect and are affected by biotic processes over time scales ranging from a single growing season to decades to centuries. Hence, cation exchange capacity (CEC), soil acidity (pH), soil water content, nutrient content and flux, and carbon storage and flux, are of primary concern. Detailed information about the soils of this region comes primarily from two sources, Scott Burns’s 1980 dissertation on soil distribution and development in the Niwot Ridge-Green Lakes region, and an extensive series of publications by M. I. Litaor. Burns provided classical soil descriptions based on the analysis of 97 extensive soil pit excavations.
An Evidentiary and Epistemic Shift
Authors: Oreskes Naomi
Published: November 2020

World War II dashed the hopes and dreams of many, among them Richard Field. As President of the American Geophysical Union, Field was to host the International Geological Congress when it met in Washington, D.C. at the end of the summer of 1939, an event Field was greatly anticipating. Scientists were expected from around the globe, and the permanence —or nonpermanence —of ocean basins was high on Field’s list of topics for discussion. But as the meeting was about to begin, Adolf Hitler’s armies invaded Poland; many delegates turned around mid-voyage, and others who had already arrived in Washington quickly returned home. The following year William Bowie died; two years later Charles Schuchert died at the age of eighty-four, and Field was involved in a near-fatal car crash which effectively ended his scientific career. Bowie’s and Field’s scientific goals would be realized, however, albeit not by them. Together, they had assembled an advisory committee for gravity studies that included five subsections —navigation, geophysics, tectonics, oceanology [sic], and marine microbiology—with prominent members from acaclemia, and industry in the United States and abroad and from the U.S. Navy. Their ambitions went beyond gravity: Bowie and Field hoped to foster a global science of geophysics and oceanography to explore the three-fifths of the earth that scientists had scarcely visited by enlisting the material and financial support of the U.S. Navy and other navies. The U.S. Navy, for its part, was making plans to enlist geophysicists, both figuratively and literally. When war broke out, Harry Hess joined the naval reserve, as did many other young and aspiring geophysicists and oceanographers. In 1941, Hess was called to active duty and became the captain of an assault transport, the USS Cape Johnson. Among the ship’s tasks was the echo sounding of the Pacific basin; Hess subsequently became famous for the discovery of flat-topped sea-mounts, which he named guyots after the first professor of geology at Princeton, Arnold Guyot. I less published this discovery, but much geophysical work done during the war, and after, was classified.
Future Directions in Jornada Research: Applying an Interactive Landscape Model to Solve Problems
Authors: Peters Debra P. C. , Schlesinger William H.
Published: November 2020

The long history of research at the Jornada Basin (through the Agricultural Research Service [ARS] since 1912, New Mexico State University in the late 1920s, and joined by the Long-Term Ecological Research [LTER] program in 1981) has provided a wealth of information on the dynamics of arid and semiarid ecosystems. However, gaps in our knowledge still remain. One of the most perplexing issues is the variation in ecosystem dynamics across landscapes. In this concluding chapter to this volume, we propose a new conceptual model of arid and semiarid landscapes that focuses explicitly on the processes and properties that generate spatial variation in ecosystem dynamics. We also describe how our framework leads to future research directions. Many studies have documented variable rates and patterns of shrub invasion at the Jornada as well as at other semiarid and arid regions of the world, including the Western United States, northern Mexico, southern Africa, South America, New Zealand, Australia, and China (York and Dick-Peddie 1969; Grover and Musick 1990; McPherson 1997; Scholes and Archer 1997; see also chapter 10). In some cases, shrub invasion occurred very rapidly: At the Jornada, areas dominated by perennial grasses decreased from 25% to < 7% from 1915 to 1998 with most of this conversion occurring prior to 1950 (Gibbens et al. 2005; Yao et al. 2002a). In other cases, shrub invasion occurred slowly, and sites were very resistant to invasion; for example, perennial grasses still dominate on 12 out of 57 research quadrats originally established in black grama (Bouteloua eropoda) grasslands in the early twentieth century (Yao et al. 2002b). Soil texture, grazing history, and precipitation patterns are insufficient to account for this variation in grass persistence through time (Yao et al. 2002a). It is equally perplexing that although many attempts to remediate these shrublands back to perennial grasses have led to failure, some methods worked well, albeit with long (> 50 year) time lags (Rango et al. 2002; see also chapter 14). Although variations in vegetation dynamics and shrub invasion are the most well known, other lesser known aspects of arid and semiarid systems have been found to be quite variable as well.
Supercritical Adsorption
Authors: Chimowitz Eldred H.
Published: November 2020

In this chapter, we discuss adsorption phenomena in supercritical systems, a situation that occurs in many application areas in chemical-process and materials engineering. An example of a commercial application in this area, which has achieved wide acceptance as a tool in analytical chemistry, is supercritical fluid chromatography (SFC). Not only is SFC a powerful technique for chemical analysis, but it also is a useful method for measuring transportive and thermodynamic properties in the near-critical systems. In the next section, we analyze adsorption-column dynamics using simple dynamic models, and describe how data from a chromatographic column can be used to estimate various thermodynamic and transport properties.We then proceed to discuss the effects of proximity to the critical point on adsorption behavior in these systems. The closer the system is to its critical point, the more interesting is its behavior. For very dilute solute systems, like those considered here, the energy balance is often ignored to a first approximation; this leads to a simple set of mass-balance equations defining transport for each species. These equations can be developed to various levels of complexity, depending upon the treatment of the adsorbent (stationary phase). The conceptual view of these phases can span a wide range of possibilities ranging from completely nonporous solids (fused structures) to porous materials with complicated ill-defined pore structures. Given these considerations, it is customary to make the following assumptions in the development of a simple model of adsorber-bed dynamics: . . .1. The stationary and mobile phases are continuous in the direction of the flow, with the fluid phase possessing a flat velocity profile (“plug” flow).. . . . . . 2. The porosity of the stationary phase is considered constant irrespective of pressure and temperature conditions (i.e., it is incompressible). . . . . . .3. The column is considered to be radially homogeneous, leading to a set of equations with one spatially independent variable, representing distance along the column axis. . . . . . . 4. The dispersion term in the model equation represents the combined effects of molecular diffusion and dispersion due to convective stirring in the bed. These effects are combined into an effective phenomenological dispersion coefficient, considered to be constant throughout the column. . . .
Motif Discovery in Protein Structure Databases
Authors: Glasgow Janice , Steeg Evan
Published: November 2020

The field of knowledge discovery is concerned with the theory and processes involved in the representation and extraction of patterns or motifs from large databases. Discovered patterns can be used to group data into meaningful classes, to summarize data, or to reveal deviant entries. Motifs stored in a database can be brought to bear on difficult instances of structure prediction or determination from X-ray crystallography or nuclear magnetic resonance (NMR) experiments. Automated discovery techniques are central to understanding and analyzing the rapidly expanding repositories of protein sequence and structure data. This chapter deals with the discovery of protein structure motifs. A motif is an abstraction over a set of recurring patterns observed in a dataset; it captures the essential features shared by a set of similar or related objects. In many domains, such as computer vision and speech recognition, there exist special regularities that permit such motif abstraction. In the protein science domain, the regularities derive from evolutionary and biophysical constraints on amino acid sequences and structures. The identification of a known pattern in a new protein sequence or structure permits the immediate retrieval and application of knowledge obtained from the analysis of other proteins. The discovery and manipulation of motifs—in DNA, RNA, and protein sequences and structures—is thus an important component of computational molecular biology and genome informatics. In particular, identifying protein structure classifications at varying levels of abstraction allows us to organize and increase our understanding of the rapidly growing protein structure datasets. Discovered motifs are also useful for improving the efficiency and effectiveness of X-ray crystallographic studies of proteins, for drug design, for understanding protein evolution, and ultimately for predicting the structure of proteins from sequence data. Motifs may be designed by hand, based on expert knowledge. For example, the Chou-Fasman protein secondary structure prediction program (Chou and Fasman, 1978), which dominated the field for many years, depended on the recognition of predefined, user-encoded sequence motifs for α-helices and β-sheets. Several hundred sequence motifs have been cataloged in PROSITE (Bairoch, 1992); the identification of one of these motifs in a novel protein often allows for immediate function interpretation.
Movement of Water Across Soils (Erosion)
Authors: Keefer Robert F.
Published: November 2020

Erosion is the physical wearing away of the land surface by running water, wind, or ice. Soil or rock is initially detached by falling water, running water, wind, ice or freezing conditions, or gravity. Movement of the rock or soil may follow. Erosion is the combination of detachment and movement of soil or rock. Water erosion can be subdivided into either natural or man-made. Natural or geologic erosion does not require the presence of man. This process has been going on from the moment that land masses were uplifted. An example of geologic erosion is the Grand Canyon in Arizona. Man-made erosion is also called “accelerated erosion” as it is more rapid than natural erosion. Changes that man or animals have made to the soil by cultivation, construction, or any movement of earth often result in loss of soil by erosion. Accelerated erosion involves raindrop erosion, sheet erosion, surface flow, and landscapes. For raindrop erosion to occur, there must be detachment of soil particles followed by either transportation or compaction. Sheet erosion is the slow wearing away of the surface of soil. Surface flow occurs when sufficient water collects to run downhill, resulting in small soil cuts (rills) that often develop into large ruts (gullies). Landslides or slips occur when large chunks of soil move as a unit downhill, often resulting in drops of several feet or more. As rain falls, the drops strike the soil surface moving the soil particles with energy being expended in three kinds of ways: (a) detachment— soil particles are broken into smaller pieces, (b) transportation— small soil grains are moved to a new location as they splash into the air; movement can be downward, to sides, or up eventually acting as a smoothing agent, or (c) compaction—raindrops compact soil surface on bare soil forming a crust, resulting in running the soil particles together (puddling) so that air and water can no longer enter the soil. This causes loss of infiltration and results in runoff.