bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil Organic Matter and Nutrient Dynamics of Shortgrass Steppe Ecosystems
Authors: Burke Ingrid C. , Mosier Arvin R.
Published: November 2020

Since the days of the IBP, there has been a strong emphasis on research about the biogeochemistry of shortgrass steppe ecosystems (e.g., Clark, 1977; Woodmansee, 1978). A major theme has been seeking to understand spatial and temporal patterns and controls of biogeochemical pools and fluxes at scales that span from several centimeters to hundreds of kilometers, and from hours to millennia. The synthesis of this work has resulted in a conceptual framework regarding the biogeochemical dynamics of the shortgrass steppe, with two key components:… 1. Spatial and temporal patterns are controlled by five 1. major factors: climate, physiography, natural disturbance, human use, and biotic interactions. Plants are the most important biotic component. The interaction of these factors as they change in time and space determines the distribution and size of biogeochemical pools and the rates of biogeochemical processes. 2. Carbon (C), nitrogen (N), and other associated biologically active elements are overwhelmingly located belowground, with more than 90% found in soils (Burke et al., 1997a). This distribution determines the biogeochemical sensitivity of the shortgrass steppe to perturbations…. These ideas have been synthesized in the development of the CENTURY ecosystem simulation model, originally developed for grasslands and agroecosystems in the shortgrass steppe region of the western Great Plains (Parton et al., 1987, and chapter 15, this volume). The model represents complex interactions among the five controlling factors to simulate C and N cycling, and has served as an organizing framework for developing hypotheses and for evaluating questions that are dif. cult to address in the field (Parton et al., chapter 15, this volume). The objectives of this chapter are to describe how nutrient pools and fluxes are distributed in the shortgrass steppe, to characterize how the five controlling factors interact to create spatial and temporal patterns, and to evaluate the potential future changes to which the biogeochemistry of the shortgrass steppe may be particularly vulnerable.
Information and its History
Authors: Headrick Daniel R.
Published: November 2020

Of the many labels pundits have suggested to identify the age we live in—the atomic age, the Postindustrial era, the space age—the expression information age has become the standard cliché. Why this label? Why now? No doubt because we have all sorts of new devices designed to keep us informed and in touch with anyone, anywhere, and at any time: beepers, cellular telephones, computers, “personal digital assistants,” and all their peripherals. We access more media of more varied sorts than ever before: dozens of television channels, soon to be hundreds; electronic networks turning into global information superhighways; and the imminent promise of cyberspace and virtual reality for everyone. In the business world, purveyors of software have dethroned computer makers, while manufacturers of audio and video equipment are turning into entertainment companies. In the wealthier countries, an ever-growing proportion of the gross domestic product comes from the information sector rather than from manufacturing, as more and more people work with computers and relax with electronic entertainment. Most of all, we face an ever-swelling tide of information in the form of Web sites, CDs, and DVDs, videotapes and video games, docudramas, data­bases, hypertexts, and infomercials, not to mention old-fashioned books, magazines, and newspapers. What, then, is this “information” that defines our epoch? To mathematicians and scientists, the term information means the reduction of uncertainty in a communication system. In that sense, any pattern of energy or matter in nature—tree rings, bits of DNA, light from a distant star, the spoor of an animal—contains information. Like the tree that falls in the forest, however, such patterns become human information only if there is a human being present who understands them. So let us leave undeciphered patterns to the scientists and think of information as patterns of energy and matter that humans understand. Information is not the same thing as knowledge, though the two concepts overlap. Knowledge refers to ideas and facts that a human mind has internalized and understood: how to fix a flat tire, the name of a really good dentist, speaking French. Acquiring knowledge means absorbing a lot of information—for example, how to use French irregular verbs correctly.
Transforming Information : The Origin Of Statistics
Authors: Headrick Daniel R.
Published: November 2020

We live in a sea of numbers. surrounded by a culture of statistics—IQs, grade point averages, gross domestic products, batting aver­ages, Dow-Jones Industrial Averages, probabilities of precipitation—it is not easy to imagine a world just awakening to the meaning of numbers. Statistics, in the sense of numbers representing data, first appeared in the eighteenth century and became a regular feature of the cultural landscape in the early nineteenth century. Nothing illustrates better the transformative power of numbers than the changing views of one of the era’s most influential thinkers, Thomas Robert Malthus. Malthus (1766 –1834) will always be remembered for his lapidary statements such as: “Population, when unchecked, increases in a geometrical ratio. Subsistence only increases in an arithmetical ratio.” This statement sounds mathematical, as if it were a law of nature, yet ominous: “if unchecked,” disaster will surely strike. That is how Malthusians, then and now, have always read it. Malthus wrote these words in 1798 to refute giddy optimists like the Marquis de Condorcet and William Godwin, who believed in the inevitability of progress. Though sincere, he wrote his Essay on Population without benefit of data. It aroused a passionate debate and encouraged the government to undertake the first census in British history in 1801. Armed with census data, Malthus revisited his ideas. He published a second edition in 1803 and, in later years, four more revised editions; they bore the same title but a different subtitle, for they were really a different work: many times longer, full of information, and much more refined. In the course of his life, Malthus changed his thinking about population and subsistence. He no longer predicted an inevitable demographic disaster but instead realized that “in no state that we have yet known, has the power of population been left to exert itself with perfect freedom.” Unlike North Americans and “uncivilized” peoples, Europeans kept their numbers under control by preventive checks, rather than waiting for famines to bring populations in line with the food supply: “An infrequency of the marriage union from the fear of a family . . . may be considered . . . as the most powerful of the checks, which in modern Europe, keep down the population to the level of the means of subsistence.”
Communicating Information Postal and Telegraphic Systems
Authors: Headrick Daniel R.
Published: November 2020

Paul revere, the american revolutionary, remembered his midnight ride of April 18, 1775, in these words: “I agreed with a Colonel Conant and some other gentlemen, that if the British went out by water, we should shew two lanthornes in the North Church steeple, and if by land, one, as a signal, for we were apprehensive it would be difficult to cross the Charles River, or git over Boston neck.” Eighteen years later, on July 12, 1793, Claude Chappe presented his semaphore telegraph to the Committee of Public Instruction of the French National Convention. At Saint-Fargeau, near Paris, Deputy Pierre Daunou sent a message to Deputy Joseph Lakanal at Saint-Martin-du-Tertre, thirty-five kilometers away: “Daunou has arrived here. He announces that the National Convention has just authorized its committee of general security to affix the seals to the papers of the representatives of the people.” Nine minutes later, Lakanal replied: “The inhabitants of this beautiful country are worthy of liberty because of their love for it and their respect for the National Convention and its laws.” Between these two dates there occurred a revolution in communication. Revere used a simple, prearranged, onetime signal containing only three potential messages: “by land,” “by sea,” or “no news.” Chappe could communicate any message, in either direction, faster than a galloping horse. This was only one of several great changes in communication that occurred in the late eighteenth and early nineteenth centuries under the pressure of revolution and war. Humans are gifted, both naturally and culturally, at communicating face-to-face. Long-distance communications, however, require elaborate systems to convey information to its destination in a timely manner. Over­coming distances is but one of the functions of communication systems. We must also draw a distinction between the transmission of information from one person to another, for example, by speech, letter, telephone, telegram, or e-mail, and the dissemination of information from one point to many, by such means as newspapers, books, pamphlets, flyers, and posters, or by radio and television broadcasts and the World Wide Web.
Cellular Automata for Imaging, Art, and Video
Authors: Hughes Joy V.
Published: November 2020

The techniques known as Cellular Automata (CA) can be used to create a variety of visual effects. As the state space for each cell, 24-bit photo realistic color was used. Several new state transition rules were created to produce unusual and beautiful results, which can be used in an interactive program or for special effects for images or videos. This chapter presents a technique for applying CA rules to an image at several different levels of resolution and recombining the results. A “soft” artistic look can result. The concept of “targeted” CAs is introduced. A targeted CA changes the value of a cell only if it approaches a desired value using some distance metric. This technique is used to transform one image into another, to transform an image to a distorted version of itself, and to generate fractals. The author believes that the techniques presented can form the basis for a new artistic medium that is partially directed by the artist and partially emergent. Images and animations from this work are posted on the World Wide Web at (http://www.scruznet.com/~hughes/CA.html). All cellular automata (CA) operate on a space of discrete states. The simplest CAs, such as the Game of Life, use a 1-bit state space. Most modern personal computers represent color as a 24-bit value, allowing for approximately 16 million possible colors. The work presented in this chapter uses a 24-bit color space that is represented in a 32-bit-long integer. This color space can be conceptualized as a three-dimensional bounded continuous vector space. Often, it is desirable to work with in the HSV (Hue, Saturation, Value) color space. Some of the rules encode the value (luminance) of a cell in the otherwise unused 8 high-order bits of a 32-bit word. The hue and saturation can be estimated “on the fly” with simple, fast algorithms. The hue is represented as an angle on the color wheel. For some rules, it is necessary to know the “distance” between two colors. Estimating the distance in perceptual space would be a difficult problem, as it would be dependent on the monitor used and the gamma exponent applied for a particular setup.
Climate Variability in the Context of Climate Change: El Niño and Other Oscillations
Authors: Rosenzweig Cynthia , Hillel Daniel
Published: November 2020

The climate system envelops our planet, with swirling fluxes of mass, momentum, and energy through air, water, and land. Its processes are partly regular and partly chaotic. The regularity of diurnal and seasonal fluctuations in these processes is well understood. Recently, there has been significant progress in understanding some of the mechanisms that induce deviations from that regularity in many parts of the globe. These mechanisms include a set of combined oceanic–atmospheric phenomena with quasi-regular manifestations. The largest of these is centered in the Pacific Ocean and is known as the El Niño–Southern Oscillation. The term “oscillation” refers to a shifting pattern of atmospheric pressure gradients that has distinct manifestations in its alternating phases. In the Arctic and North Atlantic regions, the occurrence of somewhat analogous but less regular interactions known as the Arctic Oscillation and its offshoot, the North Atlantic Oscillation, are also being studied. These and other major oscillations influence climate patterns in many parts of the globe. Examples of other large-scale interactive ocean–atmosphere– land processes are the Pacific Decadal Oscillation, the Madden-Julian Oscillation, the Pacific/North American pattern, the Tropical Atlantic Variability, the West Pacific pattern, the Quasi-Biennial Oscillation, and the Indian Ocean Dipole. In this chapter we review the earth’s climate system in general, define climate variability, and describe the processes related to ENSO and the other major systems and their interactions. We then consider the possible connections of the major climate variability systems to anthropogenic global climate change. The climate system consists of a series of fluxes and transformations of energy (radiation, sensible and latent heat, and momentum), as well as transports and changes in the state of matter (air, water, solid matter, and biota) as conveyed and influenced by the atmosphere, the ocean, and the land masses. Acting like a giant engine, this dynamic system is driven by the infusion, transformation, and redistribution of energy.
Analysis of El Niño Effects: Methods and Models
Authors: Rosenzweig Cynthia , Hillel Daniel
Published: November 2020

Knowledge of climate impacts is necessarily embedded in multifaceted, multiscaled contexts. The many facets include physical, ecological, and biological factors—as well as social, political, and economic ones—interacting on a spectrum of scales ranging from the individual to the household, the community, the region, the nation, and the world. Such complexities encompass natural as well as cultural aspects. Therefore, assessing the role of climate requires a comprehensive, integrated approach. Various methods and models have been proposed or developed to aid understanding of the relationships between agriculture and climate variability (and more specifically, ENSO) in regions around the world. Relevant methods include socioeconomic research techniques such as interviews and surveys; statistical analyses of climate and agronomic data; spatial analysis of remote-sensing observations; climate-scenario development with global and regional climate models and weather generators; and cropmodel simulations. Here we describe conceptual models that guide regional analysis, a framework of methods for regional studies, and examples of research in several agricultural regions that experience varying degrees of ENSO effects. Conceptual models are important because they can guide research and application projects and help physical, biological, and social scientists work together effectively within a common context. Equally important is the role of conceptual models in promoting effective interactions between researchers and agricultural practitioners. An early conceptual model for enhancing the usefulness of seasonal climate forecasts has been called the “end-to-end” approach (figure 5.1a). This model consists of a linear unidirectional trajectory in which El Niño events precipitate climate phenomena that, in turn, induce agronomic responses, with ensuing economic consequences. In disciplinary terms, the end-to-end trajectory begins with the physical sciences, proceeds to agronomy, and then to social science—primarily economics. The end-to-end model quickly evolved into an “end-to-multiple-ends” approach (figure 5.1b) because social science consists of many disciplines besides economics. Outcomes and insights regarding the use of seasonal climate forecasts differ, depending on whether the disciplines of economics, anthropology, political science, or sociology are involved. However, a weakness of these conceptual models is the absence of agricultural practitioners (e.g., farmers, planners, input providers, and insurers) in the research process.
“Most Beautiful Sewer”
Authors: Cumbler John T.
Published: November 2020

The reforms of the late nineteenth century did help protect New England’s drinking water. The plague of water-borne diseases that made the region’s cities so infamously dangerous to live in seemed to be in retreat. For a moment, it looked as if the new century would bring a world in which there did not have to be trade-offs between economic development and environmental quality. The ideal articulated by Lyman and Mills—that professional expertise would transcend conflicts of interests between manufacturers and reformers—seemed at hand. Yet there were still problems that these optimists overlooked. And these problems broke into view again in the new century. Despite the health gains, New England’s rivers and streams continued to receive massive influxes of pollution of both industrial wastes and human sewage. The larger cities along the major river systems continued their practice of dumping raw sewage downstream, while manufacturers still saw running water as a natural disposal system for their wastes. Industrial wastes, although less central in the conversation around public health and the environment, were clearly polluting water systems, and reformers never completely gave up the struggle to clean water of industrial pollutants. In its 1896 report, the Massachusetts State Board of Health discussed possible solutions to the problems of “waste liquors or sewage from those manufacturing industries in the State which pollute or threaten to pollute our rivers and ponds.” The Lawrence station experimented with different methods of removing industrial wastes. Yet the “problem of successful and economical disposal of this sewage [remained].” As people began to look at clean water as an aesthetic as well as a health issue, the ability of water to sustain live fish, which had been dismissed twenty years earlier, now became a concern. Commissions on fisheries that had focused attention on fishways and fish cultivation in the nineteenth century began to revisit the issue of water pollution as they noticed their hatchery fish dying in polluted waters; oyster growers complained to the commissions that their oyster beds were being polluted.
Corinth
Authors: Fant Clyde E. , Reddish Mitchell G.
Published: November 2020

No city in the ancient world both benefited and suffered from its location more than Corinth. Situated on the main north-south route between northern and southern Greece, and with two good ports that linked it to Italy on the west and Asia Minor on the east, Corinth quickly became a center for commerce. But the location of Corinth also had its downside. The city often found itself caught in the middle between hostile neighbors, Athens to the north and Sparta to the south. Armies crisscrossed its streets as often as merchants, and more than once the city had to arise from ashes and rubble. Today only Athens attracts more interest in Greece for its historic antiquities than Corinth. It ranks as a must-see location for every traveler to Greece. Ancient Corinth is located less than two hours south of Athens. Tours run often from local hotels. Likewise, a rental automobile gives easy access and makes it possible to see nearby sites of interest not on the usual tours. The great city of Corinth prospered for many reasons. In addition to its prominence as a center for trade and commerce, agriculture also flourished in the area. The soil around the city was thin and rocky, but just to the west, along the Nemean River, a rich plain produced heavy harvests of grain and other crops. Raisins were first developed there, and the word currant is a medieval corruption of Corinth. Tourism was another important source of income. The famous Isthmian Games, second only to the Olympic Games and more prestigious than those held in Delphi and Nemea, brought thousands of tourists to Corinth every two years and further added to its fame and fortune. During its early period Corinth also attracted many travelers to its famous (or notorious) Temple of Aphrodite atop the Acrocorinth (“high Corinth,” or upper Corinth, the portion of the city atop the 1,900-foot mountain to the southeast of the city). Additionally, according to Plutarch, these multiple sources of wealth caused Corinth to become one of the three great banking centers of Greece, along with Athens and Patrae.
Mitylene
Authors: Fant Clyde E. , Reddish Mitchell G.
Published: November 2020

The beautiful island of Mitylene, known also as Lesvos or Lesbos, serves only as a footnote in the biblical account of the journeys of the Apostle Paul, but its fine museums and splendid scenery make it well worth including in visits to the Greek islands. Noted since antiquity as a place of unusual warmth and sunshine, even in winter, this third largest of the Greek islands produces the finest olive oil in all of Greece. The interior of the island is mountainous and forested, and the northern side of the island, around picturesque Methymna, provides excellent beaches. Mitylene (also the name of the capital city) lies less than 10 miles off the Turkish coast. It can be reached by flights from Athens and Thessaloniki (approximately one hour); ferries also run from these ports, but the crossing time is 9–12 hours. There is a ferry that connects the island to Ayvalik, Turkey; Pergamum is only 35 miles inland. Until the 6th century B.C.E., when Pitticus, one of the Seven Sages of Greece, served as sole ruler of the island (r. 589–579 B.C.E.), the towns of Mitylene and Methymna struggled for dominance of the island. During this time Mitylene developed a strong maritime fleet, extended its commerce as far as Egypt, and achieved fame for its notable poets, Alcaeus and Sappho (6th century B.C.E.). The poetry of Sappho was greatly admired by both Solon and Plato, who called her the tenth Muse. An aristocrat who established a school for women at Mitylene, Sappho became world-famous, or infamous, because of her love poetry concerning women. Much of the ridicule directed toward her came from the Athenian comic poets, who lampooned the greater freedom given to women on Mitylene. In the 4th century B.C.E., the famous philosophers Aristotle and Epicurus both taught on Mitylene. Julius Caesar first won distinction as a military commander when the Romans invaded the island in the 1st century B.C.E. Over the following centuries the island suffered repeated invasions by one world power after another until 1462, when it was taken by the Turks, who retained possession of it until 1912.
Samos
Authors: Fant Clyde E. , Reddish Mitchell G.
Published: November 2020

The island of Samos, one of the most pleasant of all the Greek islands, played an important role in both Greek and Roman history. The significance of Samos was due to its strategic location and its fame from three sources: the Great Temple to Hera, one of the most renowned in the ancient world; the Tunnel of Eupalinus, one of the great engineering feats of antiquity; and two of its most famous citizens, the moralist Aesop and the mathematician Pythagoras, of Pythagorean theorem fame. Samos is located only 1 mile from the shore of western Turkey. It received its name, according to Herodotus, because of its mountainous terrain. Samos means “high land” and seems to have been derived either from the Phoenician word sama or from the Ionian word samo, both of which have the same meaning. (Another island to the north has a similar name, Samothrace, which means the samos of nearby Thrace.) This relatively small island, 14 miles wide and 27 miles long, shows evidence of occupation at least as early as the 4th millennium B.C.E. Later, abundant evidence attests to further occupation in the Early Bronze Age by the Mycenaeans. Likewise, the Ionians established colonies on the island during the early Iron Age and it subsequently became a great naval power. Sometime during the 8th century B.C.E., Samos obtained land on the opposite coast of Asia Minor, which led to ongoing conflict with neighboring Priene. The most famous, and infamous, ruler of Samos was Polycrates, the tyrant who ruled from approximately 550 B.C.E. until 522 B.C.E., when he was lured to Asia Minor and subsequently crucified by the Persians. During his reign, according to Strabo, the naval fleet of Samos became the first to rule the Aegean Sea since the days of the Minoan civilization. Polycrates established a cultured court, encouraged fine arts, and invited the famous hydraulics engineer Eupalinus of Megara to construct the great water tunnel that became known as the Tunnel of Eupalinus. Other public works projects included the construction of great walls around the city.
Myra
Authors: Fant Clyde E. , Reddish Mitchell G.
Published: November 2020

At one time one of the most important cities in Lycia, Myra almost has passed into obscurity. In addition to some interesting tombs and a theater, the most enduring legacy of ancient Myra is the tradition that developed around its most famous resident and bishop, St. Nicholas, who was the historical person behind the legend of Santa Claus. Popular etymology explained the name of the city as being derived from the Greek word for myrrh, an aromatic spice, but this is unlikely. Myra was a city in the Lycian region of Anatolia, along the Mediterranean coast approximately 85 miles southeast of modern Antalya. The ruins of ancient Myra lie about a mile north of Demre (or Kale), a small town along highway 400, the coastal road. Signs in the town point the way to Myra. The ancient city was considered a port city, even though it was about 3.5 miles from the coast. Its port was actually Andriace, but the name Myra often included the city proper and its port at Andriace. Thus, for example, when Acts 27:5 states that the ship carrying Paul landed at Myra, the actual port would likely have been Andriace. Whether Paul and the others with him went to Myra after disembarking from the ship is not known. The Myrus, or Andracus, River (Demre Çayï) flowed past the city on its way to the Mediterranean. Settled probably as early as the 5th century B.C.E., Myra became one of the leading cities of the Lycian League by the 2nd century B.C.E. Myra was one of the six most important members of the league, which consisted of twenty-three cities. As such, it was entitled to three votes in the league (the maximum allowed). In spite of its importance, the city does not seem to have played a major role in ancient history. During Roman times the city apparently enjoyed good relations with Rome. Augustus (and after him, Tiberius as well) was honored by the people of Myra by their bestowing on him the title of “imperator of land and sea, benefactor and savior of the whole universe.”
Philadelphia
Authors: Fant Clyde E. , Reddish Mitchell G.
Published: November 2020

The ancient city of Philadelphia is primarily remembered as one of the seven cities mentioned in the book of Revelation. Because the city was in an earthquake-prone area, not much remains to be seen of ancient Philadelphia. What might still exist lies buried, for the most part, under the modern city. Situated approximately 30 miles southeast of the site of ancient Sardis on highway 585, Alaşehir is the name of the modern city located on the site of ancient Philadelphia. Philadelphia was on a plateau in the Cogamus River valley (today the Alaşehir Çayï), a tributary of the Hermus River. In antiquity, the Persian Royal Road from Sardis to Susa (in modern Iran) ran through Philadelphia. Prior to the Hellenistic founding of the city of Philadelphia, an earlier settlement here was known as Calletebus, dating back several centuries. The city was named for Attalus II Philadelphus, the Attalid king of Pergamum from 159 to 138 B.C.E., whose loyalty to his brother Eumenes II Soter, who preceded him as king (r. 197–159 B.C.E.), earned him the nickname “Philadelphus,” meaning “brotherly love.” Either Eumenes or Attalus founded the city, which was in the Lydian region of ancient Anatolia. After Attalus III (r. 138–133 B.C.E.) bequeathed the Pergamene kingdom to the Romans in 133 B.C.E., Philadelphia came under Roman control. The area around Philadelphia was a fertile agricultural area, especially good for growing grapes. Unfortunately, the area was also susceptible to frequent earthquakes. A particularly devastating earthquake struck the area in 17 C.E., destroying the city of Sardis and doing extensive damage to Philadelphia. To help the city recover from this disaster, Emperor Tiberius remitted the tribute owed to Rome for a period of five years. In gratitude, Philadelphia took the name Neocaesarea and dedicated a temple to Tiberius. Although the city was slow to recover from the devastation caused by the earthquake and its aftershocks, it eventually prospered under Roman rule. By the 5th century it was sometimes referred to as “little Athens” because of its many temples and religious festivals.
Ecosystems in Zones of Conflict: The Case for Bandwidth Management
Authors: van Eeten Michel J. G. , Roe Emery
Published: November 2020

What profession that is core to ecosystem management is described in the following passage? . . . [Their professional] representation of a . . . system can be typified as physical, holistic, empirical, and fuzzy; . . . [treating] the system more as a whole than in terms of individual pieces; ... [expecting] uncertainty rather than deterministic outcomes...; [taking] uncertainty or “fuzziness” . . . to be inevitable and, to some degree, omnipresent; [seeing] ambiguity . . . pervade the entire system, and . . . [suspecting] the unsuspected at every turn. . . . [T]he underlying notion [in their professional culture] is that no amount of rules and data can completely and reliably capture the actual complexity of the system . . . [I]t is more important . . . for [these professionals] to maintain an overview of the behavior of the whole system than to have detailed knowledge about its components. . . . [They] tend to be very wary of [the pressure to intervene], primarily because it runs counter to a basic attitude of conservatism fostered by their culture: “when in doubt, don’t touch anything.” Their reluctance to take any action unless it is clearly necessary arises from the awareness that any operation represents a potential error, with potentially severe consequences. (Von Meier 1999, pp. 104-107) . . . We suspect that many readers would see ecologists (writ large again) as the professional group whose views are being described. Ecologists, as we have seen, frequently describe the ecosystem in just such terms: it responds to external disturbances, the whole system is more than the sum of its parts, it displays nondeterministic behavior, its complexity can never be fully captured and, therefore, management is extremely challenging, with managers always reluctant to intervene—at least in major ways—in ecosystems they do not know, because this potentially creates more problems than it solves. However, ecologists are not the group being described, and here is the surprise. Though the quoted phrases are almost textbook ecology material, the professional culture discussed here is in fact that of line operators in high reliability organizations (HROs).
Species Diversity and Ecosystem Processes in Water-Limited Systems
Authors: Shachak Moshe , Pickett Steward T.A.
Published: November 2020

There are many relationships between ecosystem properties and species (Jones and Lawton, 1995) with the potential links described by five hypotheses: 1. The null hypothesis claims that there is no effect of species diversity on ecosystem processes. The following hypotheses imply biological mechanisms. 2. The diversity–stability hypothesis predicts that ecosystem productivity and recovery increase as the number of species increases (Johnson et al. 1996). 3. The rivet hypothesis predicts a threshold in species richness, below which ecosystem function declines steadily and above which changes in species richness are not reflected by changes in ecosystem function (Ehrlich and Ehrlich 1981; Vitousek and Hooper 1993). 4. The redundant species hypothesis states that species loss has little effect on ecosystem processes if the losses are within the same functional group (Walker 1992) 5. The idiosyncratic response hypothesis suggests that as diversity changes so do ecocosystem processes (Lawton 1994, Lawton and Brown 1994). There have been both field and laboratory attempts to test these hypotheses, (Naeem and Li 1998), however, the interpretation and the generality of the results remain contentious (Tilman 1999). A fundamental reason for such uncertainty is that the hypotheses are not driven by a comprehensive theory of the relationship between species properties and ecosystem processes (Tilman et al., 1997). We propose that the foundations for the necessary theory are in models of the distribution of resources and their utilization by organisms. This is because ecosystem processes such as primary production, decomposition, mineralization, and evapotranspiration are dependent on the processing of resources by the species that are producers, consumers, and decomposers. A theory that links the direct participation of species in ecosystem processes may resolve differences among the various hypotheses or identify how they complement each other. From a community perspective, a theory of resource utilization is based on two alternative assumptions: 1. The rate of ecosystem processes is determined by the few species that are most efficient in using and converting resources. For example, in a desert system, dominant species are those that are proficient in using water for biomass production or in converting inorganic matter into organic materials.
Resource Partitioning and Biodiversity in Fractal Environments with Applications to Dryland Communities
Authors: Ritchie Mark E. , Olff Han
Published: November 2020

Arid and semiarid ecosystems (drylands) often contain a higher diversity of animals and plants than would be expected from their low productivity. High spatial heterogeneity of resources and physical habitats, exhibited at a wide range of spatial scales (Rundel 1996, Holling 1992, Peterson et al. 1998), may be a major factor explaining such high diversity. For example, at extremely small scales (<10 cm), branched plant material and various soil physical processes can create spatial niches for invertebrates, cyanobacteria, and other cryptogamic organisms (Lightfoot and Whitford 1991). At somewhat larger scales (<10 m), desert shrubs may aggregate water and organic material in “islands of fertility,” yielding a highly patchy heterogeneous distribution of resources (e.g., seeds, water) for other plants and animals (Gibbens and Beck 1988, Halvorson et al. 1997, chapter 13 this volume, chapter 11 this volume). At even larger scales (>100 m), soil erosion patterns create topographic variation that locally concentrates available water and nutrients, yielding a marked heterogeneity in the distribution of productivity across the landscape (Milne 1992). These heterogeneous distributions of physical environments, biotic material, and resources are likely to have strong effects on biodiversity. Ecologists have long associated greater spatial heterogeneity with higher species diversity (MacArthur 1964; Brown 1981; May 1988). Within a particular physical environment (habitat), this association exists presumably because collections of species that use similar resources, or “guilds,” can coexist whenever they can more finely divide up space and different-sized resource “packages” (Hutchinson and MacArthur 1959, Brown 1981, 1995, Morse et al. 1985, Peterson et al. 1998). The partitioning of space and different resource patches may be constrained by the different body sizes of species within guilds (Hutchinson and MacArthur 1959, Morse et al. 1985, Belovsky 1986, 1997, Brown 1995, Siemann et al. 1996). However, the mechanism by which body size and spatial heterogeneity of habitats and resources determine species diversity remains unclear (May 1988, Brown 1995, Siemann et al. 1996, Belovsky 1997). Resource partitioning and spatial heterogeneity therefore may strongly influence diversity in drylands, where, for example, well-known guilds of granivorous vertebrates and invertebrates are structured by competition for different sizes of seeds and seed patches (Brown et al. 1979, Davidson et al. 1980, 1985).
Radon In Your Basement
Authors: Goldstein Inge F. , Goldstein Martin
Published: November 2020

We once saw a science fiction movie in which a monster from outer space is first detected because it sets Geiger counters clicking furiously. We were reminded of that movie by the story of how radon in homes first came to wide public attention. A nuclear power plant was built in a town in Pennsylvania, and like all such plants was equipped with radiation detectors, both to protect the health of employees and to prevent anyone from removing nuclear fuel from the plant. A newly employed engineer at the plant registered a high radioactivity when he walked by the detectors. This was not only alarming but surprising: the plant was not yet operating, and there should not have been any radioactive material around. It was quickly established that the source of the radiation was not the plant but the engineer’s house in a nearby suburban community, which had levels of radioactivity almost a thousand times greater than federal standards permit in mines. The radioactivity came from radon gas seeping into the house from the ground. Cigarette smoking is responsible for about 90% of lung cancers, but 10% of the victims of this disease had never smoked. It was already known that miners exposed to radon gas in uranium mines suffered a high rate of lung cancer, and the question immediately arose: could radon gas in homes be another cause of lung cancer? Radon in homes is not a consequence of the atomic bomb or the building of nuclear power plants; it is one of the major sources of the natural background radiation we are all exposed to. It is present even in outdoor air, and at higher concentrations in homes, castles, peasants’ hovels, and caves as long as people have lived in them. It is a product of the decay of the element uranium. Uranium is present to some extent in all minerals, so we expect to find more radon in houses built of stone or mineral products like stone, concrete, and gypsum than in houses built of wood, and we expect to find more of it in basements than in attics.
Negative-Energy States and Quantum Electrodynamics
Authors: Dyall Kenneth G. , Faegri Knut
Published: November 2020

We now return to the problem of the negative-energy solutions that appeared when we solved the free particle Dirac equation in the previous chapter. The energy eigenvalues obtained there were either E+ = +√(m2c4 + p2c2) or E− = − √(m2c4 + p2c2) . The minimum absolute values we can have are therefore |E| = mc2 for p = 0 (that is, the particle at rest). As the momentum of the particle increases, we generate a continuum of solutions, either below − mc2 or above + mc2. This is a general feature of all solutions we will obtain from the Dirac equation—we will have continuum solutions on both sides of an energy gap stretching from − mc2 to + mc2, in addition to any discrete solutions. Classically and nonrelativistically we would expect a free particle to have a positive energy. The addition of a rest mass term mc2, which is definitely also positive, should not change this. However, the fact that we now have negative-energy states means that a single particle in a positive-energy state could spontaneously fall to a negative energy state with the emission of a photon. The interaction with the radiation field occurs via the operator α • A. The radiative transition moment therefore connects the large component of the positive-energy solution with the small component of the negative-energy solution. As we have seen, both of these should be large in magnitude, giving a large transition moment. Calculations (Bjorken and Drell 1964) show that the transition rate into the highest mc2 section of the negative continuum is approximately 108 s−1, and the rate of decay into the whole continuum is infinite. Any bound state would therefore immediately dissolve into the negative continuum with the emission of photons. This is clearly an unphysical situation. To resolve this dilemma, Dirac postulated in 1930 that the negative-energy states are fully occupied. The implications of this postulate are significant and wide-ranging.
One-Electron Atoms
Authors: Dyall Kenneth G. , Faegri Knut
Published: November 2020

The development of quantum chemistry, that is, the solution of the Schrödinger equation for molecules, is almost exclusively founded on the expansion of the molecular electronic wave function as a linear combination of atom-centered functions, or atomic orbitals—the LCAO approximation. These orbitals are usually built up out of some set of basis functions. The properties of the atomic functions at large and small distances from the nucleus determines to a large extent what characteristics the basis functions must have, and for this purpose it is sufficient to examine the properties of the hydrogenic solutions to the Schrödinger equation. If we are to do the same for relativistic quantum chemistry, we should first examine the properties of the atomic solutions to determine what kind of basis functions would be appropriate. However, the atomic solutions of the Dirac equation provide more than merely a guide to the choice of basis functions. The atoms in a molecule retain their atomic identities to a very large extent, and the modifications caused by the molecular field are quite small for most properties. In order to arrive at a satisfactory description of the relativistic effects in molecules, we must first of all be able to treat these effects at the atomic level. The insight gained into the effects of relativity on atomic structure is therefore a necessary and useful starting point for relativistic quantum chemistry. As in the nonrelativistic case, most of the salient features of the atomic systems are exposed in the treatment of the simplest of these, the hydrogen-like one-electron atoms. In Hartree atomic units the time-independent Dirac equation yields the coupled equations where we have shifted the energy by −mc2 (with m = 1), as discussed in section 4.6. We will use this shifted energy scale for the rest of the book unless otherwise explicitly indicated. V is here a scalar, central potential.
Core Approximations
Authors: Dyall Kenneth G. , Faegri Knut
Published: November 2020

When we think of chemical bonding, we usually think only of the valence orbitals. It is these orbitals that form bonds, and the core orbitals are not involved in the chemistry. To be sure, this is only a qualitative picture, but it raises the question of whether we really need to consider the core orbitals in our calculations. For heavy elements, the number of core orbitals is not small. An element such as platinum, from the third transition series, has 30 orbitals in the first four shells that could be classed as core orbitals. If these remain essentially atomic over some region of the molecular potential energy surface, they might as well be fixed in their atomic form. That is, we would make a frozen-core approximation, and all that the core orbitals are doing is supplying a nonlocal static potential that could be evaluated once and used for the remainder of the calculation. As relativistic effects are to a large extent localized in the core region, they could be included in the frozen-core potential. We could then treat the valence orbitals and the orbitals on the light atoms nonrelativistically, as we did in the previous chapter. This would save all the work of calculating the relativistic integrals, and the calculation would be as cheap as a nonrelativistic calculation. There is one main difficulty with this idea, and that is the orthogonality of the rest of the orbitals to the frozen core. The basis sets we use in molecular calculations are not automatically orthogonal to the core of any one atom: we must make them so by some procedure, such as Schmidt orthogonalization. But this involves taking linear combinations of the core and valence orbitals, and then we not only have to calculate all the integrals involving the core, we also have to transform them to the orthogonal basis. The reintroduction of the core integrals means that we have to calculate all the relativistic contributions that we had previously put into the frozen-core potential. Obviously, this is not a satisfactory state of affairs. Two solutions to this problem are in common use.
The Role of Insect Parasitoids in Population Cycles of the Spruce Needleminer in Denmark
Authors: Münster-Swendsen Mikael
Published: November 2020

The spruce needleminer, Epinotia tedella (Cl.) (Lepidoptera: Tortricidae), is a small and abundant moth associated with Norway spruce (Picea abies Karst.). Larvae mine spruce needles, usually those more than 1 year old, and each requires about 35 needles to meet its food demands. In central Europe, the spruce needleminer is regarded as a temporary, serious pest when densities reach several thousand per square meter. However, it seldom causes significant damage in Scandinavian countries. An exception was the heavy infestation in southern Denmark in 1960-61. The spruce needleminer has one generation per year. Adults emerge in June and deposit eggs singly on spruce needles. Larvae mine the needles from July through October and then descend on silken threads in November to hibernate in the forest litter as prepupal larvae in cocoons. Pupation occurs in early May and lasts 3-4 weeks. Like many other forest defoliators, spruce needleminers are associated with a diverse fauna of parasitic Hymenoptera (parasitoids) (Münster-Swendsen 1979). Eggs are attacked by a minute wasp (Trichogramma sp.) that kills the embryo and emerges as an adult a few weeks later. Because spruce needleminer eggs have all hatched by this time, the parasitoids must oviposit in the eggs of other insect species. In other words, this parasitoid is not host-specific and therefore not expected to show a numerical response to spruce needleminer population changes. Newly hatched moth larvae immediately bore into needles and, because of this, are fairly well protected against weather and predators. However, specialized parasitic wasps (parasitoids) are able to deposit their eggs inside a larva by penetrating the needle with their ovipositor. Two species, Apanteles tedellae (Nix.) and Pimplopterus dubius (Hgn.), dominate the parasitoid guild and sometimes attack a large percentage of the larvae (Münster -Swendsen 1985). Parasitized larvae continue to feed and, in November, descend to the forest floor to overwinter with unparasitized individuals. In late April, however, the parasitoids take over and kill their hosts. Besides mortality from endoparasitoids, up to 2% of the larvae die within the mine due to an ectoparasitoid and a predatory cecidomyid larva.