bluuebunny/crossref_metadata_2025 huggingface dataset:
The Quasi-Quintennial Timescale—Synthesis
Authors: Smith Raymond C. , Yuan Xiaojun
Published: November 2020

The El Nino–Southern Oscillation (ENSO) is one of the most important contributors to interannual variability on Earth (Diaz and Markgraf 2000). It is an aperiodic phenomenon that tends to reoccur within the range of 2 to 7 years, and it is manifest by the alternation of extreme warm (El Niño) and cold (La Niña) events. There is also evidence (Allen 2000) that the aperiodic ENSO phenomenon must be considered in conjunction with climate fluctuations at decadal to multidecadal time frames that may modulate ENSO’s lower frequency variability. Numerous studies show global climatic impacts associated with the ENSO phenomenon. Further, there is considerable evidence to indicate that ENSO impacts the climate of both middle and high latitudes, and a recent analysis (figure S.1, discussed below) provides a global picture of warm versus cold ENSO conditions. Consequently, it is not surprising that many LTER sites, from the Arctic to Antarctic, show evidence of ENSO-related fluctuations in environmental variables. The quasi-quintennial timescale of variability is second only to seasonal variability in driving worldwide weather patterns. Consequently, an important theme in part II is the worldwide influence of ENSO-related climate variability and the teleconnected spatial patterns of this variability. Also, a common theme for several ecosystems discussed in this section is their high sensitivity to small climatic changes that are subsequently amplified and cascaded through the system. For example, the narrow temperature threshold for an ice-to-water phase change may create a pronounced nonlinear ecosystem response to what is a relatively small temperature shift (as demonstrated for the McMurdo Dry Valleys). Or alternatively, this narrow temperature threshold may shift a sea ice–dominated ecosystem (Palmer LTER) to a more oceanic marine ecosystem by reducing the seasonality and magnitude of the sea ice habitat. Such nonlinear amplifications of small climatic changes can increase the ecological response and make it more detectable within the natural background of variability. We explore these themes here. To illustrate the global footprint of ENSO variability, composites of yearly averaged El Niño and La Niña conditions for surface air temperature (SAT) and sea surface temperature (SST, Reynolds and Smith 1994) were generated.
Introductory Overview
Authors: Goodin Douglas G.
Published: November 2020

Timescale is the organizing framework of this volume. In various sections, we consider the effects of climate variability on ecosystems at timescales ranging from weeks or months to centuries. In part III, we turn our attention to interdecadal-scale events. The timescales we consider are not absolutely defined, but for our purposes we define the interdecadal scale to encompass effects occurring with recurring cycles generally ranging from 10 to 50 years. A recurring theme in many of the chapters in this section is the effect on ecosystem response of teleconnection patterns associated with recognized quasi-periodic atmospheric circulation modes. These circulation modes include the well-known El Niño– Southern Oscillation (ENSO) phenomenon, which is generally thought to recur at shorter, interdecadal timescales but also includes some longer-term periodicities. Several other climate variability modes, including the Pacific North American index (PNA), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and North Pacific index (NP) also show strong interdecadal scale signatures and figure prominently in the chapters of part III. McHugh and Goodin begin the section by examining the climate record at several North American LTER sites for evidence of interdecadal-scale fluctuation. They note that interdecadal-scale contributions to climate variability can best be described in terms of two types of variation: (1) discontinuities in mean value, and (2) the presence of trends in the data. Evaluation of interdecadal periodicities in LTER data is complicated by the relatively short time series of observations available. McHugh and Goodin approach the problem mainly through the use of power spectrum analysis, a widely used tool for evaluating the periodicity in a time series of data. Principal components analysis is used to decompose the time series of growing-season climate data for each of the LTER sites into their principal modes of variability. These modes are then subjected to power spectrum analysis to evaluate the proportions of the variance in the data occurring at various timescales. McHugh and Goodin’s results suggest that significant effects on precipitation and temperature at interdecadal timescales are uncommon in these data, although significant periodicities at both shorter and longer frequencies do emerge from the data (a finding of relevance to other sections of this volume).
Century to Millennial Timescale—Synthesis
Authors: Goodin Douglas G. , Smith Raymond C.
Published: November 2020

At longer timescales, the interaction among climate, ecosystems, and the abiotic components of the environment become increasingly important. These relationships are apparent in the three chapters in part IV. Fountain and Lyons (chapter 16), examining the McMurdo Dry Valleys (MCM) ecosystem in Antarctic, provide an excellent example of a case where past climatic variations truly dictate current ecosystem status. The relatively large climate variations at MCM have concentrated nutrients that could not have been attained without this climate variability. Fountain and Lyons infer climate change from geomorphic evidence of past glacier positions and lake level heights as well as more recent isotopic results from ice cores and temperature measurements from boreholes. They focus on evidence from the most recent 60,000 years. Monger (chapter 17) provides an analysis of millennial-scale climate and ecosystem variability at the Jornada LTER site in southern New Mexico. Monger notes the difficulty of untangling prehistoric climate/ecosystem interactions, where researchers must rely on indirect proxy indicators in lieu of measured data. Monger analyzes a number of proxy data sources, including paleolake levels, plant remnants preserved in packrat middens, fossil pollens, carbon isotope ratios in paleosols, and erosion rates. Although noting the danger of circular reasoning in using proxy data (i.e., ecosystem response used to infer information about climatic change, which is in turn inferred from ecosystem response) Monger uses these data to construct a cogent picture of climate change at the Jornada site (JRN) since the Last Glacial Maximum (LGM) about 18,000–20,000 years b.p. Using remains of beetles, Elias (chapter 18) constructs a temperature history of the Colorado Alpine since the LGM. These late Holocene insect records show a progression from warmer-than-modern to coolerthan- modern summers, and back to warm again. All the authors in this section provide examples to show that it is at century to millennial timescales that ecosystems form, are broken apart and imprinted by the past, and reformed in new configurations. The McMurdo Dry Valleys is the most poleward-terrestrial ecosystem where streams, lakes, and soil are interconnected. In this polar desert, the biotic system must adopt a strategy to survive the winter in isolation, and the disturbance and formation of the landscape has been primarily dictated by climate and associated abiotic processes. During the last glacial period, the Ross Ice shelf entered Taylor Valley, damming the valley and forming a 200-m-deep lake (23.8 kyrs).
Virtues and Vices of Government Control
Authors: Goldsmith Jack , Wu Tim
Published: November 2020

Pierre Omidyar’s self-composed one-line autobiography reads: “Technologist, founder of eBay, trying to make the world a better place.” As his life’s progression suggests, of the many 1990s Internet billionaires, Omidyar’s disposition and outlook may most truly reflect the ethos of the West Coast. During his early “technologist” period he had a pony tail, wore aviator sunglasses, and worshipped the Apple Macintosh. It was during this period, in 1995, that he started eBay in his spare time, as a kind of hobby. “It was just an idea that I had, and I started it as an experiment, as a side hobby basically, while I had my day job.” In media legend the inspiration was his fiancée, Pam, who wanted to meet like-minded collectors of PEZ dispensers. But Omidyar’s account of his company’s origins emphasizes a different point. “The whole idea there was just to help people do business with one another on the Internet. And people thought it was impossible because how could people on the Internet—remember this is 1995— how could they trust each other? How could they get to know each other? And I thought that was silly. . . . [P]eople are basically good [and] honest.” It didn’t take long for eBay to realize that not everyone was good and honest: As this chapter shows, eBay quickly learned that to prevent fraud, enforce its contracts, and ensure stability in its auction services, it would depend critically on government coercion and the rule of law provided by a stable country like the United States. These are a few of the many complex benefits that only territorial sovereigns can bring, and without which most aspects of the Internet that we love and cherish would not exist. In this chapter and throughout part 3, we study these largely hidden virtues of government control of the Internet. As the story of China has already made clear, and as we discuss further in what follows, government control of the Internet is not always a happy prospect, for governments often rule unwisely and often clash with one another in destructive ways. Our aim in this part is to give a balanced account of these virtues and vices, and to show how the future of the Internet will be shaped by domestic politics and international relations, as interest groups and countries fight for control and influence over the once-borderless medium.
School Finance Reform
Authors: Hochschild Jennifer L. , Scovronick Nathan
Published: November 2020

IN A WEALTHY NORTHEASTERN STATE, two schools are near each other geographically but far apart in every other way. The school in the city sits beside an abandoned lot in a community that has lost most of its industrial jobs. “The physical appearance of the school is bleak, depressing. The hall is dark and dingy. . . . The playground outside is all brown wood and it is completely surrounded by hard pavement.” The library has not been used for 13 years; even the faculty bathrooms have no toilet paper or soap. The gym leaks. There is one computer for every 35 students, and none of the classrooms is wired for the Internet. The principal has trouble attracting qualified teachers in many fields and has none trained in computer instruction; according to the scholar who looked at these schools, teachers mainly use the computers to keep the students busy playing games when they have completed their worksheets. In this school 98 percent of the students are non-Anglo, more than two-thirds are eligible for free or reduced-price school lunches, almost three in ten are in special education. The residents of the district have a per capita income of $17,000 a year. In the suburb nearby, the school is “housed in a modern building and surrounded by large, well-maintained athletic fields. [It] boasts such amenities as a spacious school library furnished with rows upon rows of book stacks, and a high-ceilinged auditorium with theater-style seating and a grand piano on stage. Not only does the school have computers in every classroom, it also has a fully equipped computer lab, staffed by an instructor.” There is one computer for every four students, all wired for Internet use. Teachers have aides as well as access to “resource teachers” who specialize in various academic fields, help with curricula, and give “guest lectures” in classrooms. Most students participate in the orchestra, chorus, or specialized bands (or perhaps all three). One fourth-grade teacher, a graduate of Vassar College, was chosen over more than 200 competitors for her job, and along with the others in the school is paid considerably more than the state average. In this school 95 percent of the students are Anglo, fewer than one percent are eligible for free or reduced-price lunches, and only 5 percent are in special education. Residents of the district have a per capita income of $70,000.
Challenging the American Dream
Authors: Hochschild Jennifer L. , Scovronick Nathan
Published: November 2020

MULTICULTURAL EDUCATION, whether as a curricular reform or as a general goal for education, swept the nation’s schools during the 1990s. As generally understood and practiced, it does not challenge the American dream; it is a central way of teaching respect for difference and part of the continuing process of redefining the common American culture. Similarly, bilingual education is usually intended to help students pursue success within the mainstream, not to remain outside it. But some Americans go beyond claims for respect and incorporation. They seek to use multicultural or bilingual education to enable members of their group to attain distinctive treatment within public schools, or they promote changes in school curricula or methods of teaching that reflect their racial identity or religious beliefs in ways that challenge the American dream. They promote “allegiance to groups,” in Albert Shanker’s terms, or they insist on the value of difference. Some of these advocates do not believe that fostering individual success should be a central value of public schooling, or they reject the usual formulation of democratic citizenship, or they believe that the whole ideology of the American dream is an exercise in power thinly disguised as a formula for fair treatment. When they couch alternatives in the language of discrimination or make proposals in the context of school failure, their impact can be politically volatile. These issues of religion and culture show the acute difficulty of balancing the claims of one, some, and all in American public schooling, as well as the virtues and defects of using the American dream as the framework for that balancing act. To the degree that proponents—of multicultural education, cultural maintenance, African-centered pedagogy, or religious values—appeal to fairness, challenge discrimination, or demand respect for diverse viewpoints, they can and should gain broad support. But when advocates of particular groups seek to use public schools to help them maintain their separate identity, try to separate themselves within schools, or propose to have an entirely separate education within the public school system, support appropriately drops. If they try to transform all the schools in accordance with their particular cultural views or religious beliefs in rejection of the American dream, support in the wider community melts away, as it should.
Mammalian Herbivore Population Dynamics in the Alaskan Boreal Forest
Authors: Rexstad Eric , Kielland Knut
Published: November 2020

The population dynamics of boreal mammals differ strikingly from those of mammals in temperate and tropical ecosystems in their extraordinary fluctuations in abundance (Elton 1924). These fluctuations lead to strong top-down direct effects in which herbivores reduce the biomass of their preferred foods, such as birch and willow, and predators reduce the biomass of herbivores (Chapter 13; Sinclair et al. 2000). These effects are clearly demonstrated in experiments that exclude herbivores or their predators. Some authors have argued that bottom-up influences of food supply on herbivores are negligible because food augmentation to herbivores in the presence of predators had no detectable effect in reducing herbivore decline (Sinclair et al. 2001). Several members of the mammalian herbivore guild are also important as a human subsistence resource. Dynamics of moose (Alces alces) and snowshoe hare (Lepus americanus) can be altered by human harvest. Overexploitation by humans may reduce moose populations to densities where they can be predator-limited—the so-called predator pit (Messier 1994). In this chapter, we present information on dynamics of some mammalian herbivores in the Alaskan boreal forest and potential drivers that are responsible for these dynamics. We omit discussions of the dynamics of porcupines (Keith and Cary 1991), red squirrels (Boonstra et al. 2001a), and beavers (Donkor and Fryxell 1999), as studies of these species have not been conducted in Alaska’s boreal forests. Moose are thought to have arrived in Alaska during the Illinoian glaciation, about 400,000 yr B.P. (Pewe and Hopkins 1967). They may have retreated to refugia in central Alaska during subsequent glacial advances (Peterson 1955) and expanded at times when climate was warmer. Moose populations in North America have more than doubled over the past 30–40 years, to approximately 890,000 animals (Kelsall 1987). The Koyukuk River drainage in the northern interior, for example, is presently known for its large moose populations. However, the oral tradition of moose hunting in the Koyukuk is relatively recent. Native elders recall that, in their youth, moose were extremely rare and that moose did not figure prominently in the local subsistence economy until the 1930s.
Running Waters of the Alaskan Boreal Forest
Authors: Oswood Mark W. , Hughes Nicholas F.
Published: November 2020

Running waters reflect the character of their landscape. Landscapes influence their streams by supplying dissolved ions to the water, determining the organic matter supply to stream foodwebs, and influencing water temperature and water flows (Gregory et al. 1991, Hynes 1975). The water that feeds streams has passed over and through the vegetation, soils, and rocks of the valley. Just as urine carries the chemical imprint of metabolic activities (such as diabetes), the kinds and amounts of dissolved matter delivered to stream channels carry the signature of the valley’s parent materials and biota. Riparian (streamside) vegetation similarly regulates the balance of carbon sources to stream consumers. In valleys with sparse riparian vegetation, abundant light at the streambed allows in-stream primary production by protists and plants to dominate. Where riparian vegetation forms a canopy over the stream, leaves and needles from shrubs and trees dominate carbon supplies to consumers because low light limits contributions from in-stream primary producers (Vannote et al. 1980). Water temperature and flow are complexly determined by climatic controls (e.g., air and soil temperatures, patterns of precipitation), landscape physiography (e.g., shading of streams by valley walls), and the filter of lightabsorbing and water-transpiring riparian vegetation. Thus, streams in the desert biome of the American Southwest, with intermittent droughts and floods, high water temperatures, and abundant light, are very different habitats from the cool, dark waters of perennial streams in the temperate rain forest of the Pacific Northwest coast (Fisher 1995). Likewise, streams in the boreal forest of Alaska (and in the cold circumboreal forests of the world) take their cues from the landscape. Cold permeates the ecology of the boreal landscape and the running waters therein. The consequences of high-latitude climate on running waters are at least three: creation of ice in both terrestrial and running water systems; limited inputs of organic matter and nutrients to foodwebs; and thermal effects of low water temperatures on biological processes (Oswood 1997). For forested streams, a good case can be made for autumn as the beginning of the stream’s “fiscal” year. Autumnal leaf fall from riparian vegetation provides a major proportion of the annual energy budget to stream foodwebs.
The Role of Fine Roots in the Functioning of Alaskan Boreal Forests
Authors: Ruess Roger W. , Hendrick Ronald L.
Published: November 2020

The patterns of production described in Chapter 11 tell only half of the story about boreal forest production because a large proportion of the carbon (C) acquired by plants is allocated belowground in ways that have traditionally been extremely difficult to quantify. Work in the Bonanza Creek LTER provides considerable insight into the patterns, causes, and consequences of this belowground C allocation. Belowground allocation has a number of important ecosystem consequences beyond the simple fact that C allocated belowground comes at the expense of aboveground growth. Belowground and aboveground tissues differ substantially in the rates of C and nitrogen (N) incorporation into new tissue, the ratio of growth to respiration, and the rate of tissue decay. For example, despite the small biomass of fine roots relative to aboveground tissues in forest ecosystems, disproportionate amounts of C and N cycle annually through fine roots, which grow, die, and decompose very rapidly and have high N concentrations (Hendrick and Pregitzer 1992, Ruess et al. 1996, 2003). The objectives of this chapter are to (1) summarize our understanding of the structure and function of fine-root systems in forest types within the Bonanza Creek Experimental Forest, (2) compare our findings with the results of studies of other boreal and temperate ecosystems in order to develop a broader understanding of fine-root function, and (3) identify critical research gaps in our understanding of the role of fine-root systems in boreal ecosystem function. Fine roots grow more rapidly than the rest of the root system in a forest and are responsible for the bulk of nutrient and water acquisition. Until recently, fine roots were defined rather arbitrarily as roots less than 1–2 mm in diameter, while roots larger than this were considered coarse roots. Only one data set for fine and coarse root biomass has been published for interior Alaskan forests (Ruess et al. 1996), which shows (1) live fine-root biomass ranging from 221 g m-2 in floodplain white spruce stands to 832 g m-2 in upland birch-aspen stands, (2) a positive correlation between fine-root and coarse-root biomass, with coarse-root biomass averaging 50% greater than fine roots, and (3) no relationship between aboveground biomass and fine or coarse root biomass.
Patterns of Biogeochemistry in Alaskan Boreal Forests
Authors: Valentine David W. , Kielland Knut
Published: November 2020

As the northernmost forest on Earth, boreal forests endure a combination of environmental challenges common only in subalpine forests elsewhere: extremely cold winters, short growing seasons, cold soils, and limited nutrient availability. Consequently, decomposition has lagged plant production, making circumpolar boreal forest soils one of the largest terrestrial reservoirs of carbon (C). Soil organic matter also constitutes a major source of nutrients, particularly nitrogen (N), that promote plant productivity when released during decomposition. If current trends in high-latitude warming continue (Chapter 4), how will accelerated soil C losses from decomposition compare to the C gains from enhanced plant productivity? This remains an open question of great interest to climate modelers seeking to incorporate biological feedbacks into future generations of general circulation models. This chapter builds on earlier chapters on plants (Chapters 11 and 12), herbivores (Chapter 13), and soil microbes (Chapter 14) to describe the patterns and processes of C and N dynamics in Alaska’s boreal forest, paying particular attention to responses of these processes to the interacting influences of disturbance and climatic variations that occur across the landscape and through time. Other nutrients have received less attention in Alaskan research, and that data gap is reflected in this chapter. Interior Alaska’s boreal forest is a patchwork of successional forest types. The major physiographic zones into which we categorize them reflect the contrasting influences of two major disturbance types: fire in upland and lowland areas results in multiple secondary successional pathways, while a more ordered array of forest types results from a combination of primary succession and variation in flooding frequency during succession on active floodplains (Chapter 7). Within each general physiographic zone (uplands and lowlands, floodplains), differences in the postdisturbance environment further influence vegetation establishment, plant species composition, and, ultimately, element cycling. The state factor approach has proven useful in understanding landscape variation in biogeochemistry (Chapter 1; Van Cleve et al. 1991). As with other aspects of ecosystem function, element cycling reflects control exerted by major state factors: climate, parent material, potential vegetation, topography, and time since the most recent disturbance event.
Timber Harvest in Interior Alaska
Authors: Wurtz Tricia L. , Ott Robert A.
Published: November 2020

The most active period of timber harvesting in the history of Alaska’s interior occurred nearly a century ago (Roessler 1997). The beginning of this era was the year 1869, when steam-powered, stern-wheeled riverboats first operated on the Yukon River (Robe 1943). Gold was discovered in Alaska in the 40-Mile River area in 1886, a find that was overshadowed 10 years later by the discovery of gold in the Klondike, Yukon Territory. By 1898, Dawson City, Yukon Territory, was reported to have 12 sawmills producing a total of 12 million board feet of lumber annually (Naske and Slotnick 1987). Over the next 50 years, more than 250 different sternwheeled riverboats operated in the Yukon drainage, covering a large part of Alaska and Canada’s Yukon Territory (Cohen 1982). This transportation system required large amounts of fuel. Woodcutters contracted with riverboat owners to provide stacked cordwood at the river’s edge, at a cost of $7.14 in 1901 (Fig. 18.1; Cohen 1982). Between 100 and 150 cords of wood were required to make the 1400-km round trip from the upper Yukon to Dawson City (Trimmer 1898). Over time, woodcutters moved inland from the rivers’ edges, significantly impacting the forest along many rivers of the Yukon drainage (Roessler 1997). The growth of the town of Fairbanks required wood for buildings and flumes as well as for fuel. In Fairbanks’s early days, all electrical generation was by wood fuel at the N.C. Company’s power plant. From the founding of the town in 1903 through the 1970s, white spruce harvested in the Fairbanks area was used exclusively by local sawmills, which produced small amounts of green and air-dried lumber. In 1984, however, the Alaska Primary Manufacturing Law was struck down by the U.S. Supreme Court, removing the legal barrier to round-log export of timber harvested from State lands. During the late 1980s and 1990s, many high-quality logs from State and private land timber sales were exported, primarily to Pacific Rim countries. Declining markets ended this trend in the late 1990s, and there have been no significant exports since the market collapse.
Communication of Alaskan Boreal Science with Broader Communities
Authors: Sparrow Elena B. , Dawe Janice C.
Published: November 2020

An important responsibility of all researchers is to communicate effectively with the rest of the scientific community, students, and the general public. Communication is “a process by which information is exchanged between individuals through a common system of symbols, signs or behavior” (Merriam-Webster 1988). It is a two-way process that requires collaborations, best-information exchange practices, and effective formal and informal education. Communication of this knowledge and understanding about the boreal forest is important because it benefits scientists, policymakers, program managers, teachers, students, and other community members. Good data and a firm knowledge base are needed for improving understanding of the functioning of the boreal forest, implementing best-management practices regarding forests and other resources, making personal and communal decisions regarding livelihoods and quality of life, coping with changes in the environment, and preparing future cadres of science-informed decision makers. Communication among scientists is an essential step in the research process because it informs researchers about important ideas and observations elsewhere in the world and allows boreal researchers to contribute to general scientific understanding. For example, the Bonanza Creek LTER has developed its research program by incorporating many important concepts developed elsewhere, including ecosystem dynamics (Tansley 1935), succession (Clements 1916), state factors (Jenny 1941), predator interactions (Elton 1958), and landscape dynamics (Turner et al. 2001). Through active research and regular communication and collaboration with the international scientific community, these “imported” ideas have been adapted to the boreal forest and new ideas and insights have been developed or communicated to the scientific community, as described in detail throughout this book. New ideas have originated among boreal researchers, and their “export” has sparked research elsewhere in the world (Chapter 21). The pathways of communication are changing. Alaskan boreal researchers have participated actively in traditional modes of communication, including hundreds of peer-reviewed publications, several books, reports intended for managers, and participation in meetings and workshops. However, some of the greatest benefits of longterm research reside in the records of changes that occur. These long-term data are now available to the rest of the world through internet Web sites that house databases, publications, photographs, and other information (http://www.lter.uaf.edu).
Genetic Process Engineering
Authors: Weiss Ron , Knight Thomas F. ,Jr.,
Published: November 2020

In this chapter we present an engineering discipline to obtain complex, predictable, and reliable cell behaviors by embedding biochemical logic circuits and programmed intercellular communications into cells. To accomplish this goal, we provide a well-characterized component library, a biocircuit design methodology, and software design tools. Using the cellular gates,we introduce genetic process engineering, a methodology for modifying the DNA encoding of existing genetic elements to achieve the desired input/output behavior for constructing reliable circuits of significant complexity.We also describe BioSpice, a prototype software tool for biocircuit design that supports both static and dynamic simulations and analysis of singlecell environments and small cell aggregates. The goal of our research is to lay the foundations of an engineering discipline for building novel living systems with well-defined purposes and behaviors using standardized, well-characterized components. Cells are miniature, energy efficient, self-reproduce, and can manufacture biochemical products. These unique characteristics make cells attractive for many novel applications that require precise programmed control over the behavior of the cells. The applications include nanoscale fabrication, embedded intelligence in materials, sensor/effector arrays, patterned biomaterial manufacturing, improved pharmaceutical synthesis, programmed therapeutics, and as a sophisticated tool for in vivo studies of genetic regulatory networks. These applications require synthesis of sophisticated and reliable cell behaviors that instruct cells to make logic decisions based on factors such as existing environmental conditions and current cell state. For example, a cell may be programmed to secrete particular timed sequences of biochemicals depending on the type of messages sent by its neighbors. The approach proposed here for engineering the requisite precision control is to embed internal computation and programmed intercellular communications into the cells. The challenge is to provide robust computation and communications using a substrate where reliability and reproducible results are difficult to achieve. Biological organisms as an engineering substrate are currently difficult to modify and control because of the poor understanding of their complexity. Genetic modifications to cells often result in unpredictable and unreliable behavior. A single Escherichia coli bacterial cell contains approximately 1010 active molecules, about 107 of which are protein molecules.
Fibrinolytic and Antithrombotic Therapy
Authors: Becker Richard C. , Spencer Frederick A.
Published: November 2020

Thrombotic disorders of the circulatory system represent the leading cause of morbidity, motality, and health care expenditure in the United States. Fibrinolytic and Antithrombotic Therapy provides a practical, evidence-based approach to the management of thrombotic disorders for all clinicians involved in the care of patients with these disorders. It provides not only vital conceptual information on fibrinolytic and antithrombotic therapy, but also the means to apply it to everyday decision making and patient care. Focusing on managment guidelines and critical pathways, the text stresses practicality and usability. It will be a valuable resource for the wide range of clinicians involved in the care of patients with these disorders, including cardiologists, emergency physicians, primary care physicians, hematologists, neurologists, intensivists, pharmacists, and nurse practitioners. The origins of mammalian blood coagulation can be traced back over 400 million years. Despite its long history, it is only within the past century that this complex and pivotal teleologic system has begun to be understood. Most recently, the intricacies of hemostasis and pahtologic thrombosis have come to light, leading the way toward new, more effective, and safer treatment modalities. The Second Edition of Fibrinolytic and Antithrombotic Therapy, even more concise and clinically relevant than the First, provides vital, evidence-based information on management of patients with arterial and venous thrombotic disorders. Since the First Edition, the text has been expanded to cover the evolving topics of atherothrombosis, thrombocardiology, hematologic/thrombophilic conditions, and vascular medicine. It includes up-to-date guidelines for antithrombotic and fibrinolytic therapy, and offers concise summaries of current "standards of care." Chapters are dedicated to discussions of patient-specific therapeutics and to the importance of genomics, proteomics, and metabolomics in defining genotype-phenotype relationships, while throughout the book coagulation, inflammation, and vascular medicine are newly examined as elements in an intricatley-linked triad of biochemical and cellular based phenomenology.
Direct Thrombin Inhibitors
Authors: Becker Richard C. , Spencer Frederick A.
Published: November 2020

The pivotal role of thrombin in all phases of coagulation, cellular proliferation, and cellular interactions involved centrally in inflammatory processes provides an attractive target for pharmacologic inhibition. The development of direct thrombin inhibitors has evolved rapidly to include both intravenous and oral preparations. Hirudin is extracted from the parapharyngeal gland of the medicinal leech Hirudo medicinalis. Several derivatives and recombinant preparations have been developed, including the most widely used agent lepirudin (Refludan). Hirudin binds to both the catalytic and fibrinogen-binding sites of thrombin and thus is considered a bivalent inhibitor. The plasma half-life of hirudin is 50 to 65 minutes, with a biologic half-life of 2 hours (Verstraete et al., 1993). The properties of heparin, hirudin, and bivalirudin are highlighted in Table 16.1. The predominant renal clearance of hirudin must be emphasized for safe clinical use. Hirudin forms a tight complex with thrombin, inhibiting the conversion of fibrinogen to fibrin as well as thrombin-induced platelet aggregation (Verstraete, 1997). These actions are independent of the presence of antithrombin, and also affect thrombin bound to fibrin. On the downside, the ability of thrombin to complex with thrombomodulin, activating protein C, is also inhibited. Hirudin does not bind to platelet factor , nor does it elicit antibodies that induce platelet and endothelial cell activation; thus, it can be safely administered to patients with heparin induced thrombocytopenia (HIT). Hirudin does have weak immunogenicity, so diminished (or rarely increased) responsiveness after repeated dosing is possible. The use of hirudin in the management of heparin-induced thrombocytopenia is discussed in Chapter 29.
Anticoagulants
Authors: Becker Richard C. , Spencer Frederick A.
Published: November 2020

Because of the narrow therapeutic index of warfarin and unfractionated heparin (UFH), monitoring their anticoagulant effects is required. On the other hand, lowmolecular- weight heparin (LMWH) and fibrinolytic agents need to be monitored only under certain circumstances. Although newer anticoagulants will not require routine monitoring for dose titration, a means to determine their systemic effects and individual (patient-specific) response to administration will likely have roles in clinical practice. The prothrombin time is used to monitor vitamin K antagonist therapy. This test is sensitive to the plasma concentrations (activity) of clotting factors II (prothrombin), V, VII, and X. Vitamin K antagonists affect the vitamin K–dependent factors II, VII, IX, and X, as well as proteins C, S, and Z. Thus, the prothrombin time does not reflect the effect of vitamin K antagonists on some factors (IX and proteins C, S, and Z) and is sensitive to others (factor V) (not directly influenced by treatment). The prothrombin time is not an ideal test for monitoring vitamin K antagonists; however, its simplicity and widespread availability have established its place in clinical practice. By convention, prothrombin times are now reported as international normalized ratios (INRs). This is the ratio of the patient’s prothrombin time to a control prothrombin time, raised to a power—the international sensitivity index (ISI). The latter reflects the calibration of the thromboplastin used for the prothrombin time testing to an internationally agreed upon standard. In many laboratories the reagent currently used is a recombinant thromboplastin, which has an ISI of 1.0 There are several cautions related to interpreting the results of prothrombin time tests that are worth monitoring. Since the test is sensitive to the level of factor V in the plasma, improper sample storage or delayed testing may cause loss of factor V (activity) and yield prothrombin time values above the expected range. High concentrations of heparin may also prolong the prothrombin time; this usually occurs when the sample is obtained within a few minutes of administering a bolus dose. Direct thrombin inhibitors, such as hirudin, bivalirudin, argatroban, and ximelagatran, may also prolong the prothrombin time to a variable degree.
Elements of the Disarticulated Skull
Authors: Kimbel William H. , Rak Yoel , Johanson Donald C. , Holloway Ralph L. , Yuan Michael S.
Published: November 2020

The 1970s collection of hominin cranial remains from Hadar is notoriously weak in its representation of the frontal bone. Besides the complete but distorted frontal of the A.L. 333-105 juvenile (Kimbel et al., 1982), only two very incomplete adult specimens provided glimpses of frontal morphology: A.L. 288-1 (Johanson et al., 1982b) and A.L. 333-125 (Asfaw, 1987). With the recovery of the almost complete frontal bone of A.L. 444-2, we are able to fill one of the last remaining gaps in our knowledge of the Hadar hominin adult skull. Another frontal specimen, A.L. 438-1b, contributes important information on the glabellar and supraglabellar regions, which are missing or poorly preserved in A.L. 444-2. The A.L. 444-2 frontal bone features prominent, laterally projecting supraorbital bars, strongly convergent temporal lines, and a transversely broad squama with only moderate postorbital constriction. The minimum distance between the temporal lines (30 mm) in the plane of the postorbital constriction is much smaller than the postorbital constriction itself (77 mm), creating on each side an extensive, almost horizontally inclined facies temporalis that, in coronal section, slopes gradually from the inferior temporal lines to the medial wall of the temporal fossa. In between the temporal lines, the supraglabellar region bears a mild hollow that grades smoothly onto the superior surface of the supraorbital bars. Neither a supratoral sulcus nor a trigonum frontale is present. The supraorbital bars are wide anteroposteriorly, measuring 16 mm at the right lateral break, about 42 mm lateral to the midline. The preserved portions of the anterior supraorbital margins are aligned coronally, forming right angles with the midsagittal line. At the lateral break on each side, the margin actually occupies a slightly more anterior plane than the middle part of the margin, suggesting an anteriorly prominent superolateral corner of the orbit. At the medial break through the left supraorbital, about 22 mm lateral to the midline, the anterior margin begins to swing out toward glabella (this area is damaged on the right side). The extent of anterior glabellar protrusion is suggested by the preserved supraglabellar plate, whose superior surface projects in the midline about 5 mm beyond the anterior supraorbital margins.
Ethnic, Religious, and Nationalist Factors in Human Conflict
Authors: Hamburg David A. , Hamburg Beatrix A.
Published: November 2020

Contemporary education must try hard to understand where we as a species came from and how our ancient heritage and recent historical transformation contribute to our current tendencies toward hatred and violence. If we are to overcome or control these destructive tendencies, we must grasp the powerful currents that make the task at once difficult and essential. Development of our ancestors took place in the context of small, face-to-face groups that provided the security of familiarity, support in times of stress, shared coping strategies, and enduring attachments that sustained hope and adaptation for a lifetime. Reciprocity was crucial in relationships, both within and between groups. Disapproval in the form of reduced sharing, social isolation, and the threat of rejection from one’s group were powerful sanctions that reinforced conformity to group norms. Indeed, the importance of sharing within the primary group was strongly conveyed to children from infancy onward. These basic facts of small-scale, traditional life have been enduring and powerful from earliest mankind to the present day. They apply to the hunting and gathering societies in which our ancient ancestors spent several million years, to the extended families of agricultural village societies, and to the primary groups of the homogeneous neighborhoods in preindustrial towns of the past that foreshadowed modern industrial and postindustrial societies. Our ancient ancestors’ world began to change drastically with the onset of agriculture 10,000 years ago. The existing evidence clearly shows that—once humans developed agriculture, settled in larger population groups, accumulated goods, and came to rely on designated areas for growing food and grazing animals—a widespread intergroup hostility became common, and at times, severe. Patterns of intergroup violence in preindustrial societies have been confirmed and described in detail by anthropologists and historians. Whatever the evolutionary background and its biological legacy, the historical record clarifies that aggressive behavior between individuals and between groups has been a prominent feature of human experience for at least several thousand years. Everywhere in the world, aggression toward others has been facilitated by a pervasive human tendency toward harsh dichotomizing between the positively valued we and the negatively valued they. Such behavior has been easily learned, practiced in childhood play, encouraged by custom, and rewarded by most human societies.
A Framework for Understanding and Addressing School Violence
Authors: Hamburg David A. , Hamburg Beatrix A.
Published: November 2020

The increased violence in American schools over the past decade has stimulated serious scholarship to determine the major factors underlying such violence and to develop school-based strategies for preventing it. One of the most comprehensive and systematic efforts to make sense of this body of research was presented in a book edited by Delbert S. Elliot, Beatrix A. Hamburg, and Kirk R.Williams in 1998.1 In this book scholars from the fields of social ecology, child and adolescent development, criminology, psychiatry, sociology, educational psychology, and public health presented relevant new perspectives, methodology, and data from their diverse fields. The authors developed an ecological, life course, developmental approach. The ultimate goal was to integrate diverse bodies of knowledge into a comprehensive approach to designing new basic research as well as rigorous program evaluation methods. Five themes emerged within this approach. These are summarized as follows:… 1. The interconnectedness of family, peer group, school, and neighborhood influences 2. The dynamic interaction between the individual and social contexts in influencing developmental patterns 3. Collaboration and comprehensiveness as requirements for effective prevention programs 4. The need for a public health approach to violence prevention 5. Rigorous implementation of evidence-based programs and strategies for preventing violence… This theme speaks to the ecological nature of the approach, which relates not only to the interrelationships among individuals within society but also to the connectedness and interplay across larger spheres of influence such as schools, neighborhoods, workplaces, and other social institutions. An important factor in youth violence is that as a result of a cascade of major social changes in family, labor force participation, and neighborhood cohesiveness, the family, and neighborhood social institutions once responsible for youth development have been undermined. This has shifted more responsibility to the schools to fill the gap. Since 1960, urbanization, changed roles of women, and powerful media impacts has converged in a troubling mix. For both married couple families and single parent households, the parental labor force participation has sharply increased. In 1985, 63 percent of all children in the United States had working mothers. By 1998, 71 percent of all school age children ages 6 to 18 had working mothers.