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  • Cambridge University Press  (29,448)
  • Annual Reviews
  • 1995-1999  (16,310)
  • 1985-1989  (16,075)
  • 1965-1969  (7,449)
  • 1950-1954  (2,919)
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  • 101
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    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 17 (1999), S. 189-220 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Natural killer (NK) cells are populations of lymphocytes that can be activated to mediate significant levels of cytotoxic activity and produce high levels of certain cytokines and chemokines. NK cells respond to and are important in defense against a number of different infectious agents. The first indications for this function came from the observations that virus-induced interferons alpha/beta (IFN-alpha and -beta) are potent inducers of NK cell-mediated cytotoxicity, and that NK cells are important contributors to innate defense against viral infections. In addition to IFN-alpha/beta, a wide range of other innate cytokines can mediate biological functions regulating the NK cell responses of cytotoxicity, proliferation, and gamma interferon (IFN-gamma) production. Certain, but not all, viral infections induce interleukin 12 (IL-12) to elicit NK cell IFN-gamma production and antiviral mechanisms. However, high levels of IFN-alpha/beta appear to be unique and/or uniquely dominant in the context of viral infections and act to regulate other innate responses, including induction of NK cell proliferation in vivo and overall negative regulation of IL-12 production. A detailed picture is developing of particular innate cytokines activating NK cell responses and their consorted effects in providing unique endogenous milieus promoting downstream adaptive responses, most beneficial in defense against viral infections.
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  • 102
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    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 17 (1999), S. 331-367 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Four members of the tumor necrosis factor (TNF) ligand family, TNF-alpha, LT-alpha, LT-beta, and LIGHT, interact with four receptors of the TNF/nerve growth factor family, the p55 TNF receptor (CD120a), the p75 TNF receptor (CD120b), the lymphotoxin beta receptor (LTbetaR), and herpes virus entry mediator (HVEM) to control a wide range of innate and adaptive immune response functions. Of these, the most thoroughly studied are cell death induction and regulation of the inflammatory process. Fas/Apo1 (CD95), a receptor of the TNF receptor family activated by a distinct ligand, induces death in cells through mechanisms shared with CD120a. The last four years have seen a proliferation in knowledge of the proteins participating in the signaling by the TNF system and CD95. The downstream signaling molecules identified so far-caspases, phospholipases, the three known mitogen activated protein (MAP) kinase pathways, and the NF-kappaB activation cascade-mediate the effects of other inducers as well. However, the molecules that initiate these signaling events, including the death domain- and TNF receptor associated factor (TRAF) domain-containing adapter proteins and the signaling enzymes associated with them, are largely unique to the TNF/nerve growth factor receptor family.
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  • 103
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    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 17 (1999), S. 369-397 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Exciting breakthroughs in the last two years have begun to elucidate the structural basis of cellular immune recognition. Crystal structures have been determined for full-length and truncated forms of alphabeta T cell receptor (TCR) heterodimers, both alone and in complex with their peptide-MHC (pMHC) ligands or with anti-TCR antibodies. In addition, a truncated CD8 coreceptor has been visualized with a pMHC. Aided in large part by the substantial body of knowledge accumulated over the last 25 years on antibody structure, a number of general conclusions about TCR structure and its recognition of antigen can already be derived from the relatively few TCR structures that have been determined. Small, but important, variations between TCR and antibody structures bear on their functional differences as well as on their specific antigen recognition requirements. As observed in antibodies, canonical CDR loop structures are already emerging for some of the TCR CDR loops. Highly similar docking orientations of the TCR Valpha domains in the TCR/pMHC complex appear to play a primary role in dictating orientation, but the Vbeta positions diverge widely. Similar TCR contact positions, but whose exact amino acid content can vary, coupled with relatively poor interface shape complementarity, may explain the flexibility and short half-lives of many TCR interactions with pMHC. Here we summarize the current state of this field, and suggest that the knowledge gap between the three-dimensional structure and the signaling function of the TCR can be bridged through a synthesis of molecular biological and biophysical techniques.
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  • 104
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    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 17 (1999), S. 555-592 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract In B lymphocytes, a signaling complex that contributes to cell fate decisions is the B cell antigen receptor (BCR). Data from knockout experiments in cell lines and mice have revealed distinct functions for the intracellular protein tyrosine kinases (Lyn, Syk, Btk) in BCR signaling and B cell development. Combinations of intracellular signaling pathways downstream of these PTKs determine the quality and quantity of BCR signaling. For example, concerted actions of the PLC-gamma2 and PI3-K pathways are required for proper calcium responses. Similarly, the regulation of ERK and JNK responses involves both PLC-gamma2 and GTPases pathways. Since the immune response in vivo is regulated by alteration of these signaling outcomes, achieving a precise understanding of intracellular molecular events leading to B lymphocyte proliferation, deletion, anergy, receptor editing, and survival still remains a challenge for the future.
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  • 105
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    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 17 (1999), S. 593-623 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Phagocytosis of pathogens by macrophages initiates the innate immune response, which in turn orchestrates the adaptive response. In order to discriminate between infectious agents and self, macrophages have evolved a restricted number of phagocytic receptors, like the mannose receptor, that recognize conserved motifs on pathogens. Pathogens are also phagocytosed by complement receptors after relatively nonspecific opsonization with complement and by Fc receptors after specific opsonization with antibodies. All these receptors induce rearrangements in the actin cytoskeleton that lead to the internalization of the particle. However, important differences in the molecular mechanisms underlying phagocytosis by different receptors are now being appreciated. These include differences in the cytoskeletal elements that mediate ingestion, differences in vacuole maturation, and differences in inflammatory responses. Infectious agents, such as M. tuberculosis, Legionella pneumophila, and Salmonella typhimurium, enter macrophages via heterogeneous pathways and modify vacuolar maturation in a manner that favors their survival. Macrophages also play an important role in the recognition and clearance of apoptotic cells; a notable feature of this process is the absence of an inflammatory response.
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  • 106
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    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 17 (1999), S. 781-828 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract The immune system relies on cell death to maintain lymphoid homeostasis and avoid disease. Recent evidence has indicated that the caspase family of cysteine proteases is a central effector in apoptotic cell death and is absolutely responsible for many of the morphological features of apoptosis. Cell death, however, can occur through caspase-independent and caspase-dependent pathways. In the case of cells that are irreversibly neglected or damaged, death occurs even in the absence of caspase activity. In contrast, healthy cells require caspase activation to undergo cell death induced by surface receptors. This review summarizes the current understanding of these two pathways of cell death in the immune system.
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  • 107
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    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 17 (1999), S. 973-976 
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
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  • 108
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    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 61 (1999), S. 1-17 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract I was pleased to receive the invitation to write this prefatory chapter. In doing so, I join a number of physiologists whose work and writings I have often admired. There are two aspects of my experience in physiology that I discuss here. The first concerns my own research accomplishments. The second is my role in developing three departments of physiology and fostering the careers of others. While I take pleasure in the former, the overall contribution of the latter was undoubtedly greater.
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  • 109
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    Annual Review of Physiology 61 (1999), S. 19-43 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Regulation of gastrointestinal (GI) motility is intimately coordinated with the modulation of ionic conductances expressed in GI smooth muscle and nonmuscle cells. Interstitial cells of Cajal (ICC) act as pacemaker cells and possess unique ionic conductances that trigger slow wave activity in these cells. The slow wave mechanism is an exclusive feature of ICC: Smooth muscle cells may lack the basic ionic mechanisms necessary to generate or regenerate slow waves. The molecular identification of the components for these conductances provides the foundation for a complete understanding of the ionic basis for GI motility. In addition, this information will provide a basis for the identification or development of therapeutics that might act on these channels. It is much easier to study these conductances and develop blocking drugs in expression systems than in native GI muscle cells. This review focuses on the relationship between ionic currents in native GI smooth muscle cells and ICC and their molecular counterparts.
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  • 110
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    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 61 (1999), S. 45-84 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Ion channels are the unitary elements that underlie electrical activity of gastrointestinal smooth muscle cells and of interstitial cells of Cajal. The result of ion channel activity in the gastrointestinal smooth muscle layers is a rhythmic change in membrane potential that in turn underlies events leading to organized motility patterns. Gastrointestinal smooth muscle cells and interstitial cells of Cajal express a wide variety of ion channels that are tightly regulated. This review summarizes 20 years of data obtained from patch-clamp studies on gastrointestinal smooth muscle cells and interstitial cells, with a focus on regulation.
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  • 111
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    Annual Review of Physiology 61 (1999), S. 117-142 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract The enteric nervous system exerts local control over mixing and propulsive movements in the small intestine. When digestion is in progress, intrinsic primary afferent neurons (IPANs) are activated by the contents of the intestine. The IPANs that have been physiologically characterized are in the intrinsic myenteric ganglia. They are numerous, about 650/mm length of small intestine in the guinea pig, and communicate with each other through slow excitatory transmission to form self-reinforcing assemblies. High proportions of these neurons respond to chemicals in the lumen or to tension in the muscle; physiological stimuli activate assemblies of hundreds or thousands of IPANs. The IPANs make direct connections with muscle motor neurons and with ascending and descending interneurons. The circular muscle contracts as an annulus, about 2-3 mm in minimum oral-to-anal extent in the guinea pig small intestine. The smooth muscle cells form an electrical syncytium that is innervated by about 300 excitatory and 400 inhibitory motor neurons per mm length. The intrinsic nerve circuits that control mixing and propulsion in the small intestine are now known, but it remains to be determined how they are programmed to generate the motility patterns that are observed.
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  • 112
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    Annual Review of Physiology 61 (1999), S. 143-167 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Angina pectoris often results from ischemic episodes that excite chemosensitive and mechanoreceptive receptors in the heart. Ischemic episodes release a collage of chemicals, including adenosine and bradykinin, that excites the receptors of the sympathetic and vagal afferent pathways. Sympathetic afferent fibers from the heart enter the upper thoracic spinal cord and synapse on cells of origin of ascending pathways. This review focuses on the spinothalamic tract, but other pathways are excited as well. Excitation of spinothalamic tract cells in the upper thoracic and lower cervical segments, except C7 and C8 segments, contributes to the anginal pain experienced in the chest and arm. Cardiac vagal afferent fibers synapse in the nucleus tractus solitarius of the medulla and then descend to excite upper cervical spinothalamic tract cells. This innervation contributes to the anginal pain experienced in the neck and jaw. The spinothalamic tract projects to the medial and lateral thalamus and, based on positron emission tomography studies, activates several cortical areas, including the anterior cingulate gyrus (BA 24 and 25), the lateral basal frontal cortex, and the mesiofrontal cortex.
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  • 113
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    Palo Alto, Calif. : Annual Reviews
    Annual Review of Anthropology 28 (1999), S. i 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Figure 1 Figure 1 A broad reflection on some of the major surprises to anthropological theory occasioned by the history, and in a number of instances the tenacity, of indigenous cultures in the twentieth century. We are not leaving the century with the same ideas that got us there. Contrary to the inherited notions of progressive development, whether of the political left or right, the surviving victims of imperial capitalism neither became all alike nor just like us. Contrary to the "despondency theory" of mid-century, the logical and historical precursor of dependency theory, surviving indigenous peoples aim to take cultural responsibility for what has been done to them. Across large parts of northern North America, even hunters and gatherers live, largely by hunting and gathering. The Eskimo are still there, and they are still Eskimo. Around the world the peoples give the lie to received theoretical oppositions between tradition and change, indigenous culture and modernity, townsmen and tribesmen, and other cliches of the received anthropological wisdom. Reports of the death of indigenous cultures-as of the demise of anthropology-have been exaggerated.
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  • 114
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    Annual Review of Anthropology 28 (1999), S. 27-50 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Ingested nutrients and nonnutrients are presented as determinants in human evolution. The amount and quality of energy, including fat, various foods supply are important criteria in governing selection. Oxidative stress associated with respiration of energy is a factor in the etiology of dietary diseases, such as cardiovascular disease and cancer, and in aging. Evolutionary trends such as gains in brain and body sizes, greater ingestion of long-chain polyunsaturated fatty acids and cholesterol, heating of fatty food, and greater longevity increased oxidative stress while greater reliance on animals foods and less on plants decreased ingestion of exogenous antioxidants. The hypothesis that selection for nonnutrient ingestive behaviors was a compensatory mechanism for increasing antioxidants is presented within the context of a four-factor model on the origins of human medicine.
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  • 115
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    Annual Review of Anthropology 28 (1999), S. 1-25 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract The interaction of nutritional status with political structure in prehistoric New World societies is examined through bioarchaeological analysis. Overall, a general correlation is seen between political complexity and patterns of morbidity among various subsegments of the population. This relationship is strongest among egalitarian societies, in which few differences exist, and state-level societies, in which differences are readily apparent and appear to widen over time. At intermediate levels of political complexity, a less consistent picture emerges; various explanations are considered as to why the dietary differences predicted by the ethnohistorical and archaeological records are not reflected in the osteological record. Also addressed are patterns of differences in access to nutritional resources by gender at the various levels of political organization, as well as patterns of access between rural and urban centers. Future directions of study are suggested.
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  • 116
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    Annual Review of Anthropology 28 (1999), S. 51-71 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract This article reviews some of the major archeological research and resulting current debates that center around the nature of the formation of Islamic society in the Maghreb and the Iberian Peninsula from the seventh century AD through the later Middle Ages. Over the last two decades, archeology has played an increasingly important role in working out the details of how this great cultural transformation occurred and has led to considerable revision of historical interpretations of the medieval period in the western Mediterranean region. On a more general anthropological level, research in both regions presents a remarkable potential to contribute to the literature on the archeology of ethnicity, and to research into the impact of changing religion and ideology on such diverse areas of human activity as household organization, gender relations, settlement location and spatial organization, and ceramic production and distribution.
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  • 117
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    Annual Review of Anthropology 28 (1999), S. 73-108 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract War is a fraught subject. Those who study it often fight about it. This chapter examines the current state of the study of war, described and analyzed by anthropologists and nonanthropologists who employ concepts like culture in writing about the future of war. Warfare seems bound to keep us revisiting certain aspects of the past. At the same time, nothing induces change quite like conflict. Does war have a future? The preponderance of evidence-biological, archeological, ethnological-suggests that it does. But not all anthropologists agree. This in and of itself represents one of a series of gaps that begs further consideration.
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  • 118
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    Annual Review of Anthropology 28 (1999), S. 109-153 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract To better understand both the shared and special features of human growth, this article explores the evolution of growth patterns of mammals in general and primates in particular. Special attention is paid to several competing hypotheses concerning the adaptive value of the juvenile stage to the life history of the social mammals. One hypothesis claims that all social mammals have a juvenile stage of life, but although most primate species are social, not all primates show a juvenile stage of life history. There is also controversy over whether the adolescent growth spurt is a uniquely human feature. On the basis of empirical observations and evolutionary considerations, I conclude that the human adolescent growth spurt in stature and skeletal maturation is species specific, not found in any other primate species. Finally, data and theory are used to advance a philosophy of human growth. An acceptable philosophy must acknowledge the mammalian and primate foundations for the human pattern of growth. But a robust philosophy of human growth must also account for the ecology to which the human species, indeed any species, is adapted. Accordingly, a philosophy of human growth must allow for the evolution of variations on common themes and of new stages of growth that may be unique to the human species.
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  • 119
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    Annual Review of Anthropology 28 (1999), S. 155-174 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract The professionalization of archaeology in the late nineteenth century was linked to the growth of antiquities markets and the development of museums as institutions of education and social reproduction. Professional archaeologists moved into the universities in large numbers after World War II and then increasingly into the private sector after the mid-1970s. In the United States, archaeologists currently confront a highly segmented labor market with significant wage and benefits differentials, and increasing numbers face marginal employment. At the same time, descendant communities and government regulations are transforming the ways by which archaeologists have traditionally conducted their investigations.
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  • 120
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    Annual Review of Anthropology 28 (1999), S. 175-199 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract This paper provides an overview of the main approaches to the discursive analysis of racist utterances. Moreover, we discuss the notions of racism and race historically and from the point of view of different cultures and languages. We restrict ourselves to the discourse analytical concepts and methodologies, which vary greatly, both in theory and in analysis. We present one example and analyze it in detail as an illustration of the linguistic tools that help make hidden and latent meanings transparent.
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  • 121
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    Annual Review of Anthropology 28 (1999), S. 201-224 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Humans' relationships with animals, increasingly the subject of controversy, have long been of interest to those whose primary aim has been the better understanding of humans' relationships with other humans. Since this topic was last reviewed here, human-animal relationships have undergone considerable reexamination, reflecting key trends in the history of social analysis, including concerns with connections between anthropology and colonialism and with the construction of race, class, and gender identities. There have been many attempts to integrate structuralist or symbolic approaches with those focused on environmental, political, and economic dimensions. Human-animal relationships are now much more likely to be considered in dynamic terms, and consequently, there has been much interdisciplinary exchange between anthropologists and historians. Some research directly engages moral and political concerns about animals, but it is likely that sociocultural research on human-animal relationships will continue to be as much, if not more, about humans.
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  • 122
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    Annual Review of Anthropology 28 (1999), S. 285-310 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Apocalypticism and millennialism are the dark and light sides of a historical sensibility transfixed by the possibility of imminent catastrophe, cosmic redemption, spiritual transformation, and a new world order. This essay briefly surveys work by anthropologists and like-minded scholars that focuses directly on endtime movements. It then reviews at more length a varied literature focusing on American apocalypticisms and millennialisms. Turning to contemporary America, we survey the ways in which an apocalyptic/millennial sensibility-as a mode of attention, mode of knowing, and voice-has come to inhabit and structure modern American life across a wide range of registers.
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  • 123
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    Annual Review of Anthropology 28 (1999), S. 253-284 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract With the concept of environment as its organizing motif, this review focuses on two general fields of anthropological environmental research: ecological anthropology and the anthropology of environmentalism. Analysis of the complementary political and human ecology research programs is structured around four theoretical and methodological areas: transformations in the ecological paradigm, levels of analysis and articulation, the use of history, and the reemergence of space. Ethnographic analyses of the social forces of environmentalism point to civil society as an emerging and important protagonist with regard to environmental issues, and these social forces are reviewed within the categories of environmental movements, rights, territories, and discourses. A final prospective section looks at contemporary urban, viral, virtual, and warfare environments and postulates that the combination of empirical and political approaches can provide for anthropology an expanded role, one that has strong bioethical implications, in environmental debates and issues.
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  • 124
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    Annual Review of Anthropology 28 (1999), S. 225-252 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract The proposal that linguistic sounds such as phonemes, features, syllables, or tones can be meaningful, or sound-symbolic, contradicts the principles of arbitrariness and double articulation that are axiomatic to structural linguistics. Nevertheless, a considerable body of research that supports principles of sound symbolism has accumulated. This review discusses the most widely attested forms of sound symbolism and the research programs linked to sound symbolism that have influenced linguists and anthropologists most. Numerous reports of magnitude sound symbolism in the form of experimental studies and comparative surveys have been integrated into a biologically based theory of its motivation. Magnitude sound symbolism also catalyzed a number of experimental studies by psychologists and linguists in search of a universal sound-symbolic substrate underlying all languages. Although the search for a sound-symbolic substrate has been abandoned, the success rates of these studies have never been satisfactorily explained. Sound-symbolic processes have had a definitive impact on morphological analyses of phonesthemes and on historical linguists' understandings of diachronic processes. A typologically widespread form of sound symbolism occurs as a kind of lexical class known as the ideophone, which is conspicuously underdeveloped in standard average European languages, and highly perplexing for linguists and anthropologists. Although it has always been a respectable domain of inquiry in ethnopoetics and interpretive ethnography, the case for sound symbolism has of late been argued with renewed vigor on the part of psychological anthropologists and philosophers who see a paradigm shift under way.
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  • 125
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    Annual Review of Anthropology 28 (1999), S. 311-339 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Primatology in anthropology began with morphological comparisons of primates to reconstruct the evolution of humans. Naturalistic studies started in the mid-twentieth century and contributed to understanding the functions of morphological variations. Today, research in primatology employs the new paradigm of behavioral ecology and sociobiology for analysis and interpretation of variation in behavior and ecology. Grouping and group sizes of primates are explained with reference to effects of predation, defense of resources, and female defense against male infanticide. Primates avoid close consanguineous mating, usually by dispersal of males from the birthplace, though in bonobos and chimpanzees males are philopatric. In many primates, nepotistic relations among females are explained by kin selection operating on the philopatric sex. In chimpanzees, nepotism is clearest among the philopatric males. Sexual dimorphism, dominance hierarchies, intrasexual competition, and particularly infanticide by males are best explained by the action of sexual selection. Comparative studies of primates indicate that the large brains of the genus Homo (enlarged cerebral cortex) evolved after bipedalism and human dental characters and probably depended on high-quality diets. Broad comparative studies have supported the hypothesis that large brains may have evolved in response to complex social environments, but comparisons within the apes only may not support the hypothesis. Although dominant themes of current anthropology are not compatible with the epistemology, theory, or methodology of primate research and interpretation, primate studies fit easily within the future of anthropology as a four-field evolutionary study of the origins of humans and human nature.
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  • 126
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    Annual Review of Anthropology 28 (1999), S. 375-395 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Issues in the linguistic study of US Latinos are reviewed, with an emphasis on recent work in sociolinguistics. Predominant models of language contact are evaluated, as are factors contributing to variation. Among these factors are (a) the state of changes in progress; (b) the complexity of historical, socioeconomic, and demographic conditions of US Latinos; (c) the community's degree of contact with other ethnic/linguistic groups; (d) language attitudes toward the matrix and embedded languages; (e) the local evaluation and patterns of use of particular variants; and (f) the possibility of autochthonous innovation within the dialect. Questions of US Latino participation in changes beyond those in their immediate communities are addressed. The need to connect linguistic variation with other aspects of semiotic meaning is emphasized.
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  • 127
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    Annual Review of Anthropology 28 (1999), S. 341-373 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract This review describes a paradigmatic shift in anthropological studies of human movement, from an observationist view of behavior to a conception of body movement as dynamically embodied action. After outlining the scope of such study, historical and cultural reasons for the relative neglect of body movement in anthropological enquiry are examined critically and placed in the wider context of recent social and cultural theorizing about the body and the problem of dynamic embodiment. A historical overview situates earlier approaches, such as kinesics and proxemics, in relation to more recent developments in theory and method, such as those offered by semasiology and the concept of the "action sign." Overlapping interests with linguistic and cognitive anthropology are described. The emergence of a holistic "anthropology of human movement" has raised new research questions that require new resources. Theoretical insights have challenged researchers to devise new methods and to adopt or devise new technologies, such as videotape and an adequate transcription system. An example of the latter illustrates the analytic advantages of literacy in the medium.
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    Annual Review of Anthropology 28 (1999), S. 397-430 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Life history theory offers evolutionary explanations for the timing of life events, with a particular focus on age-schedules of fertility and mortality and growth. Traditional models examine trade-offs between current and future reproduction and quality versus quantity of offspring. These models can be used to understand questions concerning time of gestation, age of weaning, juvenile mortality profiles, age at maturation, adult body size, fertility rates, senescence, menopause, and the length of the life span. The trajectory of energy acquisition and its allocations is also an important part of life history theory. Modifications of these models have been developed to examine the period of learning, postweaning parental investment, and patterns of development. In this article, we combine energetic and demographic approaches in order to examine the human life course from an optimality perspective. The evolved life history solves related problems across two generations. The first set of decisions concerns how to maximize own lifetime net energy production that can be used for reproduction. The second set of decisions concerns how to maximize total offspring energy production (summed over all offspring).
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    Annual Review of Anthropology 28 (1999), S. 431-454 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Southeast Asia is probably the part of the world most closely associated by anthropologists with an interpretive concept of culture. Yet do such ideas as culture areas or local cultures retain their analytical salience when our attention turns to processes of domination, displacement, and diaspora? This article considers the state of culture theory in the anthropology of Southeast Asia today, focusing on the themes of gender, marginality, violence, and the state. Culture is increasingly viewed as an attribute of the state-an object of state policy, an ideological zone for the exercise of state power, or literally a creation of the state-whereas the state itself is comprehended in ways analogous to totalizing models of culture.
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    Annual Review of Anthropology 28 (1999), S. 509-529 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Human beings are biologically adapted for culture in ways that other primates are not, as evidenced most clearly by the fact that only human cultural traditions accumulate modifications over historical time (the ratchet effect). The key adaptation is one that enables individuals to understand other individuals as intentional agents like the self. This species-unique form of social cognition emerges in human ontogeny at approximately 1 year of age, as infants begin to engage with other persons in various kinds of joint attentional activities involving gaze following, social referencing, and gestural communication. Young children's joint attentional skills then engender some uniquely powerful forms of cultural learning, enabling the acquisition of language, discourse skills, tool-use practices, and other conventional activities. These novel forms of cultural learning allow human beings to, in effect, pool their cognitive resources both contemporaneously and over historical time in ways that are unique in the animal kingdom.
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    Annual Review of Anthropology 28 (1999), S. 455-478 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Anthropologies of late modernity (also called postmodernity, postindustrial society, knowledge society, or information society) provide a number of stimulating challenges for all levels of social, cultural, and psychological theory, as well as for ethnographic and other genres of anthropological writing. Three key overlapping arenas of attention are the centrality of science and technology; decolonization, postcolonialism, and the reconstruction of societies after social trauma; and the role of the new electronic and visual media. The most important challenges of contemporary ethnographic practice include more than merely (a) the techniques of multilocale or multisited ethnography for strategically accessing different points in broadly spread processes, (b) the techniques of multivocal or multiaudience-addressed texts for mapping and acknowledging with greater precision the situatedness of knowledge, (c) the reworking of traditional notions of comparative work for a world that is increasingly aware of difference, and (d) acknowledging that anthropological representations are interventions within a stream of representations, mediations, and unequally inflected discourses competing for hegemonic control. Of equal importance are the challenges of juxtaposing, complementing, or supplementing other genres of writing, working with historians, literary theorists, media critics, novelists, investigative or in-depth journalists, writers of insider accounts (e.g. autobiographers, scientists writing for the public), photographers and film makers, and others.
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    Annual Review of Anthropology 28 (1999), S. 479-507 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract This review asks the question: What new avenues of social science enquiry are suggested by new ecological thinking, with its focus on nonequilibrium dynamics, spatial and temporal variation, complexity, and uncertainty? Following a review of the emergence of the "new ecology" and the highlighting of contrasts with earlier "balance of nature" perspectives, work emerging from ecological anthropology, political ecology, environmental and ecological economics, and debates about nature and culture are examined. With some important exceptions, much social science work and associated popular and policy debates remain firmly wedded to a static and equilibrial view. This review turns to three areas where a more dynamic perspective has emerged. Each has the potential to take central elements of new ecological thinking seriously, sometimes with major practical consequences for planning, intervention design, and management. First is the concern with spatial and temporal dynamics developed in detailed and situated analyses of "people in places," using, in particular, historical analysis as a way of explaining environmental change across time and space. Second is the growing understanding of environment as both the product of and the setting for human interactions, which link dynamic structural analyses of environmental processes with an appreciation of human agency in environmental transformation, as part of a "structuration" approach. Third is the appreciation of complexity and uncertainty in social-ecological systems and, with this, the recognition of that prediction, management, and control are unlikely, if not impossible.
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    Annual Review of Anthropology 28 (1999), S. 553-575 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Studying human behavior in the light of evolutionary theory involves studying the comparative evolutionary history of behaviors (phylogeny), the psychological machinery that generates them (mechanisms), and the adaptive value of that machinery in past reproductive competition (natural selection). To show the value of a phylogenetic perspective, I consider the ethology of emotional expression and the cladistics of primate social systems. For psychological mechanisms, I review evidence for a pan-human set of conceptual building blocks, including innate concepts of things, space, and time, of number, of logic, of natural history, and of "other minds" and social life, which can be combined to generate a vast array of culture-specific concepts. For natural selection, I discuss the sexual selection of sex differences and similarities, and the social selection of moral sentiments and group psychology.
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    Annual Review of Anthropology 28 (1999), S. 531-552 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract Optimality theory was introduced in the early 1990s as an alternative model of the organization of natural human language sound systems. This article provides an introduction to the model for the nonlinguist. The basic principles of optimality theory are introduced and explained (GEN, CON, and EVAL). Three important constraint families are explored (Faithfulness, Alignment, and Markedness). Illustrations are provided involving syllabification and vowel harmony in Tibetan and prosodic phonotactics in Tonkawa. The article closes with two general discussions. The first addresses recurring issues in phonological and linguistic analysis and sketches how optimality theory might account for these. The second points out how the explanations arrived at through optimality theory are providing new answers to familiar questions, as well as raising new questions for study.
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    Annual Review of Anthropology 28 (1999), S. 577-598 
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Notes: Abstract As an artifact of imperial culture, Africanist anthropology is historically associated with the colonization of Africa in ways that undermine the subdiscipline's claims of neutrality and objectivity. A critical literature on the ideological and discursive inventions of Africa by the West challenges the very possibility of Africanist anthropology, to which a variety of responses have emerged. These range from historical reexaminations of imperial discourses, colonial interactions, and fieldwork in Africa, including dialogical engagements with the very production of ethnographic texts, to a more dialectical anthropology of colonial spectacle and culture as it was coproduced and reciprocally determined in imperial centers and peripheries. Understood philologically, as an imperial palimpsest in ethnographic writing, the colonial legacy in Africanist ethnography can never be negated, but must be acknowledged under the sign of its erasure.
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    Annual Review of Neuroscience 22 (1999), S. 11-28 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract The blood-brain barrier (BBB) is formed by brain capillary endothelial cells (ECs). In the late embryonic and early postnatal period, these cells respond to inducing factors found in the brain environment by adopting a set of defined characteristics, including high-electrical-resistance tight junctions. Although the factors have not been identified definitively, a great deal of information about brain ECs has been obtained, especially recently. This review concentrates on a cell biological analysis of the BBB, with an emphasis on regulation of the specialized intercellular junctions. The development of these junctions seems to depend on two primary processes: the appearance of high levels of the tight junction protein occludin and intracellular signaling processes that control the state of phosphorylation of junctional proteins. Recent studies have revealed that the BBB can be modulated in an ongoing way to respond to environmental stimuli.
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    Annual Review of Neuroscience 22 (1999), S. 1-10 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract FM1-43 and similar styryl dyes have proven useful as probes for membrane trafficking because they reversibly stain membranes, are impermeable to membranes, and are more fluorescent when bound to membranes than when in solution. Because these dyes stain membranes in an activity-dependent manner, they are ideal for studies of neurotransmitter release mechanisms such as synaptic vesicle recycling, exocytosis, and endocytosis. FM dyes have been used in conjunction with other techniques such as fluorescent calcium indicator dyes and electrophysiological techniques to elucidate mechanisms of presynaptic calcium homeostasis and modulation of neurotransmitter release. Presynaptic membranes have been marked by FM dyes in studies of synaptogenesis and reinnervation. As a probe for endocytosed membranes, these dyes have been used to examine vacuole formation in yeast. These versatile membrane dyes are useful in a variety of applications.
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    Annual Review of Neuroscience 22 (1999), S. 29-47 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Many pathways in the developing visual system are restructured and become highly organized even before vision occurs. Yet the developmental processes underlying the remodeling of visual connectivity are crucially dependent on retinal activity. Surprisingly, the immature and light-insensitive retina spontaneously generates a pattern of rhythmic bursting activity during the period when the connectivity patterns of retinal ganglion cells are shaped. Spatially, the activity is seen to spread across the retina in the form of waves that bring into synchrony the bursts of neighboring cells. Waves are present in the developing retina of higher and lower vertebrates, which suggests that this form of activity may be a common and fundamental mechanism employed in the activity-dependent refinement of early patterns of visual connections. Unraveling the cues encoded by the waves promises to provide important insights into how interactions driven by specific patterns of activity could lead to the modification of connectivity during development.
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    Annual Review of Neuroscience 22 (1999), S. 105-122 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract The hippocampus is a target of stress hormones, and it is an especially plastic and vulnerable region of the brain. It also responds to gonadal, thyroid, and adrenal hormones, which modulate changes in synapse formation and dendritic structure and regulate dentate gyrus volume during development and in adult life. Two forms of structural plasticity are affected by stress: Repeated stress causes atrophy of dendrites in the CA3 region, and both acute and chronic stress suppresses neurogenesis of dentate gyrus granule neurons. Besides glucocorticoids, excitatory amino acids and N-methyl-d-aspartate (NMDA) receptors are involved in these two forms of plasticity as well as in neuronal death that is caused in pyramidal neurons by seizures and by ischemia. The two forms of hippocampal structural plasticity are relevant to the human hippocampus, which undergoes a selective atrophy in a number of disorders, accompanied by deficits in declarative, episodic, spatial, and contextual memory performance. It is important, from a therapeutic standpoint, to distinguish between a permanent loss of cells and a reversible atrophy.
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    Annual Review of Neuroscience 22 (1999), S. 49-103 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Dr. Thomas PS Powell was one of the founders of modern neuroanatomy. His career spanned an era that saw techniques for analyzing connections in the central nervous system dramatically increase in number and resolving power. In tracing the history of his research, one can see how the introduction of each new technique provided an incremental step in analytical capacity although eventually revealing its own limitations. Also evident is the extent to which prejudices born in the days of applying earlier techniques could continue to influence the interpretation of results obtained with new ones. Powell's contributions to neuroscience were extremely wide-ranging, encompassing investigations of the circuitry of the basal ganglia, corticofugal connections, topographic maps in sensory systems, central olfactory pathways, corticocortical and commissural connections, and pathways for sensory convergence in the cerebral cortex. From these investigations, made with tract tracing techniques, much existing knowledge of forebrain organization is derived. He was also one of the earliest investigators to use electron microscopy in the investigation of the central nervous system, and his electron microscopic studies on the olfactory bulb, thalamus, cerebral cortex, and basal ganglia laid, to a large extent, the foundations for all modern research on the synaptic circuitry of these structures. He was given to synthesizing data across systems in order to arrive at common principles of brain organization. A number of these syntheses have been sources of great interest and, occasionally, controversy.
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    Annual Review of Nuclear and Particle Science 49 (1999), S. 77-123 
    ISSN: 0163-8998
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Abstract In forthcoming years, connections between cosmology and particle physics will become increasingly important with the advent of a new generation of cosmic microwave background (CMB) experiments. Here, we review a number of these links. Our primary focus is on new CMB tests of inflation. We explain how the inflationary predictions for the geometry of the Universe and primordial density perturbations will be tested by CMB temperature fluctuations, and how the gravitational waves predicted by inflation can be pursued with the CMB polarization. The CMB signatures of topological defects and primordial magnetic fields from cosmological phase transitions are also discussed. Furthermore, we review current and future CMB constraints on various types of dark matter (e.g. massive neutrinos, weakly interacting massive particles, axions, vacuum energy), decaying particles, the baryon asymmetry of the Universe, ultra-high-energy cosmic rays, exotic cosmological topologies, and other new physics.
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    Annual Review of Nuclear and Particle Science 49 (1999), S. 255-301 
    ISSN: 0163-8998
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Abstract Data and their interpretations are reviewed for J/psi and psi' production in heavy-ion collisions with particular emphasis on the recently reported anomaly in Pb-Pb reactions. The observed suppressions in pA collisions are discussed in terms of final-state absorption of a pre-meson and the pT distributions due to parton scattering in the initial state. The experimental setup is described and the various results for J/psi and psi' suppressions, including their pT-dependence, are presented. The data, in particular the observed anomalous suppression in Pb-Pb collisions, are discussed in the light of the proposed ideas, among them quark-gluon plasma formation and suppression via co-movers.
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    Annual Review of Nuclear and Particle Science 49 (1999), S. 435-479 
    ISSN: 0163-8998
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Abstract We review the direct measurements of the top quark mass Mt using the sample of events collected by the DO and CDF experiments at Fermilab. Measurements using events in the lepton plus jets, dilepton, and all-hadronic decay modes are reviewed, as is the combination of the results to yield the current world average Mt = 174.3 +- 3.2 (stat.) +- 4.0 (syst.) GeV/c2. We close by estimating the precision attainable with future data sets at Fermilab and the Large Hadron Collider.
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    Annual Review of Nuclear and Particle Science 49 (1999), S. 633-685 
    ISSN: 0163-8998
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Abstract High-energy jet distributions measured since 1992 at the Fermilab Tevatron proton-antiproton collider are presented and compared with theoretical predictions. The statistical uncertainties on these measurements are significantly reduced relative to previous results. The systematic uncertainties are comparable in size to the uncertainty in the theoretical predictions. Although some discrepancies between theory and measurements are noted, the inclusive jet and dijet cross sections can be described by quantum chromodynamics. Prospects for reducing the uncertainty in the theoretical predictions by incorporating Tevatron measurements into the proton parton distributions are discussed. Dijet distributions, in excellent agreement with quantum chromodynamics, set a 2.5-TeV limit on the mass scale of quark constituents.
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    Annual Review of Plant Physiology and Plant Molecular Biology 50 (1999), S. 601-639 
    ISSN: 1040-2519
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract Photoreduction of dioxygen in photosystem I (PSI) of chloroplasts generates superoxide radicals as the primary product. In intact chloroplasts, the superoxide and the hydrogen peroxide produced via the disproportionation of superoxide are so rapidly scavenged at the site of their generation that the active oxygens do not inactivate the PSI complex, the stromal enzymes, or the scavenging system itself. The overall reaction for scavenging of active oxygens is the photoreduction of dioxygen to water via superoxide and hydrogen peroxide in PSI by the electrons derived from water in PSII, and the water-water cycle is proposed for these sequences. An overview is given of the molecular mechanism of the water-water cycle and microcompartmentalization of the enzymes participating in it. Whenever the water-water cycle operates properly for scavenging of active oxygens in chloroplasts, it also effectively dissipates excess excitation energy under environmental stress. The dual functions of the water-water cycle for protection from photoinihibition are discussed.
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    Annual Review of Plant Physiology and Plant Molecular Biology 50 (1999), S. 695-718 
    ISSN: 1040-2519
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract The root system of a plant is as complicated as the shoot in its diversity, in its reactions with the matrix of substances, and with the myriad organisms that surround it. Laboratory studies blind us to the complexity found by careful study of roots in soil. This complexity is illustrated in the much-studied corn root system, covering the changes along the framework roots: the surface tissues and their interactions with the soil, the water-conducting xylem, whose gradual elaboration dictates the water status of the root. A conspicuous manifestation of the changes is the rhizosheath, whose microflora differs from that on the mature bare zones. The multitude of fine roots is the most active part of the system in acquiring water and nutrients, with its own multitude of root tips, sites of intense chemical activity, that strongly modify the soil they contact, mobilize reluctant ions, immobilize toxic ions, coat the soil particles with mucilage, and select the microflora.
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    Annual Review of Plant Physiology and Plant Molecular Biology 50 (1999), S. 447-472 
    ISSN: 1040-2519
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract This review discusses how the pressure probe has evolved from an instrument for measuring cell turgor and other water relations parameters into a device for sampling the contents of individual higher plant cells in situ in the living plant. Together with a suite of microanalytical techniques it has permitted the mapping of water and solute relations at the resolution of single cells and has the potential to link quantitatively the traditionally separate areas of water relations and metabolism. The development of the probe is outlined and its modification to measure root pressure and xylem tension described. The deployment of the pressure probe to determine and map turgor, hydraulic conductivity, reflection coefficient, cell rheological properties, solute concentrations and enzyme activities at the resolution of single cells is discussed. The controversy surrounding the interpretation of results obtained with the xylem-pressure probe is included. Possible further developments of the probe and applications of single cell sampling are suggested.
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    Annual Review of Plant Physiology and Plant Molecular Biology 50 (1999), S. 571-599 
    ISSN: 1040-2519
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract Many plants increase in freezing tolerance upon exposure to low nonfreezing temperatures, a phenomenon known as cold acclimation. In this review, recent advances in determining the nature and function of genes with roles in freezing tolerance and the mechanisms involved in low temperature gene regulation and signal transduction are described. One of the important conclusions to emerge from these studies is that cold acclimation includes the expression of certain cold-induced genes that function to stabilize membranes against freeze-induced injury. In addition, a family of Arabidopsis transcription factors, the CBF/DREB1 proteins, have been identified that control the expression of a regulon of cold-induced genes that increase plant freezing tolerance. These results along with many of the others summarized here further our understanding of the basic mechanisms that plants have evolved to survive freezing temperatures. In addition, the findings have potential practical applications as freezing temperatures are a major factor limiting the geographical locations suitable for growing crop and horticultural plants and periodically account for significant losses in plant productivity.
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    Annual Review of Plant Physiology and Plant Molecular Biology 50 (1999), S. 641-664 
    ISSN: 1040-2519
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract Silicon is present in plants in amounts equivalent to those of such macronutrient elements as calcium, magnesium, and phosphorus, and in grasses often at higher levels than any other inorganic constituent. Yet except for certain algae, including prominently the diatoms, and the Equisetaceae (horsetails or scouring rushes), it is not considered an essential element for plants. As a result it is routinely omitted from formulations of culture solutions and considered a nonentity in much of plant physiological research. But silicon-deprived plants grown in conventional nutrient solutions to which silicon has not been added are in many ways experimental artifacts. They are often structurally weaker than silicon-replete plants, abnormal in growth, development, viability, and reproduction, more susceptible to such abiotic stresses as metal toxicities, and easier prey to disease organisms and to herbivores ranging from phytophagous insects to mammals. Many of these same conditions afflict plants in silicon-poor soils-and there are such. Taken together, the evidence is overwhelming that silicon should be included among the elements having a major bearing on plant life.
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    Annual Review of Biomedical Engineering 1 (1999), S. 47-72 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract The dimensions, composition, and stiffness of the airway wall are important determinants of airway cross-sectional area during dynamic collapse in a forced expiration or when airway smooth muscle is constricted. Under these circumstances, airway caliber is determined by an interaction between the forces acting to open the airway (parenchymal tension and wall stiffness) and those acting to close it (smooth-muscle force and surface tension at the inner gas-liquid interface). Experimental measurements and theoretical models of the airway tube law (relationship between cross-sectional area and transmural pressure) are presented. Data are presented for the elastic properties of the wall tissue. Simulations of airway constriction in normal and asthmatic airways are discussed. To the extent possible, comparisons are presented between the various models and existing experimental data.
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    Annual Review of Biomedical Engineering 1 (1999), S. 1-18 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Richard Skalak (1923-1997) played a leadership role in the formative decades of the discipline of biomedical engineering through his technical contributions in biomechanics, his educational influence on students, and his service to many developing societies and journals. But always, the distinguishing marks of his involvement with any activity or person were his generosity, respect and tolerance for others, integrity, and curiosity. These very qualities are what first brought him as a traditional engineer trained in engineering mechanics into the young field of biomedical engineering in the 1960s, and they are what led him to new approaches to cellular and molecular engineering, tissue engineering, and orthopedic biomechanics. His technical papers and lectures on blood cell mechanics, pulmonary circulation, dental implants, and tissue growth were models of clarity and often pointed the way to new areas of exploration, while his personal writings offer advice on life, academic organizations, and the pursuit of significant work. He would be deeply appreciative that this first volume of the Annual Review of Biomedical Engineering is dedicated to his memory.
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    Annual Review of Biomedical Engineering 1 (1999), S. 19-46 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Because of an aging population and increased occurrence of sports-related injuries, musculoskeletal disorders have become one of the major health concerns in the United States. Current treatments, although fairly successful, do not provide the optimum therapy. These treatments typically rely on donor tissues obtained either from the patient or from another source. The former raises the issue of supply, whereas the latter poses the risk of rejection and disease transfer. This has prompted orthopedic surgeons and scientists to look for viable alternatives. In recent years, tissue engineering has gained increasing support as a method to treat orthopedic disorders. Because it uses principles of engineering, biology, and chemistry, tissue engineering may provide a more effective approach to the treatment of musculoskeletal disorders than traditional methods. This chapter presents a review of current methods and new tissue-engineering techniques for the treatment of disorders affecting bone, ligament, and cartilage.
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    Annual Review of Biomedical Engineering 1 (1999), S. 103-127 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract The successful application and optimization of cell transplantation will require quantitative engineering design and analysis of cells and materials in which relevant biological processes remain complex and incompletely defined. This report primarily reviews the engineering and material considerations in islet cell transplantation, including established biological constraints and biohybrid devices for cell delivery, as well as available barrier materials and the associated processing strategies directed at the control of solute transport, barrier permeability, and host responses at the biological-material interface. Also described are current areas of investigation with particular promise as enabling technologies for accelerating the clinical effectiveness of islet cell transplantation.
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    Annual Review of Biomedical Engineering 1 (1999), S. 129-152 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Hematopoietic cell culture, or ex vivo expansion of hematopoietic cells, is an enabling technology with many potential applications in bone-marrow transplantation, immunotherapy, gene therapy, and the production of blood products. Hematopoietic cultures are complex, with many different cell types at different stages of development present at any given point in time and never in steady state. Moreover, these cells interact strongly with each other and the environment through cytokines (growth factors) and adhesion molecules, as well as through their metabolism. Despite these significant challenges, cell products produced in bioreactors have shown promise in recent phase 1 clinical trials.
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    Annual Review of Biomedical Engineering 1 (1999), S. 153-175 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract By maintaining a near normal (70-120 mg/dL) glucose concentration, diabetic patients can drastically reduce the likelihood of the occurrence of diabetes complications. In the near future, subcutaneously implanted electrochemical glucose sensors will be available to provide frequent or continuous information on which timely treatment decisions, such as insulin injection or glucose source intake, can be based, as well as timely alarm signals. The currently engineered devices are of three types: (a) innocuous microsensors, with actively mass-transporting areas 〈10-3 cm2, replaced twice a week by the patient; (b) self-contained, surgeon-implanted, transmitter-containing packages of 〉1 cm2 area, operating for 〉100 days; and (c) devices transporting subcutaneous fluid to an external sensor, based on implanted microfiltration or microdialysis fibers or on iontophoretic transport of the subcutaneous fluid through the skin.
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    Annual Review of Environment and Resources 24 (1999), S. 461-486 
    ISSN: 1056-3466
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Yucca Mountain, NV, is being characterized for disposal of U.S. high-level nuclear waste, which consists predominantly of spent fuel from nuclear reactors and radioactive waste from reprocessing. In this paper, the program is presented in the context of global and U.S. nuclear energy systems and of international plans for high-level waste disposal. The potential impact of the proposed repository is discussed in the context of the U.S. Department of Energy's Total System Performance Assessment-Viability Assessment, the primary tool for assessing how the repository might operate.
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    Annual Review of Environment and Resources 24 (1999), S. 487-512 
    ISSN: 1056-3466
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In this paper, we estimate the value of energy technology research and development (R&D) as an insurance investment to reduce four risks to the United States. These four risks are (a) the costs of climate stabilization, (b) oil price shocks and cartel pricing, (c) urban air pollution, and (d) other energy disruptions. The total value is estimated conservatively to be 〉$12 billion/year. However, only about half of this total may be warranted because some R&D is applicable to more than one risk. Nevertheless, the total Department of Energy investment in energy technology R&D [~$1.5 billion/year in fiscal year 1999 (FY99)] seems easily justified by its insurance value alone. In fact, a larger investment might be justified, particularly in the areas related to climate change, oil price shock, and urban air pollution. This conclusion appears robust even if the private sector is assumed to be investing a comparable amount relevant to these risks. No additional benefit is credited for the value to the economy and to the competitiveness of the U.S. from better energy technologies that may result from the R&D; only the insurance value for reducing the potential cost of these four risks to society was estimated.
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    Annual Review of Environment and Resources 24 (1999), S. 513-544 
    ISSN: 1056-3466
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Climate policy is often discussed as a lever with which to bring about climate-friendly technical innovation and diffusion. However, quantitative policy assessments routinely treat technological change as a factor that is independent of policy. Stabilizing atmospheric concentrations of CO2 cannot be achieved through marginal changes in the way we supply and use energy. The only path to stabilization of climate over the next century that is consistent with widely accepted population and economic-growth scenarios involves substantial decoupling of energy services from carbon emissions. The required rate of structural and technical change for such a goal has been experienced only in the wake of economic and resource crises and for periods of a decade or less. Historic rates of structural and technical change averaged over a century are far from adequate for stabilizing climate. In this paper, we review technical changes in the energy system and a few instances in which energy economic models have begun to include technical change as an endogenous feature of their assessments. Finally, we consider the implications of considering endogenous technical change for critical climate policy questions, such as the cost of control and the appropriate timing of the emissions mitigation effort.
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    Annual Review of Environment and Resources 24 (1999), S. 545-569 
    ISSN: 1056-3466
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Technology largely determines economic development and its impact on the environment; yet technological change is one of the least developed parts of existing global change models. This paper reviews two approaches developed at the International Institute for Applied Systems Analysis, both of which use the concept of technological learning and aid modeling of technological change. The first approach is a micromodel ("bottom-up") of three electricity generation technologies that rigorously endogenizes technological change by incorporating both uncertainty (stochasticity) and learning into the model's decision rules. This model, with its endogenous technological change, allows radical innovations to penetrate the energy market and generates S-shaped patterns of technological diffusion that are observed in the real world. The second approach is a macro ("top-down") model that consists of coupled economic- and technological-system models. Although more stylistic in its representation of endogenous technological change, the macro model can be applied on a worldwide scale and can generate long-term scenarios that are critical for policy analysis. Both the micro- and macro models generate radical departures from currently dominant technological systems ("surprises"), including long-term scenarios with low carbon and sulfur emissions. Our focus is modeling, but for policy, the work underscores the need for huge investments before environmentally superior technologies can compete in the market.
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    Annual Review of Environment and Resources 24 (1999), S. 571-605 
    ISSN: 1056-3466
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A total of 176 countries have ratified the United Nations Framework Convention on Climate Change, thereby agreeing to limit emissions of greenhouse gases that threaten to interfere with the Earth's climate. While compliance procedures are being developed, the best indicators of implementation of the Convention are the emissions inventories of greenhouse gases that member countries must submit to the Convention as part of their national communications. We review some of the first emissions inventories from non-Annex I (developing) countries. We focus on land-use change and forestry because these activities are responsible for the major emissions of carbon in many non-Annex I parties, and because they are the only activities with the potential to remove carbon from the atmosphere and sequester it on land. The review shows first, that some developing countries have already begun to reduce emissions and second, that there are significant discrepancies between the data used in the emissions inventories and the data available in international surveys. Conceptual uncertainties also exist, such as distinguishing anthropogenic from nonanthropogenic sinks of carbon, and these will require political rather than scientific resolution. We discuss several options for counting terrestrial sources and sinks of carbon in light of the Kyoto Protocol.
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    Annual Review of Environment and Resources 24 (1999), S. 645-661 
    ISSN: 1056-3466
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Although global warming is generally linked to increasing levels of carbon dioxide, there are many other gases produced from industrial, agricultural, and energy-generating sources that can also cause the Earth's temperature to rise. Individually these gases are not likely to make a significant contribution, but, taken together, it is believed that they can rival the effects of carbon dioxide. This paper reviews the current trends of the most abundant or the most effective of these non-CO2 greenhouse gases. Methane, nitrous oxide, and the major chlorofluorocarbons (F-11 and F-12) have been the most notable greenhouse gases other than CO2. Although these gases will continue to play a role in global warming, new compounds are likely to become increasingly important. These include the fluorocarbon replacement compounds in the hydrofluorocarbon and the hydrochlorofluorocarbon groups and gases that are nearly inert in the atmosphere, persisting for thousands of years, such as the perfluorocarbons and sulfur hexafluoride.
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    Annual Review of Environment and Resources 24 (1999), S. 607-643 
    ISSN: 1056-3466
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The US-Mexico border region illustrates the challenges of binational environmental management in the context of a harsh physical environment, rapid growth, and economic integration. Transboundary and shared resources and conflicts include limited surface water supplies, depletion of groundwater, air and water pollution, hazardous waste, and conservation of important natural ecosystems. Public policy responses to environmental problems on the border include binational institutions such as the IBWC, BECC and CEC, the latter two established in response to environmental concerns about the North American Free Trade Agreement (NAFTA). Environmental social movements and nongovernmental organizations have also become important agents in the region. These new institutions and social movements are especially interesting on the Mexican side of the border where political and economic conditions have often limited environmental enforcement and conservation, and where recent policy changes also include changes in land and water law, political democratization, and government decentralization.
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    Annual Review of Biomedical Engineering 1 (1999), S. 241-263 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Extraordinary advances in molecular biology and biotechnology have led to the development of a vast number of therapeutic anti-cancer agents. To reach cancer cells in a tumor, a blood-borne therapeutic molecule, particle, or cell must make its way into the blood vessels of the tumor and across the vessel wall into the interstitium, which it then must migrate through. Unfortunately, tumors often develop in ways that hinder these steps. The goal of research in this area is to analyze each of these steps experimentally and theoretically and integrate the resulting information into a unified theoretical framework. This paradigm of analysis and synthesis has fostered a better understanding of physiological barriers in solid tumors and aided in the development of novel strategies to exploit and/or overcome these barriers for improved cancer detection and treatment.
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    Annual Review of Biomedical Engineering 1 (1999), S. 177-209 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Historically, electronic devices such as pacemakers and neuromuscular stimulators have been surgically implanted into animals and humans. A new class of implants made possible by advances in monolithic electronic design and implant packaging is small enough to be implanted by percutaneous injection through large-gauge hypodermic needles and does not require surgical implantation. Among these, commercially available implants, known as radio frequency identification (RFID) tags, are used for livestock, pet, laboratory animal, and endangered-species identification. The RFID tag is a subminiature glass capsule containing a solenoidal coil and an integrated circuit. Acting as the implanted half of a transcutaneous magnetic link, the RFID tag is powered by and communicates with an extracorporeal magnetic reader. The tag transmits a unique identification code that serves the function of identifying the animal. Millions of RFID tags have been sold since the early 1980s. Based on the success of the RFID tags, research laboratories have developed injectable medical implants, known as micromodules. One type of micromodule, the microstimulator, is designed for use in functional-neuromuscular stimulation. Each microstimulator is uniquely addressable and could comprise one channel of a multichannel functional-neuromuscular stimulation system. Using bidirectional telemetry and commands, from a single extracorporeal transmitter, as many as 256 microstimulators could form the hardware basis for a complex functional-neuromuscular stimulation feedback-control system. Uses include stimulation of paralyzed muscle, therapeutic functional-neuromuscular stimulation, and neuromodulatory functions such as laryngeal stimulation and sleep apnea.
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    Annual Review of Biomedical Engineering 1 (1999), S. 299-329 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract The cardiovascular system is an internal flow loop with multiple branches circulating a complex liquid. The hallmarks of blood flow in arteries are pulsatility and branches, which cause wall stresses to be cyclical and nonuniform. Normal arterial flow is laminar, with secondary flows generated at curves and branches. Arteries can adapt to and modify hemodynamic conditions, and unusual hemodynamic conditions may cause an abnormal biological response. Velocity profile skewing can create pockets in which the wall shear stress is low and oscillates in direction. Atherosclerosis tends to localize to these sites and creates a narrowing of the artery lumen-a stenosis. Plaque rupture or endothelial injury can stimulate thrombosis, which can block blood flow to heart or brain tissues, causing a heart attack or stroke. The small lumen and elevated shear rate in a stenosis create conditions that accelerate platelet accumulation and occlusion. The relationship between thrombosis and fluid mechanics is complex, especially in the post-stenotic flow field. New convection models have been developed to predict clinical occlusion from platelet thrombosis in diseased arteries. Future hemodynamic studies should address the complex mechanics of flow-induced, large-scale wall motion and convection of semisolid particles and cells in flowing blood.
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    Annual Review of Biomedical Engineering 1 (1999), S. 463-503 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Ionic and molecular transfer among cells occurs by a variety of transport processes operative at different length scales. Cell membrane permeability and electrical conductance derive from channel proteins producing pores at the molecular (ultrastructural) scale. Intracellular mobility involves the dynamics of motion through the complex ultrastructure of the cytoplasm. These phenomena unite in the larger-scale (microscopic) process of gross intercellular transfer. When such movement occurs among sufficiently many cells, it in turn begins to reflect their average collective (macroscopic) behavior as bulk tissue. This article surveys selected aspects of intercellular and intracellular transport, with emphasis on detailed mechanistic theory, experimental probes of cellular permeability, and systematic transcendence from small to large length scales.
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    Annual Review of Biomedical Engineering 1 (1999), S. 427-461 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Blood clots form under hemodynamic conditions and can obstruct flow during angina, acute myocardial infarction, stroke, deep vein thrombosis, pulmonary embolism, peripheral thrombosis, or dialysis access graft thrombosis. Therapies to remove these clots through enzymatic and/or mechanical approaches require consideration of the biochemistry and structure of blood clots in conjunction with local transport phenomena. Because blood clots are porous objects exposed to local hemodynamic forces, pressure-driven interstitial permeation often controls drug penetration and the overall lysis rate of an occlusive thrombus. Reaction engineering and transport phenomena provide a framework to relate dosage of a given agent to potential outcomes. The design and testing of thrombolytic agents and the design of therapies must account for (a) the binding, catalytic, and systemic clearance properties of the therapeutic enzyme; (b) the dose and delivery regimen; (c) the biochemical and structural aspects of the thrombotic occlusion; (d) the prevailing hemodynamics and anatomical location of the thrombus; and (e) therapeutic constraints and risks of side effects. These principles also impact the design and analysis of local delivery devices.
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    Annual Review of Biomedical Engineering 1 (1999), S. 559-588 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Since the introduction of medical ultrasound in the 1950s, modern diagnostic ultrasound has progressed to see many major diagnostic tools come into widespread clinical use, such as B-mode imaging, color-flow imaging, and spectral Doppler. New applications, such as panoramic imaging, three-dimensional imaging, and quantitative imaging, are now beginning to be offered on some commercial ultrasound machines and are expected to grow in popularity. In this review, we focus on the various algorithms, their processing requirements, and the challenges of these ultrasound modes. Whereas the older, mature B and color-flow modes could be systolically implemented using hardwired components and boards, new applications, such as three-dimensional imaging and image feature extraction, are being implemented more by using programmable processors. This trend toward programmable ultrasound machines will continue, because the programmable approach offers the advantages of quick implementation of new applications without any additional hardware and the flexibility to adapt to the changing requirements of these dynamic new applications.
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    Annual Review of Biomedical Engineering 1 (1999), S. 649-678 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract Much of the recent rapid progress in large-scale genomic sequencing has been driven by the dramatic improvements both in the area of biological protocols and in the availability of improved laboratory instrumentation and automation platforms. We discuss recent developments in the area of bioinstrumentation that are contributing to the current revolution in genetic analysis. Examples of systems for laboratory automation are described together with specific single-purpose instruments. Emphasis is placed on those tools that are contributing significantly to the scale-up of genomic mapping and sequencing efforts. In addition, we present a selection of more advanced measurement techniques and instrumentation developments that are likely to contribute significantly to future advances in sequencing and genome analysis.
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    Annual Review of Biochemistry 68 (1999), S. 33-57 
    ISSN: 0066-4154
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Biology
    Notes: Abstract The metal-activated hydroxide ion is a critical nucleophile in metalloenzymes that catalyze hydrolysis or hydration reactions. The most common metal used is zinc; occasionally, other transition metals such as manganese are required. Human carbonic anhydrase II and rat liver arginase serve as well-studied paradigms of zinc and manganese metalloenzymes, respectively. Comparative structure-function relationships between these two metalloenzymes highlight parallels in the chemistry of metal-activated hydroxide: (a) the protein environment of metal-bound hydroxide modulates its reactivity; (b) a hydrogen bond with metal-bound hydroxide holds it in the proper orientation for catalysis; (c) nonmetal substrate-binding sites are implicated in both enzyme mechanisms; and (d) regeneration of metal-bound hydroxide ion from a metal-bound water molecule requires proton transfer to bulk solvent mediated by a histidine proton shuttle residue. Interestingly, the electrostatics of catalysis differ between the two enzymes, in that the first step of catalysis requires formation of a negatively charged transition state in the carbonic anhydrase II mechanism, whereas a neutral transition state is approached in the arginase mechanism. This electrostatic feature may contribute to the differences in the chemistry, the metal binding sites, and the metal specificity between these two enzymes.
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    Annual Review of Biochemistry 68 (1999), S. 301-319 
    ISSN: 0066-4154
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Biology
    Notes: Abstract Eukaryotic mRNA synthesis is catalyzed by multisubunit RNA polymerase II and proceeds through multiple stages referred to as preinitiation, initiation, elongation, and termination. Over the past 20 years, biochemical studies of eukaryotic mRNA synthesis have largely focused on the preinitiation and initiation stages of transcription. These studies led to the discovery of the class of general initiation factors (TFIIB, TFIID, TFIIE, TFIIF, and TFIIH), which function in intimate association with RNA polymerase II and are required for selective binding of polymerase to its promoters, formation of the open complex, and synthesis of the first few phosphodiester bonds of nascent transcripts. Recently, biochemical studies of the elongation stage of eukaryotic mRNA synthesis have led to the discovery of several cellular proteins that have properties expected of general elongation factors and that have been found to play unanticipated roles in human disease. Among these candidate general elongation factors are the positive transcription elongation factor b (P-TEFb), eleven-nineteen lysine-rich in leukemia (ELL), Cockayne syndrome complementation group B (CSB), and elongin proteins, which all function in vitro to expedite elongation by RNA polymerase II by suppressing transient pausing or premature arrest by polymerase through direct interactions with the elongation complex. Despite their similar activities in elongation, the P-TEFb, ELL, CSB, and elongin proteins appear to play roles in a diverse collection of human diseases, including human immunodeficiency virus-1 infection, acute myeloid leukemia, Cockayne syndrome, and the familial cancer predisposition syndrome von Hippel-Lindau disease. Here we review our current understanding of the P-TEFb, ELL, CSB, and elongin proteins, their mechanisms of action, and their roles in human disease.
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    Annual Review of Biochemistry 68 (1999), S. 523-558 
    ISSN: 0066-4154
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Biology
    Notes: Abstract Risk for cardiovascular disease due to atherosclerosis increases with increasing concentrations of low-density lipoprotein (LDL) cholesterol and is inversely proportional to the levels of high-density lipoprotein (HDL) cholesterol. The receptor-mediated control of plasma LDL levels has been well understood for over two decades and has been a focus for the pharmacologic treatment of hypercholesterolemia. In contrast, the first identification and characterization of a receptor that mediates cellular metabolism of HDL was only recently reported. This receptor, called scavenger receptor class B type I (SR-BI), is a fatty acylated glycoprotein that can cluster in caveolae-like domains on the surfaces of cultured cells. SR-BI mediates selective lipid uptake from HDL to cells. The mechanism of selective lipid uptake is fundamentally different from that of classic receptor-mediated endocytic uptake via coated pits and vesicles (e.g. the LDL receptor pathway) in that it involves efficient receptor-mediated transfer of the lipids, but not the outer shell proteins, from HDL to cells. In mice, SR-BI plays a key role in determining the levels of plasma HDL cholesterol and in mediating the regulated, selective delivery of HDL-cholesterol to steroidogenic tissues and the liver. Significant alterations in SR-BI expression can result in cardiovascular and reproductive disorders. SR-BI may play a similar role in humans; thus, modulation of its activity may provide the basis of future approaches to the treatment and prevention of atherosclerotic disease.
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    Annual Review of Biochemistry 68 (1999), S. 649-686 
    ISSN: 0066-4154
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Biology
    Notes: Abstract The MCM proteins are essential replication initiation factors originally identified as proteins required for minichromosome maintenance in Saccharomyces cerevisiae. The best known among them are a family of six structurally related proteins, MCM2-7, which are evolutionally conserved in all eukaryotes. The MCM2-7 proteins form a hexameric complex. This complex is a key component of the prereplication complex that assembles at replication origins during early G1 phase. New evidence suggests that the MCM2-7 proteins may be involved not only in the initiation but also in the elongation of DNA replication. Orchestration of the functional interactions between the MCM2-7 proteins and other components of the prereplication complex by cell cycle-dependent protein kinases results in initiation of DNA synthesis once every cell cycle.
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    Annual Review of Biochemistry 68 (1999), S. 821-861 
    ISSN: 0066-4154
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Biology
    Notes: Abstract Extracellular stimuli elicit changes in gene expression in target cells by activating intracellular protein kinase cascades that phosphorylate transcription factors within the nucleus. One of the best characterized stimulus-induced transcription factors, cyclic AMP response element (CRE) -binding protein (CREB), activates transcription of target genes in response to a diverse array of stimuli, including peptide hormones, growth factors, and neuronal activity, that activate a variety of protein kinases including protein kinase A (PKA), pp90 ribosomal S6 kinase (pp90RSK), and Ca2+/calmodulin-dependent protein kinases (CaMKs). These kinases all phosphorylate CREB at a particular residue, serine 133 (Ser133), and phosphorylation of Ser133 is required for CREB-mediated transcription. Despite this common feature, the mechanism by which CREB activates transcription varies depending on the stimulus. In some cases, signaling pathways target additional sites on CREB or proteins associated with CREB, permitting CREB to regulate distinct programs of gene expression under different conditions of stimulation. This review will discuss the molecular mechanisms by which Ser133--phosphorylated CREB activates transcription, intracellular signaling pathways that lead to phosphorylation of CREB at Ser133, and features of each signaling pathway that impart specificity at the level of CREB activation.
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    Annual Review of Biochemistry 68 (1999), S. 1015-1068 
    ISSN: 0066-4154
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Biology
    Notes: Abstract In eukaryotic cells, most proteins in the cytosol and nucleus are degraded via the ubiquitin-proteasome pathway. The 26S proteasome is a 2.5-MDa molecular machine built from ~31 different subunits, which catalyzes protein degradation. It contains a barrel-shaped proteolytic core complex (the 20S proteasome), capped at one or both ends by 19S regulatory complexes, which recognize ubiquitinated proteins. The regulatory complexes are also implicated in unfolding and translocation of ubiquitinated targets into the interior of the 20S complex, where they are degraded to oligopeptides. Structure, assembly and enzymatic mechanism of the 20S complex have been elucidated, but the functional organization of the 19S complex is less well understood. Most subunits of the 19S complex have been identified, however, specific functions have been assigned to only a few. A low-resolution structure of the 26S proteasome has been obtained by electron microscopy, but the precise arrangement of subunits in the 19S complex is unclear.
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    Annual Review of Ecology, Evolution, and Systematics 30 (1999), S. 539-563 
    ISSN: 0066-4162
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract Domesticated plant taxa cannot be regarded as evolutionarily discrete from their wild relatives. Most domesticated plant taxa mate with wild relatives somewhere in the world, and gene flow from crop taxa may have a substantial impact on the evolution of wild populations. In a literature review of the world's 13 most important food crops, we show that 12 of these crops hybridize with wild relatives in some part of their agricultural distribution. We use population genetic theory to predict the evolutionary consequences of gene flow from crops to wild plants and discuss two applied consequences of crop-to-wild gene flow-the evolution of aggressive weeds and the extinction of rare species. We suggest ways of assessing the likelihood of hybridization, introgression, and the potential for undesirable gene flow from crops into weeds or rare species.
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    Annual Review of Physiology 61 (1999), S. 219-242 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract This review surveys a wide range of cellular and molecular approaches to strengthening the injured or weakened heart, focusing on strategies to replace dysfunctional, necrotic, or apoptotic cardiomyocytes with new cells of mesodermal origin. A variety of cell types, including myogenic cell lines, adult skeletal myoblasts, immortalized atrial cells, embryonic and adult cardiomyocytes, embryonic stem cells, teratoma cells, genetically altered fibroblasts, smooth muscle cells, and bone marrow-derived cells have all been proposed as useful cells in cardiac repair and may have the capacity to perform cardiac work. We focus on the implantation of mesodermally derived cells, the best developed of the options. We review the developmental and cell biology that have stimulated these studies, examine the limitations of current knowledge, and identify challenges for the future, which we believe are considerable.
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    Annual Review of Physiology 61 (1999), S. 337-362 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract ATP-sensitive K+ channels (KATP channels) play important roles in many cellular functions by coupling cell metabolism to electrical activity. By cloning members of the novel inwardly rectifying K+ channel subfamily Kir6.0 (Kir6.1 and Kir6.2) and the receptors for sulfonylureas (SUR1 and SUR2), researchers have clarified the molecular structure of KATP channels. KATP channels comprise two subunits: a Kir6.0 subfamily subunit, which is a member of the inwardly rectifying K+ channel family; and a SUR subunit, which is a member of the ATP-binding cassette (ABC) protein superfamily. KATP channels are the first example of a heteromultimeric complex assembled with a K+ channel and a receptor that are structurally unrelated to each other. Since 1995, molecular biological and molecular genetic studies of KATP channels have provided insights into the structure-function relationships, molecular regulation, and pathophysiological roles of KATP channels.
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    Annual Review of Physiology 61 (1999), S. 391-415 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract In this article, we review the basic pharmacological and biochemical features of endothelin and the pathophysiological roles of endothelin in cardiovascular diseases. Development of receptor antagonists has accelerated the pace of investigations into the pathophysiological roles of endogenous endothelin-1 in various diseases, e.g. chronic heart failure, renal diseases, hypertension, cerebral vasospasm, and pulmonary hypertension. In chronic heart failure, the expression of endothelin-1 and its receptors in cardiomyocytes is increased, and treatment with an endothelin receptor antagonist improves survival and cardiac function. Endothelin receptor antagonists also improve other cardiovascular diseases. These results suggest that the interference with endothelin pathway either by receptor blockade or by inhibition of endothelin converting enzyme may provide novel therapeutic drugs strategies for multiple disease states.
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    Annual Review of Physiology 61 (1999), S. 457-476 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Echolocating bats use audition to guide much of their behavior. As in all vertebrates, their lower brainstem contains a number of parallel auditory pathways that provide excitatory or inhibitory outputs differing in their temporal discharge patterns and latencies. These pathways converge in the auditory midbrain, where many neurons are tuned to biologically important parameters of sound, including signal duration, frequency-modulated sweep direction, and the rate of periodic frequency or amplitude modulations. This tuning to biologically relevant temporal patterns of sound is created through the interplay of the time-delayed excitatory and inhibitory inputs to midbrain neurons. Because the tuning process requires integration over a relatively long time period, the rate at which midbrain auditory neurons respond corresponds to the cadence of sounds rather than their fine structure and may provide an output that is closely matched to the rate at which motor systems operate.
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    Annual Review of Physiology 61 (1999), S. 477-496 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Neurons in the cochlear ganglion and auditory brain stem nuclei preserve the relative timing of action potentials passed through sequential synaptic levels. To accomplish this task, these neurons have unique morphological and biophysical specializations in axons, dendrites, and nerve terminals. At the membrane level, these adaptations include low-threshold, voltage-gated potassium channels and unusually rapid-acting transmitter-gated channels, which govern how quickly and reliably action potential threshold is reached during a synaptic response. Some nerve terminals are remarkably large and release large amounts of excitatory neurotransmitter. The high output of transmitter at these terminals can lead to synaptic depression, which may itself be regulated by presynaptic transmitter receptors. The way in which these different cellular mechanisms are employed varies in different cell types and circuits and reflects refinements suited to different aspects of acoustic processing.
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    Annual Review of Physiology 61 (1999), S. 573-592 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Vertebrate lungs have long been thought to have evolved in fishes largely as an adaptation for life in hypoxic water. This view overlooks the possibility that lungs may have functioned to supply the heart with oxygen and may continue to serve this function in extant fishes. The myocardium of most vertebrates is avascular and obtains oxygen from luminal blood. Because oxygen-rich pulmonary blood mixes with oxygen-poor systemic blood before entering the heart of air-breathing fishes, lung ventilation may supply the myocardium with oxygen and expand aerobic exercise capabilities. Although sustained exercise in tetrapods is facilitated by septation of the heart and the formation of a dual pressure system, a divided cardio-pulmonary system may conflict with myocardial oxygenation because the right side of the heart is isolated from pulmonary oxygen. This may have contributed to the evolution of the coronary circulation.
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    Annual Review of Physiology 61 (1999), S. 593-625 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract The mouse is an ideal species for investigation at the interface of lung biology and lung function. As detailed in this review, there are well-developed methods for the quantitative study of lung function in mice. These methods can be applied to mice in both terminal and nonterminal experiments. Terminal experimental approaches provide more detailed physiological information, but nonterminal measurements provide adequate data for certain experiments. In this review, we provide two examples of how these models can be used to further understanding of the primary pathobiology of airway responsiveness in both the absence and the presence of induced airway inflammation. The first model is a dissection of chromosomal loci linked to the variance in airway responsiveness observed in the absence of any manipulation to induce airway inflammation. The second model explores the role of T-cell costimulatory signals in the induction of airway hyperresponsiveness. As the number of mice with targeted deletions of effector genes or insertion of informative transgenes grows, additional examples are likely to accrue.
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    Annual Review of Physiology 61 (1999), S. 725-752 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Patch-clamp capacitance measurements can monitor in real time the kinetics of exocytosis and endocytosis in living cells. We review the application of this technique to the giant presynaptic terminals of goldfish bipolar cells. These terminals secrete glutamate via the fusion of small, clear-core vesicles at specialized, active zones of release called synaptic ribbons. We compare the functional characteristics of transmitter release at ribbon-type and conventional synapses, both of which have a unique capacity for fast and focal vesicle fusion. Subsequent rapid retrieval and recycling of fused synaptic vesicle membrane allow presynaptic terminals to function independently of the cell soma and, thus, as autonomous computational units. Together with the mobilization of reserve vesicle pools, local cycling of synaptic vesicles may delay the onset of vesicle pool depletion and sustain neuronal output during high stimulation frequencies.
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    Annual Review of Physiology 61 (1999), S. 753-776 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Synaptic transmission starts with the release of neurotransmitters by exocytosis of synaptic vesicles. As a relatively simple organelle with a limited number of components, synaptic vesicles are in principle accessible to complete structural and functional genetic analysis. At present, the majority of synaptic vesicle proteins has been characterized, and many have been genetically analyzed in mice, Drosophila, and Caenorhabditis elegans. These studies have shown that synaptic vesicles contain proteins with diverse structures and functions. Although the genetic studies are as yet unfinished, they promise to lead to a full description of synaptic vesicles as macromolecular machines involved in all aspects of presynaptic neurotransmitter release.
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    Annual Review of Physiology 61 (1999), S. 777-807 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
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    Notes: Abstract Regulated exocytosis involves the tightly controlled fusion of a transport vesicle with the plasma membrane. It includes processes as diverse as the release of neurotransmitters from presynaptic nerve endings and the sperm-triggered deposition of a barrier preventing polyspermy in oocytes. Cell-free model systems have been developed for studying the biochemical events underlying exocytosis. They range from semi-intact permeabilized cells to the reconstitution of membrane fusion from isolated secretory vesicles and their target plasma membranes. Interest in such cell-free systems has recently been reinvigorated by new evidence suggesting that membrane fusion is mediated by a basic mechanism common to all intracellular fusion events. In this chapter, we review some of the literature in the light of these new developments and attempt to provide a critical discussion of the strengths and limitations of the various cell-free systems.
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    Annual Review of Physiology 61 (1999), S. 809-834 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Mechanosensory hair cells of the vertebrate inner ear contribute to acoustic tuning through feedback processes involving voltage-gated channels in the basolateral membrane and mechanotransduction channels in the apical hair bundle. The specific number and kinetics of calcium-activated (BK) potassium channels determine the resonant frequency of electrically tuned hair cells. Kinetic variation among BK channels may arise through alternative splicing of slo gene mRNA and combination with modulatory beta subunits. The number of transduction channels and their rate of adaptation rise with hair cell response frequency along the cochlea's tonotopic axis. Calcium-dependent feedback onto transduction channels may underlie active hair bundle mechanics. The relative contributions of electrical and mechanical feedback to active tuning of hair cells may vary as a function of sound frequency.
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    Annual Review of Physiology 61 (1999), S. 835-856 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Nociceptors are the first cells in the series of neurons that lead to the sensation of pain. The essential functions of nociceptors-transducing noxious stimuli into depolarizations that trigger action potentials, conducting the action potentials from the peripheral sensory site to the synapse in the central nervous system, and converting the action potentials into neurotransmitter release at the presynaptic terminal-all depend on ion channels. This review discusses recent results in the converging fields of nociception and ion channel biology. It focuses on (a) the capsaicin receptor and its possible role in thermosensation, (b) ATP-gated channels, (c) proton-gated channels, and (d) nociceptor-specific Na+ channels.
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    Annual Review of Earth and Planetary Sciences 27 (1999), S. 19-53 
    ISSN: 0084-6597
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Geosciences , Physics
    Notes: Abstract Mixed-layer clay minerals are intermediate products of reactions involving pure end-member clays. They come from natural environments ranging from surface to low-grade metamorphic and hydrothermal conditions. Most often mixed layering is essentially two component, but more complicated interstratifications have also been documented. Variable tendency to form regular 1:1 interstratifications has been observed and explanations of this phenomenon have been proposed. Mixed-layer clays are either di- or trioctahedral; di/trioctahedral interstratifications are rare. Most mixed-layer clays contain smectite or vermiculte as a swelling component. Exceptions are all trioctahedral: serpentine/chlorite in low-temperature environments, and mica/chlorite and talc/chlorite at high temperatures. Solid state transformation and dissolution/crystallization are the two mechanisms responsible for the formation of different mixed-layer clays. In general, the weathering reactions that produce mixed layering are reversals of the corresponding high-temperature reactions, but the reaction paths are quite different. Weathering reactions alter smectite into kaolinite via mixed-layer kaolinite/smectite. Illite, chlorite, and micas react into mixed-layer clays involving vermiculite layer, then into vermiculite, and finally smectite. Interstratifications of smectite and glauconite, serpentine and chlorite, and smectite and talc are characteristic of early diagenesis and indicative of sedimentary environments. Three reactions involving mixed-layer clays-smectite to illite, smectite to chlorite, and serpentine/chlorite to chlorite-proceed gradually during burial diagenesis and are used for reconstructing maximum burial conditions, illite/smectite being the most useful tool. Rectorite, tosudite, talc/chlorite, and mica/chlorite are mixed-layer minerals indicative of temperatures higher than diagenetic, characteristic of low-temperature metamorphism or hydrothermal alteration.
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    Annual Review of Earth and Planetary Sciences 27 (1999), S. 359-384 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Geosciences , Physics
    Notes: Abstract In this paper, an overview is presented of coupled processes linking thermo-hydro-mechanical (THM) effects in fractured rocks. A formulation is first presented to show the linkage mathematically, which can be used as a basis for numerical solutions and for further developments. Two simple examples of hydromechanical (HM) and thermo-hydro-mechanical (THM) coupled processes are discussed to convey physical insight into such couplings. Finally, three large-scale, long-term experiments currently under way are described. These are being conducted specifically to study coupled processes in situ.
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    Annual Review of Earth and Planetary Sciences 27 (1999), S. 75-113 
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    Topics: Geosciences , Physics
    Notes: Abstract The Chicxulub crater ejecta stratigraphy is reviewed, in the context of the stratigraphy of underlying and overlying rock sequences. The ejecta sequence is regionally grouped in (a) thick polymict and monomict breccia sequences inside the crater and within 300 km from the rim of the crater known from drill holes in and close to the breater, and exposures near the border of Yucatan and Belize; (b) Gulf of Mexico region, 〈2500 m from the crater, with up to 9 m thick, complex, tsunami-wave influenced, tektite-bearing sequences in shallow marine (〈500 m deep) environments and tektite bearing, decimeter thick gravity-flow deposits in deep water sites; (c) an intermediate region between 2500 and 4000 km from the crater where centimeter thick, tektite-bearing layers occur, and (d) a global distal region with a millimeter thin ejecta layer. The distal ejecta layer is characterized by sub-millimeter sized microkrystites, often rich in Ni-rich spinels and (altered) clinopyroxene. Wherever present, the ejecta layers mark exactly the sudden mass-mortality horizon of the K/T boundary. What exactly caused the mass mortality is still uncertain, but it appears the main event leading to the K/T mass extinctions.
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    Annual Review of Earth and Planetary Sciences 27 (1999), S. 55-73 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Geosciences , Physics
    Notes: Abstract Once disregarded as noise, scattered seismic waves are finding increasing application in subsurface imaging. This sea change is driven by the increasing density and quality of seismic recordings and advances in waveform modeling which, together, are allowing seismologists to exploit their unique properties. In addition to extensive application in the energy exploration industry, seismic scattering is now used to characterize heterogeneity in the lower continental crust and subcrustal lithosphere, to examine the relationship between crustal structure and seismogenesis, and to probe the plumbing of active volcanoes. In each application, the study of seismic scattering brings wavelength-scale structure into sharper focus and characterizes the short scale-length fabric of geology.
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    Annual Review of Earth and Planetary Sciences 27 (1999), S. 287-312 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Geosciences , Physics
    Notes: Abstract The region of the solar system immediately beyond Neptune's orbit is densely populated with small bodies. This region, known as the Kuiper Belt, consists of objects that may predate Neptune, the orbits of which provide a fossil record of processes operative in the young solar system. The Kuiper Belt contains some of the Solar System's most primitive, least thermally processed matter. It is probably the source of the short-period comets and Centaurs, and may also supply collisionally generated interplanetary dust. I discuss the properties of the Kuiper Belt and provide an overview of the outstanding scientific issues.
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    Annual Review of Earth and Planetary Sciences 27 (1999), S. 149-182 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
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    Notes: Abstract Orbitally induced increase in northern summer insolation after growth of a large ice sheet triggered deglaciation and associated global warming. Ice-albedo, sea-level, and greenhouse-gas feedbacks, together with tropical warming from weakening winds in response to polar amplification of warming, caused regional-to-global (near-) synchronization of deglaciation. Effects were larger at orbital rather than millennial frequencies because ice sheets and carbon dioxide vary slowly. Ice-sheet-linked changes in freshwater delivery to the North Atlantic, and possibly free oscillations in the climate system, forced millennial climate oscillations associated with changes in North Atlantic deep water (NADW) flow. The North Atlantic typically operates in one of three modes: modern, glacial, and Heinrich. Deglaciation occurred from a glacial-mode ocean that, in comparison to modern, had shallower depth of penetration of NADW formed further south, causing strong northern cooling and the widespread cold, dry, and windy conditions associated with the glacial maximum and the cold phases of the millennial Dansgaard-Oeschger oscillations. The glacial mode was punctuated by meltwater-forced Heinrich conditions that caused only small additional cooling at high northern latitudes, but greatly reduced the formation of NADW and triggered an oceanic "seesaw" that warmed some high-latitude southern regions centered in the South Atlantic.
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    Annual Review of Earth and Planetary Sciences 27 (1999), S. 417-462 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Geosciences , Physics
    Notes: Abstract Cenozoic extension in the western United States presents a complex interrelation of extension, volcanism, and plate boundary tectonics that defeats simple notions of "active" or "passive" rifting. Forces driving extension can originate at plate boundaries, through basal traction, basal normal forces, or from buoyancy forces internal to the crust and lithospheric mantle. The latter two are most responsible for driving extension where it is observed in the Basin and Range. The complex evolution of the northern Basin and Range probably represents removal or alteration of mantle lithosphere interacting with buoyancy stored in the crust. In contrast, crustal buoyancy forces combined with a divergent plate boundary between about 28 and 16 Ma to drive extension in the southern Basin and Range. The central Basin and Range most likely extended as a result of boundary forces external to itself but arising from buoyancy forces elsewhere in the western United States.
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    Annual Review of Earth and Planetary Sciences 27 (1999), S. 463-493 
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    Topics: Geosciences , Physics
    Notes: Abstract The history of carnivorous mammals is characterized by a series of rise-and-fall patterns of diversification in which declining clades are replaced by phylogenetically distinct but functionally similar clades. Seven such examples from the last 46 million years are described for North America and Eurasia. In three of the seven turnover events, competition with replacement taxa may have driven the decline of formerly dominant taxa. In the remaining four this is less likely because inferred functional similarity was minimal during the interval of temporal overlap between clades. However, competition still may have been important in producing the rise-and-fall pattern through suppression of evolution within replacement taxa; as long as the large carnivore ecospace was filled, the radiation of new taxa into that ecospace was limited, only occurring after the extinction of the incumbents. The apparently inevitable decline of incumbent taxa may reflect the tendency for clades of large carnivorous mammals to produce more specialized species as they mature, leading to increased vulnerability to extinction when environments change.
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    Annual Review of Neuroscience 22 (1999), S. 389-442 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract We describe the formation, maturation, elimination, maintenance, and regeneration of vertebrate neuromuscular junctions (NMJs), the best studied of all synapses. The NMJ forms in a series of steps that involve the exchange of signals among its three cellular components-nerve terminal, muscle fiber, and Schwann cell. Although essentially any motor axon can form NMJs with any muscle fiber, an additional set of cues biases synapse formation in favor of appropriate partners. The NMJ is functional at birth but undergoes numerous alterations postnatally. One step in maturation is the elimination of excess inputs, a competitive process in which the muscle is an intermediary. Once elimination is complete, the NMJ is maintained stably in a dynamic equilibrium that can be perturbed to initiate remodeling. NMJs regenerate following damage to nerve or muscle, but this process differs in fundamental ways from embryonic synaptogenesis. Finally, we consider the extent to which the NMJ is a suitable model for development of neuron-neuron synapses.
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    Annual Review of Neuroscience 22 (1999), S. 487-509 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract The initial step in olfactory discrimination involves the interaction of odorous ligands with specific receptors on the surface of olfactory sensory neurons. The foundation for a molecular understanding of odor recognition in vertebrates was provided by the identification of a family of genes encoding putative odorant receptors, by Buck & Axel in 1991. Odorant receptor (OR) genes form the largest gene family in the vertebrate genome. This review summarizes progress over the past seven years. Major new insights are: Olfaction is accomplished in vertebrates by a very large number of receptors; olfactory sensory neurons express a small subset of the OR repertoire; in rat and mouse, axons of neurons expressing the same OR converge onto defined glomeruli in the olfactory bulb.
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    Annual Review of Neuroscience 22 (1999), S. 541-566 
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    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract The development of the sympathetic nervous system can be divided into three overlapping stages. First, the precursors of sympathetic neurons arise from undifferentiated neural crest cells that migrate ventrally, aggregate adjacent to the dorsal aorta, and ultimately differentiate into catecholaminergic neurons. Second, cell number is refined during a period of cell death when neurotrophic factors determine the number of neuronal precursors and neurons that survive. The final stage of sympathetic development is the establishment and maturation of synaptic connections, which for sympathetic neurons can include alterations in neurotransmitter phenotype. Considerable progress has been made recently in elucidating the cellular and molecular mechanisms that direct each of these developmental decisions. We review the current understanding of each of these, focusing primarily on events in the peripheral nervous system of rodents.
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    Annual Review of Neuroscience 22 (1999), S. 567-631 
    ISSN: 0147-006X
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    Topics: Biology , Medicine
    Notes: Abstract Human speech and birdsong have numerous parallels. Both humans and songbirds learn their complex vocalizations early in life, exhibiting a strong dependence on hearing the adults they will imitate, as well as themselves as they practice, and a waning of this dependence as they mature. Innate predispositions for perceiving and learning the correct sounds exist in both groups, although more evidence of innate descriptions of species-specific signals exists in songbirds, where numerous species of vocal learners have been compared. Humans also share with songbirds an early phase of learning that is primarily perceptual, which then serves to guide later vocal production. Both humans and songbirds have evolved a complex hierarchy of specialized forebrain areas in which motor and auditory centers interact closely, and which control the lower vocal motor areas also found in nonlearners. In both these vocal learners, however, how auditory feedback of self is processed in these brain areas is surprisingly unclear. Finally, humans and songbirds have similar critical periods for vocal learning, with a much greater ability to learn early in life. In both groups, the capacity for late vocal learning may be decreased by the act of learning itself, as well as by biological factors such as the hormones of puberty. Although some features of birdsong and speech are clearly not analogous, such as the capacity of language for meaning, abstraction, and flexible associations, there are striking similarities in how sensory experience is internalized and used to shape vocal outputs, and how learning is enhanced during a critical period of development. Similar neural mechanisms may therefore be involved.
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