Showing papers by "Dartmouth College published in 1982"
TL;DR: A composite estimate of the magnitude of past explosive eruptions, referred to as the Volcanic Explosivity Index (VEI), is proposed as a semiquantitative compromise between poor data and the need in various disciplines to evaluate the record of past volcanism as mentioned in this paper.
Abstract: A composite estimate of the magnitude of past explosive eruptions, referred to as the Volcanic Explosivity Index (VEI), is proposed as a semiquantitative compromise between poor data and the need in various disciplines to evaluate the record of past volcanism. The VEI is assigned to more than 8000 historic and prehistoric eruptions. It is shown that the VEI can help detect incompleteness and reporting biases and can help in selecting subsets of the historical record suitable for each study. The VEI is a composite estimate of Walkers (1980) magnitude and/or intensity and/or destructiveness and/or (less frequently) dispersive power, violence, and energy release rate, depending on the data that are available.
1,670 citations
TL;DR: In this paper, a recently reported calculation by chesnavich, Su and Bowers on classical trajectory study of thermal energy ion-polar molecule capture collisions is further extended.
Abstract: A recently reported calculation by chesnavich, Su and Bowers on classical trajectory study of thermal energy ion‐polar molecule capture collisions is further extended. (AIP)
1,284 citations
1,205 citations
TL;DR: A meta-analysis of findings from 65 independent evaluations of school tutoring programs showed that tutored students outperformed control students on examinations, and they also developed positive attitudes toward the subject matter covered in the tutorial programs as discussed by the authors.
Abstract: A meta-analysis of findings from 65 independent evaluations of school tutoring programs showed that these programs have positive effects on the academic performance and attitudes of those who receive tutoring. Tutored students outperformed control students on examinations, and they also developed positive attitudes toward the subject matter covered in the tutorial programs. The meta-analysis also showed that tutoring programs have positive effects on children who serve as tutors. Like the children they helped, the tutors gained a better understanding of and developed more positive attitudes toward the subject matter covered in the tutorial program. Participation in tutoring programs had little or no effect, however, on the self-esteem of tutors and tutees.
1,063 citations
TL;DR: It is demonstrated that anti-Tac suppresses TCGF induced proliferation of T cells and blocks binding of radiolabelled TCGF to cells from a cloned human continuous T-cell line.
Abstract: T-cell growth factor (TCGF or interleukin-2) is an inducible glycoprotein hormone of molecular weight 15,000 (ref. 1) synthesized and secreted by T lymphocytes following activation with antigen or mitogen2,3. TCGF is required for proliferation and expansion of T cells following antigen encounter4,5 and to maintain them in long-term culture in vitro6–9. Full expression of the human immune response requires both the induction of TCGF synthesis and the formation of specific TCGF membrane receptors10,11. Monoclonal antibodies binding TCGF have been prepared12,13. In contrast, antibodies specific for the TCGF membrane receptor have not been identified, nor has the receptor been characterized. We have prepared a monoclonal antibody, termed anti-Tac14,15, which appears to bind to the human membrane receptor for TCGF. In support of this, we now demonstrate that anti-Tac suppresses TCGF induced proliferation of T cells and blocks binding of radiolabelled TCGF to cells from a cloned human continuous T-cell line. Also we have partially purified and characterized the putative TCGF receptor. This receptor is a glycoprotein with a molecular weight (Mr) of 47,000–53,000.
794 citations
TL;DR: The evidence reviewed here supports the hypothesis that variations occur to a large extent because of differences among physicians in their evaluation of patients or in their belief in the value of the procedures for meeting patient needs.
574 citations
TL;DR: Leaves of red oak trees that had been defoliated by gypsy moth larvae during the previous year and again during the period of the study had higher values of tanning coefficients, total phenolics, hydrolyzable and condensed tannins, dry matter contents, and toughness than did leaves of undamaged trees.
Abstract: Leaves of red oak trees that had been defoliated by gypsy moth larvae during the previous year and again during the period of the study had higher values of tanning coefficients, total phenolics, hydrolyzable and condensed tannins, dry matter contents, and toughness than did leaves of undamaged trees. These changes may influence larval growth and alter the course of further outbreaks.
455 citations
349 citations
TL;DR: Video-enhanced contrast-differential interference contrast microscopy has revealed new features of axonal transport in the giant axon of the squid, where no movement had been detected previously by conventional microscopy.
Abstract: Video-enhanced contrast-differential interference contrast microscopy has revealed new features of axonal transport in the giant axon of the squid, where no movement had been detected previously by conventional microscopy. The newly discovered dominant feature is vast numbers of "submicroscopic" particles, probably 30- to 50-nanometer vesicles and other tubulovesicular elements, moving parallel to linear elements, primarily in the orthograde direction but also in a retrograde direction, at a range of steady velocities up to +/- 5 micrometers per second. Medium (0.2 to 0.6 micrometer) and large (0.8 micrometer) particles move more slowly and more intermittently with a tendency at times to exhibit elastic recoil. The behavior of the smallest particles and the larger particles during actual translocation suggests that the fundamental processes in the mechanisms of organelle movement in axonal transport are not saltatory but continuous.
337 citations
TL;DR: It is shown that the plasma membrane is not required for fast axonal transport and suggests that action potentials are not involved in the regulation of fast transport, making this model an important model for biochemical pharmacological, and physical manipulations of membranous organelle transport.
Abstract: Development of video-enhanced contrast-differential interference contrast for light microscopy has permitted study of both orthograde and retrograde fast axonal transport of membranous organelles in the squid giant axon. This process was found to continue normally for hours after the axoplasm was extruded from the giant axon and removed from the confines of the axonal plasma membrane. It is now possible to follow the movements of the full range of membranous organelles (30-nanometer vesicles to 5000-nanometer mitochondria) in a preparation that lacks a plasma membrane or other permeability barrier. This observation demonstrates that the plasma membrane is not required for fast axonal transport and suggests that action potentials are not involved in the regulation of fast transport. Furthermore, the absence of a permeability barrier surrounding the axoplasm makes this an important model for biochemical pharmacological, and physical manipulations of membranous organelle transport.
320 citations
TL;DR: Subalpine forests of the northern Appalachians are subject to significant deposition of water and chemicals via cloud droplet impaction by a method linking micrometeorological measures of turbulent transfer, a detailed representation of canopy structure, and experimentally derived capture efficiencies.
Abstract: Subalpine forests of the northern Appalachians are subject to significant deposition of water and chemicals via cloud droplet impaction. This deposition has been estimated by a method linking micrometeorological measures of turbulent transfer, a detailed representation of canopy structure, and experimentally derived capture efficiencies. Water inputs from clouds are about 46 percent, and chemical inputs range from 150 to 430 percent of the bulk precipitation.
TL;DR: In this article, six magnetic polarity sections have been established over the Potwar Plateau region of Pakistan, including the major stratotypes of the Siwalik Group, including a long normal polarity zone, which is contained within the Nagri Formation.
TL;DR: This work investigates priority rules aimed at minimizing tardiness, emphasizing a “modified duedate rule” which functions effectively in conjunction with internally-set deadlines and which adapts to both tight and loose conditions in the due-dates.
TL;DR: The analysis uses an equilibrium framework with transit ridership sensitive to the level of service provided by the bus system, and results consist of closed-form solutions for the optimal local area operating policies, which are dependent upon local conditions, transit service objectives, and coefficients of the demand and cost functions.
Abstract: Local bus service design options are analyzed in this paper, including route spacing, headway, and fare, both with and without vehicle size constraints. Optimal levels of these variables are obtained analytically for three objective functions, including profit maximization, maximization of a combination of net user benefit and operator profit, and maximization of net user benefit subject to a deficit constraint. The analysis uses an equilibrium framework with transit ridership sensitive to the level of service provided by the bus system. The major results consist of closed-form solutions for the optimal local area operating policies, which are dependent upon local conditions, transit service objectives, and coefficients of the demand and cost functions.
TL;DR: There is a remarkable similarity in neonatal survival rates, indicating that continuing communication between obstetric perinatologists and neonatologists is a prime factor in reducing mortality, rather than specific new therapeutic procedures at any single clinical center.
TL;DR: Seasonal changes in individual clearance rates, selective feeding behavior, and population grazing rates of Keratella cochlearis, Polyarthra vulgaris, polyarthra dolichoptera, and Bosmina longirostris were investigated in a eutrophic lake using five tracer foods and in situ radioisotope techniques.
Abstract: Seasonal changes in individual clearance rates, selective feeding behavior, and population grazing rates of Keratella cochlearis, Polyarthra vulgaris, Polyarthra dolichoptera, and Bosmina longirostris were investigated in a eutrophic lake using five tracer foods (Aerobacter, Rhodotorula, Chlorella, Chlamydomonas, and Euglena) and by in situ radioisotope techniques. Clearance rates ranged from
TL;DR: In this paper, a bieriterion approach to sequencing with time/cost trade-offs is presented, which produces an efficient frontier of possible schedules, and does not require the sequencing criteria to be measurable in the same units as the resource allocation cost.
TL;DR: It is found that these two fibrinogen γ chains in the rat arise by translation of two mRNAs of 1700 and 2200 nucleotides, which are produced from a single gene by alternative splice patterns.
TL;DR: Fear, conditioned to apparatus cues associated with electric shock, was measured by recording freezing and the opiate antagonist naltrexone reversed this analgesia, suggesting that the analgesia has an opiate nature.
TL;DR: Several different approaches to simulation on deforming finite elements are shown to generate the same weighted residuals formulation for the evolution of the dependent variables as mentioned in this paper, and control of node motion by means of mesh stretching in two dimensions is illustrated in the context of phase change problems.
TL;DR: The study emphasizes the important role played by layer I in the overall organization of the cerebral cortex and proposes that in the course of cortical neurogenesis all future pyramidal neurons are attracted to layer I where they establish original synaptic connections and all receive from it the same kind of primitive information needed for their maturation.
Abstract: The composition and structural organization of layer I of the human motor cortex were studied throughout the course of prenatal cortical neurogenesis with the rapid Golgi method. The components of layer I are six. The specific afferents of layer I (primitive corticipetal fibers) and the Cajal-Retzius neurons are its essential intrinsic components, while the apical dendritic bouquets of all pyramidal neurons and the axonic terminations of all Martinotti neurons are its essential extrinsic elements. These four components are recognized throughout the entire course of prenatal cortical neurogenesis. The small neurons and terminals from afferent systems of lower cortical strata, which are incorporated into layer I late in cortical neurogenesis, represent its non-essential components. The specific afferents of layer I are the first corticipetal fibers to arrive at the developing telencephalic vesicle marking the beginning of cortical neurogenesis. These primitive fibers extend throughout the surface of the cerebral vesicle establishing an external white matter. They are considered to be the stimulus for the development and maturation of the Cajal-Retzius neurons. Together they form a primitive cortical organization, the primordial plexiform layer, which precedes the appearance of the cortical plate and is considered to be common to and shared by amphibians, reptiles and mammals including man. Layer I evolves from this primordial cortical lamination. The Cajal-Retzius neurons are all characterized by a single descending axonic process which becomes a long horizontal (tangential) fiber in the lower half of layer I. Although the body and main dendrites of these neurons are only found at strategic and old cortical regions (e.g. the motor, acoustic and visual areas) their long horizontal axons extend, anteroposteriorly, throughout the entire surface of the cerebral cortex and establish synaptic connections with the apical dendrites of all pyramidal neurons regardless of location, cortical depth or functional role. In the course of cortical development, all developing pyramidal neurons ascend through the cortical plate in order to establish primary synaptic contacts with layer I. Only then, do they become ready to be displaced downward by the arrival of the next set of migrating neuroblasts. All pyramidal neurons of the cerebral cortex are actually suspended from layer I anchored to it by their apical dendritic bouquets. The need for all pyramidal neurons to reach and establish original synaptic connections with layer I could explain the remarkable ‘inside-out’ formation of the cortical plate. This fact could also explain the characteristic shape of these neurons, as well as their abundance, structural uniformity and universal radial orientation to layer I. The functional role of layer I seems to be the spreading of the same kind of primitive information to all pyramidal neurons of the cerebral cortex whether they be motor, sensory, acoustic, visual or associational in nature, or whether they be large or small. The observations presented in this study further corroborate the concept of the dual origin of the mammalian cerebral cortex. The study emphasizes the important role played by layer I in the overall organization of the cerebral cortex. It proposes that in the course of cortical neurogenesis all future pyramidal neurons are attracted to layer I where they establish original synaptic connections and all receive from it the same kind of primitive information needed for their maturation. There seems to be no obvious reason to believe that the original synaptic contacts established between all pyramidal neurons and layer I disappear in the course of cortical neurogenesis. On the contrary, the progressive growth of the apical dendritic bouquets within layer I seems to indicate that they actually expand.
TL;DR: A parallel in vivo situation is now described in imaginal discs isolated from pupariating larvae, where induction by ecdysterone appears to be a primary hormone response.
TL;DR: This prospective study of cosmetic adverse reactions by eleven dermatologists identified 487 cases of cosmetic-induced dermatitis; the face, eye, and upper arm were the most involved sites.
Abstract: This prospective study (1977-1980) of cosmetic adverse reactions by eleven dermatologists identified 487 cases of cosmetic-induced dermatitis. Approximately half of the cases were covert in nature. Eighty percent were due to allergic contact dermatitis; the face, eye, and upper arm were the most involved sites. Skin care products, hair preparations (including colors), and facial makeup products were the most commonly involved product categories. Fragrances, preservatives, lanolin and lanolin derivatives, p -phenylenediamine, and propylene glycol were the most commonly identified causative agents. The data may not be representative of the country at large because of the special interests of the dermatologists involved.
TL;DR: In this paper, the combined use of magnetic-polarity stratigraphy with fission-track dating of volcanic ashes was used to develop a new chronology for the intermontane basin of Kashmir in the northwestern Himalaya.
Abstract: The Through the combined use of magnetic-polarity stratigraphy with fission-track dating of volcanic ashes, a new chronology, spanning 4 Myr, has been developed for the intermontane basin of Kashmir in the northwestern Himalaya.
TL;DR: The discovery of the Brattleboro rat epitomizes the truism expressed by Louis Pasteur, that “ . . chance only favours the prepared mind”; * Dr. Henry A. Schroeder surely had such a mind.
Abstract: The discovery of the Brattleboro rat epitomizes the truism expressed by Louis Pasteur, that “. . . chance only favours the prepared mind”; * Dr. Henry A. Schroeder surely had such a mind. In 1960, Dr. Schroeder, then Associate Professor of Clinical Physiology at Dartmouth Medical School, was raising a colony of Long-Evans hooded rats in his private laboratories on a remote mountain in West Brattleboro, Vermont (FIGURE 1). (Following his resignation, due to illness, from his positions as Associate Professor of Medicine and Director of the Hypertension Division at Washington University School of Medicine in St. Louis, Dr. Schroeder had “retired” in 1957 to his summer home in West Brattleboro, only to resume his studies on the role of trace elements in cardiovascular diseases and aging two years later.) t Early in 1961, Dr. Schroeder’s alert assistant, Mr. Tim Vinton, noticed that the drinking bottles attached to one among hundreds of cages were always nearly empty. This cage contained a mother and her litter of seventeen young, born on February 24, 1961. Together, Mr. Vinton and Dr. Schroeder quickly determined that some of the pups were drinking excessive amounts and that this abnormality could be corrected by giving them vasopressin. It thus appeared that some of the newborn animals had hereditary hypothalamic diabetes insipidus. Most investigators might have discarded the animals as being of only peripheral interest, and a nuisance to the main purpose of their research. But not Harry Schroeder; he offered four of the six diseased rats from the original litter to the two people at Dartmouth Medical School who had worked with problems of vasopressin: to Dr. Kurt Benirschke, at that tirne Chairman of the Department of Pa th~ logy ,~ and to me.4 Having determined that the occurrence of this disorder in a common laboratory animal was apparently unique, we quickly decided that our first objective must be to produce more diseased offspring. The first animals were transferred to Hanover, New Hampshire on June 3, 1961, and after some preliminary testing, matings were begun in the middle of July. In August, 1961 we had the good fortune to have Dr. Hilda Weyl Sokol join our Department. Having rather recently completed a Ph.D. thesis on the cytophysiology of the neurohypophysis,5 she was not only vitally interested in
TL;DR: Two experiments allowed rats to drink freely two neutral flavors in simultaneous compound with two hedonically valued flavors (quinine and saccharin) and indicated that flavor-flavor associations can shift taste preferences.
Abstract: Two experiments allowed rats to drink freely two neutral flavors (almond and vanilla) in simultaneous compound with two hedonically valued flavors (quinine and saccharin). The neutral flavor previously paired with saccharin was subsequently preferred. The neutral flavor that had been paired with quinine was subsequently avoided. Experiment 3 found similar results when the animals were hand-fed a preset amount of the solution. Preference shifts were not obtained when differential amounts of the neutral flavors were consumed in isolation. The data indicate that flavor-flavor associations can shift taste preferences.
TL;DR: Toxoplasma gondii grew normally in a cell mutant that was deficient in aerobic respiration and almost completely dependent upon glycolysis, so ATP generated by oxidative phosphorylation in the host cell is not essential for parasites.
TL;DR: The authors found that the ratings varied along three dimensions: amused-warmhearted, fearful-anxious, and disgusted-scornful, and moderate homogeneity was found when the individual ratings were assigned to the centroids of these clusters.
Abstract: Subjects viewed eight short film segments and rated the strength of their responses within eight emotion categories. Principal-components analysis showed that these ratings varied along three dimensions: Amused-Warmhearted, Fearful-Anxious, and Disgusted-Scornful. Clusters of film segment centroids occupied distinct regions within this reduced space, and moderate homogeneity was found when the individual ratings were assigned to the centroids of these clusters. Further analyses concerned the reliability of the ratings over time, the effects of prior exposure, and sex differences. Ratings obtained on a subset of these film segments during a subsequent psychophysiological experiment were analyzed to test the generalizability of the results of Study 1. The factor patterns were very similar, as were tests for the homogeneity of the ratings. The structure of self-reports of elicited affect and the utility of film stimuli are discussed.
TL;DR: It is argued that the activity burst is a UR, while freezing is a CR, and that a delay, during which the rat is out of the shock-associated context, between the training and testing periods does not disrupt freezing.
Abstract: When a rat receives an electric shock delivered to the floor of an enclosure, it reacts with frenzied activity. On shock termination, the activity persists for a brief period of time and then gradually gives way to a period of freezing. Subsequent grid shocks temporarily disrupt freezing, with the length of disruption determined by shock intensity (Experiment 1). The duration of this activity burst depends predominantly on the test shock intensity but not on the training shock intensity. The reverse is true for the probability of freezing, which is positively related to training shock intensity (Experiment 2). Based on this finding, it is argued that the activity burst is a UR, while freezing is a CR. Further support that freezing is a CR is provided by Experiment 3, which demonstrates that a delay, during which the rat is out of the shock-associated context, between the training and testing periods does not disrupt freezing. A topographical analysis of the behaviors making up the activity burst is provided by Experiment 4. The postshock activity burst was composed predominantly of head movement, turning, and rearing.