Showing papers by "Dartmouth College published in 1972"
TL;DR: In this paper, the optical constants for the noble metals (copper, silver, and gold) from reflection and transmission measurements on vacuum-evaporated thin films at room temperature, in the spectral range 0.5-6.5 eV.
Abstract: The optical constants $n$ and $k$ were obtained for the noble metals (copper, silver, and gold) from reflection and transmission measurements on vacuum-evaporated thin films at room temperature, in the spectral range 0.5-6.5 eV. The film-thickness range was 185-500 \AA{}. Three optical measurements were inverted to obtain the film thickness $d$ as well as $n$ and $k$. The estimated error in $d$ was \ifmmode\pm\else\textpm\fi{} 2 \AA{}, and that in $n$, $k$ was less than 0.02 over most of the spectral range. The results in the film-thickness range 250-500 \AA{} were independent of thickness, and were unchanged after vacuum annealing or aging in air. The free-electron optical effective masses and relaxation times derived from the results in the near infrared agree satisfactorily with previous values. The interband contribution to the imaginary part of the dielectric constant was obtained by subtracting the free-electron contribution. Some recent theoretical calculations are compared with the results for copper and gold. In addition, some other recent experiments are critically compared with our results.
17,509 citations
TL;DR: In this paper, the frequency distributions of particIe size between sizes of about I and 100 p are given for both surface and deep water of the Atlantic and Pacific Oceans.
Abstract: Frequency distributions of particIe size between sizes of about I and 100 p are given for both surface and deep water of the Atlantic and Pacific Oceans. The form of the size spectra varies predictably both geographically and with depth. A hypothesis is presented to show that, to a first approximation, roughly equal concentrations of material occur at all particle sizes within the range from 1 p to about 10” p, i.e. from bacteria to whales.
1,116 citations
TL;DR: In this paper, a model of industrial and institutional buying behavior as an organizational decision-making process is proposed, and the major dimensions of the model are defined and some implications for mar...
Abstract: The authors suggest a model of industrial and institutional buying behavior as an organizational decision-making process. The major dimensions of the model are defined and some implications for mar...
853 citations
TL;DR: In this article, a real valued random function is called semi-stable if there is a constant > 0 (called the order of the process) such that for every a>O the random functions {x,t } and {a~x,} have the same joint distributions.
Abstract: A real valued random function {x,}, continuous in probability and with x o =0, is called semi-stable if there is a constant ~ > 0 (called the order of the process) such that for every a>O the random functions {x,t } and {a~x,} have the same joint distributions. If {xt} is Markovian with the stationary transition function Pt(x, E), it is obvious that this condition holds provided that xo =0 and that
375 citations
TL;DR: The authors found that less than 2% of the variance in voting choices between Nixon and Humphrey could be accounted for by opinions on Vietnam, and that the absence of issue voting could not be fully explained by voters' failings.
Abstract: The infrequency of issue voting in American presidential elections is usually attributed to a lack of policy rationality among voters. An examination of the Vietnam war issue in 1968 suggests, however, that much of the explanation may lie instead with the electoral process itself, and with the kinds of choices which are offered to citizens.Policy preferences concerning Vietnam were only weakly related to the two-party vote. Less than 2 per cent of the variance in voting choices between Nixon and Humphrey could be accounted for by opinions on Vietnam. Yet the absence of issue voting could not be fully explained by voters' failings. Most people had strong opinions about Vietnam. The public was generally able to perceive where prenomination candidates stood on the issue. People were able and willing to take account of Vietnam in evaluating other candidates.Voters did not bring their Vietnam preferences to bear upon the choice between Nixon and Humphrey because they saw little difference between the positions of the two, and because they were not certain precisely where either one stood. These perceptions, in turn, were rooted in reality. Humphrey's and Nixon's campaign speeches show that they did differ rather little on specific proposals about Vietnam. Further, both candidates indulged in so much ambiguity about Vietnam that public confusion over their positions was understandable.There are theoretical reasons for believing that candidates in a two-party system often have an incentive to converge at similar policy positions, and to be vague. If they generally do so, their behavior may contribute significantly to the apparent nonrationality of voters. In addition, it may have important implications for questions of collective rationality and social choice.
278 citations
273 citations
TL;DR: The average minimum sizes of particles retained by metal membranes (Selas Flotronics) and perforated polycarbonate membranes (General Electric Nuclepore) were similar to the stated pore sizes when relatively small seawater samples with moderate concentrations of particles were filtered.
Abstract: The average minimum sizes of particles retained by metal membranes (Selas Flotronics) and perforated polycarbonate membranes (General Electric Nuclepore) were similar to the stated pore sizes when relatively small seawater samples with moderate concentrations of particles were filtered. When large samples or high concentrations were filtered, the average retention size was less than the stated pore size. All cellulose ester membranes (Millipore) retained particles much smaller than the stated pore size, even from small samples with low particle concentrations. Glass-fiber filters had retention characteristics similar to membrane filters.
243 citations
TL;DR: Although the actual amounts of exposures of the population were small, the greatest health hazard to the population at large came from atmospheric testing of atomic bombs, O”Sr being a fission product.
236 citations
227 citations
TL;DR: The growth of the seaweeds Laminaria longicruris, L. digitata and Agarum cribrosum were followed by SCUBA divers for two years, and it was found that the blades behaved like moving belts of tissue, eroding at the tips while growing at the bases, so that a total year's growth amounted to 1 to 5 times the initial length.
Abstract: The growth of the seaweeds Laminaria longicruris, L. digitata and Agarum cribrosum were followed by SCUBA divers for two years, by punching holes 10 cm from the junction of stipe and blade, and recording at intervals the distance the holes had moved. As the holes approached the tip of the blade, new holes were punched at the base. It was found that the blades behaved like moving belts of tissue, eroding at the tips while growing at the bases, so that a total year's growth amounted to 1 to 5 times the initial length. Larger, older plants had wider and thicker blades, and the biomassincrease was roughly proportional to the square of the lengthincrease. Growth was most rapid in January to April, slow in July to October. As a conservative estimate, the summer biomass of the various species of seaweeds had a turnover of 4 to 10 times in the course of 1 year. Applying these figures to an earlier survey of biomass, it is estimated that annual production of seaweeds in St. Margaret's Bay, Nova Scotia, Canada, amounts to 603 gC/m2 averaged over the whole bay, 1750 gC/m2 averaged over the sea-weed zone, or 648.000 gC/m of shore line. Approximate calorific equivalents are 6030 kcal/m2 over the whole bay, or 6480×103 kcal/m of shore line.
226 citations
TL;DR: It is concluded that cortisol initially stimulates synthesis in the nucleus of a specific form of RNA that initiates synthesis of a protein that inhibits glucose transport, and two alternative functions are proposed for the hormone in this temperature-sensitive transformation.
TL;DR: In this paper, the South Cascade Glacier area of the Northern Cascades is both intensive and extensive in chemical weathering, and pedogenic clay assemblages which vary according to bedrock mineralogy, distinctive water types which coexist with discrete bedrock types and the striking chemical transformation of water as it runs over bedrock.
TL;DR: The distribution of the variance of phytoplankton abundance in the mixed layer follows a minus-five-thirds power relationship over a range of length scales from 10 to 1000 m as discussed by the authors.
TL;DR: An intertidal and underwater survey of the zonation of seaweed in St. Margaret's Bay, NovaScotia, Canada showed 8 major zones as one proceeded away from shore, but carbon content and calorific value of dry matter showed little difference with species or season.
Abstract: An intertidal and underwater survey of the zonation of seaweed in St. Margaret's Bay, NovaScotia, Canada showed 8 major zones as one proceeded away from shore: (1) Fucus and Ascophyllum; (2) Chorda with filamentous browns; (3) Chondrus crispus; (4) Zostera marina; (5) Laminaria digitata with L. longicrusis; (6) Laminaria longicruris; (7) L. longicruris with Agarum cribrosum; (8) Agarum cribrosum with Ptilota serrata. Zostera occurred at the same level as O. crispus but replaced it in sheltered water. Ascophyllum was more abundant in sheltered water. L. digitata was confined to the more exposed, steeper shore. The average horizontal extent of the seaweed zone was 369 m, and the greatest depth of significant amounts of seaweed 20 to 30 m. Laminaria longicruris contributed 36% of the total biomass, and Laminaria spp. and Agarum together constituted 83%, while intertidal seaweeds contributed less than 10% of the biomass. The estimated average total biomass per m of shore line was 1,481 kg fresh weight, 326 kg dry weight, 98 kg carbon, or 980x103 kcal. When averaged over the whole area of the bay, the corresponding figures were 1.38 kg/m2 fresh weight, 0.30 kg/m2 dry weight, 91 g/m2 carbon or 912 kcal/m2. Dry matter of Laminaria was 15 to 27% of fresh weight in blades, 10 to 12% in stipes. The dry matter content of blades was least in spring and highest in autumn, but carbon content and calorific value of dry matter showed little difference with species or season.
TL;DR: In this article, the authors investigated the structural evolution of the Cajal-Retzius cells of layer I, the Martinotti neurons of layer VI, the pyramid-like neurons (the polymorphous or spindle cells) of layer V, and the pyramidal neurons of the cat neocortex.
Abstract: The individual prenatal ontogenetic history of the horizontal neurons (the Cajal-Retzius cells) of layer I, the Martinotti neurons of layer VI, the pyramid-like neurons (the polymorphous or spindle cells) of layer VI, and the pyramidal neurons of layer V of the cat neocortex have been investigated. These neurons undergo, in the course of prenatal ontogenesis, a series of significant changes in their dendritic and axonic arborizations resulting in their complete structural transformation. Some of these changes have led to the appearance of new types of neurons quite different from the original in their morphological features as wells as in the territory of distribution of their axons. The horizontal neurons of layer I (superficial plexiform layer) come to assume the morphological characteristics of Cajal-Retzius cells late in prenatal ontogenesis. Also, the pyramid-like neurons of layer VI (deep plexiform layer) acquire the features of polymorphous (spindle) neurons of layer VI late in prenatal neocortical ontogenesis. Certainly, the resulting functional transformations that these neuronal changes cause are important and of great significance in the understanding of the organization of the mammalian neocortex. In the course of prenatal ontogenesis the following occur: the horizontal neurons of layer I lose their axonic connections with layer VI and acquire an increasing relevance in the structural organization of layer I; the pyramid-like neurons of layer VI lose their axonic and dendritic connections with layer I and undergo pronounced regressive changes in their dendritic and axonic arborizations; and the Martinotti neurons lose their axonic connections with layer I and also undergo regressive changes in their dendritic arborizations. In addition, the structural-functional interrelationships among these three neurons, which are quite prominent during early neocortical ontogenesis, fade away in the course of late prenatal ontogenesis and possibly disappear altogether by the time of birth in the cat. These three neurons are the basic neuronal elements of the early, precallosal organization (the primordial neocortical organization) of the mammalian neocortex. Phylogenetically, these three types of neurons are very old ones and have been described in the cerebral cortices of amphibians and reptiles. Therefore, it is not surprising that the early, precallosal organization of the mammalian neocortex should resemble the structural organization of the reptilian (general cortex) neocortex. It is postulated in this communication that these neuronal transformations are the result of a restructuring in the organization of the mammalian neocortex which follows the arrival of the callosal fibers and of a new type of corticipetal fibers at the pyramidal plate. this restructuring represents a transformation of the fibrillary-neuronal structure of the mammalian neocortex from its early, precallosal (reptilian) organization into a more distinctly mammalian one. The mammalian neocortical organization is characterized by the sequential maturation of several strata of true pyramidal neuronal systems. In the course of prenatal ontogenesis the fibrillar and neuronal elements of the early, precallosal neocortical organization lose progressively their relevance in the structural organization of the mammalian neocortex while the new pyramidal neuronal systems acquire an increasing relevance in it.
TL;DR: A computer-based method of finding ñ from chosen combinations of measured R or T values is described, which can give accurate results in some regions where other methods may be less sensitive.
Abstract: The reflectance R and transmittance T of thin absorbing films deposited on a transparent substrate are calculated for normal and oblique incidence, s and p polarization, and different film thicknesses. The results are presented as contours of constant R and T on the n plane, where n is the complex refractive index. The conditions for sensitive dependence of measured quantities on n are examined. A computer-based method of finding n from chosen combinations of measured R or T values is described. Oblique incidence measurements on thin films can give accurate results in some regions where other methods may be less sensitive. Accurate film-thickness values can be obtained from the optical measurements.
TL;DR: In this article, a characterization of X by its boundary function is given, where the boundary function actually determines X in the sense that X~ is the conditional expectation of X~ with respect to ~.
Abstract: X~o" = lira Xt, and if X is a uniformly integrable martingale then the boundary function actually determines X in the sense that X~ is the conditional expectation of X~ with respect to ~ In general however the boundary function may provide very little information on X In this paper we give a characterization of X by its
TL;DR: In this paper, living mass and respiratory rate were estimated by several methods on large water samples taken at several depths at each of two ocean stations, at both surface and deep water.
Abstract: Estimates of living mass and respiratory rate were made by several methods on large water samples taken at several depths at each of two ocean stations. Total microbial biomass estimates based on ATP determinations gave reasonable results in relation to phytoplankton biomass, total particulate organic carbon, and total particulate volume as determined by an electronic particle counter. Respiratory rate estimates based on 0, uptake, electron transport system activity, and ATP were in moderately good agreement in surface water but diverged widely in deep water. Heterotrophic uptake of specific organic compounds seems to be related to numbers of active bacteria and not related to total microbial respiration. Photosynthetic rates and release of dissolved photosynthate are reported for both stations.
TL;DR: Comparison of the spectra in the 1500–1750 cm−1 region reveals that the Raman lines from carbonyl group vibrations of uracil are about sevenfold more intense than those of guanine and cytosine for both paired and unpaired states and will thus dominate the specta of RNA.
Abstract: Laser-excited Raman spectra of the double-helical complexes poly A·poly U and poly G·poly C are reported for 2H2O and H2O solutions. The spectra are discussed in relation to their use as quantitative reference spectra for determining the dependence of the Raman scattering of RNA on secondary structure. The Raman line at 815 cm−1, due to the phosphodiester group, exhibits the same intrinsic intensity in spectra of poly A·poly U and poly G·poly C and is thus dependent only upon the amount of ordering of the helix and not on the kinds of nucleotides involved. The hypochromic Raman lines in spectra of poly A·poly U are identified and their intensity changes are determined quantitatively over the temperature range 32–85°C. Comparison of the spectra in the 1500–1750 cm−1 region reveals that the Raman lines from carbonyl group vibrations of uracil are about sevenfold more intense than those of guanine and cytosine for both paired and unpaired states and will thus dominate the spectra of RNA. The Raman frequencies in this region are also compared with previously reported infrared frequencies and give evidence of being strongly perturbed by base-stacking interactions in the helices.
TL;DR: Exogenous epinephrine caused a fifteen-fold increase in urea elimination expressed as fraction of filtered load excreted, while urine flow rates doubled and the excretion of chloride and trimethylamine oxide increased 2·6 and 3·8-fold, respectively.
TL;DR: Freeze-etch electron microscope studies of the morphogenesis and morphology of Sindbis virus confirmed results obtained by other workers employing thin-sectioning techniques and provided the following new information.
Abstract: Freeze-etch electron microscope studies of the morphogenesis and morphology of Sindbis virus confirmed results obtained by other workers employing thin-sectioning techniques. The 68-nm virion was found to have a nucleocapsid 36 nm in diameter surrounded by a double-layered, unit membrane. The membranous envelope is acquired as the capsid buds through the plasma membrane of the infected cell. The freeze-etch technique also provided the following new information. (i) At any one time, budding occurs in patches rather than evenly over the cell surface. (ii) The nucleocapsid is composed of capsomers 7 nm in diameter. (iii) The capsid interacts strongly with the membrane, both prior to budding and after maturation. (iv) The 7- to 10-nm particles characteristic of the internal faces of plasma membranes, which presumably represent host membrane proteins, are present in early stages of budding but disappear as morphogenesis progresses. (v) Fusion of the cell membrane at the base of the budding virion is a two-step process; the inner leaflet fuses into a sphere before the outer one. (vi) The outer surface of the viral envelope is covered with 4-nm subunits with a center-to-center spacing of 6 nm.
TL;DR: In this article, the results of these studies indicate that short term exposures of clay minerals to humic acids yield mainly physically bound organo-clay complexes while some chemisorbed bonding takes place through carboxyl groups.
TL;DR: The rate of growth of Clione and its ultimate size seemed to be regulated more by the size of the available prey than by its abundance, both in the laboratory and in the field.
TL;DR: This paper proposes an extension of the additive algorithm that utilizes insights generated while solving the original problem to do subsequent analysis upon it and for seeking new optima in light of parameter changes.
Abstract: The procedures for postoptimality analysis that are so much a part of linear programming studies have no simple counterparts in an integer programming context In the case of Balas' Additive Algorithm, however, it would appear that the capacity of the technique to facilitate certain types of postoptimality analysis has not been fully exploited This paper proposes an extension of the additive algorithm that utilizes insights generated while solving the original problem to do subsequent analysis upon it In particular, procedures are developed for doing limited parameter ranging and for seeking new optima in light of parameter changes
TL;DR: The present acidity and sulfur content of the upland streams of New England can be accounted for on the basis of the rainout and washout of sulfuric acid from the atmosphere.
Abstract: The present acidity and sulfur content of the upland streams of New England can be accounted for on the basis of the rainout and washout of sulfuric acid from the atmosphere. In spite of this excess acid flux over the New England landscape, the rate of cationic denudation of upland watersheds is relatively low.
TL;DR: This examination consists of a review of relatively direct assessments of the validity of the hypothesis, of the status of the "intake-rejection" dimension and difficulties in its application, and of the relative merits of viewing cardiovascular events as causes rather than effects in psychologically relevant tasks.
Abstract: It is the purpose of this paper to examine critically Lacey's (1959, 1967; Laccy, Kagan, Laccy, & Moss, 1963) recent hypothesis about the relation between cardiovascular responses—especially heart rate—and performance on sundry tasks. This examination consists of a review of relatively direct assessments of the validity of the hypothesis, of the status of the "intake-rejection" dimension and difficulties in its application, and of the relative merits of viewing cardiovascular events as causes rather than effects in psychologically relevant tasks.
TL;DR: In this article, the authors examined the ways in which the performance of Oakland's mayor diverged from a model of political leadership, and identified some of the factors that support or limit such leadership.
Abstract: Observers of city politics have often stated that political leadership—usually mayoral leadership—is a crucial ingredient in a city's ability to deal with its problems. And studies of successful leaders in urban systems have led to the formulation of a model of the “political entrepreneur” who is adept at accumulating political resources and pyramiding them to gain increased influence. Based on four years of observation of politics in Oakland, California, this study suggests that successful mayoral leadership and resource-pyramiding may be limited by governmental structure, the personality of the mayor, and the nature of the political system. In Oakland, fragmented institutional authority and the council-manager form of government have created obstacles for elected officials. A privately oriented, “nonpolitical” mayor has avoided publicity and has tended to underutilize, rather than pyramid, his resources. Finally, in an amorphous political system characterized by a lack of group and party activity, a mayor is denied both information and support. By examining the ways in which the performance of Oakland's mayor diverges from a model of political leadership, we can identify some of the factors that support or limit such leadership.
TL;DR: Interruption of the afferent pathways for a variety of respiratory mechanoreceptors failed to eliminate the neural oscillation characteristic of purring, suggesting the existence of a high frequency oscillatory mechanism within the central nervous system.
TL;DR: A plastic encasement of those aneurysms which cannot be clipped might be the best technique, providing the material is sufficiently strong, non-toxic, closely adherent to the vessel, does not engender heat, and does not cause complications as discussed by the authors.
Abstract: 1.
Muscle wrapped about the internal carotid artery in dogs did not engender an early, dense, or even late satisfactory envelopment by fibrous tissue.
2.
Two failures of muscle wrapping of human intracranial aneurysms are reported and studied pathologically.
3.
Cotton induced a dense, fibrotic response about intracranial blood vessels in dogs and in two human cases. It may account for some of the successes previously attributed to muscle wrapping.
4.
A plastic encasement of those aneurysms which cannot be clipped might be the best technique, providing the material is sufficiently strong, non-toxic, closely adherent to the vessel, does not engender heat, and does not engender complications. The ideal material has not yet been, discovered.