Showing papers by "Columbia University published in 1969"

Proposed Experiment to Test Local Hidden Variable Theories.

Abstract: A theorem of Bell, proving that certain predictions of quantum mechanics are inconsistent with the entire family of local hidden-variable theories, is generalized so as to apply to realizable experiments. A proposed extension of the experiment of Kocher and Commins, on the polarization correlation of a pair of optical photons, will provide a decisive test between quantum mechanics and local hidden-variable theories.

Tectonics of the Caribbean and Middle America Regions from Focal Mechanisms and Seismicity

Abstract: Seismic data strongly support recent theories of tectonics in which large plates of lithosphere move coherently with respect to one another as nearly rigid bodies, spreading apart at ocean ridges, sliding past one another at transform faults, and underthrusting at island arcs. Boundaries between adjacent plates of lithosphere are defined by belts of high seismic activity. Redetermination of more than 600 hypocenters in the Middle America region and previous studies in the Galapagos and Caribbean regions define the boundaries of two relatively small, nearly aseismic plates in the region of interest. The first, the Cocos plate, is bordered by the East Pacific rise, the Galapagos rift zone, the north-trending Panama fracture zone near 82° W., and the Middle America arc; the second, the Caribbean plate, underlies the Caribbean Sea and is bounded by the Middle America arc, the Cayman trough, the West Indies arc, and the seismic zone through northern South America. Focal mechanisms of 70 earthquakes in these regions were determined to ascertain the relative motion of these two plates with respect to the surrounding regions or plates. The results show underthrusting of the Cocos plate beneath Mexico and Guatemala in a northeasterly direction and beneath the rest of Central America in a more north-northeasterly direction. The Cocos plate is spreading away from the rest of the Pacific floor at the East Pacific rise and at the Galapagos rift zone. Motion is right-lateral strike-slip along the Panama fracture zone, a transform fault connecting the Galapagos rift zone and the Middle America arc. At the same time, the Caribbean plate is moving easterly with respect to the Americas plate, which is here taken to include both North and South America and the western Atlantic. Left-lateral strike-slip motion along steeply dipping fault planes is observed on the Cayman trough. The Americas plate is underthrusting the Caribbean in a westerly direction at the Lesser Antilles and near Puerto Rico. Unlike the Lesser Antilles, however, motion at present is not perpendicular to the Puerto Rico trench but instead is almost parallel to the trench along nearly horizontal fault planes. Computations of rates of motion indicate that underthrusting is at a higher rate in southeastern Mexico and Guatemala than in western Mexico and that the Caribbean is moving at a lower rate relative to North America than is the Cocos plate.

Rational singularities with applications to algebraic surfaces and unique factorization

Abstract: © Publications mathématiques de l’I.H.É.S., 1969, tous droits réservés. L’accès aux archives de la revue « Publications mathématiques de l’I.H.É.S. » (http:// www.ihes.fr/IHES/Publications/Publications.html) implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/conditions). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright.

On the Interpretation of Discriminant Analysis

Abstract: With the availability of “canned” computer programs, it is extremely easy to run complex multivariate statistical analyses. However, it is not as easy to interpret the output of these programs. Thi...

Conflicts: Productive and Destructive*

Abstract: It is a great honor and delight for me to receive the Kurt Lewin Memorial Award. As you know, Kurt Lewin has had a profound influence on my life and work. I have been influenced by his value orientations as well as his theoretical orientations. He believed than an intellectually significant social science has to be concerned with the problems of social action and social change and that intelligent social action has to be informed by theory and research. He rejected both a heartless science and a mindless social action. I am proud to have had this remarkable man as a teacher and as a guide. I wish to discuss the characteristics of productive and destructive conflict and to consider the conditions which give rise to one or another type. Although actual conflicts are rarely purely benign or malign, it is useful for analytic purposes to consider the simple cases. Doing so highlights not only the differences in theoutcomes of conflict but also the differences in types of processes by which the outcomes are derived. Let me start with the dull but necessary chore of defining Some of the key terms that I shall be using. A conflict exists whenever incompatible activities occur. The incompatible actions may

Time-dependent fluorescence depolarization and Brownian rotational diffusion coefficients of macromolecules

Abstract: Using a distribution function formalism, we have derived relations between the time-dependent fluorescence polarization anistropy r(t) = [I‖(t) − I⟂(t)]/[I‖(t) + 2I⟂(t)] and the Brownian rotational diffusion coefficients of macromolecules It is shown that in the most general case of a completely asymmetric body, five exponentials appear in r(t) Reduction to previously obtained simpler expressions are presented and discussed Experiments were performed to measure r(t) for the complex of 1-anilino-8-naphthalene sulfonate (ANS) and apomyoglobin The results revealed a spherical geometry, with a radius of 208 A Similar experiments were performed on the ANS–apohorse radish peroxidase complex The results were inconclusive towards the geometry of the complex, but when assumed to be spherical, the radius was estimated to be 296 A, consistent with the larger molecular weight of horse radish peroxidase

Intracellular Organic Phosphates as Regulators of Oxygen Release by Haemoglobin

Abstract: 2,3-Diphosphoglycerate is present in the red cells of many species at about equimolar concentration to haemoglobin. It lowers the oxygen affinity and thus facilitates oxygen unloading because it is preferentially bound to deoxyhaemoglobin in the ratio of one mole per tetramer.

Pliocene-Pleistocene Sediments of the Equatorial Pacific: Their Paleomagnetic, Biostratigraphic, and Climatic Record

Abstract: Magnetic stratigraphy of 15 oriented cores from the equatorial Pacific was determined as far back as the Gilbert reversed-polarity epoch. Ranges of selected species of four major microfossil groups (diatoms, silicoflagellates, foraminifers and Radiolaria) are compared with the record of geomagnetic reversals during the last 4.5 m. y. in eastern equatorial Pacific deep-sea cores. Characteristics of the fossil assemblages are used as criteria for recognition of most of the paleomagnetic reversals that occurred during this interval. Two zones of major paleontological change occur characterized by extinctions of several species and coiling direction changes in some foraminifers. The first change comes in the middle of the Gauss normal magnetic series (about 3 m.y. B.P.) and the second near the Olduvai magnetic event (about 2.0 m.y. B.P.). Seven equatorial foraminiferal species, two radiolarian species, and two diatom species become extinct near reversals. The establishment of the true chronostratigraphic relationships of these selected microfossil species allows us to date zonations of previous authors and provides absolute dates that can be used in worldwide correlation of marine sediments. The percentage of calcium carbonate was determined throughout the lengths of four cores. Eight distinct carbonate cycles are present in the Brunhes series, having periodicities of about 75,000 years in the upper Brunhes to over 100,000 years in the lower Brunhes. It is possible to correlate these carbonate cycles among our cores and also to correlate them with the previous work of Arrhenius who equated the carbonate peaks with glacial stages and the troughs with interglacial stages. This interpretation is supported by paleomagnetic and C14 dating of the last carbonate high which is synchronous with the Wisconsin glaciation (80,000 to 11,500 years B.P.). It, therefore, is probable that there were eight major glacial fluctuations during the last 700,000 years. During the last 400,000 years there is good correlation between the carbonate cycles of the Pacific and evidence of climatic fluctuations in the Atlantic established by Ericson and Wollin (1968) and Emiliani (1966) based on fossil abundances and oxygen isotope ratios, respectively. The rates of sedimentation during the Brunhes series range between 3.5 mm/1000 years for siliceous ooze to 17.5 mm/1000 years for highly calcareous sediment.

A two-state analysis of fixed-interval responding in the pigeon.

Abstract: The behavior of pigeons on six geometrically spaced fixed-interval schedules ranging from 16 to 512 sec is described as a two-state process. In the first state, which begins immediately after reinforcement, response rate is low and constant. At some variable time after reinforcement there is an abrupt transition to a high and approximately constant rate. The point of rapid transition occurs, on the average, at about two-thirds of the way through the interval. Response rate in the second state is an increasing, negatively accelerated function of rate of reinforcement in the second state.

Spin up in neutron stars: the future of the vela pulsar.

Abstract: Assuming that the speed up of the Vela pulsar was caused by a “starquake”, a number of predictions can be made, and the event can be taken as evidence that the interior of the pulsar is a superfluid.

Time-Dependent Semiclassical Scattering Theory. II. Atomic Collisions

Abstract: We derive "classical" equations for the relative motion of two atoms as their insides make a given quantum transition. The classical changes in relative energy and angular momentum associated with this description just balance the corresponding quantum changes in internal energy and angular momentum for the transition involved. The work is based on a generalization of Hamilton's principle, suggested in a natural way by Feynman's formulation of quantum mechanics; the semiclassical scattering theory which emerges is, in essence, a justification and extension of the impact-parameter method. Applications to low-energy atomic collisions are discussed briefly.

Time-dependent semiclassical scattering theory. i. potential scattering.

Abstract: The semiclassical theory of potential scattering is derived from Feynman's path-integral formulation of quantum mechanics. Since the partial-wave expansion is avoided, the results are applicable to scattering by a noncentral field. Special attention is given to the conditions for validity of the semiclassical approximation.

Locally homogeneous complex manifolds

Abstract: In this paper we discuss some geometric and analytic properties of a class of locally homogeneous complex manifolds. Our original motivation came from algebraic geometry where certain non-compact, homogeneous complex manifolds arose natural ly from the period matrices of general algebraic varieties in a similar fashion to the appearance of the Siegel upper-half-space from the periods of algebraic curves. However, these manifolds arc generally not Hermit ian symmetric domains and, because of this, several interesting new phenomena turn up. The following is a description of the manifolds we have in mind. Let Gc be a connected, complex semi-simple Lie group and B c Gc a parabolic subgroup. Then, as is well known, the coset space X = Gc/B is a compact, homogeneous algebraic manifold. I f G ~ Gc is a connected real form of Gc such tha t G N B = V is compact, then the G-orbit of the origin in X is a connected open domain D ~ X, and D = G/V is therefore a homogeneous complex mani. /o/d. Let F c G be a discrete subgroup such tha t the normalizcr N(F) intersects V only in the identity. Since F acts properly discontinuously without fixed points on D, the quotient space Y = F \\ D inherits the structure of a complex manifold. We shall refer to a manifold of this type as a locally homogeneous complex mani]old. One case is when G=M is a maximal compact subgroup of Gc. Then necessarily F ={e), and D = X is the whole compact algebraic manifold. These varieties have been the subject of considerable study, and their basic properties are well known. The opposite extreme occurs when G has no compact factors. These non-compact homogeneous domains D then include the Hermit ian symmetric spaces, about which quite a bit is known, and also include important and interesting non-classical domains which have been discussed relatively little. I t is these manifolds which are our main interest; however, since the

Diversity and origin of abyssal tholeiite from the Mid-Atlantic Ridge near 24° and 30° North latitude

Abstract: On cursory examination of hand specimens and thin sections, the abyssal tholeiite in a dredge haul may appear to be uniform in composition. Chemical analyses of a considerable number of fragments, however, have always revealed the existence of regular compositional variation in them. The MgO content decreases with increasing SiO2. In abyssal tholeiites with relatively low Al2O3 contents, the SiO2, total iron, Na2O and P2O5 contents tend to increase and the MgO content tends to decrease with increasing iron/magnesia ratio, probably owing to crystallization differentiation. In a certain dredge haul, high-alumina abyssal tholeiites (with Al2O3 contents near or over 17%) occur in association with low-alumina abyssal tholeiites. The magma of high-alumina abyssal tholeiites would be generated from that of low-alumina abyssal tholeiites by differentiation at a depth around 30 km. In pillow lavas of abyssal tholeiite free from weathering and metamorphism, the chilled rim of the pillow usually has virtually the same chemical composition as the more crystalline core except for a decrease of K2O content toward the rim. On the other hand, the weathered rim of pillow lavas shows marked compositional change. The Fe2O3/FeO ratio of unweathered abyssal tholeiite is in the range of 0.1 to 0.3. This ratio and the H2O− and H2O+ contents increase with advancing weathering.

Chemical modification of the active site of the acetylcholine receptor.

Abstract: The receptor for acetylcholine in the subsynaptic membrane of the electroplax of Electrophorus electricus is a protein with a disulfide bond in the vicinity of the active site. This disulfide can be reduced and reoxidized with concomitant inhibition and restoration of the response to acetylcholine and other monoquaternary ammonium-depolarizing agents. Conversely, the bisquaternary hexamethonium, normally a competitive inhibitor, causes depolarization, and the activity of decamethonium is increased following reduction of the disulfide. The reduced receptor can be alkylated by various maleimide derivatives and is then no longer reoxidizable. Some quaternary ammonium maleimide derivatives act as affinity labels of the reduced receptor, alkylating it at a rate three orders of magnitude faster then do uncharged maleimide derivatives. Other types of potential affinity labels also react only with the reduced receptor and the resulting covalently attached quaternary ammonium moieties interact with the active site, strongly activating the receptor. These results suggest a model for the active site and its transitions in which an activator such as acetylcholine bridges between a negative subsite and a hydrophobic subsite in the vicinity of the disulfide, causing an altered conformation around the negative subsite and a decrasee of a few angstroms in the distance between the two subsites.

The effects of prostaglandins on the intraocular pressure of the rabbit.

Abstract: 1. The effects of intracameral injections of prostaglandins E1, E2, F1a, F2a, and A1 were studied on the intraocular pressure (IOP) of rabbits anaesthetized with urethane. 2. With the exception of prostaglandin F1a, all the prostaglandins studied were found to be capable of producing a large, sustained rise in IOP, accompanied in many cases by miosis. 3. A marked decrease in response to repeated injections was found with all the prostaglandins studied; this effect was more pronounced following a large initial response to the prostaglandin. 4. The descending order of potency in their ability to raise IOP was as follows: prostaglandin E1≈E2>F2a>A1>F1a. 5. Intracameral injections of prostaglandins E1 and E2 resulted in an increase in the protein content of the aqueous humour, which was related to the magnitude of the sustained increase in IOP. 6. Stabilization of the blood-aqueous barrier with polyphloretin phosphate markedly reduced both the IOP response and the effect of prostaglandin E2 on the protein content of the aqueous humour. 7. It is concluded that the production of local vasodilatation and increased permeability of the blood-aqueous barrier play an important part in the effect of prostaglandins on the IOP. The involvement of prostaglandins in the response of the rabbit eye to irritation is discussed.

Synaptic relationships in the plexiform layers of carp retina.

Abstract: The synaptic contacts made by carp retinal neurons were studied with electron microscopic techniques. Three kinds of contacts are described: (1) a conventional synapse in which an accumulation of agranular vesicles is found on the presynaptic side along with membrane densification of both pre- and postsynaptic elements; (2) a ribbon synapse in which a presynaptic ribbon surrounded by a halo of agranular vesicles faces two postsynaptic elements; and (3) close apposition of plasma membranes without any vesicle accumulation or membrane densification.

Compartmentation of Amino Acid Metabolism

Abstract: Compartmentation of metabolic events has received increasing attention in recent years. In the area of amino acid metabolism heterogeneous functional pools have been postulated for microorganisms,(1–3) plants,(4,5) and animal tissues.(6–8) The concept of metabolic compartmentation was suggested because of observations that could not be explained by the simple precursor-product relationship as described by Zilversmit, Entenman, and Fishler.(9)

Geomagnetic Reversal in Brunhes Normal Polarity Epoch

Abstract: The magnetic stratigraphly of seven cores of deep-sea sediment established the existence of a short interval of reversed polarity in the upper part of the Brunches epoch of normal polarity. The reversed zone in the cores correlates well with paleontological boundaries and is named the Blake event. Its boundaries are estimated to be 108,000 and 114,000 years ago +/- 10 percent.

Compartmentation of glutamate metabolism in brain. Evidence for the existence of two different tricarboxylic acid cycles in brain.

Abstract: 1. (14)C from [1-(14)C]glucose injected intraperitoneally into mice is incorporated into glutamate, aspartate and glutamine in the brain to a much greater extent than (14)C from [2-(14)C]glucose. This difference for [1-(14)C]glucose and [2-(14)C]glucose increases with time. The amount of (14)C in C-1 of glutamate increases steadily with time with both precursors. It is suggested that a large part of the glutamate and aspartate pools in brain are in close contact with intermediates of a fast-turning tricarboxylic acid cycle. 2. (14)C from [1-(14)C]acetate and [2-(14)C]acetate is incorporated to a much larger extent into glutamine than into glutamate. An examination of the time-course of (14)C incorporated into glutamine and glutamate reveals that glutamine is not formed from the glutamate pool, labelled extensively by glucose, but from a small glutamate pool. This small glutamate pool is not derived from an intermediate of a fast-turning tricarboxylic acid cycle. 3. It is proposed that two different tricarboxylic acid cycles exist in brain.