Showing papers by "Columbia University published in 1972"

Sea-Floor Spreading in the North Atlantic

Abstract: The magnetic anomaly lineation pattern in the North Atlantic Ocean (between the latitudes of 15° N. and 63° N.) has been examined in light of the hypotheses of sea-floor spreading and plate tectonics. There is no evidence of significant subduction or deformation along the margins of the Atlantic since the Late Triassic, and thus the sea-floor spreading that has occurred since that time has resulted in continental drift only. The rate and direction of drift between Europe and North America and between Africa and North America have differed at all times since the Late Triassic. Although Eurasia may have been rifted from North America in the Jurassic, the major phase of drift did not begin until the Late Cretaceous. Separation varied from 5.0 to 4.0 cm/yr (at a latitude of 45° N.) from the Cretaceous until 53 m.y. ago. The rate of separation slowed about 53 m.y. ago. The average rate was slightly less than 2 cm/yr for the intervals from 53 m.y. to 38 m.y. ago and from 38 m.y. to 9 m.y. ago. The sediment discontinuity found by others at about the location of anomaly 5 on both flanks of the Mid-Atlanti.c Ridge, north of the Azores, thus cannot be explained by a discontinuity or drastic slowing in the rate of spreading. From 9 m.y. to the present, separation has been at a rate somewhat greater than 2.0 cm/yr. The initiation of rifting between Africa and North America may have occurred 200 m.y. ago. However, we have assumed that the active phase of drift did not begin until 180 m.y. ago. The separation proceeded at an average rate of 4.0 cm/yr from 180 m.y. to 81 m.y. ago; 3.4 cm/yr from 81 m.y. to 63 m.y. ago; 2.4 cm/yr from 63 m.y. to 39 m.y. ago; 2.0 cm/yr from 38 m.y. to 9 m.y. ago; and 2.8 cm/yr from 9 m.y. ago to the present (the rates are computed for a latitude of 35° N.). We have fitted together lineations of the same age but from opposite sides of the ridge axis in the same fashion that previous workers have fitted together continental margins. Each fit is described by a pole and angle of rotation about the pole. Each fit gives the paleogeographic relations of the respective continents and oceanic plates for the particular age of the lineation. We conclude from these paleogeographic reconstructions that there was probably no Late Cretaceous (81 m.y. to 63 m.y. ago) sea-floor spreading in the Arctic, but that the relative motion between Eurasia and North America in the Arctic region was compressional during this interval. This compression may have been accommodated by subduction at Bowers Ridge (which appears to be an inactive island-arc trench system) and subduction in eastern Siberia. It also may have been accommodated by compressional deformation in the Brooks Range, the Verkhoyansk Mountains, and the Sverdrup Basin (in central northern Canada). All the spreading in the Arctic region that has occurred since the Late Cretaceous has taken place in the last 63 m.y. The locus of this spreading has been the Mid-Arctic Ridge which lies between the Lomonosov Ridge and the Eurasian continental shelf. The effect of this spreading has been to separate the pre-existing Lomonosov Ridge from the Eurasian continental shelf. The Alpha Cordillera has not been the locus of sea-floor spreading in the Cenozoic. The exact pattern of the separation of Greenland from North America is not known. There may have been minor rifting in the Labrador Sea during the Jurassic. However, the major phase of drift occurred from the Late Cretaceous to the late Eocene. The final separation of Eurasia (Spitsbergen), Greenland, and North America did not occur until the middle Eocene. The pattern of magnetic lineations suggests that the well-documented counterclockwise rotation of the Iberian Peninsula occurred between the Late Triassic and the Late Cretaceous, and that there has been little, if any, counterclockwise rotation subsequent to that time. We have used the derived poles and the angular rates of rotation to compute isochrons which give the age of the basement in the North Atlantic. The basement ages agree well with other data such as those obtained as the result of JOIDES drilling. The isochrons sometimes give greater ages which can be reconciled with the drilling results by involving subsequent volcanism, but in no case do the isochrons give smaller ages. The Keathley sequence of magnetic anomalies which lie just seaward of the quiet zone and southwest of Bermuda in the western Atlantic and northwest of Dakar in the eastern Atlantic, has been given an age of about 130 to 155 m.y. Comparison of the isochrons with the magnetic lineations indicate that two important shifts of the ridge axis may have occurred. The first, in the region south of the New England Seamounts and the Canary Islands was a 200-km eastward jump or migration that took place prior to 155 m.y. ago; the second in the region north of the New England Seamounts and Canary Islands but south of the Azores was a more complex westward shift of 150 km maximum extent that occurred between 135(?) m.y. and 72 m.y. ago. We have also computed a pattern of synthetic fracture zones or flow lines. Previous workers have proposed that the South Atlas fault, the western Canary Islands, and the New England Seamounts lie along a fundamental fault or fracture zone. We note that these features are approximately parallel to one of these synthetic flow lines. The seaward escarpment bounding the southern Bahamas as well as several well-surveyed fracture zones and other bathymetric features are parallel to the synthetic fracture zones.

A Working Model of Skill Acquisition with Application to Teaching

Abstract: (1972). A Working Model of Skill Acquisition with Application to Teaching. Quest: Vol. 17, No. 1, pp. 3-23.

World-Wide Correlation of Mesozoic Magnetic Anomalies, and Its Implications

Abstract: In the course of correlating three sets of Mesozoic magnetic lineations in the western Pacific (the Phoenix, Japanese, and Hawaiian lineations), Larson and Chase (1972) determined a paleomagnetic pole for the Pacific plate for the Early Cretaceous. Using this pole we have derived a magnetic reversal model for the Hawaiian lineation set. We then have used this model to correlate the entire Hawaiian lineation set to the entire Keathley lineation set in the western North Atlantic. On the basis of these correlations and drill holes associated with the lineation patterns, we have extended the geomagnetic reversal time scale back to the base of the Late Jurassic (162 m.y. B.P.). A period of reversals occurred corresponding to the Hawaiian and Keathley lineations from 150 o t 110 m.y. B.P., and these reversals are bracketed by long periods of dominantly normal polarity (the Cretaceous and Jurassic magnetic quiet zones). This magnetic reversal time scale significantly alters previous notions of the timing and origin of sea-floor spreading features in the Atlantic Ocean. It implies that the Bay of Biscay opened sometime during the interval between 150 and 110 m.y. B.P.; that drift in the South Atlantic was initiated at sometime during the interval from 110 to 85 m.y. B.P. (probably close to 110 m.y. B.P.); and that the seaward portion of the marginal quiet zones of the eastern United States and northwestern Africa resulted from sea-floor spreading during the Late Jurassic period of dominantly normal magnetic polarity prior to 150 m.y. B.P. In the Pacific during the late Mesozoic, spreading was occurring from at least five spreading centers joined at two triple points. The vast majority of the Pacific Basin today is occupied by only the Pacific-plate side of these spreading patterns. This implies that an area equal to most of the Pacific Basin has been subducted beneath the surrounding continents since the Early Cretaceous. Our magnetic reversal time scale calls for a rapid pulse of spreading from about 110 to 85 m.y. B.P. at all the spreading centers in both the Atlantic and Pacific Oceans. This implies a pulse of rapid subduction around the rim of the Pacific that we relate to episodes of large-scale plutonism in eastern Asia, western Antarctica, New Zealand, the southern Andes, and western North America during the Late Cretaceous.

Human prolactin - 24-hour pattern with increased release during sleep.

Abstract: Human prolactin was measured in plasma by radioimmunoassay at 20 minute intervals for a 24-hour period in each of six normal adults, whose sleep-wake cycles were monitored polygraphically A marked diurnal variation in plasma concentrations was demonstrated, with highest values during sleep; periods of episodic release occurred throughout the 24 hours

Alcohol and tension reduction. A review.

Abstract: The literature on the tension-reducing effects of alcohol is reviewed. Much of the evidence is negative, equivocal and often contradictory.

Sea-Floor Spreading and the Cenozoic History of the East-Central Pacific

Abstract: The east-central Pacific between 20° N. and 45° S. records several patterns of sea-floor spreading. Three distinct spreading centers are now active in the area, and total spreading rates across one of them, the East Pacific Ridge, are the fastest observed anywhere. The present East Pacific Ridge between 20° N. and 45° S. has maintained its present configuration only during the last 9 m.y. Prior to 10 m.y. ago, a north-northwest-trending ridge was active throughout the east-central Pacific, and the fossil crest of this ridge can be identified in the basin east of the present ridge axis between 10° S. and 30° S. and west of the ridge axis between 20° N. and the equator. Between the equator and 20° N., the north-northwest-trending ridge system has been continuously active since at least the Late Cretaceous, but 5 to 10 m.y. ago the position of the axis jumped to the east. South of the Chile Fracture Zone at 36° S., the north-northwest-trending Chile Ridge appears to be a still active segment of this old ridge system. Spreading on the north-northeast-trending East Pacific Ridge began more than 50 m.y. ago at 55° S. and grew northward so that opening at 35° S. began about 20 m.y. b.p. Between 10° N. and 10° S., spreading about the present axis was initiated only during the last 10 m.y. Analysis of magnetic anomalies associated with north-trending ridges near the equator is of limited value because of the extremely low amplitudes of the anomalies generated by the ridge. However, although identification of individual anomalies is tenuous at best, comparison of relative amplitudes and shapes with computed models offers limited support of the hypothesis of Francheteau and others (1970) that the Pacific Plate has migrated northward since the Late Cretaceous.

The Ortega Hypothesis: Citation analysis suggests that only a few scientists contribute to scientific progress.

Abstract: Let us consider, then, some general conclusions that may be drawn from the findings reported in this study. The data allow us to question the view stated by Ortega, Florey, and others that large numbers of average scientists contribute substantially to the advance of science through their research. It seems, rather, that a relatively small number of physicists produce work that becomes the base for future discoveries in physics. We have found that even papers of relatively minor significance have used to a disproportionate degree the work of the eminent scientists. Although the conclusions of this paper may be reasonably clear, the implications of these data for the structure of scientific activity, at least in physics, need careful consideration.

Late Mesozoic Evolution of the Western Pacific Ocean

Abstract: A set of east-trending magnetic anomalies located in the western equatorial Pacific Ocean near the Phoenix Islands is Early Cretaceous in age. The use of magnetic reversal model studies shows that this lineated anomaly pattern correlates with one east of Japan that trends east, and with one west of Hawaii that trends northwest. These patterns were formed in their present relative positions, but about 40° (4,500 km) south of their present geographic locations. The configuration of these three contemporaneous sets of magnetic anomalies implies that the Late Mesozoic tectonic pattern consisted of five spreading centers joined at two triple points. In this interpretation, the oldest part of the Pacific Ocean lies just east of the Mariana Trench and is Early Jurassic in age. This Mesozoic system evolved into the Cenozoic spreading pattern recorded in the eastern Pacific Ocean. The details of this transition are open to speculation because it occurred during a period in the Late Cretaceous that lacked magnetic reversals. We propose a model that suggests the northern triple point jumped southeast about 2,000 km at 100 m.y. B.P., and that the Emperor Trough was a transform fault of large offset during the Late Cretaceous. The southern triple point migrated rapidly toward the south-southeast, approximately parallel to the Eltanin Fracture Zone–Louisville Ridge complex that we extend o t the westernmost of the Phoenix lineation fracture zones.

Casework: A Psychosocial Therapy

Abstract: Part One: The Theoretical Framework Chapter 1: Casework: Then and Now Chapter 2: The Psychosocial Frame of Reference: An Overview Chapter 3: Examples of Clinical Social Work Practice Chapter 4: The Hollis Classification of Casework Treatment Part Two: Treatment: An Analysis of Procedures Chapter 5: Sustainment, Direct Influence, and Exploration-Description-Ventilation Chapter 6: Reflective Discussion of the Person-Situation Configuration Chapter 7: Reflective Consideration of Pattern-Dynamic and Developmental Factors Chapter 8: Psychosocial Therapy and the Environment Chapter 9: The Client-Worker Relationship Part Three: Diagnostic Understanding and the Treatment Process Chapter 10: Initial Interviews and the Psychosocial Study Chapter 11: Assessment and Diagnostic Understanding Chapter 12: Choice of Treatment Objectives Chapter 13: Choice of Treatment Procedures Chapter 14: Family Therapy and Psychosocial Casework: A Theoretical Synthesis Chapter 15: The Clinical Practice of Family Therapy Chapter 16: Couple Treatment: Problems in Relationships Chapter 17: Couple Treatment: Clinical Issues and Techniques Chapter 18: Crisis Intervention and Brief Treatment Chapter 19: Termination Chapter 20: The Psychosocial Approach: Clinical Case Examples Chapter 21: Studying and Working with the Hollis Typology Appendix Bibliography

A Simplified Method for the Quantitative Determination of Testosterone-Estradiol-Binding Globulin Activity in Human Plasma

Abstract: A rapid and simple method for the measurement of testosterone-estradiol-binding globulin in human plasma is described. The bind- ing protein is saturated with dihydrotestosterone (DHT), precipitated with 50% ammonium sul- fate, and the mass of bound DHT determined from the known specific activity of the added steroid. Normal values, expressed as M-g DHT bound/100 ml serum are: men, 0.93 ±. 0.06 (SEM); women, 1.85 ± 0.13; pregnancy, 12.4 ± 0.67. Elevated values were observed in men with cirrhosis of the liver and patients with thyrotoxi- cosis. Normal values were observed in abstinent alcoholics and in pregnant subjects with diabetes or hypertension. (/ Clin Endocrinol Metab 34: 983, 1972)

Theory of finite deformations of porous solids

Abstract: Communicated by G. TEMPLE 1. Introduction. The linear mechanics of fluid-saturated porous media as developed by the author was reviewed and discussed in detail in two earlier papers [l], [2]. In its final form it is based on the linear thermodynamics of irreversible processes. It is applicable to the most general case of anisotropy and includes not only the basic principles of classical thermodynamics but also the effects of coupled flows of irreversible processes. Thermoelastic dissipation is also implicit since the heat flux is nothing but one of the internal thermodynamic coordinates of the system. The solid matrix itself may be viscoelastic. Actually the theory is even more general since it takes into account the viscoelastic interaction of the fluid with the solid.due to the micromechanics of fluid penetration in cracks which are much smaller than the pores. An important concept derived from the existence of a dissipation function for the fluid is that of “Viscodynamic operator” [2]. This is an operational symmetric tensor which describes the frequency-dependent behavior of the fluid. The symmetric character of this tensor leads to important conclusions in the theory of acoustic propagation. Regarding the extension to non-linear problems a first step is constituted by a theory which introduces the non-linear superposition of a state of initial stress and incremental deformations [3]. This also leads to an analysis of finite deformations based on stress-rates. In this case the deformation is considered as a continuous sequence of incremental deformations 141. The concepts and methods introduced in this incremental theory lead quite naturally to the next development which considers a description of finite deformation using material coordinates. In particular the concept of pressure function for a porous medium which was introduced in the theory of incremental deformations [3] provides one of the essential means by which this extension of the theory can be accomplished. The mechanics of porous media is thus brought to the same level of development of the classical theory of finite deformations in elasticity. In order to restrict the length of the paper, the theory is presented in the context of quasi-static and isothermal deformations.

The influence of temperature on the solubility of monosodium urate.

Abstract: The limited solubility of monosodium urate in the presence of physiological sodium concentrations is shown to fall sharply with decreasing temperature. It is suggested that this phenomenon may play a role in determining the clinically observed distribution of tophi and the susceptibility of certain joints to acute gouty arthritis.

Nigrostriatal and nigrothalamic fibers in the rhesus monkey

Abstract: Lesions in caudal parts of the substantia nigra (SN) produced in 11 monkeys were localized to lateral, medial and central regions. Resulting degeneration was studied by the Wiitanen technic in transverse and sagittal sections. Ascending nigral efferents project into Forel's field H where they divide into medial and lateral bundles. Fibers of the medial bundle terminate in portions of the ventral lateral (VLm) and ventral anterior (VAmc) thalamic nuclei. Quantitatively larger numbers of fibers project laterally dorsal to, and within, the subthalamic nucleus. These nigral efferents traverse the internal capsule and globus pallidus to enter the putamen (P) and parts of the caudate nucleus (CN). Nigral efferent fibers in the globus pallidus appeared entirely en passage. The location of degeneration in the putamen appeared related to the part of the SN destroyed. An apparent correspondence exists between: (1) lateral parts of SN and dorsal regions of P, and (2) medial parts of SN and ventral regions of P. The pars reticularis of SN gives rise to nigrothalamic fibers while nigrostriatal fibers arise from the pars compacta. Data suggest that reciprocal topographic relationships may exist between nigrostriatal and strionigral projections and that these fibers appear to form a closed feedback loop concerned with dopamine transport. Lesions in SN concomitantly interrupt large numbers of corticotegmental and corticothalamic fibers.

Rotation of the Corsica–Sardinia Microplate

Abstract: This article summarizes the available data that can be used to date the rotation of the small Corsica–Sardinia plate and points out the types of investigation that could clarify the problem further.

Continental Margin off Norway: A Geophysical Study

Abstract: Geophysical investigations consisting of gravity, magnetic, depth sounding, seismic reflection and refraction measurements were made aboard R/V Vema on the continental margin off Norway. Utilizing these and earlier data in the area, maps showing bathymetry, free-air gravity, magnetic residual total intensity, seismic refraction results, total sediment thickness and thickness of Cenozoic sediments have been constructed. The data are also presented as profiles across the margin. The Voring Plateau is underlain by a buried escarpment; the basement is shallow on the seaward side and deep on the landward side. A similar marginal escarpment, the Faroe–Shetland, exists farther south. These escarpments mark the site of the Tertiary opening of the Norwegian Sea. Seaward, Tertiary sediments overlie a basement generated by sea-floor spreading. Landward, a thick sequence of sediments that may be as old as Paleozoic overlies a continental basement. The magnetic quiet zone on the landward side of the escarpment is attributed to the continental nature of the basement. A nearly continuous belt of positive gravity and magnetic anomalies that exists just landward of the edge of the shelf is attributed primarily to intrabasement density contrasts in rocks that are probably Precambrian in age. It extends from northwest Scotland to the Lofoten–Vesteralen islands. The continental margin off Norway formed an epicontinental sea continuous with the North Sea in which a large amount of sedimentation kept pace with subsidence—a phenomenon which perhaps started in the late Paleozoic. The thickness of pre-Cenozoic sediments exceeds 6 km in some areas, but has a relative minimum over the belt of high density rocks of Precambrian age, which presumably underwent the least relative subsidence. We suggest that the opening of the Norwegian Sea at the marginal escarpments is associated with subsidence of the continental crust between the escarpments and the shelf where the high-density belt acts as a hinge line and accounts for the existence of the shelf break. The subsided area is characterized by a regional free-air gravity low. The marginal Voring Plateau Escarpment formed at the opening of the Norwegian Sea served to dam the Tertiary sediments and develop the V0ring Plateau. The Norwegian Channel is shown not to be of tectonic origin. The Tertiary basin of the North Sea continues northward under the continental margin off Norway.

Three Dimensional Reconstruction from Serial Sections

Abstract: This article describes a technique for studying the detailed morphology of the central nervous system of a simple animal.

Elasticity, Piezoelectricity and Crystal Lattice Dynamics

Abstract: A review of some recent developments in the area between the dynamical theory of crystal lattices, in the harmonic approximation, and the classical, linear theories of elasticity and piezoelectricity.