Showing papers by "New York University published in 1979"
TL;DR: In this paper, the authors show that positive solutions of second order elliptic equations are symmetric about the limiting plane, and that the solution is symmetric in bounded domains and in the entire space.
Abstract: We prove symmetry, and some related properties, of positive solutions of second order elliptic equations. Our methods employ various forms of the maximum principle, and a device of moving parallel planes to a critical position, and then showing that the solution is symmetric about the limiting plane. We treat solutions in bounded domains and in the entire space.
2,792 citations
TL;DR: It is shown that euthyroid calf serum depleted of L-T3 andL-T4 by this procedure yields serum which, when used as a medium supplement, results in biological responses identical to those obtained with media supplemented with thyroidectomized calf serum.
Abstract: GH1 cells are a clonal strain of rat pituitary tumor cells which synthesize GH and PRL. We have previously demonstrated that these cells respond to physiological concentrations of L-T3 and L-T4 when cultured with medium supplemented with thyroidectomized calf serum to achieve a thyroid hormone-depleted state under cell culture conditions. In this study, we describe a method to deplete euthyroid calf serum of L-T3 and L-T4 using an anion exchange resin. We demonstrate that the procedure only minimally alters the low molecular weight anion components of the serum and does not change the total protein content or the electrophoretic pattern of serum proteins. Moreover, we show that euthyroid calf serum depleted of L-T3 and L-T4 by this procedure yields serum which, when used as a medium supplement, results in biological responses identical to those obtained with media supplemented with thyroidectomized calf serum. In addition, resin treatment does not alter the growth-promoting properties of the serum if the thyroid hormone concentration is restored. This procedure should be useful in preparing thyroid hormone-depleted serum for cell culture studies in situations where thyroidectomy is not feasible or would require surgical procedures on a large number of small animals.
643 citations
TL;DR: This study shows that lateral cerebral ventricular enlargement is associated with chronic schizophrenia and suggests that this is not a result of treatment, and shows that the 44 chronic schizophrenic patients who had never been treated with electroshock therapy (EST) had larger ventricles than controls.
Abstract: • To investigate if cerebral ventricular enlargement is associated with chronic schizophrenia, computerized tomography scans from 73 psychiatric patients were compared with 56 asymptomatic volunteers all less than 50 years old. Ventricular size was significantly greater in the subgroup of 58 chronic schizophrenic patients than in the controls. Of the chronic schizophrenic patients, 40% were outside the control range; 53% exceeded 2 SDs of the control mean. Neither duration of illness nor length of hospitalization correlated with ventricular size. The 44 chronic schizophrenic patients who had never been treated with electroshock therapy (EST) had larger ventricles than controls. A group of seven nonchronic schizophrenic patients also had enlarged ventricles; the eight patients who were either schizoaffective or nonschizophrenic did not differ from controls. This study shows that lateral cerebral ventricular enlargement is associated with chronic schizophrenia; it suggests that this is not a result of treatment.
538 citations
TL;DR: The experimental results reported here show that after adaptation to a particular grating the sensitivity of a single neurone to that grating may be reduced more than its sensitivity to other gratings.
Abstract: PROLONGED viewing of a grating pattern produces striking ‘after-effects’, involving changes in the detectability, apparent size, orientation and contrast of subsequently viewed gratings1–3. Studies of perceptual after-effects have been used to infer properties of neurones in the human visual cortex2,4,5 similar to those pattern-selective neurones whose sensitivities have been directly measured in the visual cortex of cats and monkeys6,7. Such inferences are based on two assumptions: first, that perceptual changes result from changes in the distribution of activity within the responding population of neurones; second, that the effect of adaptation on each neurone of the population is to reduce its sensitivity uniformly to all stimuli. The experimental results reported here support the first but challenge the second assumption, as they show that after adaptation to a particular grating the sensitivity of a single neurone to that grating may be reduced more than its sensitivity to other gratings.
461 citations
TL;DR: In this article, it is shown that the firing frequencies of individual cells over a cerebellar cortical area may be interpreted as a spatially distributed, finite, series expansion of a time function, which is reconstructed, by summation, in the nucleus where the cortical cells project.
413 citations
TL;DR: Three experiments suggest that adults' judgments of collision time are best predicted by two-dimensional spatiotemporal values which are invariant over object sizes, distances traversed, approach velocities, and several lower-order variables such as absolute angular size.
Abstract: Many subhuman species and human infants, children, and adults can use two-dimensional information of relative rate of angular-size change to anticipate collisions between the self and approaching objects or surfaces. But extant studies have not determined what information is used when subjects view simulated approach events providing two-dimensional information and three-dimensional information (distance and distance change), as well as lower-order visual information contained in real approach events. Three experiments suggest that, given these several possibilities, adults' judgments of collision time are best predicted by two-dimensional spatiotemporal values which are invariant over object sizes, distances traversed, approach velocities, and several lower-order variables such as absolute angular size. However, collision time is substantially underestimated, with absolute amount of underestimation increasing as a function of actual time-to-collision. Large constant errors and loss of judgment linearity ...
382 citations
TL;DR: The incidence of dementia in Parkinson's disease (PD) was tenfold higher than among controls (similarly aged spouses of PD patients), and dementia is held to be related more to the disease than to age.
Abstract: In 520 patients with parkinsonism seen over eight years, 168 (32%) had moderate to marked dementia. Although the demented patients were older than the nondemented patients (70.4 versus 65.5 years), the incidence of dementia in Parkinson's disease (PD) was tenfold higher than among controls (similarly aged spouses of PD patients), and dementia is held to be related more to the disease than to age.
Demented patients, in addition to being older, developed PD later, were more severely involved in a shorter time, and responded less well to levodopa. It is suggested that PD with dementia may represent a different disorder from PD without dementia.
381 citations
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TL;DR: In this paper, the authors explore the implications of human capital and search behavior for both the interpersonal and life-cycle structure of inter-firm labor mobility and find that individual differences in firm-specific complementarities and related skill acquisitions produce differences in mobility behavior and in the relation between job tenure, wages and mobility.
Abstract: In this essay we explore the implications of human capital and search behavior for both the interpersonal and life-cycle structure of inter-firm labor mobility. The economic hypothesis which motivates the analysis is that individual differences in firm-specific complementarities and related skill acquisitions produce differences in mobility behavior and in the relation between job tenure, wages and mobility. Both "job duration dependence" and "heterogeneity bias" are implied by this theory. Exploration of longitudinal data sets (NLS and MID) which contain mobility, job and wage histories of men in the 1966-76 decade yield several findings, among others: 1. The initially steep and later decelerating declines of labor mobility with working age are in large part due to the similar but more steeply declining relation between mobility and length of job tenure. 2. Given tenure levels, the probability of moving is predicted positively by the frequency of prior moves and negatively by education. The inclusion of prior moves in the regression reduces the estimated tenure slope because it helps to remove the "heterogeneity bias" in that slope. 3. The popular "mover-stayer model" is rejected by the existence of tenure effects on mobility. 4. Differences in mobility during the first decade of working life do not predict long-run differences in earnings. However, persistent movers at later stages of working life have lower wage levels and flatter life-cycle wage growth. 5. The analysis calls for a reformulation of earnings (wage) functions. Inclusion of tenure terms in the function permits separate estimates of returns to general and specific human capital after correction for heterogeneity bias. A rough estimate is that 50 percent of life-time wage growth is due to general (transferable) experience and 25 percent each to firm-specific experience and inter-firm mobility.
374 citations
TL;DR: The current approach is to take into consideration the probability of cosmetic improvement by surgical removal in conjunction with education of the patient and/or family that malignant melanomas have been known to occur in congenital nevocytic nevi but are probably rare except in nevi of large size.
Abstract: The subject of the relationship between congenital nevocytic nevi and malignant melanomas has many controversial aspects. Data are insufficient to come to firm conclusions concerning how often melanomas supervene in such nevi and to determine the prognosis of those melanomas. What data are available indicate that malignant melanomas develop in a substantial percentage of large (giant) nevocytic nevi. This lends support to those who recommend surgical excision of such large lesions, when feasible. On the other hand, the information currently available concerning the association of malignant melanomas with medium- and small-sized congenital nevocytic nevi (i.e., those less than 20 cm in largest diameter) is scanty. Because of this lack of data on congenital nevocytic nevi, our current approach is to take into consideration the probability of cosmetic improvement by surgical removal in conjunction with education of the patient and/or family that malignant melanomas have been known to occur in congenital nevocytic nevi but are probably rare except in nevi of large size. Such information provided to the patient and/or family will often help in making the decision for removal or continued observation. A Congenital Nevocytic Nevus Registry has been established in the Oncology Section of the Skin and Cancer Unit at New York University Medical Center in the attempt to begin a long-term prospective study which might eventually provide some meaningful information concerning the natural history of such lesions, including the incidence of malignant melanomas.
352 citations
TL;DR: In this article, the theory of Coulomb ionization of $L$ shells by low-velocity heavy charged particles whose atomic number is small compared to the atomic number of the target atom is extended to projectiles with velocities comparable to or larger than the $L $-shell orbital velocity, and the effect of the repulsion between the projectile and the target nucleus is accounted for by a Coulomb-deflection factor.
Abstract: The theory of Coulomb ionization of $L$ shells by low-velocity heavy charged particles whose atomic number is small compared to the atomic number of the target atom is extended to projectiles with velocities comparable to or larger than the $L$-shell orbital velocities. At large impact parameters projectiles polarize the shell, and at small impact parameters they increase the binding energies of the electrons to be excited. The polarization effect is incorporated in accordance with the perturbed stationary-state (PSS) approximation. The effect of the repulsion between the projectile and the target nucleus is accounted for by a Coulomb-deflection factor (C). This CPSS theory is developed further to include relativistic effects (R) of the target wave function through a procedure that reproduces the results of numerical calculations for heavy target atoms. With electron capture by the projectiles as an additional channel of ionization, the CPSSR theory is compared with experiment.
TL;DR: It is postulate that the gp groE complex contains 14 subunits in a cylindrical aggregate with 7-fold rotational symmetry, which is involved in the morphogenesis of several bacteriophages.
TL;DR: More than one etiology may account for the structural abnormalities found in chronic schizophrenia patients, as enlarged cerebral ventricles in chronic schizophrenic patients suggest a process of mild cerebral atrophy occurs in some.
Abstract: • Enlarged cerebral ventricles in chronic schizophrenic patients suggest a process of mild cerebral atrophy occurs in some. To see if this process involves the cerebral cortex, the widths of the Sylvian fissure, the interhemispheric fissure, and three cortical sulci were measured blindly on computerized tomography (CT) scans of 75 chronic psychiatric patients and 62 asymptomatic volunteers, all less than 50 years of age. A total of 19 of the 60 patients with chronic schizophrenia had at least one abnormality. All 15 patients with other diagnoses were within the control range. Comparing those chronic schizophrenic patients with abnormalities to those without them, there were no significant differences in age, length of illness or treatment, and length of hospitalization. From this and ventricular size data, two thirds of the chronic schizophrenics had some cerebral structural abnormality. Ventricular enlargement did not correlate significantly with cortical abnormalities. Therefore, more than one etiology may account for the structural abnormalities found in chronic schizophrenic patients.
TL;DR: In this article, the authors present a ray model showing that this dependence is due to interference between a narrow bundle of axial rays and rays associated with the leaky Rayleigh wave excited on the surface.
Abstract: The output voltage of the reflection acoustic microscope depends on the location on the object surface in a way that is characteristic of its elastic properties. We present a ray model showing that this dependence is due to interference between a narrow bundle of axial rays and rays associated with the leaky Rayleigh wave excited on the surface.
TL;DR: It is proved that all subtour-elimination and all comb inequalities define facets of the symmetric travelling salesman polytope.
Abstract: We investigate several classes of inequalities for the symmetric travelling salesman problem with respect to their facet-defining properties for the associated polytope. A new class of inequalities called comb inequalities is derived and their number shown to grow much faster with the number of cities than the exponentially growing number of subtour-elimination constraints. The dimension of the travelling salesman polytope is calculated and several inequalities are shown to define facets of the polytope. In part II (“On the travelling salesman problem II: Lifting theorems and facets”) we prove that all subtour-elimination and all comb inequalities define facets of the symmetric travelling salesman polytope.
TL;DR: It is ten years since Beatrice and Allen Gardner first reported signing behavior by their chimpanzee Washoe, and during this period, the claims on behalf of the language abilities of non-human primates have grown steadily.
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TL;DR: A scheme for integrating the Euler equations of compressible flow in any hyperbolic case is presented in this paper, which relies on the concept of characteristics but is strictly a finite difference scheme.
TL;DR: In this paper, it is shown that for n = 1 and 2, certain decomposition techniques which have proven to be basic for n − 1 and n − 2 are not applicable for n -geqslant 3.
Abstract: This paper makes three observations with regard to several issues of a fundamental nature that apparently must arise in any general theory of linear n-dimensional systems. It is shown, by means of three specific interrelated counterexamples, that certain decomposition techniques which have proven to be basic for n = 1 and 2 are no longer applicable for n \geqslant 3 . In fact, for n \geqslant 3 , at least three equally meaningful but inequivalent notions of polynomial coprimeness emerge, namely, zerocoprimeness (ZC), minor-coprimeness (MC), and factor-coprimeness (FC). Theorems I and 3 clarify the differences (and similarities) between these concepts, and Theorem 2 gives the ZC and MC properties a useful system formulation. (Unfortunately, FC, which in our opinion is destined to play a major role, has thus far eluded the same kind of characterization.) Theorem 4 reveals that the structure of 2-variable elementary polynomial matrices is completely captured by the ZC concept. However, there is reason to believe that ZC is insufficient for n \geqslant 3 but a counterexample is not at hand. The matter is therefore unresolved.
TL;DR: In this article, the authors argue that none of these things exist, and so that the view of common sense is badly in error, and argue for this negative belief of mine.
Abstract: Human experience, it may be said, naturally leads us to have a certain view of reality, which I call the view of common sense. This view is t empered by cultural advance, but in basic fo rm it is similar for all cultures on this planet, even the most primitive and isolated. According to this prevalent view, there are various sorts of ordinary things in the world. Some of these are made by man, such as tables and chairs and spears, and in some ' advanced ' cultures also swizzle sticks and sousaphones. Some are found in nature such as stones and rocks and twigs, and also tumbleweeds and fingernails. I believe that none of these things exist, and so that the view of common sense is badly in error. In this paper , I shall argue for this negative belief of mine. It shall not be my business here to offer arguments concerning the question of whether there are any people, or conscious beings. I contras t these putat ive entities with mere things, and trust that my usage of the latter te rm follows one common way of allowing for such a distinction. Further, among such things, I shall discuss only those which are not living or alive; perhaps I may call them ordinary inanimate objects. Nothing of basic importance depends upon any such a division; it serves only to restrict my topic conveniently. A second restriction I impose on mysel f is not to discuss certain more general concepts which are intended to delineate in a 'thing-like way ' suitable portions or aspects of ' the external world ' , or of 'physical reality' . Accordingly, while I shall argue that our concept of a stone, for example , is devoid of application, I shall not make any such claim for our concept of a physical object, or for any similarly general idea. So far as these present arguments go, then, there may well be various physical objects , indeed, even of a great variety of shapes and sizes. But whatever the shapes and sizes of any such objects , none will ever be a table, a stone, or any ordinary thing. At
TL;DR: A decrease in specific [3H]spiroperidol binding to rat caudate tissue and a parallel decrease in sensitivity to apomorphine in eliciting stereotyped behavior was observed in the offspring of rat mothers treated with either haloperidol or alpha-methyl-p-tyrosine-methyl ester during pregnancy.
Abstract: A decrease in specific [3H]spiroperidol binding to rat caudate tissue and a parallel decrease in sensitivity to apomorphine in eliciting stereotyped behavior was observed in the offspring of rat mothers treated with either haloperidol or alpha-methyl-p-tyrosine-methyl ester during pregnancy. In contrast, evidence of increased dopamine-receptor sensitivity was observed in the pups if haloperidol was administered to their mothers postpartum during nursing rather than during pregnancy.
TL;DR: In this paper, a picture digitization grid based on logarithmic spirals rather than Cartesian coordinates is presented, which yields many geometric observations useful for computer graphics and picture processing.
TL;DR: It is proposed that bactericidal activity in cerebrospinal fluid is important for optimal therapy of bacterial meningitis because leukocytic phagocytosis in the subarachnoid space is inefficient.
Abstract: The bacteriostatic and bactericidal effects of chloramphenicol, ampicillin, tetracycline, and sulfisoxazole were compared against several potential meningeal pathogens. Chloramphenicol is bactericidal at clinically achievable concentrations against Haemophilus influenzae, Streptococcus pneumoniae, and Neisseria meningitidis. It is bacteriostatic against gram-negative bacilli of the family Enterobacteriaceae and against Staphylococcus aureus. Chloramphenicol has proven highly efficacious in the treatment of bacterial meningitis caused by those organisms against which it is bactericidal at low concentrations. Because leukocytic phagocytosis in the subarachnoid space is inefficient, we propose that bactericidal activity in cerebrospinal fluid is important for optimal therapy of bacterial meningitis. Chloramphenicol does not provide such activity in meningitis caused by enteric gram-negative bacilli.
TL;DR: The deep presacral-presciatic nodes were involved almost as often as the more superficial external iliac-obturator group, and metastases limited only to the deep pelvic nodes were found in 14 per cent of the cases.
TL;DR: One hundred male and female MBA students evaluated a woman applicant for a managerial position when the proportion of women in the applicant pool was varied and found that personnel decisions of both males and females were significantly more unfavorable when women represented 25% or less of the total pool as discussed by the authors.
TL;DR: In this paper, it was shown that a charged particle moving with velocity in a medium of resonance frequency may set up two types of electron-density fluctuations, which constitute a mode of energy transport from the particle track leading eventually to particle-hole excitations.
Abstract: It is shown that a charged particle moving with velocity $\stackrel{\ensuremath{\rightarrow}}{\mathrm{v}}$ in a medium of resonance frequency ${\ensuremath{\Omega}}_{0}$ may set up two types of electron-density fluctuations. Collective fluctuations trail the particle, composing a conical pattern in a relatively extended periodic wake of wavelength $\ensuremath{\sim}\frac{2\ensuremath{\pi}v}{{\ensuremath{\Omega}}_{0}}$. They constitute a mode of energy transport from the particle track leading eventually to particle-hole excitations. Single-particle interactions give rise to bow waves ahead of the particles of wavelength $\frac{2\ensuremath{\pi}\ensuremath{\hbar}}{\mathrm{mv}}$. The gradient along $\stackrel{\ensuremath{\rightarrow}}{\mathrm{v}}$, at the site of the ion, of the wake potential set up by density fluctuations, multiplied by the ionic charge, yields an expression for the retarding force of the medium on the projectile in exact agreement with the Bethe stopping-power formula appropriate to the medium. The wake of a dicluster causes forces between the constituent ions which account quantitatively for measurements of the breakup behavior of swift molecular ions in thin foils. The increase in the energy straggling of a test charge, when moving in the wake of a leading ion, is shown to be small compared with the straggling induced by its own wake under normal conditions.
TL;DR: It is shown both theoretically and experimentally that the above solution must be generalized for iontophoresis of ions which are confined to the extracellular space of the brain and that K ÷ behaves anomalously and therefore probably migrates by transcellular routes.
TL;DR: The results suggest that the 48K–55K species may originate either as host-coded species (perhaps induced by the virus) that share determinants with T Ag or perhaps as SV40-encoded species sharing only very little of the amino acid sequence of 94K T Ag.
TL;DR: Four lifting theorems are derived that permit a proof that all subtour-elimination as well as comb inequalities define facets of the convex hull of tours of then-city travelling salesman problem, wheren is an arbitrary integer.
Abstract: Four lifting theorems are derived for the symmetric travelling salesman polytope. They provide constructions and state conditions under which a linear inequality which defines a facet of then-city travelling salesman polytope retains its facetial property for the (n + m)-city travelling salesman polytope, wherem ≥ 1 is an arbitrary integer. In particular, they permit a proof that all subtour-elimination as well as comb inequalities define facets of the convex hull of tours of then-city travelling salesman problem, wheren is an arbitrary integer.
TL;DR: There was striking synchrony in the appearance of noradrenergic characters in the ganglion anlage and gut, and in their disappearance in cells of the gut, suggesting that expression of the adrenergic phenotype is regulated in a manner different from that of the noradRenergic phenotype.