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Showing papers by "New York University published in 1972"


Journal ArticleDOI
Urs Ramer1
TL;DR: An approximation algorithm is presented which uses an iterative method to produce polygons with a small—but not minimum—number of vertices that lie on the given curve that justifies the abandonment of the minimum-vertices criterion.

1,323 citations


Journal ArticleDOI
28 Jan 1972-Science
TL;DR: Siphon withdrawal, studied in unrestrained animals, showed marked habituation within a single ten-trial training session, and spaced training produced significantly longer lasting habituation than massed training.
Abstract: A tactile stimulus to the siphon of Aplysia produces a defensive withdrawal reflex consisting of contraction of the siphon, the gill, and the mantle shelf. We studied long-term habituation of this reflex using two types of preparations, one focusing on the siphon component and the other on the gill component of the reflex. Siphon withdrawal, studied in unrestrained animals, showed marked habituation within a single ten-trial training session. Five daily training sessions produced habituaton that built up across days and lasted for at least 3 weeks. Furthermore, spaced training produced significantly longer lasting habituation than massed training. Gill withdrawal, studied in a restrained animal, also showed long-term retention of habituation. Since the neural circuitry of gill withdrawal is relatively well understood, it may be possible to study the cellular mechanisms underlying a long-term behavioral modification.

561 citations


Journal ArticleDOI
TL;DR: The transfer of antipyrine, sodium, and l -leucine across an isolated cotyledon of human placenta was studied with an in vitro perfusion system, indicating a diffusion limitation very similar to that for monkey Placenta as measured in situ.

458 citations


Journal ArticleDOI
TL;DR: Under the optimal conditions carefully defined in the authors' experiments, superinduction produced about a 100-fold increase over the average control yield, resulting in interferon yields of about 10,000 reference units from cultures containing about 106 cells, which were similar to that obtained in cultures of human embryonic kidney cells and in FS-3 cells stimulated with other double-stranded polynucleotide inducers.
Abstract: The effect of incubation with interferon prior to the stimulation of interferon production (priming) and of sequential treatment with cycloheximide and actinomycin D (superinduction) on the interferon yield from polyinosinic-polycytidylic acid (poly I·poly C)-induced diploid human foreskin cell cultures (FS-3 strain) was studied. Suitable priming with interferon produced, on the average, about an eightfold increase over the control yield, with a greater increase noted on some occasions when the control interferon yield was very low. Under the optimal conditions carefully defined in our experiments, superinduction produced about a 100-fold increase over the average control yield, resulting in interferon yields of about 10,000 reference units from cultures containing about 10 6 cells. Combined superinduction and priming did not produce yields markedly higher than obtainable by superinduction alone. Essentially similar results were obtained in cultures of human embryonic kidney cells and in FS-3 cells stimulated with other double-stranded polynucleotide inducers. However, stimulation of cells with certain concentrations of a mixture of diethylaminoethyl-dextran and poly I·poly C altered the interferon response; the yield was considerably higher than in cells stimulated with poly I·poly C alone, but it could not be markedly increased further by superinduction.

450 citations


Book ChapterDOI
TL;DR: This chapter discusses the storage mechanisms in recall and the results on short-term memory are interpreted differently in light of the STS-LTS distinction.
Abstract: Publisher Summary This chapter discusses the storage mechanisms in recall. Information on the recall of words has been organized according to several theoretical views. In the case of free recall, the first reason for assuming such a flow and two separate storage mechanisms may be found in a very prominent and reliable characteristic of free recall–the serial position function. In the free recall of lists, Ss are more likely to recall the early and late items than the middle items. There are, moreover, a variety of systematic experimental effects that can be worked on this curve. In most cases, the curve is raised or lowered in all positions except the last few. The effects of similarity on LTS and STS are not established. Most of the work cited on this effect does not differentiate LTS and STS effects. The few studies that do permit the differentiation give conflicting results. Many of the results on short-term memory are interpreted differently in light of the STS-LTS distinction.

335 citations


Journal ArticleDOI
TL;DR: Canonical correlations revealed that IRI is the common denominator in both carbohydrate and lipid abnormalities in IHD, and was neither related to relative weight nor to elapsed time from onset of IHD to time of examination.
Abstract: This study evaluates interrelationships between carbohydrate and lipid metabolism during oral glucose tolerance tests (GTT) in 65 ischemic heart disease (IHD) males and 69 age-matched healthy controls (age range 45 to 69 years). The frequency of abnormal GTT, usually accompanied by type IV hyperlipoproteinemia, was significantly higher in IHD (37%) than in controls (19%). The mean immunoreactive insulin (IRI) response curve of IHD patients with abnormal GTT showed an elevated and delayed peak at 2 hours. The mean free fatty acid response curve of IHD patients had a significantly lower rebound at 3 hours. IHD patients and controls with abnormal GTT showed significantly higher and lagging lactate levels at 2 and 3 hours. Incidence of abnormal GTT was neither related to relative weight nor to elapsed time from onset of IHD to time of examination. Canonical correlations revealed that IRI is the common denominator in both carbohydrate and lipid abnormalities in IHD.

322 citations


Journal ArticleDOI
TL;DR: In this paper, a speed-dependent Voigt profile (SDVP) is derived for spectral profiles, taking into account speeddependent shift and width parameters which are calculated on the basis of an active atom-perturber interaction.
Abstract: Derivation of an expression for the spectral profile, termed a speed-dependent Voigt profile (SDVP), taking into account speed-dependent shift and width parameters which are calculated on the basis of an active atom-perturber interaction. It is shown that an analysis of line shapes in terms of simple Voigt profiles (rather than the SDVP) may lead to considerable errors in the determination of characteristic atomic parameters, especially in systems where the perturber to active atom mass ratio is large. It is also noted that the speed-dependent shift leads to an asymmetrical profile, and such a profile is displayed.

319 citations


Journal ArticleDOI
TL;DR: Evidence was obtained that C3 is primarily involved in particle attachment, whereas only IgG is able to markedly promote the ingestion of particles attached to macrophages and the possible relevance of these findings for the in vivo fate of particulate immune complexes as they interact with macrophage monolayers is discussed.
Abstract: Sheep red cells (E) sensitized with IgG antibody (EA) or with antibody and complement (EAC) interact in vitro with mouse peritoneal macrophage monolayers. The role of IgG and of C3 in the attachment and ingestion of the erythrocytes was examined by means of quantitative technique utilizing (51)Cr-labeled E. Controlled osmotic lysis permitted the separate measurement of the radioactivity associated with bound or with ingested E. IgG-(125)I was used to estimate the number of IgG molecules bound per E as a function of the IgG concentration. Control experiments showed that iodination did not influence the extent of binding of IgG to E and that the binding of IgG prepared from immune serum could be essentially ascribed to its anti-E antibody content. Only between 10(3) and 10(4) rabbit anti-E IgG molecules per erythrocyte were needed for detectable attachment and ingestion of EA (a maximum number of 6 x 10(5) IgG antibody molecules could be accomodated on one erythrocyte). Evidence was obtained that C3 is primarily involved in particle attachment, whereas only IgG is able to markedly promote the ingestion of particles attached to macrophages: (a) Addition of complement to the EA substantially increased the binding to the macrophages, whereas ingestion was increased to a smaller extent. Both binding and ingestion of EAC were markedly inhibited by papain fragments of IgG obtained from a rabbit antiserum to mouse C3. (b) Low doses (2 microg/ml) of papain fragments of IgG from a rabbit antiserum to mouse IgG markedly reduced the ingestion of EAC, whereas attachment of EAC to macrophages was inhibited to a much smaller degree. The possible relevance of these findings for the in vivo fate of particulate immune complexes as they interact with macrophages is discussed. It is suggested that in the primary immune response, when the complexes are predominantly in the form of EA (IgM) or EA (IgM) C3, they would tend to remain on the surface of the macrophages and thus be in a position to stimulate immunocompetent cells. In the secondary response, when EA (IgG) or EA (IgG) C3 predominate, the complexes would tend to be more rapidly interiorized and degraded by the mononuclear phagocytes,

319 citations


Journal ArticleDOI
15 Dec 1972-Science
TL;DR: Data indicate an immune response (Ir) gene specific for antigen E necessary but not sufficient for the development of hay fever, the first documentation of an Ir gene in man.
Abstract: Clinical ragweed pollenosis (hay fever) and IgE antibody production specific for antigen E (the major purified protein antigen from ragweed pollen extract) correlated closely with HL-A haplotypes in successive generations of seven families. HL-A associated IgE antibody responsiveness was antigen specific and extended also to IgE antibody production. These data indicate an immune response (Ir) gene specific for antigen E necessary but not sufficient for the development of hay fever. This appears to be the first documentation of an Ir gene in man.

290 citations


Journal ArticleDOI
TL;DR: Analysis of the recovery of sensitivity in the presence of background fields that initially saturate the receptor potential indicates that a gain-control mechanism operates within the receptors, at a distal stage of the visual process.
Abstract: Receptor potentials were recorded extracellularly from the all-rod retina of the skate after the application of sodium aspartate. This agent suppresses the responses of proximal elements, but leaves relatively unaffected the electrical activity of the photoreceptors (a-wave) and pigment epithelium (c-wave). Since the latter develops too slowly to interfere with the receptor response, it was possible to isolate receptor potentials and to compare their behavior in light and dark adaptation with earlier observations on the S-potential, b-wave, and ganglion cell discharge. The results show that the photoreceptors display the full complement of adaptational changes exhibited by cells proximal to the receptors. Thus, it appears that visual adaptation in the skate is governed primarily by the photoreceptors themselves. Of particular interest was the recovery of sensitivity in the presence of background fields that initially saturate the receptor potential. Analysis of this recovery phase indicates that a gain-control mechanism operates within the receptors, at a distal stage of the visual process.

279 citations


Journal ArticleDOI
TL;DR: In this article, the Lenz-Jensen statistical model for the stopping power of a particle of charge at a given impact parameter with an electron bound isotropically and harmonically to the origin with a frequency was considered.
Abstract: We consider in a classical formulation the interaction of a particle of charge ${Z}_{1}e$ incident at a given impact parameter with an electron bound isotropically and harmonically to the origin with a frequency $\ensuremath{\omega}$. Using a perturbation expansion that assumes that the displacement of the bound electron is small compared to the impact parameter, and integrating over the impact parameter from some minimum value to infinity, we are led to an expression for the stopping power. The leading term in this expansion is proportional to ${({Z}_{1}{e}^{2})}^{2}$ and is the usual result for this type of model, while the second term gives us the ${({Z}_{1}{e}^{2})}^{3}$ correction. The ${Z}_{1}^{3}$ correction for the Lenz-Jensen statistical model for the atom is presented. The predictions of this theory are in excellent agreement with available experimental data.

Journal ArticleDOI
G. Stotzky1
01 Nov 1972
TL;DR: In this paper, activity, ecology, and population dynamics of Microorganisms in Soil are discussed, and the authors propose a method to detect the presence of microorganisms in the soil.
Abstract: (1972). Activity, Ecology, and Population Dynamics of Microorganisms in Soil. CRC Critical Reviews in Microbiology: Vol. 2, No. 1, pp. 59-137.

Journal ArticleDOI
TL;DR: Comparisons of thyroxine with that obtained by competitive protein binding assay and triiodothyronine with those determined by the previously developed radioimmunoassay afford excellent agreement.

Journal ArticleDOI
TL;DR: In this paper, the short distance behavior of field operator products is analyzed and it is shown that under certain conditions operator product expansions can be derived which give complete information on the short-distance behavior and lead to the construction of composite field operators.
Abstract: The short distance behavior of field operator products is analyzed. It is shown that under certain conditions operator product expansions can be derived which give complete information on the short distance behavior and lead to the construction of composite field operators.

Journal ArticleDOI
TL;DR: Pattern recognition by parallel devices is investigated by studying the formal language recognition capabilities of one-dimensional cellular automata, finding that nondeterministic bounded cellular Automata can recognize the context-free languages in real time.

Journal ArticleDOI
TL;DR: This paper presents a method for detecting edges in a digitized picture that has great flexibility because of the global approach and some experimental results are given, which show the performance of this method with noisy pictures.

Journal ArticleDOI
TL;DR: Serotonin and dopamine, both likely transmitter substances in Aplysia, stimulated formation of adenosine-3',5' monophosphate (cAMP) in ganglia, connectives, and identified nerve cell bodies, suggesting that receptors for the response are localized throughout the nervous system, as is adenyl cyclase.
Abstract: Serotonin and dopamine, both likely transmitter substances in Aplysia, stimulated formation of adenosine-3',5' monophosphate (cAMP) in ganglia, connectives, and identified nerve cell bodies. This widespread distribution suggests that receptors for the response are localized throughout the nervous system, as is adenyl cyclase. Both synthesis of cAMP-(3)H from precursor previously labeled in incubations with adenine-(3)H and total content of cAMP were stimulated up to 15-fold. The acetylcholine analogue carbachol, glutamate, norepinephrine, and histamine were inactive. Full stimulation occurred within 2-4 min of applying serotonin; the extent of the effect was half maximal at 6micro serotonin. Even in the continued presence of serotonin, the increased cAMP diminished with time. When serotonin was removed, tissue remained refractory for 15-20 min; sensitivity returned after 25 min. Serotonin stimulated cAMP after removal of extracellular Na, K, or Cl and in isotonic sucrose, with all extracellular ions removed. Elevating Mg, which blocked the stimulation of cAMP caused by synaptic activity, did not affect the response to serotonin. Thus the response appeared to be independent of transmitter release and of changes in synaptic potentials and current flow. The role of cAMP in neuronal functioning remains to be determined. Conditions which markedly increased cAMP in neurons, however, did not affect the rate of RNA synthesis, nor did they alter the distribution of phosphorylated adenine or uridine nucleotides.

Journal ArticleDOI
06 Dec 1972-Nature
TL;DR: Crystals of monosodium urate, like silica, rupture lysosomes and liposomes in media which do not constrain hydrogen bonding, which may account for crystal-induced gouty inflammation as well as explain why men rather than women get acute gout.
Abstract: Crystals of monosodium urate, like silica, rupture lysosomes and liposomes in media which do not constrain hydrogen bonding. Liposomes are rendered susceptible to urate-induced lysis if they contain cholesterol and testosterone, but refractory if they contain 17-β-oestradiol. Similar events in vivo may account for crystal-induced gouty inflammation as well as explain why men rather than women get acute gout.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the accuracy of forecasts produced by nine mechanical forecasting techniques and three groups of analysts, including exponential weighted moving averages, naive models, simple moving average, and regressions.
Abstract: This paper examines the accuracy of forecasts produced by mechanical forecasting techniques and three groups of analysts. The nine mechanical forecasting techniques are variations of exponentially weighted moving averages, naive models, simple moving averages, and regressions. One-, two-and three-year forecasts are used to evaluate these techniques. The mechanical techniques exhibit statistically significant differences in their ability to forecast earnings per share, with the exponentially weighted moving averages producing the best forecasts. One-year forecasts produced by the best of the mechanical forecasting techniques were compared to the corresponding analysts' projections. No statistically significant difference could be discerned.

Journal ArticleDOI
TL;DR: A computational method developed to describe, by means of a histogram, the distribution of affinities in an antibody sample found that low affinity antibodies persist in approximately constant amounts from day 7 to 1 yr after immunization.


Journal ArticleDOI
TL;DR: It is suggested that the T cell receptor for antigen is not a conventional tetrameric Ig, and Radiolabeling of mixtures of B cells and thymocytes suggest that the method may detect as little as 250 molecules of Ig per cell.
Abstract: Thymocytes, bone marrow cells, and their derived T and B cell populations were examined for the presence of Ig by the cell surface radioiodination technique. Both IgM and IgG were identified on bone marrow cells. Thymocytes and T cells had no detectable cell surface Ig. Radiolabeling of mixtures of B cells and thymocytes suggest that the method may detect as little as 250 molecules of Ig per cell. Based on these findings, we suggest that the T cell receptor for antigen is not a conventional tetrameric Ig.

Journal ArticleDOI
TL;DR: Of the anaerobic, nonsporulating, gram-negative bacilli, those of the genus Bacteroides are most frequently associated with serious infections in man, and all were resistant to the aminoglycosides, polymyxins, and semisynthetic penicillinase-resistant penicillins.
Abstract: Of the anaerobic, nonsporulating, gram-negative bacilli, those of the genus Bacteroides are most frequently associated with serious infections in man. Forty clinical isolates of the species Bacteroides fragilis were tested quantitatively against 24 antibiotics by an agar-dilution method under anaerobic conditions. Clindamycin, the most active antibiotic studied, had a median MIC of 0.19 ng/ml. Rifampin, erythromcyin, lincomycin, and chloramphenicol also inhibited all isolates in clinically attainable concentrations. More than half of the strains tested were resistant to tetracycline. Some isolates were susceptible to penicillin G, ampicillin, carbenicillin, and the cephalosporins, and all were resistant to the aminoglycosides, polymyxins, and semisynthetic penicillinase-resistant penicillins. The genus Bacteroides consists of nonsporulating, gram-negative bacilli which are obligate anaerobes. These organisms predominate numerically in the normal bacterial flora of the large bowel and are important components of the normal flora of the oral cavity and the urogenital tract [1]. Although they have long been recognized as significant human pathogens, the literature on infec

Journal ArticleDOI
TL;DR: Theospholipase activity mainly responsible for phospholipid breakdown was phospholipsase At, and heating at 120 °C at 2.7 kg/cm2, inactivated all phospholIPase activity.

Journal ArticleDOI
TL;DR: It is shown for Chlorella that the magnetic field induces a reorientation of the entire cell, and this results imply that chlorophyll in vivo possesses a higher degree of orientation than previously thought.

Journal ArticleDOI
Peter D. Lax1
TL;DR: In this paper, the formation and decay of shock waves are discussed and a model of the wave formation and the decay is proposed. The American Mathematical Monthly: Vol. 79, No. 3, pp. 227-241.
Abstract: (1972). The Formation and Decay of Shock Waves. The American Mathematical Monthly: Vol. 79, No. 3, pp. 227-241.

Journal ArticleDOI
20 Sep 1972-Nature
TL;DR: Temperature sensitive mutant cells were isolated from animal cells by multiple culturing in the presence of 5-fluoro-2′-deoxyuridine and properties of the mutants are described.
Abstract: Temperature sensitive mutant cells were isolated from animal cells by multiple culturing in the presence of 5-fluoro-2′-deoxyuridine. Properties of the mutants are described.

Journal ArticleDOI
01 Sep 1972-Blood
TL;DR: Evidence that the proportion of complement-receptor lymphocytes (CRL) is greatly increased in the circulation in most cases of chronic lymphocytic leukemia (CLL) is presented and results suggest that CLL preferentially affects B cells.

Journal ArticleDOI
TL;DR: Theoretical positron-lifetime spectra are derived for targets with structures such that positrons can diffuse into interstices where they remain trapped until, after a distinct lifetime, they annihilate with an electron into $\ensuremath{\gamma}$ quanta as discussed by the authors.
Abstract: Theoretical positron-lifetime spectra are derived for targets with structures such that positrons can diffuse into interstices where they remain trapped until, after a distinct lifetime, they annihilate with an electron into $\ensuremath{\gamma}$ quanta. Exact expressions and convenient approximate formulas for different structural geometries are presented. The contribution of trapped positrons to the angular correlation between the two annihilation $\ensuremath{\gamma}$ quanta is derived. The propagation of errors in determining positron-diffusion constants or, conversely, parameters of the target microstructure from positron-annihilation characteristics is discussed.

Journal ArticleDOI
25 Feb 1972-Nature
TL;DR: The catecholamine hypothesis of affective disorders, which associates decreased functional catechlamines with depression, has been tested by measurement of noradrenaline in plasma or urine or the NA metabolites, normetanephrine and VMA in urine, and results have led to conflicting results.
Abstract: THE catecholamine hypothesis of affective disorders1,2, which associates decreased functional catecholamines with depression, has been tested by measurement of noradrenaline (NA) in plasma or urine or the NA metabolites, normetanephrine and VMA in urine3–5. Probably only a small percentage of these compounds originate from the central nervous system6, and so it is not surprising that this has led to conflicting results.