Showing papers in "Science in 1960"
TL;DR: By emphasizing the very aspects that might result in their denial of them were they less plain the authors can keep the principle explicitly present in their minds untit they see if its implications are, or are noty as unpleasant as their subconscious might suppose.
Abstract: because of a belief that it is best to use that wording which is least likely to hide the fact that we still do not comprehend the exact limits of the principle. For the present, I think the 6'threat of clarity\" (3) is a serious one that is best miniInized by using a formulation that is admittedly unclear; thus can we keep in the forefront of our minds the unfinished work before us. The wording given has, I think, another point of superiority in that it seems brutal and dogmatic. By emphasizing the very aspects that might result in our denial of them were they less plain we can keep the principle explicitly present in our minds untit we see if its implications are, or are noty as unpleasant as our subconscious might suppose. The meaning of these somewhat cryptic remarks should be come clear further on iIl the discussion. What does the exclusion principle mean? Itoughly this: that (i) if two noninterbreeding populations \"do the same thing\"-that is, occupy precisely the same ecological niche in Elton's sense (4)-and (ii) if they are \"sympatric\"that is, if they occupy the same geographic territory-and (iii) if population A multiplies even the least bit faster than population B, then ultimately A will completely displace B, which will become extinct. This is the 44weak form' of the principle. A1ways in practice a stronger form is used, based on the removal of the hypothetical character of condition (iii). We do this because we adhere to what may be caIled the axiom of inequality, which states that no two things or processes
3,062 citations
Journal Article•
2,433 citations
IBM1
787 citations
TL;DR: Increases in the size of the pupil of the eye have been found to accompany the viewing of emotionally toned or interesting visual stimuli, and a technique for recording such changes has been developed.
Abstract: Increases in the size of the pupil of the eye have been found to accompany the viewing of emotionally toned or interesting visual stimuli. A technique for recording such changes has been developed, and preliminary results with cats and human beings are reported with attention being given to differences between the sexes in response to particular types of material.
767 citations
TL;DR: The principle of stability for a sample layered in a density-gradient liquid column is discussed, and a method for separating ribonucleoprotein particles by means of sedimentation in the ultracentrifuge is described.
Abstract: The principle of stability for a sample layered in a density-gradient liquid column is discussed, and a method for separating ribonucleoprotein particles by means of sedimentation in the ultracentrifuge is described.
731 citations
TL;DR: In this article, a theory of the kinetics of death is presented based upon the experimentally determined Gompertz function and the postulates that the distribution of stress magnitudes is a Maxwell-Boltzmann distribution and an organism dies when stress magnitude exceeds the organism's maximum ability to compensate therefor.
Abstract: A theory of the kinetics of death is presented which is based upon the experimentally determined Gompertz function and the postulates that the distribution of stress magnitudes is a Maxwell-Boltzmann distribution and an organism dies when stress magnitude exceeds the organism's maximum ability to compensate therefor. The theory predicts a zero-order loss of function versus age. This is borne out in human males by independent observation. The theory permits several independent calculations of the value of B, the percent of loss per year of physiologic function. The calculated values range from 0.9 to 1.4 percent per year and agree closely with the observed rates in human males. The theory predicts an inverse linear relationship between Gompertz slope and ln R/ sub 0/ (intercept), which is closely confirmed by observation. The theory predicts that the mean ratio of maximum reserve capacity to average demand lies between 7 and 11. Independent physiologic measurement data are in reasonable agreement with these values. The theory predicts the observed effects of prolonged or instantaneous exposure of experimental animals to ionizing radiation. The relative deleteriousness (D) of various national environments can be calculated. They have been found to differ by approximately 50 percent. We have beenmore » unable to make an independent test of these relative values. Despite the fact that it is derived for a homogeneous population the theory is shown to be not inconsistent with individual variability within a population. (auth)« less
552 citations
TL;DR: A double cannula system, allowing repeated stimulation of central structures with crystalline chemicals, was developed to study the effects of adrenergic and cholinergic stimulation of the lateral hypothalamus of rats.
Abstract: A double cannula system, allowing repeated stimulation of central structures with crystalline chemicals, was developed. This technique was employed to study the effects of adrenergic and cholinergic stimulation of the lateral hypothalamus of rats. Drug-specific effects on the feeding and drinking mechanisms, respectively, were observed.
424 citations
TL;DR: An enzyme, hydroxyindole-O-methyl transferase, that can transfer the methyl group of S-adenosylmethionine to the hydroxy group of N-acetylserotonin to form the hormone melatonin is described.
Abstract: An enzyme, hydroxyindole-O-methyl transferase, that can transfer the methyl group of S-adenosylmethionine to the hydroxy group of N-acetylserotonin to form the hormone melatonin is described. This enzyme, which is highly localized in the pineal gland, also O-methylates serotonin.
399 citations
391 citations
TL;DR: It was discovered that viruses of previously recognized types and of closely related new types apparently have etiologic roles in a new and highly dangerous epidemic disease syndrome.
Abstract: Epidemiologic, clinical, and etiologic studies were carried out on a newly recognized, frequently fatal, pediatric disease syndrome which occurred in urban areas infested with Aedes aegypti mosquitoes. Four types of dengue virus (two of which are new), chikungunya virus, and another virus yet to be identified were isolated from the blood of patients. Dengue viruses, types 2 and 3, were isolated from the mosquitoes. Ample serologic confirmation was obtained of concurrent hemorrhagic fever and infection with one or more of these viruses. Thus, it was discovered that viruses of previously recognized types and of closely related new types apparently have etiologic roles in a new and highly dangerous epidemic disease syndrome.
TL;DR: Ways of finding the pigment and explanations of some of the features of seasonal response are described, including blue or a bluish-green protein that exists in two forms interconvertible by light.
Abstract: Flowering of plants depends upon the length of the night. This control of flowering is one of the methods of adaptation of species by which an unfavorable season is anticipated. It implies a time-measuring system that distinguishes between light and darkness through mediation of a pigment. Ways of finding the pigment and explanations of some of the features of seasonal response are described. The pigment, now called phytochrome, is a blue or a bluish-green protein that exists in two forms interconvertible by light. Phytochrome is present to the extent of about 1 part in 10 million in many plant tissues. 18 references, 4 figures.
TL;DR: It is proposed that a search for sources of infrared radiation should accompany the recently initiated search for interstellar radio communications.
Abstract: If extraterrestrial intelligent beings exist and have reached a high level of technical development, one by-product of their energy metabolism is likely to be the large-scale conversion of starlight into far-infrared radiation. It is proposed that a search for sources of infrared radiation should accompany the recently initiated search for interstellar radio communications.
TL;DR: Microelectrodes for electrophysiological use have been prepared easily and quickly by electrolytically sharpening platinum iridium alloy wire and coating with molten glass.
Abstract: Microelectrodes for electrophysiological use have been prepared easily and quickly by electrolytically sharpening platinum iridium alloy wire and coating with molten glass. The desirable combination of the electrical characteristics and strength of the platinum iridium wire with the exceptional durability of glass insulation has long been known, but earlier methods of fabrication were difficult and tedious.
TL;DR: Coesite, the high-pressure polymorph of SiO2, hitherto known only as a synthetic compound, is identified as an abundant mineral in sheared Coconino sandstone at Meteor Crater, Arizona.
Abstract: Coesite, the high-pressure polymorph of SiO2, hitherto known only as a synthetic compound, is identified as an abundant mineral in sheared Coconino sandstone at Meteor Crater, Arizona. This natural occurrence has important bearing on the recognition of meteorite impact craters in quartz-bearing geologic formations.
TL;DR: The great informers of events in the outside world seem obviously to be the visual and auditory channels.
Abstract: The great informers of events in the outside world seem obviously to be the visual and auditory channels. Depending somewhat on how the information is to be used, what chains of responses it will set off, we cast messages in visual or auditory form. Not exceptionally but more commonly than not, we code them auditorily: 1) If rapidly successive data are to be resolved. Audition is more useful than vision as a means of making temporal discriminations. Also, auditory reaction times are typically faster. 2) Where the recipient is preoccupied with other tasks or in a condition of reduced alertness and we wish to \"break in\" with unexpected messages or warnings. 3) Listening habits being what they are, where relatively brief, easy, highly meaningful materials are to be apprehended and remembered. 4) Where flexibility of message transmission is important. The voice spontaneously gives inflectional shadings and emphases. 5) Where, out of a larger mass of
TL;DR: This observation identifies the algal substance in the stomach contents of euphausids, the diet of pygoscelid penguins, which inhibits the penguin gastrointestinal microflora.
Abstract: An acidic algal substance has been isolated and characterized as the sodium salt. Synthetic sodium acrylate possesses chemical and antibacterial properties identical with those of the natural product. This observation identifies the algal substance in the stomach contents of euphausids, the diet of pygoscelid penguins, which inhibits the penguin gastrointestinal microflora.
TL;DR: Modifications in the use of penicillin have made it possible to obtain, with regularity, mutants of Escherichia coli blocked in a desired step in arginine biosynthesis.
Abstract: Certain improvements are described in the use of penicillin for isolating auxotrophic mutants of bacteria. By obtaining exponential growth before the penicillin is added, and by minimizing the duration of the treatment, cross-feeding is decreased and much denser populations can be screened. These modifications have made it possible to obtain, with regularity, mutants of Escherichia coli blocked in a desired step in arginine biosynthesis.
TL;DR: α-Methyl-3,4-dihydroxy-DLphenylalanine has been found to be an effective inhibitor of aromatic amino acid decarboxylation in man and decreased formation of serotonin, tryptamine, and tyramine from the precursor amino acids.
Abstract: α-Methyl-3,4-dihydroxy-DLphenylalanine has been found to be an effective inhibitor of aromatic amino acid decarboxylation in man. This was shown by decreased formation of serotonin, tryptamine, and tyramine from the precursor amino acids. Reduction of amine biosynthesis is associated with lowering of blood pressure in hypertensive patients and a transient sedative effect.
TL;DR: Observed volumes of flow are sufficiently large to make it clear that the rectal gland of the spiny dogfish can remove from the blood relatively large amounts of sodium chloride, and presumably this is its function.
Abstract: The rectal gland of the spiny dogfish, Squalus acanthias, secretes a fluid which is essentially a sodium chloride solution with a concentration about twice that of the plasma and greater than that of sea water. Observed volumes of flow are sufficiently large to make it clear that the rectal gland can remove from the blood relatively large amounts of sodium chloride, and presumably this is its function.
TL;DR: Some splitting of the pepsin-treated antibody molecule occurs on carboxymethylcellulose at pH 5.4, and univalent fragments thus formed can be partially recombined by passage through IR-120 cation-exchange resin at room temperature or by treatment with a difunctional organic mercurial.
Abstract: The molecular weight of the active, major component isolated from a peptic digest of rabbit antibody was found to be 106,000. After treatment with a disulfide-splitting reagent, the molecular weight was 56,000, and the products migrated as a single peak in the ultracentrifuge. he univalent fragments thus formed can be partially recombined by passage through IR-120 cation-exchange resin at room temperature or by treatment with a difunctional organic mercurial. Some splitting of the pepsin-treated antibody molecule occurs on carboxymethylcellulose at pH 5.4.
TL;DR: What is presented is that the replication of DNA can be examined and at least partially understood at the enzymatic level even though the secret of how DNA directs protein synthesis is still locked in the cell.
Abstract: The knowledge drawn in recent years from studies of bacterial transformation and viral infection of bacterial cells combined with other evidences, has just about convinced most of us that deoxyribonucleic acid (DNA) is the genetic substance. We shall assume then that it is DNA which not only directs the synthesis of the proteins and the development of the cell but that it must also be the substance which is copied so as to provide for a similar development of the progeny of that cell for many generations. DNA, like a tape recording, carries a message in which there are specific instructions for a job to be done. Also like a tape recording, exact copies can be made from it so that this information can be used again and elsewhere in time and space. Are these two functions, the expression of the code (protein synthesis) and the copying of the code (preservation of the race) closely integrated or are they separable? What we have learned from our studies over the past five years and what I shall present is that the replication of DNA can be examined and at least partially understood at the enzymatic level even though the secret of how DNA directs protein synthesis is still locked in the cell.
TL;DR: Rat heart cells, separated by trypsin treatment and grown attached to glass in a liquid medium, exhibit periodic contractions similar to a whole beating heart.
Abstract: Rat heart cells, separated by trypsin treatment and grown attached to glass in a liquid medium, exhibit periodic contractions similar to a whole beating heart. The rate of beating, which is up to 150 beats per minute, is affected by cardiac drugs and by metabolic substrates and inhibitors.