Showing papers by "University of Arizona published in 1974"
TL;DR: In this paper, the albedo of a cloud is proportional to optical thickness for thin clouds, but changes more slowly with increasing thickness as the number of cloud nuclei is increased.
1,776 citations
1,436 citations
TL;DR: A comparison of western Aleutian Islands with and without sea otter populations shows that this species is important in determining littoral and sublittoral community structure and suggests that sea otters indirectly affects island fauna associated with macrophyte primary productivity.
Abstract: A comparison of western Aleutian Islands with and without sea otter populations shows that this species is important in determining littoral and sublittoral community structure. Sea otters control herbivorous invertebrate populations. Removal of sea otters causes increased herbivory and ultimately results in the destruction of macrophyte associations. The observations suggest that sea otter reestablishment indirectly affects island fauna associated with macrophyte primary productivity.
1,077 citations
TL;DR: In this paper, the existence of integrals of Toda's exponential lattice is proved by a different method, which shows the Toda lattice to be a finite-dimensional analog of the Korteweg-de Vries partial differential equation.
Abstract: Following recent computer studies which suggested that the equations of motion of Toda's exponential lattice should be completely H\'enon discovered analytical expressions for the constants of the motion. In the present paper, the existence of integrals is proved by a different method. Our approach shows the Toda lattice to be a finite-dimensional analog of the Korteweg-de Vries partial differential equation. Certain integrals of the Toda equations are the counterparts of the conserved quantities of the Korteweg-de Vries equation, and the theory initiated here has been used elsewhere to obtain solutions of the infinite lattice by inverse-scattering methods.
670 citations
547 citations
TL;DR: Tree-ring data contribute to a better understanding of the nature of past climatic variations, and study of the variation of ring-width statistics through time promises to be very fruitful.
Abstract: Tree-ring data contribute to a better understanding of the nature of past climatic variations. Annual ring records several thousand years long can be constructed for a few areas, but interpretation of them requires the development of new approaches. For example, a single record of average ring width in the upper tree line environment provides a guide to past temperature fluctuations. However, comparison of this record with another, that of the arid lower forest border, from the same area permits characterization of associated precipitation and temperature anomalies that may, in turn, be linked to features of the general circulation. Other approaches that promise to be very fruitful include study of the variation of ring-width statistics through time, investigation of the physical and chemical properties of wood, and combined multivariate analysis of data for a variety of paleoclimatic indicators.
409 citations
TL;DR: In this paper, the scattering of light by a sphere with intrinsic optical activity was calculated exactly from electromagnetic theory using the constitutive equations appropriate for an optically active, isotropic medium.
344 citations
TL;DR: It is concluded that large paddle electrodes should be used for delivering direct current countershocks, and that during elective cardioversion, consecutive discharges should be delivered at time intervals greater than three minutes.
Abstract: The effect of varying both paddle electrode size and the time interval between direct current countershock on myocardial necrosis was studied. Forty-two dogs were divided into seven groups of six dogs each. All dogs were given ten consecutive, 240 watt-second countershocks (delivered energy into a 50 ohm load). Three groups were shocked with paddle electrode diameters of 8.0 cm (standard electrodes), two groups with paddle electrode diameters of 12.8 cm (large electrodes), and two groups with paddle electrode diameters of 4.3 cm (small electrodes). The time intervals between discharges in the groups shocked with the standard electrodes were 15 seconds, one minute, and three minutes. The time interval between discharges in the groups shocked with small and large electrodes was 15 seconds and three minutes. Myocardial necrosis was quantitated by precordial electrocardiographic mapping recorded minutes after, and by gross and microscopic examination of the hearts four days after direct current countershock. ...
325 citations
TL;DR: In this article, the Pioneer 10 vector helium magnetometer was used along with models of the intrinsic magnetic field of Jupiter and its magnetosphere, and a model of the Jovian magnetosphere was presented in which the essential feature is an eastward current sheet that forms an annulus with Jupiter at the center.
Abstract: Data obtained by the Pioneer 10 vector helium magnetometer are presented along with models of the intrinsic magnetic field of Jupiter and its magnetosphere. Data acquired between 2.84 and 6.0 Jupiter radii, where the intensity of the planetary field ranged between 1900 and 18,400 gamma, were used to develop a six-parameter eccentric dipole model of the field. The dipole so derived has a moment of 4.0 G (R sub J) cubed and a tilt angle with respect to Jupiter's rotation axis of 11 deg. A model of the Jovian magnetosphere is presented in which the essential feature is an eastward current sheet that forms an annulus with Jupiter at the center. At large distances from the planet the current sheet is nearly parallel to Jupiter's equator but, in general, does not lie in it. The current sheet is warped, so that it is above the equator on one side and below it on the other. The current sheet rotates with the planet, more or less like a rigid body, this behavior causes an apparent up and down motion and periodic crossings of the current sheet by Pioneer.
279 citations
TL;DR: A " two-hit " hypothesis of the evolution of myeloma is proposed, which permits appreciatior of the inter-relation of chronic lymphocytic leukaemia, the various lymphomas, plasma-cell tumours, and rarer variants.
250 citations
TL;DR: It is concluded that localization of the apparent hormonal form of vitamin D3, 1α,25-dihydroxycholecalciferol, in the nucleus of the target tissue is probably involved in the physiologic response of calcium transport.
TL;DR: It is postulated that the specific cytosol receptor for 1α,25-dihydroxycholecalciferol functions to transport the hormone to its ultimate site of action in the nuclear chromatin.
TL;DR: A purified, metabolically active preparation of brain microvessels was isolated from bovine cerebral cortex by using a simple procedure involving mild disruption of the tissue by homogenization and trapping of the vessels on nylon sieves to permit in vitro metabolic and structural studies of small blood vessels.
Abstract: A purified, metabolically active preparation of brain microvessels was isolated from bovine cerebral cortex by using a simple procedure involving mild disruption of the tissue by homogenization and trapping of the vessels on nylon sieves. This preparation permits in vitro metabolic and structural studies of small blood vessels.
TL;DR: In this article, a general theory of electrodynamic fluctuations in tunnel junctions is developed using standard many-body techniques, and the quasiparticle, pair, and quasiphoton-pair current power spectra are determined.
TL;DR: In this paper, a protein binding assay with a sensitivity of 80 picograms has been developed for 1α,25dihydroxyvitamin D3, the hormonal form of vitamin D3.
Abstract: A competitive protein binding assay with a sensitivity of 80 picograms has been developed for 1α,25-dihydroxyvitamin D3, the hormonal form of vitamin D3. lα,25-Dihydroxyvitamin D3 displaced tritiated hormone from a cytosol-chromatin receptor preparation isolated from chick small intestine, providing a simple assay for the hormone. The concentration of lα, 25-dihydroxyvitamin D3 in human plasma, as determined by this assay, is approximately 6 nanograms per 100 milliliters; in patients with renal disease the concentration of this kidney-produced hormone is significantly lower.
TL;DR: The surface morphology and optical properties of Mercury resemble those of the moon in remarkable detail and record a very similar sequence of events, suggesting Mercury is probably a differentiated planet with a large iron-rich core.
Abstract: The surface morphology and optical properties of Mercury resemble those of the moon in remarkable detail and record a very similar sequence of events. Chemical and mineralogical similarity of the outer layers of Mercury and the moon is implied; Mercury is probably a differentiated planet with a large iron-rich core. Differentiation is inferred to have occurred very early. No evidence of atmospheric modification of landforms has been found. Large-scale scarps and ridges unlike lunar or martian features may reflect a unique period of planetary compression near the end of heavy bombardment by small planetesimals.
TL;DR: Jupiter's magnetic field and its interaction with the magnetized solar wind were observed with the Pioneer 10 vector helium magnetometer, suggesting substantial plasma effects inside the magnetosphere, such as thermal pressure, centrifugal forces, and differential rotation.
Abstract: Jupiter's magnetic field and its interaction with the magnetized solar wind were observed with the Pioneer 10 vector helium magnetometer. The magnetic dipole is directed opposite to that of the earth with a moment of 4.0 gauss R_J^3 (R_J, Jupiter radius), and an inclination of 15° lying in a system III meridian of 230°. The dipole is offset about 0.1 R_J north of the equatorial plane and about 0.2 R_J toward longitude 170°. There is severe stretching of the planetary field parallel to the equator throughout the outer magnetosphere, accompanied by a systematic departure from meridian planes. The field configuration implies substantial plasma effects inside the magnetosphere, such as thermal pressure, centrifugal forces, and differential rotation. As at the earth, the outer boundary is thin, nor diffuse, and there is a detached bow shock.
TL;DR: The results implicate dopaminergic or classical α-adrenergic receptors (or both) in inhibition of MSH release by catecholamines, and implicate β-adRenergic receptors in stimulation of MSh release by the bioamines.
Abstract: Release of melanophore stimulating hormone (MSH) from the vertebrate pars intermedia is under inhibitory control by the hypothalamus. Removal of the rat pituitary or the neurointermediate lobe of the frog (Rana pipiens) to in vitro incubation medium results in rapid uninhibited release of MSH. This secretion is inhibited by norepinephrine, epinephrine, phenylephrine, and dopamine, and the inhibition is antagonized by α-adrenergic receptor blocking agents. Isoproterenol stimulation of MSH secretion from isolated glands is blocked by pro-pranolol, a β-adrenergic receptor antagonist. These results implicate dopaminergic or classical α-adrenergic receptors (or both) in inhibition of MSH release by catecholamines, and implicate β-adrenergic receptors in stimulation of MSH release by the bioamines.
TL;DR: The use of optimal control theory is used to obtain optimal strategies for the control of a prey-predator system and it is feasible to control a pest by means of an insecticide that destroys only the predators but leaves the pests unharmed.
Abstract: The purpose of this contribution is to illustrate the use of optimal control theory to obtain optimal strategies for the control of a prey-predator system. Two types of control variables are used. One control variable is the rate of release of predators or preys which are bred in laboratories. The other type of control variable is the rate of application of an insecticide. An interesting and unexpected result is that it is feasible to control a pest by means of an insecticide that destroys only the predators but leaves the pests unharmed. This is because the prey-predator system is a dynamical system. The level of the control variable and the timing of its application can be manipulated to produce desired responses from the dynamical system. Another interesting result is that the system can be controlled by releasing pests which have been bred in laboratories. These results may be useful in formulating an integrated control scheme for the management of a pest.
TL;DR: EPR and magnetic susceptibility measurements reported here indicate that in the pH range 1–11, the oxidized form of the protein can exist in four magnetically distinguishable states, quite similar in magnetic properties to the acid forms of metmyoglobin and methemoglobin.
TL;DR: The data are consistent with the hypothesis that the M RNA controls toxin production, and the two RNAs, L and M, seem to be regulated together.
Abstract: Killer strains of Saccharomyces cerevisiae contain two species of double-stranded ribonucleic acid (dsRNA) with molecular weights estimated at 2.5 × 106 (L) and 1.4 × 106 (M). The M component appears to have a high adenine content. All mutants of killer which are defective for both the toxin and immunity functions lack the M dsRNA. One of these mutants has a novel dsRNA with a molecular weight of 5 × 105. Another class of killer mutants contains strains which are defective for either the toxin or the immunity function. They include temperature-sensitive killers, superkillers, and immunity-minus strains. The dsRNA profile of temperature-sensitive killers resembles that of the standard killer. The superkiller has 2.5 times more of the M dsRNA (1.4 × 106 daltons) than does the standard killer. Immunity-minus killers have, in addition to the two dsRNAs species of standard killer, a novel dsRNA with a molecular weight of 2.5 × 105. The data are consistent with the hypothesis that the M RNA controls toxin production. In addition, the two RNAs, L and M, seem to be regulated together. When the M RNA is missing, the amount of L is either greatly elevated or greatly reduced.
TL;DR: It is tentatively suggested that the effects evoked by stimulation of the Th 11 segment after chronic C 3 hemisection were due to stimulation of long descending propriospinal neurones originating in the lower cervical and upper thoracic segments, their axon trajectory being in the middle of the lateral funiculus.
Abstract: Stimulation of the lateral funicle was performed at different segmenta levels in the cat in order to investigate the connecxions of long propriospinal neurones with ipsilateral lumbosacral motoneurones and interneurones projecting directly to them. In one series of experiments the propriospinal contribution was assessed from the difference between the effect of maximal stimulation in C 1 (activating supraspinal descending fibres) and in more caudal segments (activating supraspinal and propriospinal fibres). In another series on cats with chronic hemisection in C 3 pure propriospinal effects were evoked by stimulation of the thoracic spinal cord. In both series it was shown that volleys in long propriospinal neurones evoke monosynaptic EPSPs and disynaptic EPSP and/or IPSP in many flexor and extensor motoneurones; an extracellular monosynaptic focal synaptic potential was recorded in lamina VII of Rexed. The effects evoked by stimulation of the Th 11 segment after chronic C 3 hemisection were not found after chronic Th 10 hemisection. It is therefore tentatively suggested that they were due to stimulation of long descending propriospinal neurones originating in the lower cervical and upper thoracic segments, their axon trajectory being in the middle of the lateral funiculus and conduct at velocity 100 m/sec. Other effects evoked by stimulation of Th 11 after chronic Th 10 hemisection are ascribed to antidromic activation of axons of ascending neurones.
TL;DR: The Mariner 10 television camieras imaged the planet Venus in the visible and near ultraviolet for a period of 8 days at resolutions ranging from 100 meters to 130 kilometers as discussed by the authors.
Abstract: The Mariner 10 television camieras imaged the planet Venus in the visible and near ultraviolet for a period of 8 days at resolutions ranging from 100 meters to 130 kilometers. Tle general pattern of the atmospheric circulation in the upper tropospheric/lower stratospheric region is displayed in the pictures. Atmospheric flow is symmetrical between north and south hemispheres. The equatorial motions are zonal (east-west) at approxiimnately 100 meters per second, consistent with the previously inferred 4-day retrograde rotation. Angular velocity increases with latitude. The subsolar region, and the region downwind from it, show evidence of large-scale convection that persists in spite of the main zonal motion. Dynamical interaction between the zonal motion and the relatively stationary region of convection is evidenced by bowlike waves.
TL;DR: The low Km form had sufficient activity both at air levels of CO(2) and at saturating CO(1) to account for the rates of photosynthesis by intact chloroplasts and could be stabilized in the presence of ribose 5-phosphate, adenosine triph phosphate, and MgCl(2), at low temperatures for up to 2 hours.
Abstract: The properties of a form of ribulose diphosphate carboxylase having a high affinity for CO 2 have been studied. Its apparent K m (HCO 3 − ) of 0.5 to 0.8 mm (pH 7.8) and calculated K m (CO 2 ) of 11 to 18 μm are comparable to the values exhibited by intact chloroplasts during photosynthesis. This form of the enzyme was released from chloroplasts in hypotonic media and was unstable, rapidly converting to a form having a high K m (HCO 3 − ) of 20 to 25 mm similar to that for the purified enzyme. Incubation of the enzyme with MgCl 2 and HCO 3 − yielded a third form with an intermediate K m (HCO 3 − ) of 2.5 to 3.0 mm. The low K m form had sufficient activity both at air levels of CO 2 and at saturating CO 2 to account for the rates of photosynthesis by intact chloroplasts. The low K m form could be stabilized in the presence of ribose 5-phosphate, adenosine triphosphate, and MgCl 2 , at low temperatures for up to 2 hours.
TL;DR: Data are presented to suggest that a constant capillary pressure in mesentery during changes in systemic blood pressure is primarily the consequence of the vascular geometry peculiar to this tissue.
Abstract: An interpretive model of the myogenic autoregulatory response of cat mesenteric arterioles has appeared in the literature; it describes arteriolar dimensional changes during changes in mean systemic arterial blood pressure in terms of tension-radius diagrams (Laplace relationship). The original model assumes that arteriolar pressure is a simple, linear function of systemic blood pressure and that arteriolar pressure is always 40% of systemic blood pressure. The purpose of the present study was to test the validity of these assumptions. Using the isolated, autoperfused mesentery of 14 cats, direct, simultaneous measurements of diameter and pressure were made in microvessels during changes in systemic blood pressure. Diameters and micropressures were recorded with a video filar micrometer system and a servonull transducer, respectively. Control microvascular pressure, dimensional distributions, and stress distributions were established when systemic blood pressure was set at 100 ± 10 (SD) mm Hg. Three regions of the arteriolar vasculature were defined and identified for study in terms of these control states. Pressures in the arteriolar regions were a linear function of systemic blood pressure, thus confirming the validity of the previous assumption. Capillary pressures tended not to follow this pattern; pressure in five of eight capillaries sampled was relatively independent of changes in systemic blood pressure between 100 and 40 mm Hg. The apparent constancy of capillary pressure during changes in systemic blood pressure was examined in terms of the modular arrangement of mesenteric microvessels and resistance changes, and the question of physiological regulation of capillary pressure was considered. Data are presented to suggest that a constant capillary pressure in mesentery during changes in systemic blood pressure is primarily the consequence of the vascular geometry peculiar to this tissue.
TL;DR: The in vitro whole cell reactions probably detect the normal cellular systems which are in the process of synthesizing glycoproteins and glycolipids, according toKinetic parameters and optimal ion concentrations have been determined for the glycosyltransferase activities detected when whole cells are incubated with nucleotide sugars.