Showing papers by "University of California, Davis published in 1974"
TL;DR: A type of force generator which can respond to general feedback signals from a vibrating system in order to control the vibration but which does not require the power supply of a servomechanism is described.
Abstract: A type of force generator which can respond to general feedback signals from a vibrating system in order to control the vibration but which does not require the power supply of a servomechanism is described. Computer simulation studies show that performance comparable to that of fully active vibration control systems can be achieved with the semi-active type of device. Physical embodiments of the concept are discussed and compared to hardware used in active and passive vibration control systems.
1,315 citations
TL;DR: In groups of ten, indidual starlings, Sturnus vulgaris, spent significantly less time in surveillance than did individuals in smaller groups and responded more quickly than single birds to a flying model hawk.
497 citations
TL;DR: Some of the physiological bases for differences among species in water-use efficiency and drought resistance are examined, with special attention given to CO 2 assimilation and transpiration.
426 citations
TL;DR: The question, "how much genetic differentiation occurs in the process of speciation," must be unfolded into two separate questions concerning the two stages of the process, and the genetic differentiation occurring between allopatric populations that are likely to give rise to different species if and when they become, at least partially, sympatric.
Abstract: Evolution consists of changes in the genetic constitution (gene pool) of populations. The process of evolution may be seen in two ways-which have been called anagenesis and cladogenesis (Rensch, 1960). Changes occurring within a given phylogenetic line as time proceeds, are anagenetic evolution. They result in increased adaptation to the environment, and often reflect changes of the physical or biotic conditions of the environments. Cladogenesis occurs when a phylogenetic lineage splits into two or more independently evolving lineages. The great diversity of the living world is the result of cladogenetic evolution, which results in adaptation to a greater variety of niches, or ways of life. Among cladogenetic processes, the most decisive one is speciation, the process by which one species splits into two or more species. Species are groups of populations reproductively isolated from any other such groups. Species are independent evolutionary units. Adaptive changes occurring in an individual or population may be extended to all members of the species by natural selection; however, they cannot be passed on to different species. One of the most important questions in evolutionary genetics is the amount of genetic differentiation occurring in the speciation process. Speciation may occur by a variety of processes. In sexually reproducing organisms speciation most generally occurs according to the model of "geographic speciation." Two main stages may be recognized in this process. First, allopatric populations of the same species become genetically differentiated, mostly as a consequence of their adaptation to different environments. This genetic differentiation can only occur if the populations are geographically separated for some time, and there is no or very little migration between them. The second stage takes place when genetically differentiated populations come into geographic contact. If the gene pools of two populations are sufficiently different, progenies from interpopulational crosses are likely to have less fitness than progenies from intrapopulational crosses. Mating preferences are affected by genes. Alleles that decrease the probability of mating with individuals of a different population will, then, be selected against, while alleles increasing the probability of intrapopulational mating will be favored by natural selection. Eventually, the process may result in two reproductively isolated populations, and thus two different species. The question, "how much genetic differentiation occurs in the process of speciation," must be unfolded into two separate questions concerning the two stages of the process. The first question concerns the genetic differentiation occurring between allopatric populations that are likely to give rise to different species if and when they become, at least partially, sympatric. The second question refers to the amount of genetic differentiation taking place after sympatry, when the populations become reproductively isolated. 1 This is paper number XII in a series: "Enzyme variability in the Drosophila willistoni group." 2 Supported by NSF grant GB32895. 'Present address: Dept. of Biology, Brock University, St. Catherines, Ontario, Canada. 'Address: Department of Zoology, University of Indiana, Bloomington, Indiana.
389 citations
Journal Article•
292 citations
TL;DR: At comparable levels of dynamic forearm exercise patients with CHF have an inadequate arteriolar dilation and their augmented oxygen extraction is not sufficient to prevent them from shifting more completely to anaerobic metabolism.
Abstract: Patients with severe congestive heart failure (CHF) have been found to have a diminished response to the metabolic arteriolar dilator stimulus of ischemia. In order to evaluate a more physiologic stimulus and the possible metabolic consequences of this vascular abnormality, 22 normal subjects (N) and seven patients with severe CHF performed rhythmic forearm exercise by squeezing a rubber bulb to 25, 50, or 100 mm Hg for 5 sec, four times/min, for 5 min. During the last half of the 10 sec relaxation phases, forearm blood flow (FBF) was measured plethysmographically. Not only was FBF reduced at rest in CHF (CHF:2.00 ± 0.31; N: 3.10 ± 0.27 ml/min·100 ml, P < 0.02) but it was reduced at each level of exercise as well (CHF: 4.05 ± 0.71, 5.57 ± 0.71, 6.68 ± 3.09; N: 7.10 ± 0.76, 11.15 ± 1.24, 20.32 ± 1.93 ml/min·100 ml, P < 0.01). Forearm oxygen extraction, calculated from brachial venous and systemic arterial blood, was consistently increased in CHF and was sufficient to maintain a normal forearm oxygen consum...
244 citations
TL;DR: The mitral echographic spectrum of MVPS is comprised of three different abnormal patterns of systolic prolapse: buckling in midsystole, pansYstolic bowing, and pansystolic collapse.
Abstract: The variety of echographic features associated with the mitral valve prolapse syndrome (MVPS) is not yet completely understood. Therefore, ultrasound recordings were obtained in 33 patients in whom mitral prolapse had been documented by biplane left ventricular cineangiography. Echographic abnormailities of the mitral leaflets during systole were recorded in 26/27 MVPS patients and 6/6 with ruptured chordae tendineae. In MVPS, the midsystolic mitral buckling, emphasized in early echocardiographic studies, was observed in only 12 patients. In our study, the most common aberrancy was abnormal pansystolic mitral motion in 14 patients, which in 12 was similar to the pansystolic bowing observed in all six patients with torn chordae. An additional echographic abnormality in MVPS was localized mitral collapse throughout systole in 10/14 patients with pansystolic prolapse; this finding was the most striking defect noted in five, in two of whom it was the only disturbance. Phonocardiography in MVPS showed typical midsystolic click and/or late systolic murmur in only 15/26 patients of whom ten had midsystolic mitral buckling. A variety of systolic clicks and/or murmurs occurred in the 14 patients with generalized bowing and/or localized collapse throughout systole on echocardiography. Thus, the mitral echographic spectrum of MVPS is comprised of three different abnormal patterns of systolic prolapse: buckling in midsystole, pansystolic bowing, and pansystolic collapse. These echocardiographic disorders commonly occur in the absence of classical auscultatory findings in MVPS and the most frequent abnormality on ultrasound is pansystolic bowing of both mitral leaflets.
227 citations
TL;DR: The morphological events that occur when the vitelline envelope of an unfertilized egg of Xenopus laevis is transformed into the fertilization envelope (FE) surrounding the zygote are reported.
215 citations
199 citations
TL;DR: The hypothesis that protein polymorphisms are selectively neutral is tested by examining four predictions derived from the hypothesis and the results are at variance with every one of the predictions.
Abstract: We have studied genetic variation at 30-32 loci coding for enzymes in natural populations of five species of Drosophila. The average proportion of heterozygous loci per individual is 17.7 ± 0.4%. The average proportion of polymorphic loci per population is 69.2 ± 2.6% or 49.8 ± 2.2%, depending on what criterion of polymorphism is used. The following generalizations are advanced: (1) The amount of genetic polymorphism varies considerably from locus to locus. (2) At a given locus, populations of the same species are very similar in the amount and pattern of genetic variation. (3) However, at some loci large differences sometimes occur between local populations of the same species. (4) The amount of variation at a given locus is approximately the same in all five species. (5) When different species are compared, the pattern of the variation is either essentially identical or totally different at a majority of loci. We have tested the hypothesis that protein polymorphisms are selectively neutral by examining four predictions derived from the hypothesis. Our results are at variance with every one of the predictions. We have measured the amount of genetic differentiation, D, between taxa of various degrees of evolutionary divergence. The average value of D is 0.033 for local populations, 0.228 for subspecies, 0.226 for semispecies, 0.538 for sibling species, and 1.214 for morphologically distinguishable species. Our results indicate that a substantial degree of genetic differentiation (22.8 allelic substitutions for every 100 loci) occurs between allopatric populations that have diverged to the point where they might become different species if they were to become sympatric. However, very little additional genetic change is required for the development of complete reproductive isolation. After the speciation process is completed, species continue to diverge genetically from each other.
197 citations
TL;DR: Both branching enzyme fractions stimulate the previously described “unprimed activity” catalyzed by α-glucan synthetase fraction III about 11- to 14-fold, however, branching enzyme did not stimulate the primed activity.
TL;DR: Peptic hydrolysis of the resulting derivatized proteins has led to the formation of several radioactive peptides, which contain S -carbamoylmethyl-[ 14 C]-4′-phosphopantetheine, possibly two closely related species of acyl carrier proteins occur in spinach leaves.
TL;DR: Sections through various levels of small intestine from adult male rats were examined by fluorescence microscopy after treatment with fluorescein isothiocyanate-labeled lectins to show a difference in surface components in cells at various portions on the villi and the dependence of these differences on the region of intestine.
Abstract: Sections through various levels of small intestine from adult male rats were examined by fluorescence microscopy after treatment with fluorescein isothiocyanate-labeled lectins from Dolichos biflorus, Lotus tetragonolobus, Ricinus communis, and Triticum vulgare (wheat germ). The latter three lectins reacted with the microvillar portion of the epithelial cells lining the crypts and villi in sections of intestine adjacent to the pylorus. This pattern of reactivity was sharply altered along the first 15 cm of intestine so that in sections distal to this point the luminal surfaces of only those epithelial cells in the crypts and at the base of the villi reacted with the L. tetragonolobus and R. communis lectins, whereas the wheat germ lectin reacted with the surfaces of the cells lining the villi. In sections from the distal end of the small intestine, all three lectins reacted with the surfaces of cells only at the base of the villi and in the crypts. These results show a difference in surface components in cells at various portions on the villi and the dependence of these differences on the region of intestine. The D. biflorus lectin reacted with approximately 25% of the goblet cells at each level of intestine studied whereas the reactivities of the goblet cells with the other three lectins were dependent upon the region of intestine.
TL;DR: It appears probable that greening higher plant tissues possess an alternate route to δ-aminolevulinic acid in which the carbon skeleton of glutamate (and α-ketoglutarate) is incorporated intact into the first committed metabolite of the chlorophyll pathway.
Abstract: δ-Aminolevulinic acid was accumulated by greening cucumber ( Cucumis sativus L. var. Alpha green) cotyledons, barley ( Hordeum sativum var. Numar) leaves, and bean ( Phaseolus vulgaris L. var. Red Kidney) leaves in the presence of various 14 C-labeled precursors and levulinic acid, a competitive inhibitor of δ-aminolevulinic acid dehydrase. The radioactivity in the accumulated δ-aminolevulinic acid was measured. The most effective labeled precursors were the 5 carbon dicarboxylic compounds glutamate, glutamine, and α-ketoglutarate. 14 C-Labeled glycine and succinate were relatively poor. The carboxyl and the methylene carbons of glycine were incorporated into δ-aminolevulinic acid to about equal extent. The carboxyl carbon of glutamate was incorporated almost as well as the internal carbons of the same compound. These results are inconsistent with the succinyl CoA-glycine succinyl transferase (δ-aminolevulinic acid synthetase) mode of δ-aminolevulinic acid production. When the same experiments were performed on turkey blood (which, as avian blood in general, possesses δ-aminolevulinic acid synthetase), δ-aminolevulinic acid was labeled most effectively from glycine-2- 14 C, moderately well from glycine-1- 14 C and glutamate-3,4- 14 C and not at all from glutamate-1- 14 C. It appears probable that greening higher plant tissues possess an alternate route to δ-aminolevulinic acid in which the carbon skeleton of glutamate (and α-ketoglutarate) is incorporated intact into the first committed metabolite of the chlorophyll pathway.
TL;DR: In vitro studies with tissue soluble fractions and plasma from rats fed diets with low or high selenium levels suggest that seenium is not an exchangeable or a dialyzable cofactor for GSH peroxidase.
Abstract: The effect of dietary selenomethionine on the enzyme activities of the glutathione (GSH) peroxicla.se system in rat tissues was studied. The activity of GSH peroxidase decreased to varying degrees in tissues from animals fed a basal low selenium Tonila yeast diet for 17 days. The relative decrease was plasma > kidney, heart, liver and lung > erythrocytes > testes. The activity of GSH peroxidase in all tissues except testes was significantly and linearly increased above that of the nonsupplemented controls when selenium-depleted animals were subsequently fed the same diet supplemented with 2 ppm selenium for 11 days. The relative increase was plasma > kidney > heart, erythrocytes, lung, and liver > testes. Dietary selenium did not significantly alter the activities of GSH reductase and glueose-6-phosphate (G-6-P) dehydrogenase. Intra- peritoneal administration of actinomycin D or puromycin neither effectively suppressed the increase of GSH peroxidase activity nor inhibited the activities of GSH reductase and G-6-P dehydrogenase; however, it is possible that insufficient dosages were ad ministered. In vitro studies with tissue soluble fractions and plasma from rats fed diets with low or high selenium levels suggest that selenium is not an exchangeable or a dialyzable cofactor for GSH peroxidase. These studies provide further evidence of the essentiality of selenium for the activity of GSH peroxidase. J. Nutr. 104: 444-451,
TL;DR: Diffusion, when followed by sequestering, probably accounts for the accumulation of Cd observed in intact barley plants.
Abstract: The uptake of cadmium by excised root tissue of barley (Hordeum vulgare L. cv. Arivat) was investigated with respect to kinetics, concentration, and interactions with various cations. The role of metabolism in Cd absorption was examined using a range of temperatures, anaerobic treatments, and chemical inhibitors. The uptake and distribution of Cd in intact barley plants was also determined. A large fraction of the Cd taken up by excised barley roots was apparently the result of exchange adsorption and was displaced by subsequent desorption with unlabeled Cd, Zn, Cu, or Hg. Another fraction of Cd which could not be displaced by desorption in unlabeled Cd was thought to result from strong irreversible binding of Cd, perhaps on sites of the cell wall. The fraction of the Cd taken up beyond that by exchange adsorption by fresh roots was a linear function of temperature, and inhibited by conditions of low oxygen and by the presence of 2,4-dinitrophenol. It was concluded that this fraction of Cd entered excised barley roots by diffusion. Diffusion, when followed by sequestering, probably accounts for the accumulation of Cd observed in intact barley plants.
TL;DR: A mixed microbial culture was adapted to growth on parathion to determine the feasibility of using microorganisms to detoxify concentratedParathion in agricultural wastes and the nitro group was removed in stoichiometric quantities as nitrite and hydroquinone was tentatively identified as a metabolite.
Abstract: A mixed microbial culture was adapted to growth on parathion to determine the feasibility of using microorganisms to detoxify concentrated parathion in agricultural wastes. In a 600-ml chemostat, the culture was able to degrade 50 mg of parathion per liter per h. Para-nitrophenol, produced by enzymatic hydrolysis of parathion, caused delays in exponential growth which were directly proportional to its concentration. A pseudomonad, isolated from the mixed culture, exhibited optimal growth at 0.21 mM p-nitrophenol and grew in concentrations up to 3.5 mM. In metabolic studies using [14C]p-nitrophenol, the nitro group was removed in stoichiometric quantities as nitrite and hydroquinone was tentatively identified as a metabolite.
TL;DR: In this paper, a diapiric mechanism is presented to explain geochemical data on the thermal structure of the upper mantle, and it is concluded that the data are inconsistent with the popular interpretation of the seismic low velocity zone as a partially melted region.
Abstract: A diapiric mechanism is presented to explain geochemical data on the thermal structure of the upper mantle. It is emphasised that any model to fit the data cannot be a steady state model, and it is concluded that the data are inconsistent with the popular interpretation of the seismic low velocity zone as a partially melted region.
TL;DR: In this paper, a systematic method is outlined to realize an m th-order all-pass digital transfer function using only m multipliers as a cascade of first-order and/or second-order sections.
Abstract: A systematic method is outlined to realize an m th-order all-pass digital transfer function using only m multipliers as a cascade of first-order and/or second-order all-pass sections. The realization is based on the multiplier extraction approach in which the n th-order filter section is considered as a digital (n + 1) -pair of which n pairs of input and output terminal variables are constrained by n multipliers. The transfer matrix parameters of the digital (n + 1) -pair, containing only delays and adders, are first identified from which the realization is obtained by inspection. Both canonic and noncanonic realizations are derived. All realizations are then compared with regard to the effect of multiplication roundoff and hardware requirements.
TL;DR: The data suggest that in human subjects, morphine induces a peripheral venous and arteriolar dilation by a reflex reduction in sympathetic alpha adrenergic tone but seems to attenuate the sympathetic efferent discharge at a central nervous system level.
Abstract: To evaluate the effects of morphine on the peripheral venous and arterial beds, 69 normal subjects were evaluated before and after the intravenous administration of 15 mg morphine. Venous tone was determined by three independent techniques in 22 subjects. The venous pressure measured in a hand vein during temporary circulatory arrest (isolated hand vein technique) fell from 20.2+/-1.4 to 13.4+/-0.9 mm Hg (P 0.1). Of note is that the initial reaction to morphine was a pronounced venoconstriction, demonstrated during the first 1-2 min after the drug. (Isolated hand vein pressure increased to 37.2+/-5.4 mm Hg, P < 0.01). This rapidly subsided, and by 5 min a venodilation was evident. Morphine did not attenuate the venoconstrictor response to a single deep breath, mental arithmetic, or the application of ice to the forehead when measured by either the isolated hand vein technique or the equilibration technique. To evaluate the effects of morphine on the peripheral resistance vessels in 47 normal subjects, forearm blood flow was measured plethysmographically before and 10-15 min after the intravenous administration of 15 mg of morphine. Although mean systemic arterial pressure was unchanged, forearm blood flow increased from 2.92+/-0.28 to 3.96+/-0.46 ml/min/100 ml (P < 0.01), and calculated vascular resistance fell from 42.4+/-5.2 to 31.6+/-3.2 mm Hg/ml/min/100 ml (P < 0.01). When subjects were tilted to the 45 degrees head-up position, morphine did not block the increase in total peripheral vascular resistance that occurs; however, it did significantly attenuate the forearm arteriolar constrictor response (before morphine, + 25.7+/-5.4; after morphine, + 13.7+/-5.3 mm Hg/ml/min/100 ml, P < 0.05). However, morphine did not block the post-Valsalva overshoot of blood pressure, nor did it block the increase in forearm vascular resistance produced by the application of ice to the forehead. Similarly, morphine did not block the arteriolar or venoconstrictor effects of intra-arterially administered norepinephrine. Morphine infused into the brachial artery in doses up to 200 mug/min produced no changes in ipsilateral forearm VV[30], forearm blood flow, or calculated forearm resistance. Intra-arterial promethazine, atropine, and propranolol did not block the forearm arteriolar dilator response to intravenous morphine; however, intra-arterial phentolamine abolished the response. These data suggest that in human subjects, morphine induces a peripheral venous and arteriolar dilation by a reflex reduction in sympathetic alpha adrenergic tone. Morphine does not appear to act as a peripheral alpha adrenergic blocking agent but seems to attenuate the sympathetic efferent discharge at a central nervous system level.
TL;DR: Autoradiographs show that dissolved organic substrates assimilated by bacteria are linked to the formation of capsular materials, which are important in building detrital aggregates.
Abstract: Microbial uptake of 3H-labeled glucose and acetate was studied in water samples from various depths in the Pacific Ocean and Lake Tahoe, California. Microzones of incorporation were identified by comparison of autoradiographic detection of the uptake of 3H-labeled organic substrates with scanning electron micrographs of detritus (nonliving particulate matter and associated microflora). In both freshwater and marine systems, immediate (within 4 hr) accumulation of dissolved organic compounds was detected mainly in bacterial cells and filaments. With continued incubation, the label was dispersed throughout detrital particles, with localization greatest in bacteria. Uptake of both substrates by attached microorganisms was significantly higher in the cuphotic than in the aphotic zone as was the extent of detrital aggregation. Autoradiographs show that dissolved organic substrates assimilated by bacteria are linked to the formation of capsular materials, which are important in building detrital aggregates.
TL;DR: Log-log regression analysis was used to compare tissue weights for common body weight and to develop equations for predicting tissue weights from body weights.
TL;DR: Results are reported from an experiment designed to test the hypothesis that different genetic variants are favoured in different environmental niches, in which populations of Drosophila were exposed to experimental environments of various degrees of heterogeneity.
Abstract: ONE of the major problems of contemporary population genetics is how to account for the large amount of genetic variation occurring in natural populations. Considerable controversy exists between those people proposing that the variation is adaptively neutral, and those arguing that most of the variation is maintained by balancing selection. One of the processes of balancing selection postulated, is based on the idea that different genetic variants are favoured in different environmental niches. We report results from an experiment designed to test this hypothesis in which populations of Drosophila were exposed to experimental environments of various degrees of heterogeneity. The rationale is simple—if genetic variation is adaptively neutral, all populations should maintain about the same amount of genetic variation; if the ‘environmental heterogeneity’ hypothesis is correct, the degree of genetic variation in a population should be correlated with the degree of heterogeneity of its environment.
TL;DR: In this article, the relative abundances and characteristics of rock types, series, and complexes through time reflect both general and subtle features of crustal and upper-mantle environments.
Abstract: Studies of the relative abundances and characteristics of rock types, series, and complexes through time reflect both general and subtle features of crustal and upper-mantle environments. These studies also suggest salient aspects of the dynamothermal and global tectonic history of the last 3,500 m.y. Among the many petrochemical indices, the ratio K 2 O/Na 2 O reflects both the degree of differentiation (fractionation) of igneous rocks and the more or less mature (residuate) nature of clastic sediments. Accordingly, this ratio is a guide to the thickness, composition, and stability of source and crusial site of rock emplacement. Average K 2 O/Na 2 O of rocks, rock complexes, and terranes decreasing from 1 are typical of rock series formed in primitive borderland and arc-to–oceanic-crustal sites. Average values of K 2 O/Na 2 O increasing from 1 characterize rock series evolving in and on more mature arc-to-continental sites. Relative abundances of the most common and characteristic rock assemblages of various ages and their weighted average K 2 O/Na 2 O suggest profound episodicity in crustal evolution and global tectonics. At least three macro-episodes of major significance are defined: the Archean, >2,500 m.y. B.P.; the Proterozoic-Paleozoic, 250 m.y. B.P.; and the Mesozoic-Cenozoic, ∼250 m.y. B.P. to present. Within these macro-episodes, there are innumerable subordinate episodes and variously developed rock cycles. Most major Archean rocks, rock complexes, and terranes have a K 2 O/Na 2 O of Archean thermal gradients varied abruptly both vertically and laterally from very steep to moderate and created highly unstable, thin to thick, labile lithosphere and protocrusts commonly inhospitable to the evolution of widespread, highly fractionated calc-alkaline series or mature sediments. Heat transfer was largely via convection and advection. The advective loss was undoubtedly large, associated especially with the extrusion of floods of ultramafic to felsic magmas and related upward streaming of volatiles. Culmination of major Archean orogenies and subsequent thermal decay about 2,500 m.y. B.P. induced relative crustal quiet and resetting of most Archean Rb/Sr and K/Ar radiomentric clocks between 2,600 and 2,400 m.y. B.P. In the early Proterozoic (∼1,700 to 2,300 m.y. B.P.), many segments of the megacontinent(s) were sufficiently cool, thickened, and fractionated to remain quasi-coherent, deforming and cracking internally as well as marginally above convecting mantle forces. Widespread, relatively ensialic orogenic regions evolved above many thinner sialic zones. These were repeatedly refractionated and redated as they became populated by igneous series with K 2 O/Na 2 O commonly 2 O/Na 2 O as high as 2 or more. Sedimentary K 2 O/Na 2 O increased much faster than did the igneous ratio, as blankets, basins, and prisms of more mature, frequently recycled sediments formed on all the continents. Two of the several major Proterozoic orogenic episodes culminated at about 1,700 m.y. B.P. and 1,000 m.y. B.P. The latter, often called the “Greenville Event,” between 1,000 and 1,200 m.y. B.P., is characterized by the evolution of both K- and Na-rich terranes and distinctive granulite and anorthositic-charnokitic complexes. Most of these Grenville rock complexes evolved between and on relatively thicker, more fractionated continental crust than did the Archean granulites, as indicated by the relative abundance of less telescoped prograde terranes. The Grenville thermal pulses and decay involving much advective and convective heat loss again reset numerous Rb/Sr and K/Ar ages of rocks emplaced 100 to 2,000 m.y. earlier. A post-Grenville relatively amagmatic period of 400 to 500 m.y. after 1,000 m.y. B.P., preceded the incipient rifting of large continental segments as the great Pan–African-Appalachian-Her-cyian-Caledonian orogenies waxed. But large-scale drift of most of these continental segments seems precluded by the continuing alignment of the older, including Archean, fold belts and by the predominantly continental rock component emplaced in most Proterozoic and Paleozoic orogens. Weighted average K 2 O/Na 2 O of Proterozoic igneous complexes are commonly > 1.2 and, in sedimentary sequences, often > 2. Nevertheless, the occurrences of lower Paleozoic ophiolite, blueschist, and less fractionated rock complexes in many Phanerozoic orogens suggest the onset of the large-scale continental rifting and global drift characteristic of post-Permian time. These events are reflected in variously depressed lower Paleozoic K 2 O/Na 2 O and, subsequently, in the plunge of average K 2 O/Na 2 O of major Mesozoic rock complexes to near Archean lows of ∼0.5 to 0.9, especially in the circum-Pacific. The petrochemical and structural data indicate the significant differences as well as similarities between the Archean and post-Permian. The Archean was dominated by the evolution and aggregation of protocontinents, arcs, and intervening oceanic crusts. The post-Permian was dominated by the unique fragmentation and widespread drift (>1,500 km) of large, thick, cool, fractionated, continental fragments and by the birth of new large ocean basins and island-arc chains.
TL;DR: It is shown that a second-order digital notch filter is uniquely characterized by two distinct parameters, the notch frequency and the 3-dB rejection bandwidth, as a result, such a filter can be realized using only two multipliers.
Abstract: It is shown that a second-order digital notch filter is uniquely characterized by two distinct parameters, the notch frequency and the 3-dB rejection bandwidth. As a result, such a filter can be realized using only two multipliers. Methods are outlined to design a notch filter for a prescribed notch frequency and a prescribed 3-dB rejection bandwidth, along with procedures for postdesign adjustment of these parameters. All two-multiplier, canonic and noncanonic, notch filter configurations are developed using the multiplier extraction approach. These networks are then compared with regard to the effect of internal multiplication roundoff errors. Results of computer simulation of the notch filter configurations are also included.
TL;DR: When challenged with a range of potential inhibitors, the cinnamic acid 4-hydroxylase behaved in a manner that is fairly typical of the more extensively studied P-450 monooxygenases of nonplant tissues.
TL;DR: Temporal aspects of nocturnal activity of bannertail kangaroo rats were measured in the field and the effects of a laboratory ‘moon’ were opposite to those of the real moon uponbannertails in theField.
TL;DR: The results support the idea that relatively few proteins make up the bulk of the seed protein, with sedimentation coefficients related to the bands obtained by electrophoretic separation.
Abstract: Soybean (Glycine max) storage proteins were characterized by sedimentation and by polyacrylamide gel electrophoresis under dissociating (8 m urea) and nondissociating conditions. Three sedimenting classes of proteins were found, with sedimentation coefficients of 2.2S, 7.5S, and 11.8S. The coefficients were related to the bands obtained by electrophoretic separation. The results support the idea that relatively few proteins make up the bulk of the seed protein.
TL;DR: Observations of living salps by SCUBA diving in the Florida Current and Gulf of California (Mexico) indicate that they filter feed with a continuously renewed mucus net, which appears to contain much undigested material and may carry significant amounts of carbon out of surface waters.
Abstract: Observations of living salps by SCUBA diving in the Florida Current and Gulf of California (Mexico) indicate that they filter feed with a continuously renewed mucus net. Ninety-one percent of 1420 salps (6 species) examined were feeding in this manner. Particles collected range from about 1 mm to less than 1 μm. Compact fecal pellets appear to contain much undigested material and may carry significant amounts of carbon out of surface waters.