Showing papers by "University of British Columbia published in 1970"
697 citations
TL;DR: Trust and suspicion appear to underlie many social interactions Thus it is not surprising that they occupy an important role in various efforts to account for the stability or instability of a wide variety of human relationships as discussed by the authors.
Abstract: Trust and suspicion appear to underlie many social interactions Thus it is not surprising that they occupy an important role in various efforts to account for the stability or instability of a wide variety of human relationships One of the earliest systematic formulations of these concepts appeared in this journal over a decade ago (cf Deutsch, 1958) Yet little progress has been made since then toward a more satisfactory conceptualization of trust and suspicion This paper is devoted to the examination of both the theoretical and the methodological considerations relevant to the empirical study of trust and suspicion
523 citations
TL;DR: Discrete programming, which includes integer programming and combinatorial optimization problems, is discussed and Fibonacci search is presented as an example of a nonfinite branch-and-bound procedure employing an optimal convergence rule.
Abstract: The branch-and-bound procedure is formulated in rather general terms and necessary conditions for the branching and bounding functions are precisely specified. Results include the standard properties for finite procedures, plus several convergence conditions for infinite procedures. Discrete programming which includes integer programming and combinatorial optimization problems, is discussed and Fibonacci search is presented as an example of a nonfinite branch-and-bound procedure employing an optimal convergence rule.
328 citations
TL;DR: In this article, a model for grain boundary sliding is developed in which sliding occurs by the movement of dislocations along, or adjacent to, the boundary by a combination of climb and glide.
Abstract: A model for grain boundary sliding is developed in which sliding occurs by the movement of dislocations along, or adjacent to, the boundary by a combination of climb and glide. Under these conditions the strain rate due to sliding is proportional to [sgrave]2/d, where [sgrave] is the applied stress and d is the average grain diameter. It is shown that reports in theliterature of enhanced creep rates at low stresses and/or small grain sizes may be explained by assuming that the various deformation mechanisms, including sliding, operate independently.
310 citations
TL;DR: It was concluded that F- binds to the enzyme possibly as a magnesium-fluoride complex, the consequence of which is greater reactivity of the catalytic site than that produced by Mg++ alone.
296 citations
TL;DR: Improved methods for rearing and screening large numbers of flies permitted the recovery of 10 mutations exhibiting a reversible temperature-dependent adult paralysis among 1.1×106 flies tested, and several non-conditional mutations affecting adult movement were recovered.
Abstract: Improved methods for rearing and screening large numbers of flies permitted the recovery of 10 mutations exhibiting a reversible temperature-dependent adult paralysis among 1.1×106 flies tested. Of the 10 mutations, two were allelic to parats,two were alleles in a new locus, stoned (stn), and six fell into a third area, the shibire (shi) locus. Several of the shi alleles cause embryonic, larval and adult paralysis at 29° C as well as structural anomalies of various tissues. In addition to the ts mutations, several non-conditional mutations affecting adult movement were recovered.
232 citations
TL;DR: It is concluded that the K(m)-temperature relationship is adaptive, and that the critical process during thermal acclimatization, in cases where enzymes show sharp changes in K( m) with temperature, is the synthesis of a new enzyme variant that is better suited for catalysis and control of catalysis under the conditions of theacclimatized state.
Abstract: 1. The effects of acclimatization temperature on the catalytic properties of acetylcholinesterase from rainbow-trout brain were examined. 2. Trout brain acetylcholinesterase occurs in two distinct forms. A single ;warm' variant of the enzyme is present after acclimatization to 17 degrees C; a single ;cold' variant appears after acclimatization to 2 degrees C. Both forms are present in fish after acclimatization to an intermediate temperature. 3. The K(m) values of the enzyme variants for acetylcholine are temperature-dependent, the lowest values coinciding with the acclimatization temperature at which each enzyme was induced. 4. It is concluded that the K(m)-temperature relationship is adaptive, and that the critical process during thermal acclimatization, in cases where enzymes show sharp changes in K(m) with temperature, is the synthesis of a new enzyme variant that is better suited for catalysis and control of catalysis under the conditions of the acclimatized state.
225 citations
TL;DR: The density of a deposit-feeding amphipod H&e&z axtecu was varied experimentally in undisturbed sediment cores taken from Marion Lake, British Columbia to compare microflora production with Hyalella’s daily calorific requirement at various densities.
Abstract: The density of a deposit-feeding amphipod H&e&z axtecu was varied experimentally in undisturbed sediment cores taken from Marion Lake, British Columbia. Epibenthic algal production, total community respiration, and bacterial oxygen consumption were measured after 4%hr in situ incubation. As density increased community respiration also increased, in a nonlinear manner. Epibenthic algal production was stimulated within the range of natural amphipod densities, but declined at higher densities. Bacterial respiration was stimulated at amphipod densities up to four times those observed in the lake and also declined at higher densities. These data were used to compare microflora production with Hyalella’s daily calorific requirement at various densities. At natural densities, less than 10% of daily microBora production would be required to supply the energy necessary for observed rates of amphipod growth, respiration, and egg production. Fecal pellets produced by HyccE&z were rapidly colonized by microorganisms. Autotrophic microorganisms increased, while respiration of heterotrophic microorganisms and solution decreased organic content of feces. Dissolved organic compounds excreted by Hya2eZla significantly increased the rate of recolonization of fecal material.
221 citations
TL;DR: An attempt is made to apply a certain class of optimal control theory to obtain an optimal controller to improve the dynamic response of a power system.
Abstract: In recent years important research has been done in the area of system optimization by control engineers. Many theoretical results have been published but application examples have mainly been on low-order systems. An attempt is made to apply a certain class of optimal control theory, known as the state regulator problem, to obtain an optimal controller to improve the dynamic response of a power system. The system differential equations are written in the first-order state variable form. A cost functional is then chosen, and the matrix Riccati equation is solved. Puri's and Gruver's method is applied for the numerical computation, and the system is made initially stable by shifting the system eigenvalues.
218 citations
TL;DR: In this paper, the effect of strain history on the resistance to liquefaction is investigated by means of triaxial and simple shear tests, and it is shown that the resistance of a saturated sand to liquidation is very much influenced by the previous strain history.
Abstract: The resistance of a saturated sand to liquefaction under cyclic loading has been assumed to depend only on the void ratio, effective stress system and intensity of cyclic loading. The effect of strain history on the resistance to liquefaction is investigated here by means of triaxial and simple shear tests. The resistance of a saturated sand to liquefaction as measured in laboratory tests is very much influenced by the previous strain history. Partial liquefaction which occurs at small shear strains greatly increases the resistance to liquefaction in subsequent tests. Cycles of large shear strains, or quasi-static shear strains > 7.5%, reduces the resistance to liquefaction. The increase in resistance to liquefaction created by a very small shear strain may result from the elimination of small local instabilities in the original sand structure. The loss of resistance caused by larger shear strains is thought to be due to either the creation of a uniform metastable structure or the development of a nonuniform structure.
TL;DR: The defense of the territories against intrusions by other grazers permits the growth of a thick algal film on which the Lottia can effectively graze, and their response to predatory snails may be a defense mechanisms.
Abstract: Lottia gigantea, a large (up to 8 cm in length) limpet of the California and northern Mexican coast, lives in association with an approximately 1,000 cm2 area of algal film in which its grazing marks can be seen, whereas the remainder of the rock surface is usually free of any visible film. These areas of algal film represent the territories of the Lottia; within them the animals do all their grazing. They keep their territories free of other organisms by shoving off any intruders: other Lottia, grazing limpets of the genus Acmaea, predatory snails, and sessile organisms such as anemones and barnacles. Within 2—3 weeks after Lottia were removed from their territories, the density of Acmaea in these territories increases to that found outside them, and the algal film disappeared. Apparently the defense of the territories against intrusions by other grazers permits the growth of a thick algal film on which the Lottia can effectively graze. Their reaction to sessile organisms prevents these animals from encroaching on and covering the territory. Their response to predatory snails may be a defense mechanisms.
TL;DR: A complete algorithm for the computer solution of steady-state fluid flows in networks is given, with particular stress placed on fast solution, minimal storage requirements and simplicity of the input data.
Abstract: A complete algorithm for the computer solution of steady-state fluid flows in networks is given. Particular stress is placed on fast solution, minimal storage requirements and simplicity of the input data. Although the Hardy Cross method is the classical method of solution of this type of problem, convergence is slow for large networks. To overcome this problem, the whole network is considered simultaneous, and this produces a large system of non-linear equations. Newton's method is applied, which results in an iterative solution of a system of linear equations. In order to reduce computer storage requirements and to simplify the data input, a number of algorithms from graph theory are involved. The resulting matrix of coefficients associated with the system of linear equations is banded and symmetric for which efficient (in time and memory requirements) methods of solution exist.
TL;DR: Acetoacetate is oxidized in the brain through the operation of the citric acid cycle, as shown by the accelerating effect of glucose on acetoacetate oxidation in adult rat brain slices, by the inhibitory effects of malonate in both infant and adult brain slices and by its conversion into glutamate and related amino acids in both tissues.
Abstract: 1. Acetoacetate or dl-β-hydroxybutyrate increases the rate of oxygen consumption to a smaller extent than that brought about by glucose or pyruvate in adult rat brain-cortex slices but to the same extent as that in infant rat brain-cortex slices. 2. The rate of 14CO2 evolution from [1-14C]glucose considerably exceeds that from [6-14C]glucose in respiring infant rat brain-cortex slices, in contrast with adult brain-cortex slices, suggesting that the hexose monophosphate shunt operates at a greater rate in the infant rat brain than in the adult rat brain. 3. The rate of 14CO2 evolution from [3-14C]acetoacetate or dl-β-hydroxy[3-14C]butyrate, in the absence of glucose, is the same in infant rat brain slices as in adult rat brain slices. It exceeds that from [2-14C]glucose in infant rat brain but is less than that from [2-14C]glucose in adult rat brain. 4. Acetoacetate is oxidized in the brain through the operation of the citric acid cycle, as shown by the accelerating effect of glucose on acetoacetate oxidation in adult brain slices, by the inhibitory effects of malonate in both infant and adult brain slices and by its conversion into glutamate and related amino acids in both tissues. 5. Acetoacetate does not affect glucose utilization in adult or infant brain slices. It inhibits the rate of 14CO2 formation from [2-14C]glucose or [U-14C]-glucose the effect not being wholly due to isotopic dilution. 6. Acetoacetate inhibits non-competitively the oxidation of [1-14C]pyruvate, the effect being attributed to competition between acetyl-CoA and CoA for the pyruvate-oxidation system. 7. Acetoacetate increases the rate of aerobic formation of lactate from glucose with both adult and infant rat brain slices. 8. The presence of 0.1mm-2,4-dinitrophenol diminishes but does not abolish the rate of 14CO2 formation from [3-14C]acetoacetate in rat brain slices. This points to the participation of ATP in the process of oxidation of acetoacetate in infant or adult rat brain. 9. The presence of 5mm-d-glutamate inhibits the rate of 14CO2 formation from [3-14C]acetoacetate, in the presence or absence of glucose. 10. Labelled amino acids are formed from [3-14C]acetoacetate in both adult and infant rat brain-cortex slices, but the amounts are smaller than those found with [2-14C]glucose in adult rat brain and greater than those found with [2-14C]glucose in infant rat brain. 11. Acetoacetate is not as effective as glucose as a precursor of acetylcholine in adult rat brain but is as effective as glucose in infant rat brain slices. 12. Acetoacetate or β-hydroxybutyrate is a more potent source of acetyl-CoA than is glucose in infant rat brain slices but is less so in adult rat brain slices.
TL;DR: In this paper, the authors present an analysis of the croyances politiques of John Foster Dulles, in the context of code-comportement, a concept defined by National Archives of the US.
Abstract: On admet que les comportements sont largement tributaires de la perception du milieu physique et social ambiant. Celle-ci, en retour, est conditionnee par un ensemble de croyances sur ce qui a ete, ce qui est, ce qui sera et ce qui devrait etre. De la sorte, les croyances fournissent un « code » plus ou moins coherent, qui nous sert a comprendre et a interpreter les signaux captes par nos sens dans l'environnement. Si nous postulons une telle relation « code-comportement », les croyances touchant a la nature de l'histoire et de la politique s'averent etre un fonds particulierement significatif, pour comprendre la conduite des acteurs politiques.Nathan Leites, dans ses etudes sur le « code operationnel » bolchevique, poursuivit une telle voie d'approche des croyances politiques. Afin de rendre plus systematiques certains aspects des travaux de Leites, Alexander George proposa dix questions – cinq d'ordre philosophique et cinq d'ordre instrumental – qui, posees a un acteur donne, permettent de saisir l'essentiel de ses croyances politiques dans ses reponses. Cet article constitue une etude des croyances de John Foster Dulles a partir de ces dix questions.Nos donnees proviennent d'abord des nombreux ecrits de Dulles – il est d'ailleurs rare de trouver un materiel aussi considerable dans le cas d'un personnage politique contemporain, car nous n'avons qu'un acces limite aux documents d'Etat et meme prives en un tel cas. Des memoires du temps de l'administration Eisenhower, de meme que des monographies, des questionnaires et des lettres echangees avec les collegues de Dulles nous permirent de completer ce materiel de base. Nous avons aussi tente d'examiner de facon critique ses politiques, la ou c'etait possible, afin de deceler les points de coherence et de contradiction entre ses attitudes affirmees d'une part, et ses actes politiques concrets d'autre part. A l'exception des croyances de Dulles relatives a l'Union Sovietique, qui ont deja fait l'objet d'une etude quantitative, nous utiliserons ici des methodes qualitatives d'analyse.Nous presenterons les donnees recueillies par cette analyse sous forme d'une serie de quelque quarante croyances touchant a l'histoire et a la politique. Par exemple,CROYANCE 3. La presence d'ennemis a l'exterieur assure la cohesion de la societe.CROYANCE 7. La guerre froide est un jeu dont les operations se neutralisent mutuellement.CROYANCE 16. L'evolution ultime de l'histoire tend vers un ordre naiurel fonde sur la loi morale.CROYANCE 23. L'interet du monde libre tend a coīncider avec la loi morale.CROYANCE 25. La pire menace a la paix vient d'une possibilite de guerre due a une erreur de calcul.CROYANCE 30. Les leaders politiques auront davantage et un meilleur appui du public s'ils s'adressent a son sens moral, plutot qu'a ses interets.CROYANCE 33. Une fois qu'on a defini ses interets, la credibilite exige qu'on les defende tous.En conclusion, nous chercherons les origines de ces croyances chez Dulles: par exemple, dans son temperament personnel, dans ses roles et statuts, ou encore dans la configuration societale de son milieu; puis nous discuterons de l'utilite du concept de « code operationnel » comme instrument d'analyse.
TL;DR: The evidence attests to the possibility that the pineal organ of at least some fishes is involved in the mediation of the gonadal changes effected by changing photoperiods, as well as suggesting a possible mode of action of the melatonin.
TL;DR: In this paper, the spectral line shapes can be fitted well by the four-parameter theory of Fano, which was developed to account for the interference of a sharp intra-atomic transition with an overlapping ionizing continuum.
Abstract: When a sharp absorption line of a defect or impurity center is overlapped by a broad vibronic band, interference can occur between the two types of transition. We find several examples of this effect in the optical spectrum of ${\mathrm{V}}^{2+}$ in octahedral fluoride coordination. The spectral line shapes can be fitted well by the four-parameter theory of Fano, which was developed to account for the interference of a sharp intra-atomic transition with an overlapping ionizing continuum. We justify the application of this theory to the vibronic problem, and calculate some of the parameters in terms of other spectroscopic data, obtaining good agreement with experiment.
TL;DR: The follow‐up data of 4389 treated cases of preclinical squamous carcinoma of the cervix is presented and shows the need for prolonged and careful follow-up of patients with carcinoma in situ.
TL;DR: There appears to be a relationship between the degree of repair synthesis and on the other hand frequency of cells entering S-phase, incidence of metaphase plates with chromatid breaks, flow of cells from G2 into pro-metaphase and “uncoiling” of metaphases chromosomes or heterochromatic segments of interphase nuclei.
Abstract: The oncogenic and mutagenic 4-nitroquinoline 1-oxide (4NQO) induces DNA-repair synthesis (unscheduled DNA synthesis) in diploid, aneuploid, normal and neoplastic human and Syrian-hamster cells. DNA-repair synthesis occurs in nuclei at G1, G2 and S-phase and in metaphase chromosomes of Syrian-hamster cells exposed to 4NQO. DNA-repair synthesis was separated from DNA-replication synthesis associated with chromosome replication at S-phase by arginine deprivation. The degree of [ 3 H]TdR incorporation into nuclear DNA is dependent on the dose of 4NQO (5·10 −8 to 1·10 −5 M ) and on the amount of DNA per cell. The time course of DNA-repair synthesis induced by 4NQO or UV was examined on non-dividing cells which were arrested by an arginine-deficient culture medium: an early occurring peak is followed by an abrupt decline at about 8 h post-treatment which is succeeded by a prolonged low level incorporation of [ 3 H]TdR. The effect of a completed and uncompleted repair synthesis on the flow of cells into S-phase and on the frequency of chromosome anomalies was studied on cells arrested by arginine deprivation and triggered to divide by addition of arginine. There appears to be a relationship between the degree of repair synthesis and on the other hand frequency of cells entering S-phase, incidence of metaphase plates with chromatid breaks, flow of cells from G2 into pro-metaphase and “uncoiling” of metaphase chromosomes or heterochromatic segments of interphase nuclei.
TL;DR: The biogenesis of rosmarinic acid (alpha-O-caffeoyl-3,4-dihydroxyphenyl-lactic acid), the second most common ester of caffeic acid in the plant kingdom, was studied in Mentha arvense and Mentha piperita and showed that endogenous ros marinic acid had a low turnover rate.
Abstract: The biogenesis of rosmarinic acid (alpha-O-caffeoyl-3,4-dihydroxyphenyl-lactic acid), the second most common ester of caffeic acid in the plant kingdom, was studied in Mentha arvense and Mentha piperita. Administration of (14)C-labelled compounds showed that, whereas the caffeoyl moiety was formed from phenylalanine via cinnamic acid and p-coumaric acid, the 3,4-dihydroxyphenyl-lactic acid moiety was formed from tyrosine and 3,4-dihydroxyphenylalanine. Time-course studies and the use of labelled rosmarinic acid showed that endogenous rosmarinic acid had a low turnover rate. The caffeoyl moiety did not appear to contribute to the formation of insoluble polymers, as has been suggested for chlorogenic acid in other plants.
TL;DR: In this paper, composite diagrams of spectra and cospectra were constructed from eight cases of velocity component and temperature measurements made over the water by an acoustic anemometer, and their universal form was discussed.
Abstract: Composite diagrams of spectra and cospectra were constructed from eight cases of velocity component and temperature measurements made over the water by an acoustic anemometer. Their universal form is discussed.
TL;DR: Evidence is obtained in another eukaryotic system for the universal role of methionine as the initiating amino-acid in protein synthesis.
Abstract: Evidence is obtained in another eukaryotic system for the universal role of methionine as the initiating amino-acid in protein synthesis.
TL;DR: In this article, physiological responses were recorded while 48 male Ss viewed a series of 30 slides of homicide scenes, nude females, or ordinary objects, and half the Ss saw the same slide 30 times while the others saw a different slide on each trial.
Abstract: Physiological responses were recorded while 48 male Ss viewed a series of 30 slides of homicide scenes, nude females, or ordinary objects. Half the Ss saw the same slide 30 times while the others saw a different slide on each trial. The physiological responses given by all six groups involved were those generally associated with an OR—increase in skin conductance, cardiac deceleration, and digital vasoconstriction. In addition, a biphasic cephalic vasomotor response, consisting of constriction followed by dilation, was observed. Stimulus presentation was also accompanied by a sharp reduction in eyeblink rate.
The physiological and eyeblink responses given by Ss who saw a different homicide scene on each trial were generally greater and more resistant to habituation than were those given by other Ss. Ss repeatedly shown the same homicide scene gave relatively small cardiac and cephalic vasomotor responses, and showed rapid habituation of the electrodermal response.
TL;DR: In support of the concept that the biochemical changes induced by methionine intoxication are mediated through an hepatic ATP insufficiency is the finding that adenine, administered to intoxicated animals completely reverses the hypoglycemic effects of methionines.
Abstract: L-methionine 10 mMole/Kg. per day administered orally to guinea pigs leads to a state characterized early by fatty liver, hypoglycemia and aminoacidemia and later by hypothermia, profound hypoglycemia and death within 60 hours. Paralleling the development of this state is a progressive fall in hepatic ATP probably caused by binding of available hepatic ATP to methionine, thus forming increasing and substantial amounts of hepatocellular S-adenosylmethionine and S-adenosylhomocysteine. In support of the concept that the biochemical changes induced by methionine intoxication are mediated through an hepatic ATP insufficiency is the finding that adenine, administered to intoxicated animals completely reverses the hypoglycemic effects of methionine. The possibility that a similar mechanism of intoxication occurs in human methionine ingestion and hypermethioninemic states is discussed.
TL;DR: A Mg2+-dependent enzyme which will phosphorylate protamines and histones has been isolated and purified approximately 30-fold from rainbow trout testis and can satisfy the requirement of a high ionic strength for maximal activity.
TL;DR: The microbiological extraction of zinc from a high‐grade zinc sulfide concentrate has been investigated, using a pure strain of Thiobacillus ferrooxidans, with positive effects on zinc extraction rate and in some instances on final zinc concentration in solution.
Abstract: The microbiological extraction of zinc from a high-grade zinc sulfide concentrate has been investigated, using a pure strain of Thiobacillus ferrooxidans. Conditions such as temperature, pH, pulp density, nutrient, concentration, and specific surface of solids have been studied in terms of their effects on zinc extraction rate and in some instances on final zinc concentration in solution. Where appropriate, optimum conditions for leaching have been specified.
TL;DR: In this article, numerical methods have been used to investigate the steady incompressible flow past oblate and prolate spheroids for Reynolds numbers up to 100, and the ratio of minor to major axis of the spheroid investigated were 0·9, 0·5 and 0·2, together with 1·0, which represents the limiting case of a sphere.
Abstract: Numerical methods have been used to investigate the steady incompressible flow past oblate and prolate spheroids for Reynolds numbers up to 100. The ratio of minor to major axis of the spheroids investigated were 0·9, 0·5 and 0·2, together with 1·0, which represents the limiting case of a sphere. The pressure distribution and the skin and form drag coefficients were numerically evaluated for the various Reynolds numbers. Streamlines, equi-vorticity lines and equivelocity lines are presented and show in detail the flow characteristics.
TL;DR: The increase in sulphated anionic glycosaminoglycans would seem to be directly related to cartilage formation but the high level of hyaluronic acid content in stages 21–25, when myotube formation as well as sclerotome aggregation are occurring, could indicate that it plays some developmental role in somitogenesis.
Abstract: An investigation of the appearance of glycosaminoglycans in the axial region (dermatome, myotome, scleratome, neural tube and notochord) of the developing chick embryo during early somite differentiation (stages 17–28; 2.5 to 5.5 days of age) was conducted with biochemical methods for comparison with a previously conducted histochemical analysis (Kvist and Finnegan, '70). The biochemical analysis confirmed that the weakly acidic anionic glycosaminoglycan observed histochemically was hyaluronic acid and that the sulphated anionic glycosaminoglycan was mainly chondroitin-4- and/or chondroitin-6-sulphate (chondroitin-sulphate A and/or C). Trace amounts of dermatan-sulphate (chondroitin-sulphate B) were found and, since some glucosamine was present in the sulphated fractions, it is possible that a small amount of heparin was present. This latter observation could account for the polysulphated material seen with histochemical methods.
Quantitatively, the hyaluronic acid concentration (uronic acid/gm dry weight of tissue) was at a peak between stages 21–25 and exceeded the chondroitin-sulphate concentration in axial tissues until stage 25, after which time chondroitin-sulphate concentration increased very rapidly, concomitant with perichordal cartilage formation, while hyaluronic acid concentration began slowly to decline. Thus, whereas hyaluronic acid concentration was 2.5 times that of chondroitin-sulphate at stage 17, this ratio was nearly completely reversed by stage 28.
The increase in sulphated anionic glycosaminoglycans would seem to be directly related to cartilage formation but the high level of hyaluronic acid content in stages 21–25, when myotube formation as well as sclerotome aggregation are occurring, and its subsequent decrase could indicate that it plays some developmental role in somitogenesis.
TL;DR: In this article, a theory for two-dimensional incompressible potential flow external to a symmetrical bluff body and its wake is presented, where the desired flow-separation points are made the critical points of a conformal transformation to a complex plane in which surface sources in the wake create stagnation conditions at critical points.
Abstract: A theory is presented for two-dimensional incompressible potential flow external to a symmetrical bluff body and its wake. The desired flow-separation points are made the critical points of a conformal transformation to a complex plane in which surface sources in the wake create stagnation conditions at the critical points. The stagnation streamlines then transform to tangential separation streamlines in the physical plane, with separation at the desired pressure. The position and strength of the sources are determined by the requirements of separation position and pressure coefficient. The flow inside the separation streamlines is ignored and base pressure is assumed constant at the separation value. Features of the theoretical model include a finite wake width, a pressure distribution on the separation streamlines decreasing asymptotically towards the free stream value at infinity and a simple analytic expression for the pressure distribution on the body. Comparisons of the theory with experimental data and with other theories are presented for the normal plate, the circular cylinder, the 90° wedge, and the elliptical cylinder. Although simpler to apply than the other theories, the present theory produces at least as good agreement with the experimental data.
TL;DR: A temperature-sensitive division mutant of Escherichia coli was isolated by using differential filtration to select for filaments at 42 C and normal cells at 30 C, suggesting the temperature- sensitive element is required for cell division late in the cell cycle.
Abstract: A temperature-sensitive division mutant of Escherichia coli was isolated by using differential filtration to select for filaments at 42 C and normal cells at 30 C Cells shifted from 30 to 42 C stop dividing almost immediately, suggesting the temperature-sensitive element is required for cell division late in the cell cycle Cells returned to 30 from 42 C divide abruptly, suggesting accumulation of division potential at 42 C Inhibitors of protein, deoxyribonucleic acid, and ribonucleic acid synthesis do not block division during the recovery period at 30 C Cycloserine does not stop cell division, vancomycin shows some effect on cell division, whereas penicillin completely stops cell division during this period The addition of high concentrations of NaCl to filaments at 42 C results in a burst of cell division The final cell number is equivalent to the control which is grown at 30 C if sufficient salt is added (11 g/liter, final concentration) After the original burst, cell division ceases at the nonpermissive temperature even at increased osmolality Chloramphenicol, puromycin, vancomycin, and penicillin prevent division during the recovery in the presence of NaCl Kinetic data indicate division potential decays to a reversible inactive intermediate which rapidly decays to an irreversible inactive form Conversion of division potential to the inactive form is correlated with a 100- to 1,000-fold derepression of the synthesis of division potential The mutation appears to involve a stage in cross-wall synthesis which is required during the terminal stages of division