Showing papers by "University of California, Santa Barbara published in 1969"

Allelopathy as a factor in ecological process

Abstract: Allelopathie (chemische Hemmung) ist ein Faktor bei okologischen Prozessen wie Konkurrenz, Dominanz, Sukzession, Produktivitat. Es ist zu erwarten das die von Pflanzen ausgeschiedenen Chemikalien sich in der Umgebung der Pflanze ansammeln, bis sie fur andere Pflanzen, oder fur ihre eigene Entwicklung, eine hemmende Konzentration erreichen. Auch steht es fest, das manche Pflanzen sich so gegen Tierfras schutzen. Biochemische Produkte kommen weitgehend in biotischen Wechselwirkungen vor und allelopathische Effekte spielen in fast allen naturlichen oder angepflanzten Pflanzengemeinschaften eine Rolle.

On optimum quantization

Abstract: The problem of minimizing mean-square quantization error is considered and simple closed form approximations based on the work of Max and Roe are derived for the quantization error and entropy of signals quantized by the optimum fixed- N quantizer. These approximations are then used to show that, when N is moderately large, it is better to use equl-interval quantizing than the optimum fixed- N quantizer if the signal is to be subsetiuently buffered and transmitted at a fixed bit rate. Finally, the problem of optimum quantizing in the presence of buffering is examined, and the numerical results presented for Gaussian signals indicate that equllevel quantizing yields nearly optimum results.

Honey bee recruitment to food sources: olfaction or language?

Abstract: Honey bee recruits locate food sources by olfaction and not by use of distance and direction information contained in the recruitment dance. Recruitment efficiency increases as odor of the food source accumulates in the hive, from hour to hour and from day to day. Flight patterns, landing patterns, bee odor, and Nassanoff secretion apparently do not aid in recruitment of bees.

l-Arabinose Binding Protein from Escherichia coli B/r

Abstract: A protein which is capable of binding l-arabinose-1-(14)C has been isolated from l-arabinose-induced cultures of Escherichia coli B/r. Analysis for this l-arabinose-binding protein (ABP) in a number of l-arabinose-negative mutants suggests that the ABP is not coded for by any of the known genetic units of the l-arabinose complex yet is under the control of the regulator gene araC. The ABP has been purified and found to bind l-arabinose, d-fucose, d-xylose, and l-ribulose with decreasing affinities. The K(m) for l-arabinose is 5.7 x 10(-6)m. The molecular weight, as determined by equilibrium centrifugation, was found to be 32,000. The protein was observed to have many features that liken it to other recently isolated binding proteins that have been implicated in the active transport of small molecules.

Generators for topological entropy and expansiveness

Abstract: The notion of topological entropy was introduced by Adler, Konheim, and McAndrew in [1], with some indications of the analogy to measure theoretic entropy. In this paper, we investigate the topological analogue of generators of measure-preserving transformations. The structure of flows with generators is examined, with the main result (Theorem (2.7)) being that every such flow is a transformation group homomorphic image of a subflow of a symbolic flow. The notion of expansiveness in topological dynamics has been extensively investigated. In Section 3, we show that the discrete flows with generators are precisely the expansive flows. This connection between topological entropy and topological dynamics enables us to obtain significant information about each concept. On the one hand, the large class of flows which are known to be expansive yields flows in which the existence of a generator is not apparent. Moreover, we show that distal flows do not support generators since they are not expansive. On the other hand, we use the results from studying generators to obtain a new result about expansive flows as well as an alternate proof of a result due to W. Gottschalk [4, p. 345]. Moreover, we note some additional properties of flows with generators. Finally, in Section 4, we generalize the definition of a generator to an arbitrary transformation group. Although the notion of topological entropy is no longer applicable, we use the same techniques to provide results on expansive transformation groups analogous to those of expansive discrete flows. Throughout this paper, X will denote a compact Hausdorff space and 50 a homeomorphism of X onto X. We introduce some modifications in the notation of [1]. Since the finite open covers are cofinal, it is no restriction to consider only finite open covers, and we shall do so. Moreover, we use the notion of refinement (i.e., q / i s refined by \"¢/\" (q/-<~/') if each member of ~¢\" is contained in some member of q/) and joins for any cover (i.e., whether it is an open cover or not). We let z~¢ denote the collection of finite open covers of X. Finally if q /E d and m, n are integers such that m < n, then q/m,, = n \\ / 5 0 i q / . All other notation follows [1]. j=ra

Multi-regge baryon exchange and central interactions.

Abstract: We find that the double differential cross section for $\mathrm{pp}$ inelastic collisions at high energy can be well reproduced over a range of two decades by a simple version of the multi-Regge model, in which baryon exchange is responsible for large momentum transfers to the final proton. The model is an asymptotic one, and we show predictions at 70 and 200 GeV/c.

Geology and Petrology of the Mt. Hood Area: A Study of High Cascade Volcanism

Abstract: High Cascade volcanoes include all those formed along the Cascade trend during the Pliocene, Pleistocene, and Recent epochs. They have extruded lavas ranging from basalt to rhyolite, but dominantly andesite. The products of this intense period of volcanism were studied i n a 300-square-mile area surrounding and including Mt. Hood, Oregon. The object of the study was to obtain field and geochemical evidence bearing on the origin of andesitic magmas. The High Cascade lavas of the Mt. Hood area were erupted onto a surface formed by the Miocene Yakima Basalt. Late Miocene activity was mild, producing a few scattered andesite volcanoes. These centers of activity shed epiclastic and pyroclastic debris into basins on each side of the emerging mountain belt. Volcaniclastic debris and interbedded flows accumulated to local thicknesses near 1400 feet before Pliocene time. Early Pliocene activity was intense; andesite was erupted from several centers and locally accumulated to thicknesses of several thousand feet. A few basalt flows preceded the andesites and may be genetically related to the far more voluminous olivine andesite and pyroxene andesite. A shallow pluton of quartz-diorite was intruded into some of these lavas during the late part of this period. Two late Pliocene volcanic centers erupted sequences of olivine basalt, olivine andesite, and pyroxene andesite. Other centers erupted voluminous andesite not associated with basalts. The composite cone of the Mt. Hood volcano was built during late Pleistocene time. It is composed of olivine-, pyroxene-, and hornblende-dacite lavas and pyroclastic debris. Contemporaneous basalts and olivine andesites were erupted from many nearby vents, which are not directly connected with the Mt. Hood volcano. The main cone growth ceased before the Fraser Glaciation, but a plug-dome of hornblende andesite was extruded through the southern slope about 2000 years ago. Other late Pleistocene activity yielded flows of olivine basalt and olivine andesite. Several domes and flows of hornblende dacite were also extruded. Chemical analyses were obtained from 158 samples, for which relevant field relations are known. Plots of the Differentiation Index (normative Ab + An + Or + Qz) against lime, total alkalis, potash, and soda serve to characterize lavas from various eruptive centers. Andesites directly associated with high-alumina basalt contain significantly more potash than andesites not associated with basalts, such as those found at Mt. Hood. Field relations coupled with chemical data lead to the following conclusions: (1) the Mt. Hood lava did not differentiate from high-alumina basalt magma; (2) the Mt. Hood lavas are probably not a single series of magmas related by differentiation, but may be a series of similar magmas generated through time by some process, such as supracrustal anatexis; (3) olivine basalts magmas do differentiate to form andesite; (4) all olivine basalts in the Mt. Hood area were differentiated or contaminated prior to eruption; and (5) several recognizably different magma series were erupted through time—some are related to a basalt parent; others, to a primary andesite.

Depth adjacency in simultaneous contrast

Abstract: The Gelb phenomenon, as an example of whiteness contrast, was investigated with three amounts of separation in depth between the test and induction disc. The cue of binocular disparity was used to vary the perceived depth between the discs. It was found that the magnitude of the contrast effect decreased with an increase in the perceived depth between the two discs. This change was regarded as an instance of the adjacency principle. The problem of whether the binocular disparity cue per se or perceived depth was the significant variable was discussed. The consequences of the results were considered with respect to the relation between whiteness constancy and whiteness contrast and the problem of neural localization of the contrast effect.

Behavior and Physical Factors Causing Migration and Aggregation of the Sand Crab Emerita Analoga (Stimpson)

Abstract: Migration and distribution of Emerita on sand beaches can be explained in terms of water flow and a simple behavioral response. Wash zones of sand beaches are bounded burrow out of fluid sand and so are kept within the boundaries of the wave wash. As the position of a wash zone is shifted with the tide, Emerita are carried in it to new locations on the beach. Lateral flow within the wave wash distributes Emerita into clumps along the shore. See full-text article at JSTOR

Proterozoic eucaryotes from eastern california

Abstract: Both procaryotic and eucaryotic nannofossils occur in chert from the upper Beck Spring Dolomite (Pahrump Group) in northeastern San Bernardino County, California. These fossils include the oldest reasonably certain records to date of chlorophycean and chrysophycean algae, and hence of the eucaryotic or mitosing cell. Associated with these are cyanophycean procaryotes of still more ancient affinities. Indirect radiometric evidence implies an age of 1.2 to 1.4 aeons (1.2 to 1.4 × 109 years) for the enclosing rocks. Associated stromatolites are consistent with such an age assignment.

Positive Contrast in the Runway Obtained with Delay of Reward

Abstract: The failure to find positive contrast effects in the runway may be attributed to a ceiling effect that can be overcome with the use of delay of reward. Rats were trained one trial a day in a runway with small, medium, or large reward. When a shift to large reward was combined with delay of reward, shift groups slowed down less than controls.

The effect of object familiarity on the perception of size and distance

Abstract: The perceived sizes and perceived distances of familiar objects were investigated in two experiments in which images of familiar objects were presented monocularly, one at a time, in an otherwise dark field of view. It was found that the angular size of the objects as well as their familiar size determined reported size. Reported distances were increasingly underestimated as a function of increasing simulated distances of the objects. The results are consistent with the conclusion that, as a function of the retinal size of the objects, the observer perceives the familiar objects as off-sized, and, that as a consequence of these off-sized perceptions, the observer's judgements of the object distances reflect inferential rather than perceptual processes.

Effect of intrahypothalamic infusion of acetylcholine on behavioural and physiological thermoregulation in the rat.

Abstract: CHANGES in body temperature can be produced by local application of drugs to the preoptic and anterior area of the hypothalamus The direction of these responses varies with the drug and the species1–4 The physiological response induced by the drug may be accompanied by a complementary behavioural thermoregulatory response: local heating of the hypothalamus, which produces physiological heat dissipation responses5, also results in decreases in rate of response for peripheral heat6,7 Similarly, local cooling produces increased rectal temperature and increased rates of response for heat7,8

Changes in the Ultraviolet Sensitivity of Escherichia coli During Growth in Batch Cultures

Abstract: The ultraviolet (UV) sensitivity of Escherichia coli B/r harvested at various times during growth in batch cultures was measured. The results showed a period of increased UV sensitivity in late log phase, just before the cultures entered stationary phase. This increase in sensitivity was associated with a decreased shoulder in the UV survival curves. The postirradiation division delay of survivors was shortest for cells harvested during the period of maximal sensitivity. This period of increased UV sensitivity during late log phase was not found in the radiation-sensitive, repair-deficient mutant B(s-1) (a strain which is unable to excise pyrimidine dimers from UV-damaged deoxyribonucleic acid). These results suggest that the variation in UV sensitivity of E. coli B/r as a function of time of harvesting of the cells from batch cultures is related to the varying capacities of these populations to repair UV-damaged deoxyribonucleic acid. Further experiments designed to elucidate the mechanism underlying this variation in UV sensitivity indicated that it arises from the partial depletion of nutrients in the medium during late log phase. We suggest that growth in such depleted media leads to a depression in the intercellular concentration or activity of one or more of the repair enzymes concerned with the repair of damaged deoxyribonucleic acid.

Efficiency of Motor Learning as a Function of Intertrial Rest

Abstract: The efficiency of two practice schedules was examined on two large muscle motor tasks. There were four groups of subjects (N = 160); each individual in a group performed on one of the two motor tasks under one of the two conditions. Distributed practice consisted of alternating 30-second trials of practice and rest; massed practice was continuous for 8 minutes. Comparisons made during the last minute of practice prior to the rest pause revealed that the massed groups had significant decrements in performance level. In contrast, after the rest period, when both groups were on a distributed schedule, no difference was found in the amount of learning. Learning was found to be a function of the number of trials and independent of the conditions of practice.

Arabinose-Leucine Deletion Mutants of Escherichia coli B/r

Abstract: The control of ara gene expression was studied in mutants of Escherichia coli B/r containing deletions which fused the l-arabinose gene complex with the leucine operon (the normal gene order being araDABIOC...leuDCBAO). Complementation experiments with stable merodiploids showed that expression of ara genes cis to araC-leu deletions was controlled by the trans-acting product of the araC gene. Expression of ara genes cis to araB-leu deletions was under leucine control. These studies confirm the existence of a region between genes araC and araB essential for normal activator controlled expression of the ara structural genes. One deletion was characterized as an araO-leu deletion. Its effect on ara gene expression was unique in that ara genes were susceptible to potential regulation by both l-arabinose and leucine. These experiments suggest that two different species of messenger ribonucleic acid (mRNA) may be produced for the ara-leu region as a result of this deletion. One, under l-arabinose-activator control, is initiated in the l-arabinose region; the other, under leucine control, is initiated in the leucine region. The latter indicates that araI can be transcribed. Whether araI is transcribed in the former instance (mRNA made under activator control) remains to be established.

Radicals of semigroup rings

Abstract: by JULIAN WEISSGLASSJ(Received 20 March, 1968; revise 9 Decemberd , 1968)1. Introduction Le.t RD denote the contracted semigroup rin ofg the completely 0-simplesemigroup D over the ring R. Th Reees structure theor ofy completely 0-simple semigroupsis used to obtain necessar any d sufficient conditions tha RDt have zero radical (Theore 3.8)m.By using Amitsur's constructio of thne upper 7c-radical w [1]e ar,e able to treat the Jacobson,Baer (prime), Levitzki (locall any nilpotentd possibl thy )e ni radicall s simultaneously Our.results generaliz ae theorem of Munn [6] on semigroup algebra osf finite 0-simple semigroups.2. Preliminaries.(A) RADICALS Le. t n b properte a y of rings If. th rine g R has property n we say Ris a 7r-ring W. calel an idea al n-ideal if as a rin igt is a Tt-ring W. e say th rineg R is n-semisimple if it has no nonzero 7t-ideals.Following Amitsu [1]r , w define e a sequenc oef ideals o f R, U

Effects of physical training on the body composition add diet of females.

Abstract: A study was conducted to determine the effects of two different physical training programs on the body composition and dietary patterns of college females. Ten members of the women's tennis team and five members of the women's swimming team at the University of California, Santa Barbara, were subjects. Measurements were made of body density by underwater weighing, subcutaneous skinfold fat, estimated percent of body fat, and calorie intake by seven-day dietary histories. Both groups were measured three times during 16 weeks of sports training. No significant F ratios (.05 level) were found within or between the two groups for any of the experimental variables measured. Apparently, physical activity without strict dietary control has little effect in modifying the body composition or dietary patterns.