Showing papers by "San Diego State University published in 1972"

Ecosystem Alteration by Mosquitofish (Gambusia affinis) Predation

Abstract: In artificial pools Gambusia affinis greatly reduced rotifer, crustacean, and insect populations and thus permitted extraordinary development of phytoplankton populations (2x108 cells per milliliter). Other effects included decreased optical transmissivity and increased temperature of the water, decreased amounts of dissolved inorganic phosphorus, and increased amounts of dissolved organic phosphorus, inhibition of Spirogyra, and replacement of one annelid, Chaetogaster, by another, Aeolosoma.

Student evaluations of teachers.

Abstract: Rodin and Rodin point out that there are two ways of judging teaching through students—ascertaining how much students have learned and obtaining student evaluations of teacher effectiveness. Some commonly accepted notions regarding student evaluations are challenged in this article, which comments on the results obtained in a number of studies. The authors suggest that “students are less than perfect judges of teaching effectiveness”—at least if teaching effectiveness is measured by how much students learn. This paper, reprinted from Science, helps to set the stage for the remaining articles in this issue.

The in-vitro acid-growth response: Relation to in-vivo growth responses and auxin action.

Abstract: We have examined in detail the characteristics of the hydrogen-ion extension response in frozen-thawed Avena coleoptile sections (in-vitro acid-growth response). These data allow us to compare the in vitro response with the in-vivo extension responses initiated by auxin and hydrogen ions. The in-vitro response has three characteristics in common with the in-vivo responses: a similar Q10 (3–4 between 15 and 25°C, but almost 1 between 25 and 35°); a minimum yield stress; and a lack of stored growth (i.e., an inability to induce a potential for growth during periods of reduced wall tension). Both the in-vivo and in-vitro acid-growth responses have a threshold pH of about 4.5 and give an optimum response at pH values of 3 and below. These similarities suggest that the in-vitro and in-vivo acid-growth responses have a common wall-loosening and wall-extension mechanism. We have also examined the effects of Pronase, sodium lauryl sulfate (SLS), elevated temperatures, calcium, and potassium ions on the in-vitro acid-growth response. We suggest that hydrogen ions do not activate wall-associated enzymes, but act to hydrolyze non-enzymatically some acid-labile linkages in the cell wall. Furthermore, we suggest that auxin induces cell elongation either by causing the release of hydrogen ions from the protoplast or by causing the appearance in the wall of an enzyme which can hydrolyse the acid-labile linkages.

Polyandry in the American Jaçana (Jacana spinosa)

Abstract: LITTLE is known about the biology of any of the Jacanidae, a circum- tropical family of shorebirds that inhabit freshwater swamps and marshes. The lack of knowledge reflects the limited field research done on tropical aquatic birds in general (Birkenholz and Jenni, 1964; Lack, 1968; Orians and Paulsen, 1969). The reversal of roles of the sexes in the American Jaana (Yacana spinosa), in which males incubate eggs and rear young without help from the females has long been known (Miller, 1931). The same reversal of sex roles occurs in the Pheasant-tailed Jaana (Hydro- phasianus chirurgus) (Hoffmann, 1949, 1950.), in the Bronze-winged Ja- ana (Meto'pidius indicus) (Mathew, 1964; Collier, pers. obs.), and prob- ably in the African Greater Jagana (Actophilornis a/ricana) (Miller, 1951). Furthermore, both Hoffmann and Mathew studied small breeding popula- tions consisting of one female and two or three males. Although they inves- tigated very small, unmarked populations, and almost all of Hoffmann's excellent data were gathered in Peking at the northernmost distributional limits of the Pheasant-tailed Jaana, there is little doubt that these two species are polyandrous. Polyandry is a rare form of social organization in birds (Lack, 1968; Orians, 1969). It is known or postulated to occur in some Tinamiformes, Charadriiformes (Rostratulidae, Jacanidae), Gruiformes (Turnicidae, Pedi- onomidae, Mesitornithidae, and one Rallidae). Polyandry has been sug- gested, but not substantiated, in a number of other orders. Although the Phalaropidae have been considered polyandrous, HShn (1965, 1967) and Johns (1969) have recently shown that Wilson's Phalarope (Steganopus tricolor) is probably monogamous though it may be promiscuous. After reviewing the literature on the other two phalaropes, HShn (1967) con- cludes that no real evidence of their polyandry exists. True polyandry, defined here as one female being mated simultaneously or having simultaneous pair bonds with more than one male, is difficult to distinguish from promiscuity and successive polyandry. When polyandry is suspected, it must be verified in the field with individually marked birds. The purpose of this paper is to document polyandry and certain related phenomena in the American Jaana.. To our knowledge there are no previ- ous accounts of polyandry based on the study o.f a marked population of birds. Both authors are currently working on other aspects of the biology of the American Jagana (population dynamics and food habits, Collier; and behavior and social organization, Jenni).

Bioclimate, leaf temperature, and primary production in red mangrove canopies in south florida'

Abstract: used as input data for the model. The model produced realistic leaf temperatures, leaf resistances, transpiration rates, and primary production rates and was used to indicate the relative importance of environmental variables in influencing leaf temperature, transpiration, and primary production. Maximum leaf temperatures occurred at the top of the canopy in June and the overcast day in January, but at the bottom of the canopy on the clear day in January. The model presently calculates water uptake as a constant rate to leaves and does not include a redistribution of water within the plant. The calculated transpiration was about 20% of the total water loss of the stand, the remaining loss coming directly from the moist substrate under the canopy. The inclusion in the model of stomatal movements reduced daily transpiration under conditions of mild water stress by 0.04 cm day-1. Total evapotranspiration was 0.67 cm day-', and transpirational water loss was 0.12 cm day-'. Levels in the middle of the canopy had the highest transpiration rate because of their high leaf area, but leaves at the top had the highest transpiration rate per unit leaf area. Leaf water deficits great enough to initiate stomatal closure occurred early in the morning at the top of the canopy in June on clear days, later in the morning at the top of the canopy in June on cloudy days, early in the afternoon at the top of the canopy in January on clear days, and not at all at the top of the canopy in January on cloudy days. Leaf water deficits did not develop within the canopy in either June or January. Net photosynthesis calculated with the model was 5.6 g organic matter m-2 day-' for sunny days and 3.5 for cloudy days in June. Gross photosynthesis per unit leaf area was greater at the top of the canopy than at the bottom, but the middle levels of the canopy had the greatest production. The efficiency of water utilization increased from top to bottom of the canopy. A weighted monthly estimate for production was 3.4 for June and 2.2 for January, giving an average annual net production rate of 2.8 g organic matter m-2 day-'. The model predicts that the maximum photosynthesis for mangrove stands will occur with a leaf-area index of about 2.5 if no acclimation to shade within the canopy occurs. A leaf area greater than about 2.5 may decrease production. The environmental variables with the greatest influence on primary production were air temperature and humidity. Production was decreased by increasing air temperature and increasing humidity. Increasing total solar radiation increased production up to a point, then decreased it. Increasing the diffuse fraction of the total solar radiation increased production. Increasing infrared radiation decreased production. Production and transpiration increased with increasing leaf-area index

Three-Dimensional Vibrations of Orthotropic Cylinders

Abstract: A method to analyze the three-dimensional vibrations of orthotropic cylinders is presented. The field equations are in the form of three coupled, second-order differential equations with nine elastic constants. The vibration problem is solved by means of the Frobenius method, using power series expansion in the radial coordinate, and assuming sinusoidal dependence on the longitudinal and circumferential coordinates and on time. Frequency equation for the free vibration of solid circular cylinders is derived and a numerical example is given. An extensive study of the dynamic behavior of orthotropic cylinders can be made by this analysis.

The rise of the mesophytic flora

Abstract: The Mesophytic Era began in the Permian when advanced gymnosperms migrated from the uplands, where they had evolved during the latter half of the Pennsylvanian, down into the depositional basins. The Mesophytic Flora orginated at least in part near the paleoequator. The Pennsylvanian tropical uplands where much of this flora evolved were probably cooler, less rainy, and had greater seasonal variations in rainfall than most tropical uplands do now. The Mesophytic Flora appears to have originated in the Pennsylvanian because for the first time stocks of plants (conifers and advanced seed ferns) were available that could really flourish in upland environments. Evolution of the Mesophytic Flora may also have been promoted in the Pennsylvanian by forced migrations of the upland vegetation, by the sparseness of the plants, by climatic changes, and by the high CO2:O2 ratio in the atmosphere.

Mineral ion composition and osmotic relations of Atriplex confertifolia and Eurotia lanata.

Abstract: Periodic collections of Atriplex confertifolia and Eurotia lanata leaf tissue throughout the growing season were analyzed for osmotic potential, water content, and concentration of Na+, K+, soluble Ca++, Cl-, and SO4-- ions. Ionic concentrations of these two species exhibited marked similarities to corresponding values for European members of the same genera. Atriplex confertifolia, like many other Atriplex species, behaves as an alkali halophyte and accumulates Na+, while E. lanata appears to favor accumulation of K+ as did its European counterpart, E. ceratoides.The analyses showed a much broader range of tissue moisture contents and osmotic potentials during the season for Atriplex than for Eurotia. The differences in leaf water relations between the two species are possibly related to the greater NaCl accumulation by Atriplex as compared to Eurotia. An apparent advantage exists for Atriplex in prolonging physiological activity and carbon gain in the dry portion of the late summer by NaCl accumulation.

Barnacle fouling of the ornate diamondback terrapin, malaclemys terrapin macrospilota

Abstract: Balanomorph barnacles are one of the more common and conspicuous elements that comprise the epifaunal community of marine and brackish water turtles. We had the opportunity recently of examining a female ornate diamondback terrapin, Malaclemys terrapin macrospilota Hay, fouled by both barnacles and mollusks. Allen & Neil (1952) noted that commonly diamondback terrapins are fouled by barnacles, but they failed to cite any species. The purpose of this note, therefore, is to record the unique occurrence of an oyster, a gastropod, and two species of barnacles on M. t. macrospilota. The terrapin was collected by Charles Cowles on 9 December 1962 in the shal lows off Shired Island in the California Swamp, Dixie County, Florida (approxi

Absence of auxin-induced stored growth in Avena coleoptiles and its implication concerning the mechanism of wall extension.

Abstract: We have reinvestigated the ability of Avena coleoptiles to undergo auxin-induced stored growth (stored growth is defined as the ability of a cell to store up a potential for extension during periods of reduced turgor which can be converted into extra extension upon restoration of normal turgor). We could detect little or no stored growth, with either moderate (1–2 bar) or more severe (3–5 bar) reductions in turgor, and with varying periods (10–100 min) of reduced turgor. Earlier reports of a stored growth potential (e.g., Cleland and Bonner, 1956) are shown to be in error, in that the apparent growth potential is probably an artifact of the use of argon or nitrogen as an inhibitor of auxin action. The absence of stored growth reported here is not due to a direct inhibitory effect of the osmoticum itself on auxin action, since coleoptiles can extend in response to auxin even in the presence of mannitol if an external force is applied to the section to replace the normal turgor. These results show that the two components of cell-wall extension, wall loosening and wall extension, usually are inseparable. Two possible explanations are considered; the walls may be extending by the process of chemical creep, or the wall loosening may only occur when the load-bearing bonds are under tension.

Mark-Recapture Techniques for Population Estimates of Pogonomyrmex Ant Colonies: an Evaluation of the 32P Technique

Abstract: Population studies of the California harvester ant, Pogonomyrmex californicus (Buckley), were carried out in the summer of 1967. Colonies were excavated to obtain information on population size and structure. The number of workers remained rather constant at about 4500 per colony. Winged reproductives were found in late June just before they swarmed July 7. Estimates of population density were made using the mark-recapture technique with Phosphorous-32. These estimates underestimated the actual population density by 83 to 92% and violated several assumptions of the mark-recapture technique, indicating that this method is unsuitable for population estimations.

Fluvial and estuarine sediments exposed along the oude maas (the netherlands)

Abstract: Sedimentary structures are examined in recent alluvium that was deposited in an environment transitional between fluvial and estuarine. The depositional sequence in vertical section reveals three units, that vary according to type and association of sedimentary structures, and lithology. 1 The lower unit is characterized by large-scale trough cross-stratification. Sedimentary structures suggest a fluvial environment in which water and sediment movement were uni-directional but subject to periodic fluctuations. 2 The middle unit displays an alternation of small-and large-scale cross-stratification, which is directionally bi-modal due to tidal action. Both water and sediment movement were bi-directional and highly variable in intensity. A vertical gradation in dimension of structures shows successive weakening of tidal currents as deposition proceeded. 3 The upper unit is characterized by flaser and lenticular bedding and small-scale trough cross-stratification, ascribed to an estuarine regime of low intensity. The observed transition from a fluvial to an estuarine environment is tentatively related to increased tidal action, caused by the destruction of large parts of reclaimed land bordering the Oude Maas, following severe floods in this area during the 14th and 15th centuries, A.D.

Language in Ethiopia: implications of a survey for sociolinguistic theory and method

Abstract: Work of the Language Survey of Ethiopia is drawn on to illustrate that social surveys can contribute to scientific theories and methods as well as to policy making. Findings with regard to four general problems are indicated: a metric of linguistic distance (considered here in terms of selection of diagnostic traits for linguistic areas, subgrouping of related languages, and dialect variation within a language; measurement of basic cognate frequencies; and testing of mutual intelligibility, a typology of the processes of language spread (lingua franca, mother tongue, superposed variety); verbal deference behavior (in use of Amharic second person pronouns); and pidginization (Simplified Italian of Ethiopia). Some comparisons to findings in sociolinguistics research elsewhere are made. (Language surveys; measurement of linguistic distance; language spread; social meaning and mode of address; pidginization.)

Aspects of the circulatory system of Pollicipes polymerus J. B. Sowerby (Cirripedia: Thoracica)

Abstract: The circulatory system of Pollicipes polymerus exhibits a high degree of organization which precludes it from being referred to as an open system. The system is arbitrarily divided into four parts: (1) the circulation of the peduncle and mantle; (2) the distributive circulation of the body, which provides hemolymph to most of the cephalic gut, to the maxillary gland, and to the cirri; (3) the peripheral circulation which distributes blood from the cirri to the peripheral areas of the thoracic region, to most of the thoracic gut, and from the scutal sinus to the peripheral areas of the cephalic region; and (4) the collecting circulation, which conveys hemolymph mostly from the peripheral circulation of the body to the peduncle. There also may be a circulation that is comparable to the vertebrate lymphatic system. Pumping of hemolymph can be attributed to three pairs of skeletal muscles that compress the dorsolateral channels. These muscles are unique for crustacean muscles in that they do not appear to be striated. The rostral vessel appears to be a vestige of a heart in which the pump muscles have been lost. There is a similarity of the rostral vessel to the heart of Calanus finmarchicus (a copepod). This is additional evidence linking the cirripeds with the copepods within the Maxillopoda. Electron microscope observations of the walls of the midsagittal vessels indicate that there is a more or less random layering of cellular and noncellular elements within the wall. Muscle cells appear to be incorporated in the vessel wall.

Imagery-mediated habituation of the orienting reflex

Abstract: The effect of repeatedly imagining a stimulus on later OR habituation to the real event was studied. Groups of college Ss imagined the occurrence of either a light or a tone for 10 trials. A third group received 10 500-Hz tones and a fourth group received no stimulation. All Ss then received 10 habituation trials to the 500-Hz tone. Ss who had imagined tones showed significantly greater habituation of the GSR component of the OR than Ss imagining a light or receiving no stimulation. This group was not significantly different from Ss who had received real tones prior to the habituation stimuli. The results suggest that the imagery process aided in the formation of a Sokolovian neuronal model which accelerated habituation. The results further suggest that OR habituation may be a component in various desensitization therapies which employ imagery techniques.

Coerciveness and Change: Cross-National Trends

Abstract: Among the many questions which may be asked with reference to conflict, three seem of particular importance. The first focuses on the genesis of conflict and seeks to understand why it is that men rebel. The second has to do with conflict as an ongoing process. The antagonists have entered the arena, and their moves and countermoves are scrutinized in some detail. The third question explores the consequences and outcomes of conflict. This can be limited to asking which side emerged victorious (and there are also Pyrrhic victories), or the impact of conflict can be traced within the political and social system and its culture. Did political and social change occur and, if so, in which aspect of polity and society? Each question seems to imply a different theoretical emphasis. Theorists interested in the genesis of violence and

On maximally flat low-pass filters with ripple in the stopband

Abstract: Maximally flat (MF) low-pass filters of order n with exactly n , or n - 1 finite zeros are investigated and are compared with the same order Butterworth filter, i.e., the MF filter with no finite zeros. It is seen that the MF filter with finite imaginary zeros exhibits sharper cutoff at the edge of the passband and ripple in the stopband. It is shown that the MF filter that maximizes the magnitude of the slope at cutoff is characterized by equal ripple in the stopband. This filter is shown to be the Inverse Chebyshev. Expressions for cutoff slope and for transition bandwidth are derived and are compared with those of the Butterworth filter. The step responses of the Inverse Chebyshev and of the Butterworth are also compared.

The orienting reflex and amount and direction of conceptual novelty

Abstract: The galvanic skin response component of the orienting reflex (OR) was recorded for four groups of 11 Ss. They viewed seven numeric stimuli presented sequentially, then a test stimulus (TS) which was out of sequence by ±3 or ±15 units, followed by a resumption of the sequence. It was found that ORs to the TS were a function of the amount of disparity between that TS and the “expected” stimulus and that direction of that disparity was not an effective manipulation. There were no such systematic changes in OR recovery to the following in-sequence stimulus. The results were related to previous research using both numeric and simple sensory stimuli and to Sokolov’s account of the OR.

Some influences of temperature on the rearing of the grunion Leuresthes tenuis, an atherine fish

Abstract: Grunion Leuresthes tenuis (Ayres), an atherine fish, were reared, from artificially fertilized eggs to 160 days posthatching, at temperatures from 18.0° to 25.4° C. The rearing was carried out in five 60 l rectangular containers and two hard moulded plastic pools holding 60 and 450 l. The growth rate was highly correlated with temperature at least up to metamorphosis. Thereafter, the effect of temperature on growth, within lethal limits, appeared to be lost or at least masked by other factors. At low densities, after metamorphosis, growth was proportional to the population density. Size and shape of the rearing containers also influenced the growth rate.