Showing papers by "San Diego State University published in 1986"

The Role of Attitude toward the Ad as a Mediator of Advertising Effectiveness: A Test of Competing Explanations:

Abstract: Attitude toward the ad (Aad) has been postulated to be a causal mediating variable in the process through which advertising influences brand attitudes and purchase intentions. Previous conceptual a...

Students' Views of Mentors in Psychology Graduate Training.

Abstract: This study examined the prevalence and role of mentors in graduate training from the viewpoint of students. Ninety graduate psychology students from a large midwestern university responded to a survey about the characteristics of mentors, the roles mentors play in their professional and social lives, and why some students do not have a mentor. Over 50% of the respondents had mentors. Inability to find a satisfactory mentor was the predominant reason for not having one. Findings suggest that mentors serve supportive functions and promote professional productivity as indicated by research involvement, publications, and conference papers. Personality characteristics distinguish good from poor mentors much more frequently than do intellectual competence or professional activity.

Relations Between Permeability and Electrical Resistivity in Granular Aquifers

Abstract: Increased demand for quantitative answers to ground-water problems, particularly associated with the use of numerical models, has increased the need to accurately determine the distribution of hydraulic parameters. Researchers have attempted to find correlations between electrical resistivity and the permeability of fresh-water aquifers since 1951. Several recent studies report either direct or inverse relations between apparent formation factor and aquifer permeability. The basis for these relations is a direct or inverse relation between porosity and permeability and, as matrix conduction effects are not taken into account, constant fluid conductivity is either implicitly or explicitly assumed. Laboratory experiments conducted on granular materials suggest that matrix conduction (surface conduction) effects are either as important as, or dominant over, porosity-permeability relations. Our experiments on granular materials show only weak relations between true formation factor and permeability. Relations between apparent formation factor and permeability are good only for constant fluid conductivity. Most importantly, the strongest relationship found was that between permeability and matrix conductivity. These data suggest either that (1) relations between permeability and apparent formation factor must be applied in very restricted geologic environments and only where fluid conductivity remains relatively constant, or (2) more fundamental relations between matrix conductivity and aquifer permeability should be applied.

Information-processing Abnormalities: Trait- and State-dependent Components

Abstract: Schizophrenics were compared to schizoaffective, bipolar, and nonpsychotic depressed patients in a visual masking paradigm in which an informational target stimulus was followed at varying intervals by a noninformational masking stimulus. In limiting the availability of the sensory signal provided by the target stimulus, the mask was used to probe how information from the environment enters and is processed by the central nervous system. The use of the masking paradigm was originally based on the hypothesis that thought disorder is a result of a more primary dysfunction in the processes that precede and result in thought. Results confirmed previous findings of a performance deficit in the schizophrenics when compared to nonpsychotic controls. Schizoaffective and bipolar patients also showed evidence of impaired processing, however. Results were interpreted in terms of a trait/state formulation in which impaired information processing is seen as a fundamental trait of schizophrenia spectrum disorders and as a state that can covary with psychotic illness in general. A unifying concept centers on the effects of psychopathological conditions on an individual's processing resources that results in either underprovision or overprovision of information from sensory input to complex cognitive operations dependent on the cerebral cortex. Findings from a variety of paradigms are consistent with those of the masking paradigm in revealing that the processing deficits of schizophrenics are time dependent and occur in the 500 ms following stimulus input.

Coherence and Academic Writing: Some Definitions and Suggestions for Teaching

Abstract: Coherence in written text is a complex concept, involving a multitude of reader- and text-based features. Perhaps because of this, we writing instructors and the textbooks we use often discuss coherence in a vague or incomplete manner. This article reviews current coherence literature, defines coherence in broad terms, then presents a three-lesson revision unit based on modern coherence principles. In this unit, ESL students "deconstruct" the assignment prompt and prepare their own first drafts of an essay response. Then they examine a fellow student's first draft from the "top down," evaluating the thesis in relationship to the prompt and to the assertions within the essay and analyzing the information structure intended to guide readers through the text. Conclusions are drawn about the success of this group revision technique and the necessity for providing sequential exercises to improve coherence.

Low-rate speech encoding using vector quantization and subband coding

Abstract: Vector quantization (VQ), subband coding (SBC) and linear predictive coding (LPC) are three of the most effective data compression schemes used for medium-to-narrow band speech coding. In this study, we have attempted to improve the quality of encoded speech by using various combinations of these three coding methods. Waveform coders with rates 2400-9600 bits per second resulted in overall signal-to-distortion ratios of 6-12 dB. We have obtained somewhat lower values for segmented SNR's in the case of straight waveform encoding and higher values for the residually excited subband coded VQ quantizers as expected. However, informal listening tests yielded noticeable improvements over those of straight waveform VQ results. The best quality and the lowest transmission rates were achieved by a residually excited subband coded vector quantization system coupled with a three-way classifier with design parameters: LPC order P=14; 32-band complete binary tree QMF filter bank implementation of SBC and VQ waveform encoding with dimension K=32 at an overall bitrate of 3,100 bps.

Fish-flamingo-plankton interactions in the Peruvian Andes1

Abstract: The zooplankton and flamingo populations of 20 high elevation (3,700-4,700 m) lakes in the Andes of southern Peru were assessed on one to three occasions each. Some of these lakes have cyprinodont fish (Orestias spp.), others do not. Lakes with fish usually have a sparse zooplankton dominated by cyclopoid copepods and chydorid cladocerans; the others tend to have an abundant zooplankton dominated by Calanoid copepods and daphnids or by Artemia. Chilean flamingos (Phoenicopterus chilensis) are usually absent or scarce on lakes with fish and present in large numbers where fish are absent. We suggest that the distribution of this flamingo in the Central Andes, and in South America generally, is determined primarily by the distribution of fish, with which it competes for invertebrate prey. The patterns above are complicated by the impact on Orestias populations of man, of fish-eating birds, and of introduced, non-native fish (Salmo gairdneri, Basilichthys bonariensis). Though neglected by most ecologists, “strong competitive interactions among distantly related organisms. . . are probably widespread and important in natural ecosystems. In most habitats the important kinds of food resources are used by several major taxa of potentially competing consumers” (Brown and Davidson 1977, p. 880). For example, competition exists between seabirds and man for fish (Furness 1982); among whales, seals, seabirds, fish, and cephalopods for krill (May et al. 1979; Fumess 1982); between insects and birds for 1 This research was supported by grants from the National Geographic Society, the U.S. National Science Foundation (DEB 76-02888) and the Universidad National de Tacna. nectar (Carpenter 1979); among insects, birds, and mammals for seeds (Smith and Balda 1979; Brown et al. 1979); between birds and reptiles for insects (Pianka 197 1; Wright 1979); and among intertidal algae, molluscs, crustaceans, anemones, etc. for space (Woodin and Jackson 1979). Yet until publication of the proceedings of a recent symposium on “Competition between distantly related taxa” (1979, Am. Zool. 19: 1027-l 175) there was not a single review article on the phenomenon of “distant competition.” And the chapters on interspecific competition in ecology textbooks still typically ignore it. Causes of this neglect include the rigid taxonomic specialization of many ecologists (Brown and Davidson 1977) and methodological difficultiesthe fact

Use of an analytical model to study limitations on net photosynthesis in Arbutus unedo under field conditions.

Abstract: From field gas-exchange measurements on Arbutus unedo growing in Portugal, parameter values necessary to apply an analytical, physiologicallybased model of C 3 photosynthesis were obtained. The model successfully simulated measured diurnal photosynthetic responses in Arbutus during periods without water stress, under both natural and CO2-saturating conditions. The model was used to analyze those factors limiting primary productivity during each of the experimental days. Due to a large investment in ribulose bisphosphate (RuBP) regeneration capacity, irradiance was rarely limiting, even during cloudy periods, but the limitation imposed by stomatal conductance was quite large, averaging over 30%. The fact that experimental leaves were maintained in a horizontal position is at least partially responsible for these results. Possible other reasons for this apparent excess of RuBP regeneration capacity visa-vis RuBP carboxylase-oxygenase concentration are discussed.

Flight physiology of intermediate-sized fruit bats (pteropodidae)

Abstract: Up to eight physiological parameters were measured on members of four species of fruit bats with a size range of 0.188-0.650 kg as they flew in a wind tunnel. Regression lines were calculated for the relationships between body masses of bats and their power inputs (P 1 ), heart and respiratory rates. These were compared to similar relationships for flying birds. Respiratory evaporation dissipated only 10% of the heat produced. At ambient temperatures (T a ) above 15°C, heat loss was facilitated by vasodilation of feet and wing membranes, but this mechanism became less effective at high T a when thermal differential between wings and air was reduced. Bats are apparently unable to increase greatly their respiratory evaporation, and overheated at T a of 25–30°C. At low T a ) the flight ability of two bats was reduced, suggesting that reduced coordination or even freezing of wings might be a general problem for bats flying at T a close to 0°C. The endurance of three bats was so much greater near the middle of their speed ranges that the maximum flight distances ought to be achieved at these velocities, even though the cost of transport would be lower at higher speeds. Endurance at an airspeed was proportional to the relative power input (P i /P i,min ) raised to the power of −7.45; flying at a speed that raised P i /P i,min by 10% reduced endurance by half.

Depth of root symbiont occurrence in soil.

Abstract: The woody legume Prosopis glandulosa (mesquite) growing in the California Sonoran Desert develops functional root symbiotic associations (N2-fixing nodules, vesicular-arbuscular mycorrhizal fungi) at depths greater than 4 m in moist soil above a seasonally stable water table. Population densities of symbiotic microorganisms are substantially greater at depth than near the surface. Inferences of plant symbiotic dependence based upon examination of surface roots and soil may be incorrect since deep roots can support the symbioses which are critical for plants utilizing deep water.

Fertility and Adaptation: Indochinese Refugees in the United States

Abstract: Levels of fertility among Indochinese refugees in the United States are explored in the context of a highly compressed demographic transition implicit in the move from high-fertility Southeast Asian societies to a low-fertility resettlement region. A theoretical model is developed to explain the effect on refugee fertility of social background characteristics, migration history and patterns of adaptation to a different economic and cultural environment, controlling for marital history and length of residence in the U.S. Multiple regression techniques are used to test the model, which was found to account for nearly half of the variation in refugee fertility levels in the United States. Fertility is much higher for all Indochinese ethnic groups (Vietnamese, Chinese-Vietnamese, Cambodian, Lao, Hmong) than it is for American women; the number of children in refugee families is in turn a major determinant of welfare dependency. Adjustments for rates of natural increase indicate a total 1985 Indochinese population of over one million, making it one of the largest Asian-origin populations in the United States. This remarkable phenomenon has occurred in less than a decade. Implications of these findings for public policy are discussed, focusing on family planning, maternal and child health needs, and the attainment of refugee economic self-sufficiency.

Infrence for non-negative autoregressive schemes

Abstract: The object of this paper is the statistical analysis of Several Closely related models arising in water quality analysis. In particular, concern is with the autoregressive scheme Xr = ρXr−1 + Yr where 0 < ρ < 1 and Y's are i.i.d, and non-negative. The estimation and testing problem is considered for three parametric models - Gaussian, uniform and exponential - as well as for the nonparametric case where it is assumed that the Y's have a positive continuous distribution.

Age-related differences in the pleasantness of chemosensory stimuli.

Abstract: Modest decrements in both taste threshold sensitivity and, more recently, suprathreshold sensitivity have been associated with the aging process. The present study was designed to investigate the existence of changes in preference for various concentrations of single tastes and of the same single tastes in more complex chemosensory mixtures. In this study, 300 participants from three different age groups (18-26, 32-45, over 65) rated for pleasantness four concentrations of sodium chloride, sucrose, and citric acid presented in both aqueous and beverage bases. Results showed significant effects of age, stimulus background, stimulus, concentration, and of several interactions, and they suggest that elderly subjects find salt and sugar pleasanter at higher concentrations than younger subjects do.

Fertility and adaptation: Indochinese refugees in the United States.

Abstract: Levels of fertility among Indochinese refugees in the United States are explored in the context of a highly compressed demographic transition implicit in the move from high-fertility Southeast Asian societies to a low-fertility resettlement region. A theoretical model is developed to explain the effect on refugee fertility of social background characteristics migration history and patterns of adaptation to a different economic and cultural environment controlling for marital history and length of residence in the U.S. The chief source for the data and analyses is the Indochinese Health and Adaptation Research Project (IHARP) San Diego State University. "Multiple regression techniques are used to test the model which was found to account for nearly half of the variation in refugee fertility levels in the United States. Fertility is much higher for all Indochinese ethnic groups than it is for American women; the number of children in refugee families is in turn a major determinant of welfare dependency. Adjustments for rates of natural increase indicate a total 1985 Indochinese population of over one million making it one of the largest Asian-origin populations in the United States." (EXCERPT)