Showing papers by "Brigham Young University published in 1984"

Allocatable Fixed Inputs and Jointness in Agricultural Production: Implications for Economic Modeling

Abstract: Allocatable fixed inputs, such as land, are a potentially important source of jointness in agriculture. As with other causes of jointness, they necessitate multiple-product systems for modeling product supply and input demand. In other important ways, however, their analytical implications are very different from other causes of jointness. Model specification differs. Demand functions for the quantities of each input used in the production of individual commodities can be derived if a primal approach is used, but such allocation equations cannot in general be identified from a dual specification. Available allocation data are not even useful in such dual estimations.

Toxicity, accumulation, and elimination of polycyclic aromatic sulfur heterocycles inDaphnia magna

Abstract: A series of polycyclic aromatic sulfur heterocycles (PASH) were compared to their sterically and structurally similar polycyclic aromatic hydrocarbons (PAH) for toxicity, bioconcentration, and elimination inDaphnia magna. The PASH were generally more toxic than their analogous PAH. Benzo[b]thiophene and benzo[b]naphtho[2,1-d]thiophene were bioconcentrated to a greater extent than naphthalene and chrysene, respectively. However, dibenzothiophene and phenanthrene exhibited similar uptake curves. No clear trend was observed for elimination differences between PASH and PAH.

Optimization versus response-strength accounts of behavior.

Abstract: Pigeons were run in both single-key and concurrent-key experiments in which, over most of the range of response rates, an increase in response rate gave rise to a continuous decrease in reinforcement rate. In spite of the fact that a low response rate would have produced a high reinforcement rate, all birds responded at relatively high rates, thus keeping reinforcement rates substantially below the maximum possible. In the concurrent-key experiment, in addition to responding at relatively high rates, the birds' ratios of responses approximately matched the corresponding ratios of obtained reinforcers. The results are inconsistent with most theories of optimal performance, which assume that organisms behave in ways that either maximize reinforcement value or minimize deviations from a free-behavior point. On the other hand, the results are consistent with the assumption that reinforcement strengthens the tendency to respond.

Mutagenic activity of methyl-substituted tri-and tetracyclic aromatic sulfur heterocycles

Abstract: A number of polycyclic aromatic sulfur heterocycles have been identified in coal-derived products and in shale oils. The mutagenic activity of some of these compounds, including dibenzothiophene, benzo[b]naphtho[1,2-d]thiophene, benzo[b]naphtho[2,1-d]thiophene and benzo[b]naphtho[2,3-d]thiophene have been determined using the Salmonella/microsome mutagenicity test. These compounds demonstrated either very weak or no mutagenic activity. The methyl derivatives of each of these four compounds were assayed for mutagenic activity. Salmonella typhimurium TA98 was used as the tester strain. All assays required a rat-liver homogenate metabolic activator. Five of the methylated derivatives, 1-methylbenzo[b]naphtho[1,2-d]thiophene, 3-methylbenzo[b]naphtho[1,2,-d]thiophene, 1-methylbenzo[b]-naphtho[2,1-d]thiophene, 6-methylbenzo[b]naphtho[2,1-d]thiophene and 4-methylbenzo[b]naphtho[2,3-[d]thiophene demonstrated mutagenic activity. However, activity was observed only at high concentrations of the metabolic activator.

Parental Influences of Adolescent Self-Esteem*:

Abstract: Two contemporary theoretical explanations of adolescent self-esteem, symbolic interaction and social learning, were investigated and compared. Special attention focused on the relative effect of selected variables, representing each explanation, on four dimensions of self-esteem. A stratified random sample of 184 families with adolescents provided self-report data. Multiple regression and bivariate analysis resulted in evidence for the general conclusions that: (1) adolescent self-esteem was more a function of the reflected appraisal of the parents than it was of adolescents modeling their parents' self-esteem; and (2) female adolescents were more likely to be influenced by their parents than were male adolescents. In addition, the study suggests that when researchers investigate adolescent self-esteem, it is essential that they take into account its various dimensions, as well as the sex of the parent and the-adolescent.

Anti-piracy system using separate storage and alternate execution of selected proprietary and public portions of computer programs

Abstract: A system for computer software protection includes a random access memory (RAM) device and one or more read-only memory (ROM) devices. The RAM and ROMs are connected in parallel to a data transfer bus, and to an address bus. Selected proprietary portions of a program are pre-stored in the ROMs prior to distribution to system users, and the remaining portions of the program are stored on an external storage medium such as a diskette which is made available for access and use by system users. When using the program, the portion of the program stored on the external storage medium is loaded into the RAM. In executing the program, the system commences executing, in turn, each program instruction contained in the RAM until it is instructed to transfer to one of the ROMs for execution of the proprietary portions of the program stored in the ROMs. If a system user makes an unauthorized copy of the portion of the program stored on the external storage medium, since the proprietary portions of the program are stored in the ROMs, the unauthorized copy will be incomplete and will not be able to run without the proprietary portions of the program which are maintained in the ROMs.

Electronic inverter, particularly for use as ballast

Abstract: Disclosed is a system for supplying high frequency alternating current to gas discharge lamps, such as fluorescent lamps, and the like and a unit that can be placed in or adjacent to a lighting fixture to convert a direct current supply into high frequency AC and also to provide the ballast needed for operation of the gas discharge lamps. A preferred inverter network includes a symmetrical, class B, push-pull current-limited, tuned-collector, sinusoidal oscillator which is self starting, highly efficient and stable over a wide range of input voltage, with or without load. Circuits are disclosed for dimming the lights, for supplying heating current to lamp filaments at high voltage at the start and much reduced voltage after the arc has been struck in the lamps served by the ballast unit, and this reduction in filament current takes place automatically without switches, resistors or other expensive and energy consuming means.

Biochemical characters and the reconstruction of turtle phylogenies: relationships among batagurine genera

Abstract: -Phenetic and cladistic approaches were used to assess relationships among 22 species representing 17 genera of batagurine turtles, and 2 species representing 2 genera of emydine turtles. Phenograms and cladograms were constructed from a total of 90 variable enzyme products (electromorphs) of 14 gene loci. Phenograms were generated by UPGMA clustering using genetic similarity, identity, and distance matrices, and a Wagner tree was constructed from a binary-coded character matrix. A qualitative locus-by-locus cladistic approach was also attempted, and in this as well as in our application of the Wagner algorithm, a species of the sister group family Testudinidae was used as the outgroup taxon. Results of the three approaches are evaluated relative to each other, and relative to relationships that have previously been proposed with other lines of evidence. Some of the clades generated by one or more of the approaches used in this study are particularly strongly corroborated by chromosomal and osteological data sets. High genetic distances between some taxa, and high levels of inferred homoplasy suggest that divergence among many species approaches the limits of electrophoretic resolution and, as a result, several cladistic hypotheses are presented for some taxa. Where results are inconclusive, however, they are useful to the extent that they draw attention to contradictory data sets and alternative hypotheses of intergeneric relationships. [Cladistics; electrophoresis; Emydidae; Emydinae; Batagurinae; turtle systematics.] In the nearly two decades since the widespread application of starch-gel electrophoresis to systematic and evolutionary problems, most studies have focused on spatial genetic variation within species or the degree of relative genetic differentiation among closely related species (reviews by Ayala, 1975; Avise, 1976; Nevo, 1978). Furthermore, most studies of species relationships have been phenetic assessments of intrageneric genetic similarities or distances. Avise (1974) cautioned that electrophoretic data might have only limited value in assessing intergeneric relationships, but elsewhere has shown that the phenetic approach may be of use in some monophyletic groups (Avise et al., 1977). Today few would question the utility of such studies, but only very recently have systematists begun to analyze electrophoretic data using the conceptual phylogenetic approach of Hennig (1966). Some of these studies have involved the coding of character states for all variable loci and the use of computer algorithms to construct the most parsimonious trees (Mickevich and Johnson, 1976; Avise et al., 1980b), while others have been based on a locus-by-locus comparison in an attempt to determine character polarities for polymorphic enzymes (Wake et al., 1978; Baverstock et al., 1979; Avise et al., 1980a; Honeycutt et al., 1981; Patton et al., 1981; Sites et al., 1981; Honeycutt and Williams, 1982; Murphy et al., 1983). We have used all of these approaches in an attempt to clarify phylogenetic relationships among batagurine turtle genera. THE BATAGURINE TURTLES The subfamily Batagurinae is an assemblage of over 20 genera, including over two-thirds of the testudinoid family Emydidae (McDowell, 1964). Except for the Neotropical genus Rhinoclemmys, the subfamily is entirely Old World and, as a

Range Management under Uncertainty

Abstract: The problem of rangeland management is modeled as a stochastic control problem. The manager periodically chooses stocking rates and decides whether to use a treatment which improves the rangeland. His decisions have an uncertain impact on the rangeland. The theory of finite Markov chains is used to analyze the solution to the control problem. The stochastic specification of the model is varied to test the sensitivity of the optimal policies. These are quite robust except at certain levels of the range condition. Cases of a risk-neutral and risk-averse manager are studied.

Late Cenozoic mammals from central Mexico

Abstract: Historically, the knowledge of late Cenozoic mammals from central Mexico has been slow in developing. Most early studies did not include stratigraphic controls or meaningful correlations. At present the geology is incompletely known at most fossil-yielding localities. However, research in the past several years, especially in the State of Guanajuato, has provided much needed stratigraphic control relevant to collected fossils. Of the eleven faunas identified in this paper, only the Cedazo (Pleistocene), Las Tunas, Rancho El Ocote, Coecillo, and Rancho Viejo (Pliocene) have this control. These faunas, then, with several taxa reported here for the first time, are considered most important. They provide significant information about changing climates, a trend from humid, warm conditions in the Pliocene to drier and cooler conditions in the Pleistocene, and mammalian dispersals. Most fossils can be derived from North American ancestors; however, South American constituents can be identified beginning...

Leaf litter processing in aquatic systems. A two variable model

Abstract: A negative exponential model with one independent variable, days or accumulated time, was examined for adequacy as a descriptive equation for aquatic leaf litter processing. The effect of adding a second independent variable, degree days or accumulated temperature, to the model was also examined. The two variable negative exponential model was shown to have two advantages over the single variable model. The expanded model provided an adequate fit of litter processing data for more cases than the single variable model. Also, the two variable model allowed determination of rate coefficients corresponding to each temperature level of the experiment rather than assuming a single, constant rate coefficient as with the one variable model. The trends of the temperature dependent rate coefficients were useful for examining processing differences between experiments for different sites and seasons.

Ray tracing of Steiner patches

Abstract: Steiner patches are triangular surface patches for which the Cartesian coordinates of points on the patch are defined parametrically by quadratic polynomial functions of two variables. It has recently been shown that it is possible to express a Steiner patch in an implicit equation which is a degree four polynomial in x,y,z. Furthermore, the parameters of a point known to be on the surface can be computed as rational polynomial functions of x,y,z. These findings lead to a straightforward algorithm for ray tracing Steiner patches in which the ray intersection equation is a degree four polynomial in the parameter of the ray. The algorithm presented represents a major simplification over existing techniques for ray tracing free-form surface patches.

Deactivation of fused silica capillary columns with polymethylhydrosiloxanes

Abstract: In this work, an investigation of new organosilicon hydride reagents with phenyl functional groups for deactivation and surface modification of fused silica capillary columns is described. Different reagents were tested for their ability to deactivate the fused silica surface, and actual critical surface tension measurements were made using the capillary rise method. The deactivation procedure required lower optimum temperatures than conventional methods. Deactivated capillaries and coated capillary columns were prepared and tested for reproducibility, efficiency, and surface inertness towards basic and acidic compounds at the low nanogram level.

Stochastic Efficiency, Normality, and Sampling Errors in Agricultural Risk Analysis

Abstract: This paper examines the power of tests for efficiency. The relationship between sample size, parameter values, and the family of probability distributions is stressed. Some findings are that the probability of correctly ranking distributions is frequently very low regardless of sample size. It is generally lowest as distributional parameters (such as the means) of the two distributions being compared are of similar magnitudes. Further, the empirical distribution function performs extremely well as compared to maximum likelihood estimators.

Iron in higher plants: Storage and metabolic role

Abstract: Iron in the earth's crust is more oxidized now than it was when life evolved. Generally iron is available in the soil in the ferric form but must be taken up and utilized in the ferrous form. While iron is essential for life in small amounts, higher concentrations are toxic. Plants store iron for future use as ferritin which is ferric phosphate coated with protein. The protein coat apparently prevents iron toxicity or use of stored iron by pathogens. Iron is found in both heme‐proteins (cytochromes, catalase, etc.) and non‐heme proteins (ferridoxins, nitrite reductase, etc.). These enzymes are characterized by involvement in oxidation‐reduction reactions involving electron or proton transfer. One might say that life evolved around iron.

Telephone counseling and crisis intervention: A review

Abstract: The empirical research pertaining to the effectiveness of telephone counseling and referral systems personnel was critically reviewed. The assessment was organized according to several evaluation strategies that researchers have utilized to evaluate effectiveness. These strategies included, for example, client self-reports, client "shows" versus "no-shows" following referral, data pertaining to suicide rates, counselor ratings of personal effectiveness, and phone workers' ability to offer empathy to clients. It was concluded that discussions of effectiveness should be constrained by a careful consideration of the specific index of efficacy chosen by investigators as well as methodological issues associated with current research in this area. There is reason to believe that the availability of telephone crisis services may be related to reduced suicide rates among young white females. Also, there is a significant need to empirically associate counseling technique and indices of effectiveness with substantive measures of client outcome in future research. Additional topics reviewed include the probable differential effectiveness of lay workers with various presenting problems of clients, and the role that training and maturity seem to play in successful interventions. Guidelines for the use of evaluation techniques which coincide with service goals are also offered.