Showing papers by "University of Arkansas published in 1991"
Book•
01 Jan 1991TL;DR: McClary's "Feminine Endings" as mentioned in this paper is a collection of essays in feminist music criticism, addressing problems of gender and sexuality in repertoires ranging from the early seventeenth century to rock and performance art.
Abstract: A groundbreaking collection of essays in feminist music criticism, this book addresses problems of gender and sexuality in repertoires ranging from the early seventeenth century to rock and performance art. ". . . this is a major book . . . [McClary's] achievement borders on the miraculous." The Village Voice"No one will read these essays without thinking about and hearing music in new and interesting ways. Exciting reading for adventurous students and staid professionals." Choice"Feminine Endings, a provocative 'sexual politics' of Western classical or art music, rocks conservative musicology at its core. No review can do justice to the wealth of ideas and possibilities [McClary's] book presents. All music-lovers should read it, and cheer." The Women's Review of Books"McClary writes with a racy, vigorous, and consistently entertaining style. . . . What she has to say specifically about the music and the text is sharp, accurate, and telling; she hears what takes place musically with unusual sensitivity."-The New York Review of Books
865 citations
TL;DR: In this article, the authors examined the impact of stressful job demands on employee attitudes and attendance and found significant interactions between control and objective psychological demands that indicated that these demands were associated with higher levels of tardiness and sick days only under conditions of low perceived control.
Abstract: We examined the impact of stressful job demands on employee attitudes and attendance. Using Karasek's (1979) theory of job decision latitude as the conceptual foundation, we hypothesized that mental and physical work demands would interact with employee beliefs of personal control. Survey data from 90 male manufacturing employees regarding their control beliefs were combined with objective job analysis data concerning mental and physical demands and one year's worth of archival data regarding unexcused absences, sick days, and days tardy. There were significant interactions between control and objective psychological demands that indicated that these demands were associated with higher levels of tardiness and sick days only under conditions of low perceived control. In contrast, subjective workload ratings showed no relationship with tardiness and sick days, but, in interaction with control, predicted work satisfaction and voluntary absence. We discussed these results in terms of a stress process that affects health-related attendance independent of employee attitudes.
427 citations
TL;DR: The revivals of the population inversion are seen to be entirely due to the fact that the linear superposition of the two macroscopically distinct field states is coherent (i.e., a pure state), as opposed to an incoherent mixture.
Abstract: An asymptotic result is derived for the Jaynes-Cummings model of a two-level atom interacting with a quantized single-mode field, which is valid when the field is initially in a coherent state with a large average photon number. It is shown that for certain initial atomic states the joint atom-field wave function factors into an atomic and a field part throughout the interaction, so that each system remains separately in a pure state. The atomic part of the wave function displays a crossing of trajectories in the atom Hilbert space that leads to a unique state for the atom, independent of its initial state, at a specific time to (equal to half the revival time). The field part of the wave function resembles a crescent squeezed state. The well-known collapses and revivals are investigated from this perspective. The collapse appears to be associated with a "measurement" of the initial state of the atom with the field as the measuring apparatus. The measurement is not complete for finite average photon number: the system is instead left in a coherent superposition of macroscopically distinct states. At the half-revival time to this superposition of states is entirely in the field part of the state vector, so that the (pure) state of the field at that time is of the form sometimes referred to as a "Schrodinger cat. " The revivals of the population inversion are seen to be entirely due to the fact that the linear superposition of the two macroscopically distinct field states is coherent (i.e., a pure state), as opposed to an incoherent mixture.
246 citations
TL;DR: In this article, exact formulas for energy eigenvalues and eigenfunctions for both the discrete and continuous parts of the spectrum, dipole matrix elements, dc Stark effect, single and two-photon transition rates, and fine and hyperfine structures are obtained.
Abstract: The two-dimensional hydrogen problem is solved analytically. In the nonrelativistic case, exact formulas for energy eigenvalues and eigenfunctions for both the discrete and continuous parts of the spectrum, dipole matrix elements, dc Stark effect, single- and two-photon transition rates, and fine and hyperfine structures are obtained. Comparison is made between the two- and the three-dimensional cases. Some interesting aspects of the solution unique to the two-dimensional case are discussed.
235 citations
TL;DR: The inheritance of TSWV resistance was found to be a single dominant gene, which indicates a 98.7% penetrance of the resistance gene in plants infected four months after the inoculations.
Abstract: Inheritance of resistance to tomato spotted wilt virus (TSWV) derived from the cultivar ‘Stevens’ was studied. Five TSWV isolates, which differ in geographic origin and elicit different symptoms on tomato, were used to screen the resistant parent plants. Enzyme-linked immunosorbent assay (ELISA) was used to distinguish healthy and infected plants. Two susceptible advanced breeding lines were crossed with four F4 plants of a ‘Stevens’ × ‘Rodade’ obtained from South Africa (SA). There were no differences in the progeny responses of the four SA parents to TSWV. The inheritance of TSWV resistance was found to be a single dominant gene. The SA, F1, and the backcrosses to the resistant parent were found to have eight out of 612 plants infected four months after the inoculations, which indicates a 98.7% penetrance of the resistance gene.
184 citations
TL;DR: Benthic species assemblages in upstream and downstream ends of riffles and in pools were investigated seasonally in the first five orders of an alluvial gravel stream with distinct pool and riffle channel form, indicating less intense flow disturbance during floods, provides protection from the mild scouring that does occur during flooding, and provides refugia from predators.
Abstract: Benthic species assemblages in upstream and downstream ends of riffles and in pools were investigated seasonally in the first five orders of an alluvial gravel stream with distinct pool and riffle channel form. Riffles comprised < 10% of stream area and were separated by pools with extensive bedrock substrate (ca. 15–85% of total surface area) which was scoured during periodic high flow. Virtually all taxa were more abundant in riffles than in pools, except chironomids which were more equally distributed. Inconsistent results were obtained for upstream-downstream comparisons within riffles. Intermittent headwater reaches (orders 1 & 2) which supported half as many taxa retained this pattern during periods of flow, although riffles at these sites were dry from mid-June to mid-November. Pools which contained more gravel, indicating less disturbance during high flow, had a richer assemblage of benthic species than other pools. Many invertebrates in pools may have been there as a result of drift from their preferred riffle habitats, but the presence of gravel in the pools indicates less intense flow disturbance during floods, provides protection from the mild scouring that does occur during floods, and provides refugia from predators.
183 citations
TL;DR: In this paper, the authors developed sink models based on fundamental mass transfer theory to determine the magnitude and rate of adsorption and desorption of vapour phase organic compounds for several materials including carpet, painted wallboard, ceiling tile, window glass, and upholstery.
Abstract: The interaction of indoor air pollutants with interior surfaces (i.e., sinks) is a well known, but poorly understood, phenomenon. Studies have shown that re-emissions of adsorbed organic vapours can contribute to elevated concentrations of organics in indoor environments. Research is being conducted in small environmental test chambers to develop data for predicting sink behaviour. This paper reports on the development of sink models based on fundamental mass transfer theory. The results of experiments conducted to determine the magnitude and rate of adsorption and desorption of vapour phase organic compounds for several materials are presented. Five materials were evaluated: carpet, painted wallboard, ceiling tile, window glass, and upholstery. Two organic compounds were tested with each material: tetrachloroethylene (a common cleaning solvent) and ethylbenzene (a common constituent of petroleum-based solvents widely used in consumer products). The results of the experimental work are presented showing the relevant sink effect parameters for each material tested and comparing the sorptive behaviour of the two organic compounds evaluated. An indoor air quality (IAQ) model was modified to incorporate adsorption and desorption sink rates. The model was used to predict the temporal history of the concentration of total vapour phase organics in a test house after application of a wood finishing product. The predicted results are presented and compared to measured values. Suggestions for further research on indoor sinks are presented.
178 citations
TL;DR: For instance, this paper found that adolescents who perceived greater attachment to parents reported less depression and social anxiety as well as more positive perceptions of family expressiveness and cohesion, while pubertal maturity did not appear to moderate the buffering effects of attachment.
Abstract: The purpose of this study was to empirically examine the emotional distancing and buffering hypotheses. The sample was composed of 231 seventh graders (133 females and 98 males). Each adolescent completed a battery of questionnaires yielding measures of perceived attachment to mother and father, pubertal status, family expressiveness and cohesion, and feelings of depression and social anxiety. The emotional-distancing hypothesis was supported in that perceived attachment to parents was found to diminish with advanced pubertal maturity. The buffering hypothesis was also supported in that adolescents who perceived greater attachment to parents reported less depression and social anxiety as well as more positive perceptions of family expressiveness and cohesion. However, pubertal maturity did not appear to moderate the buffering effects of attachment. Results are discussed in terms of the need to further explore socialization processes associated with the child's transition into early adolescence.
162 citations
TL;DR: This example, and several others in Gossypium as well as other genera, attest to the evolutionary possibility of interspecific cytoplasmic transfer, and perhaps the origin of diploid species via reticulate speciation, without long‐term survival of nuclear genes from the maternal progenitor.
Abstract: Interspecific hybridization and introgression are important evolutionary processes in plants, but their full significance with respect to speciation at the diploid level remains unresolved. In this study, molecular markers from the plastid and nuclear genomes were used to document an unusual evolutionary history of Gossypium bickii Prokh. (Malvaceae). This species is one of three morphologically similar Australian cottons (along with G. austrate F. Muell. and G. nelsonii Fryx.) in section Hibiscoidea. In contrast to expectations based on previous morphological data, cladistic analysis of maternally inherited cpDNA restriction site mutations unites G. bickii with G. sturtianum J. H. Willis, a morphologically distant species in a different taxonomic section (Sturtia). Few restriction site mutations distinguish the plastomes of G. bickii and G. sturtianum, but these two cpDNAs are differentiated from those of G. australe and G. nelsonii by a minimum of 33 mutations (out of 640 sites scored). These two highly distinct clades are not supported by phylogenetic analyses of allozyme markers (from 58 populations) and restriction site mutations in nuclear ribosomal DNAs. Rather, phylogenies based on 83 nuclear markers indicate that G. bickii shares a more recent common ancestor with G. australe and G. nelsonii than it does with G. sturtianum. We suggest that the striking discrepancy between independent molecular phylogenies from two different genomes indicates a biphyletic ancestry of G. bickii. Our preferred hypothesis involves an ancient hybridization, in which G. sturtianum, or a similar species, served as the maternal parent with a paternal donor from the lineage leading to G. australe and G. nelsonii. Because we detected no G. sturtianum nuclear genes in G. bickii, we suggest that the nuclear genomic contribution of the maternal parent was subsequently eliminated from the hybrid or its descendent maternal lineage. Several possible mechanisms of cytoplasm transfer are suggested, including repeated backcrossing of the hybrid, as female, into the paternal donor lineage, selection against recombinant nuclear genomes and a form of apomixis known as semigamy. This example, and several others in Gossypium as well as other genera, attest to the evolutionary possibility of interspecific cytoplasmic transfer, and perhaps the origin of diploid species via reticulate speciation. In addition, this study offers an example of natural cytoplasmic introgression without long-term survival of nuclear genes from the maternal progenitor.
137 citations
TL;DR: In this paper, the 1,4-phenylene bis(dithiadiazolium) and bis(diselenadiazolinium) dichlorides were shown to be monoclinic, space group P2{sub 1}/n.
Abstract: The reactions of 1,4-phenylenebis(N,N,N{prime}-tris(trimethylsilyl)amidine) with sulfur and selenium dichlorides yield, respectively, the 1,4-phenylenebis(dithiadiazolium) and bis(diselenadiazolium) dichlorides 1,4-((E{sub 2}N{sub 2}C)C{sub 6}H{sub 4}(CN{sub 2}E{sub 2}))Cl{sub 2} (E = S, Se). Reduction of these materials with triphenylantimony affords the corresponding diradical species 1,4-((E{sub 2}N{sub 2}C)C{sub 6}H{sub 4}(CN{sub 2}E{sub 2})), which can be purified by high vacuum sublimation. The crystal structures of 1,4-((E{sub 2}N{sub 2}C)C{sub 6}H{sub 4}(CN{sub 2}E{sub 2})) (E = S, Se) are both monoclinic, space group P2{sub 1}/n. The crystal packing consists of sheets of interleaved columns of weakly associated diradical units (dimers); the mean intradimer separation is 3.34/3.37 {angstrom} (E = S/Se). The sulfur compound is an insulator, but the selenium material has a room temperature pressed pellet resistivity of about 100 {Omega} cm. Magnetic susceptibility measurements show the solids to be predominantly diamagnetic with variable amounts of paramagnetic defects in the lattice. While the exact mechanism of conduction remains to be established, these systems represent the first structurally characterized conducting materials constructed from neutral molecular radicals.
128 citations
TL;DR: It is shown that C{sub 60} has a low dielectric constant and an optical spectrum rich in structures; this is drastically different from diamond and graphite.
Abstract: The electronic and optical properties of C{sub 60} in the fcc lattice have been studied by a first-principles method. It is shown that C{sub 60} has a low dielectric constant and an optical spectrum rich in structures; this is drastically different from diamond and graphite. The spectrum shows five disconnected absorption bands in the 1.4 to 7.0 eV region with sharp structures in each band that can be attributed to critical-point transitions. This is a manifestation of the localized molecular structure coupled with long-range crystalline order.
TL;DR: Differences in life expectancy by sex appear to be due, in part, to cigarette smoking, but also to occupational, environmental, and sociodemographic factors.
TL;DR: The results indicate that the amount of degenerative change in the auricular surface is not dependent upon race or sex in any given age category.
Abstract: A recently developed technique used in the estimation of age at death is based upon the metamorphosis of the auricular surface of the ilium This technique was designed to be used in seriation to estimate the age distribution of a skeletal sample However, the technique has also been used in forensic science cases, which must be analyzed on a case-by-case basis The present study examines the use of the auricular surface technique as the single aging factor Two hypotheses are tested using a sample of 189 individuals drawn from the Terry Collection, housed at the Smithsonian Institution The hypotheses are (1) is the method equally applicable across race and sex, and (2) how well does the method perform as the single aging factor? The results indicate that the amount of degenerative change in the auricular surface is not dependent upon race or sex in any given age category However, the rate of degenerative change is too variable to be used as a single criterion for the estimation of age; the range of estimation error is simply too large for forensic science purposes
TL;DR: A new technique for the detection of amino-acids is described, which is based on their chemiluminescence reaction with tris(2,2'-bipyridyl)ruthenium(III), with the aim of finding the optimum signal to noise ratio.
TL;DR: In this article, the authors examined interorganizational relations between the US Forest Service, chambers of commerce, and tourism associations adjacent to an Arkansas National Forest and found that lack of cooperative relations among tourism organizations across all organizations was one of the main reasons for the lack of cooperation.
TL;DR: In this article, anaerobic filters have been used for almost twenty years to treat a variety of industrial wastes, yet until recently little was known about the factors affecting their design and performance.
TL;DR: In this article, the electrical single particle aerodynamic relaxation time (E-SPART) analyzer was used to measure aerodynamic size and electrostatic charge distribution of particles in real time and on a single-particle basis.
Abstract: Performance characteristics of a laser-based instrument called the electrical-single particle aerodynamic relaxation time (E-SPART) analyzer for measuring aerodynamic size and electrostatic charge distribution of particles in real time and on a single-particle basis are described. Applications of this analyzer along with experimental data of the characterization of different toners for their size and charge distributions are presented, including operational principles and methods of data acquisition. Size distribution ranged from 2.0 to 20.0 mu m in aerodynamic diameter, and the charge-to-mass distribution ranged from 0 to +or-20 mu C/g. The method is noncontact and provides both magnitude and polarity of electrostatic charge on an individual particle basis. The aerodynamic diameter and charge are measured simultaneously at an average count rate of approximately 100 particles/s. >
TL;DR: The synthesis of (4-bromomethyl-4'-methylbipyridine]ruthenium(II) hexafluorophosphate is described and a new reagent was found to selectively label the single sulfhydryl group at Cys-102 on yeast iso-1-cytochrome c to form the Ru-102-cyt c derivative.
Abstract: The synthesis of (4-bromomethyl-4'-methylbipyridine) [bis(bipyridine)]ruthenium(II) hexafluorophosphate is described This new reagent was found to selectively label the single sulfhydryl group at Cys-102 on yeast iso-1-cytochrome c to form the (dimethylbipyridine-Cys-102-cytochrome c)[bis(bipyridine)]ruthenium derivative (Ru-102-cyt c) Excitation of Ru-102-cyt c with a short light flash resulted in formation of excited-state Ru(II*), which rapidly transferred an electron to the ferric heme group to form Fe(II) When the cytochrome c peroxidase compound I (CMPI) was present in the solution, electron transfer from photoreduced Fe(II) in Ru-102-cyt c to the radical site in CMPI was observed At high ionic strength (100 mM sodium phosphate and 25 mM EDTA, pH 7), second-order kinetics were observed with a rate constant of (75 +/- 07) x 10(7) M-1 s-1 The second-order rate constant for native iso-1-cytochrome c was (67 +/- 07) x 10(7) M-1 s-1 under these conditions The second-order rate constant for electron transfer from Ru-102-cyt c to the radical site in CMPI increased as the ionic strength was decreased, reaching a value of (48 +/- 05) x 10(8) M-1 s-1 in 40 mM EDTA, pH 7 At lower ionic strength, a complex was formed between Ru-102-cyt c and CMPI, and the rate for intracomplex electron transfer to the radical site was found to be greater than 50,000 s-1(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: The epitope of MAb C11E9 binding site was shown to be protein in nature and reacted with one major protein band in Western blot from acid-urea PAGE for both L. monocytogenes and L. innocua.
Abstract: BALB/c mice were immunized with crude cell surface proteins of Listeria monocytogenes V7. Approximately 1,680 hybridomas were generated after two fusions, and the monoclone C11E9 was selected and used for further characterization. The monoclonal antibody (MAb) produced by C11E9 was immunoglobulin subclass G2b with kappa light chains. Dot and colony blot results indicated that MAb C11E9 was reactive to all the L. monocytogenes (34 of 34) and Listeria innocua (6 of 6) isolates without any cross-reaction to other organisms tested. Western blot (immunoblot) analysis of crude cell surface proteins in native polyacrylamide gel electrophoresis (PAGE) indicated that MAb C11E9 reacts with a single band in each species, with a molecular mass of 174 kDa for L. monocytogenes and 182 kDa for L. innocua. The MAb reacted with one major protein band in Western blot from acid-urea PAGE for both L. monocytogenes and L. innocua. Isoelectric focusing results indicated two immunoreactive protein bands with pIs of 8.1 and 7.4 for L. monocytogenes. Sodium dodecyl sulfate (SDS)-PAGE and Western blot analysis indicated several proteins with molecular masses of 76, 66, 56, and 52 kDa for L. monocytogenes and 66, 56, and 52 kDa for L. innocua. Reaction of MAb C11E9 to washed live cells indicated the possible binding of antibody to cell surface antigen. These cell surface antigens could be removed by 1 N HCl plus 9 M urea, 2% SDS-0.5% beta-mercaptoethanol, or 4 M guanidine-HCl. The epitope of MAb C11E9 binding site was shown to be protein in nature. Periodic acid-Schiff staining and glycoprotein immunoassay indicated that carbohydrate was absent in the epitope. The cellular locations of the MAb C11E9-reactive antigens were calculated to be 76 and 90% outside and 24 and 10% inside the cell membranes of L. monocytogenes and L. innocua, respectively, for 12- to 14-h cultures.
TL;DR: In this paper, the preparation and solid-state characterization of 1,3-phenylene-bridged bis(dithiadiazolyl) and bis(diselenadiazyl) diradicals (E = S, Se) are reported.
Abstract: The preparation and solid-state characterization of the 1,3-phenylene-bridged bis(dithiadiazolyl) and bis(diselenadiazolyl) diradicals 1,3-[(E2N2C)C6H4(CN2E2)] (E = S, Se) are reported. The isomorphous crystals of 1,3-[(E2N2C)C6H4(CN2E2)] so obtained are tetragonal, space group I41/a. Stacks of diradical molecules, linked vertically in a zigzag fashion through alternaie ends by long E- - -E contacts (mean 3.140/3.284 A, for E = S/Se), are arranged in pinwheellike clusters about the 41 and ¯4 axes, producing complex patterns of interstack E- - -E contacts. Both compounds show the presence of spin defects in the lattice, and there is a very large enhancement in the paramagnetism of the sulfur compound at high temperatures. The selenium compound is a semiconductor, with a room temperature conductivity of 2 × 10-4 S cm-1. Solid-state NMR experiments find enhanced relaxation times, which have their origin in the presence of a mobile paramagnetic defect. Extended Huckel band structure calculations show the materials to be semiconductors, with band gaps of about 1.0/0.8 eV for E = S/Se. Although the compounds adopt a columnar structure, the calculations indicate significant interactions between the stacks and the materials exhibit well-developed three dimensionality. The enhanced paramagnetism in the sulfur compound is attributed to the presence of thermally generated phase kinks in the lattice, whereas the selenium compound is classified as an intrinsic semiconductor.
TL;DR: There was considerable overlap in the patterns of personality traits that characterized the Type A components, but only a Hostility dimension was significantly related to physiological reactivity and recovery.
Abstract: The nomological validity of the Type A behavior pattern was explored. The Structured Interview (SI) and a battery of personality trait, physical health, and strain measures were administered to an occupationally diverse sample of 568 workers. Ss were also monitored for physiological reactivity and recovery (blood pressure, heart rate, skin temperature, and electrodermal response) to the SI and a subsequent Stroop Color-Word Conflict Task. A confirmatory factor analysis demonstrated that SI scores can be factored into three distinct dimensions. There was considerable overlap in the patterns of personality traits that characterized the Type A components, but only a Hostility dimension was significantly related to physiological reactivity and recovery. The results have implications for distinguishing coronary-proneness from the more traditional Type A conceptualization.
TL;DR: In this article, the performance of both dispersed gas phase and dispersed liquid phase systems under both mass transfer controlled and non-mass transfer controlled conditions was examined. But the performance was limited to a few minutes for these gaseous substrate fermentations.
TL;DR: Reuults support the hypothesis that acceptance of parasitism may be adaptive when the costs of rejection outweigh the cost of acceptance of parasite eggs, and suggest prothonotary warbler females may usually be forced to accept cowbird parasitism as a consequence of nest-site limitation.
TL;DR: Dietary fumaric acid had no adverse effects on dressing percentage, abdominal fat content, or mortality rate in broiler chickens; feed utilization was improved by the addition of all levels of f Kumaric acid.
01 Jan 1991
TL;DR: In this article, the induced thermoluminescence (TL) properties of 69 type-3 ordinary chondrites were reported, bringing to 125 the number of known types for which TL data are available.
Abstract: The present study reports recent measurements of the induced thermoluminescence (TL) properties of 69 type-3 ordinary chondrites, bringing to 125 the number of type-3 ordinary chondrites for which TL data are available. The samples include several of the particularly low petrographic type and many breccias, some of them gas-rich. The significance of the data with respect to the physical conditions affecting metamorphism is discussed. The TL data, olivine heterogeneity, carbon content, and inert-gas content were used to assign the samples to petrologic types. Twelve meteorites were identified as being type 3.0-3.2, and 10 of the breccias were found to contain material that may also be of this type. The temperature and width of the induced TL peak are also related to thermal history, with type 3.2-3.4 chondrites tending to have narrower peaks at lower glow curve temperatures than the type 3.6-3.9 chondrites. Type 3 H chondrites were found to be a higher petrographic type than the type 3 L and LL chondrites.
TL;DR: The results indicate that AF directly or indirectly affects Ca and Pi metabolism in avians, and the effects may be related to altered vitamin D and parathyroid hormone (PTH) metabolism.
Abstract: Experiments were designed to determine the effects of aflatoxicosis on avian renal function, calcium (CA), inorganic phosphorous (P1), and vitamin D metabolism, and to determine if the effects of aflatoxin are reversible upon discontinuation of toxin administration. Three‐week‐old male broiler chickens (n = 12 per treatment) received aflatoxin (AF; 2 mg/kg po) or an equal volume of corn oil, the AF carrier vehicle, for 10 consecutive days. After 10 d of treatment, half of the birds from each treatment group were anesthetized and prepared for renal function analysis, which included a 2‐h phosphate loading period. Ten days after discontinuation of AF treatment, the remaining birds in each treatment group were anesthetized and prepared for renal function analysis. AF decreased plasma 25‐hydroxy vitamin D [25(OH)D] and 1,25‐dihydroxy vitamin D [1,25(OH)2D] levels after 5 d of treatment. After 10 d of treatment, urine flow rate (V), fractional sodium excretion (FENa), and fractional potassium excretion (FEK) w...
Journal Article•
TL;DR: Logistic regression analyses revealed that adolescent pregnancy status was a function of a combination of demographic and familial variables, and adolescents who were pregnant at the time of the study perceived their families as having low levels of family strength, perceived communication with parents as closed, and were more likely to be married than their nonpregnant counterparts.
Abstract: The differences in demographic characteristics sexual practices perceptions of family functioning and individual factors among pregnant and nonpregnant adolescents were studied. 124 sexually active adolescent Caucasian females aged 12-19 years from an Arkansas clinic of which 57% were pregnant participated in a nonrandom sample in 1988-89. 62.1% were from disrupted families (39.5% divorced 12.9% remarried and 9.7% widowed). Family disruption was higher among the pregnant sample (72% vs. 50.8%). 16.9% of the total sample were high school dropouts but the majority were in the pregnant sample (28% vs. 5%). 91% of the pregnant sample had a family income of <$20000 vs. 66% of the nonpregnant sample. The procedures and instruments used are described. The following questionnaires were involved: 1) a demographic questionnaire for age race educational and marital status parents marital status and socioeconomic status; 2) a sexual history questionnaire for pregnancy status use of birth control prior pregnancies and outcomes and frequency of sexual activity; and 3) the Family Adaptability and Cohesion Evaluation Scale the Family Strengths Questionnaire the Parent Communication Scale and the Adolescent Self-Esteem Scale. Stepwise logistic regression and chi square tests were used to predict pregnancy status. 6 variables out of 11 were significantly related to pregnancy status: lower perception of family strengths problems with parent communication married low family income birth control and single parent or no parent family composition. 80% of pregnant and nonpregnant teens were predicted. The mean for perception of family strengths for pregnant vs. nonpregnant adolescents was 33.29 vs. 39.87 which means for pregnant teens a perception of a lack of pride and harmony in their families. Lower scores were also evident on the Parent Communication Scale (-1.22 vs. 2.62). Although not significant pregnant adolescents saw their families as flexible but not very cohesive and had lower self-esteem scores. Nonpregnant adolescents were more likely to use birth control than pregnant adolescents. The results support prior findings with some variation in the effect of parent and child communication and insignificant effects of perception of family adaptability and self-esteem. The limitations are the lack of generalizability to other regions and the model itself which did not assess familial factors such as parental control or other developmental factors such as self-worth. Causality is not determined.
TL;DR: Photoperiod influenced nymphal development and diapause induction in a laboratory culture of Orius insidiosus and duration of the preoviposition period was inversely related to photoperiod.
Abstract: Photoperiod influenced nymphal development and diapause induction in a laboratory culture of Orius insidiosus (Say). At 20°C, development of nymphs was significantly faster at a photoperiod of 10:14 (L:D) than at 12:12, 13:11, 14:10, or 15:9. Subsequently, diapause induction exhibited a typical long-day response; nearly 100% of adult females entered reproductive diapause when reared under short photoperiods (10:14 [L:D]), whereas at longer photoperiods (12:12, 13:11, 14:10, 15:9 [L:D]), fewer insects initiated diapause (56.8, 29.7, 5.3, 12.9%, respectively). The critical photoperiod fell between 12:12 and 13:11 (L:D). Duration of the preoviposition period was inversely related to photoperiod.
TL;DR: In this paper, the influence of distinct pool and riffle geomorphology on the longitudinal zonation of macroinvertebrate species assemblages and functional group classification was studied.
Abstract: An Ozark Plateau stream was studied to determine the influence of distinct pool and riffle geomorphology on the longitudinal zonation of macroinvertebrate species assemblages and functional group classification. All study sites were dominated by alluvial pool and riffle channel form and the first two orders became intermittent during summer months. Nine benthos samples were collected seasonally from riffles and pools at each of five sites using a vacuum benthos sampler. Diel temperature pulse and coarse particulate organic matter (CPOM) were measured at each site also. Water temperature was most variable in second order, and CPOM on riffles was not more abundant in upstream reaches. Annual average density and biomass of invertebrates were highest in third and fourth orders, respectively. Diversity was depressed in the intermittent headwaters sites. Macroinvertebrate functional groups did not exhibit strong longitudinal trends as predicted by the river continuum model, with species assemblages apparently more strongly affected by the segment-level physical template, although shredders were more abundant in the headwaters during fall and winter. This study indicates that a reach-level perspective based on channel form is a necessary complement to holistic stream ecosystem models, especially in alluvial gravel streams.