Showing papers by "San Diego State University published in 1993"
TL;DR: In this article, a new model, called cultural dynamics, articulates the processes of manifestation, realization, symbolization, and interpretation and provides a framework within which to discuss the dynamism of organizational cultures.
Abstract: Schein's (1985) model of organizational culture as assumptions, values, and artifacts leaves gaps regarding the appreciation of organizational culture as symbols and processes. This article examinee these gaps and suggests a new model that combines Schein's theory with ideas drawn from symbolic-interpretive perspectives. The new model, called cultural dynamics, articulates the processes of manifestation, realization, symbolization, and interpretation and provides a framework within which to discuss the dynamism of organizational cultures. Implications of the cultural dynamics model for collecting and analyzing culture data and for future theoretical development are presented.
1,083 citations
TL;DR: This article found that the tundra on the North Slope of Alaska has indeed become a source of carbon dioxide to the atmosphere and that this change coincides with recent warming in the Arctic, whether this is due to increases in greenhouse gas concentrations in the atmosphere or to some other cause.
Abstract: ARCTIC tundra has been a net sink for carbon dioxide during historic and recent geological times1–4, and large amounts of carbon are stored in the soils of northern ecosystems. Many regions of the Arctic are warmer now than they have been in the past5–10, and this warming may cause the soil to change from a carbon dioxide sink to a source by lowering the water table11–12, thereby accelerating the rate of soil decomposition (CO2 source)3,13–15 so that this dominates over photosynthesis (CO2 sink). Here we present data indicating that the tundra on the North Slope of Alaska has indeed become a source of carbon dioxide to the atmosphere. This change coincides with recent warming in the Arctic, whether this is due to increases in greenhouse gas concentrations in the atmosphere or to some other cause. Our results suggest that tundra ecosystems may exert a positive feedback on atmospheric carbon dioxide and greenhouse warming.
926 citations
TL;DR: The nearest-level-spacing distribution function P(s) in a disordered system near the metal-insulator transition is studied and a scaling theory of critical behavior of P(S) in finite samples is proposed and verified numerically.
Abstract: We study the nearest-level-spacing distribution function P(s) in a disordered system near the metal-insulator transition. We claim that in the limit of an infinite system there are only three possible functions P(s): Wigner surmise ${\mathit{P}}_{\mathit{W}}$(s) in a metal, Poisson law ${\mathit{P}}_{\mathit{P}}$(s) in an insulator, and a third one ${\mathit{P}}_{\mathit{T}}$(s), exactly at the transition. The function ${\mathit{P}}_{\mathit{T}}$ is an interesting hybrid of ${\mathit{P}}_{\mathit{W}}$(s) and ${\mathit{P}}_{\mathit{P}}$(s), it has the small-s behavior of the former and the large-s behavior of the latter one. A scaling theory of critical behavior of P(s) in finite samples is proposed and verified numerically.
426 citations
TL;DR: Variables observed concurrently with physical activity, such as time spent outdoors and prompts to be active, were highly associated with children's physical activity.
Abstract: Twenty-two potential correlates of children's physical activity were examined Two hundred and one Mexican-American and 146 Anglo-American families with 4-year-old children were studied Children's physical activity was directly observed in the evening at home on 4 visits for 1 hr each time Anglo-American children and male children were found to be more active Demographic variables explained 11% of the variance in children's physical activity After adjusting for demographics, 3 children's variables and 6 social-family variables did not account for significantly more variance Five environmental variables accounted for 11% additional variance Variables observed concurrently with physical activity, such as time spent outdoors and prompts to be active, were highly associated with children's physical activity
414 citations
TL;DR: Variations in physical activity and aerobic power are examined in relation to age and gender of children and adolescents to suggest that older youth and females are at increased risk of obesity because of a sedentary lifestyle.
Abstract: Variations in physical activity and aerobic power are examined in relation to age and gender of children and adolescents. Reviews of the world literature show aerobic power relative to body mass remains stable from ages 6 to 16 for males, but for females it declines about 2% per year. Overall, males are about 25% more fit than females. Reviews of nine studies using standardized self‐reports or objective measures of physical activity revealed that males are about 15 to 25% more active than females. Over the school age years, a consistent decline in physical activity is seen, with males decreasing about 2.7% per year and females decreasing about 7.4% per year. These data suggest that older youth and females are at increased risk of obesity because of a sedentary lifestyle.
408 citations
TL;DR: In this paper, a multiple scattering correction was calculated from optical density spectral for 48 phytoplankton cultures of seven species representing a variety of cell sizes, pigment groups, and call-wall types.
Abstract: : Absorption spectra measured for aquatic particles concentrated onto glass-fiber filters require a correction for the increase in pathlength caused by multiple scattering in the glass-fiber filter. A multiple scattering correction was calculated from optical density spectral for 48 phytoplankton cultures of seven species representing a variety of cell sizes, pigment groups, and call-wall types. The relationship between optical density in suspensions and on filters was not wavelength-dependent. Differences between blank filters were always spectrally neutral. Small differences between relationships for single species were inconclusive. Given the absence of wavelength-dependent effects, we report a single general quadratic relationship, OD(susp)(lambda) = 0.378 OD(filt)(lambda) + 0.523 OD(filt)(lambda)2 (r2 = 0.988), for correcting glass- fiber filter spectra. For independent samples, the average error in predicting OD(susp)(lambda) with this algorithm at any wavelength was 2%. Greatest errors were in spectral regions of low absorption. Absorption spectra for particles concentrated onto glass-fiber filters can be quantitatively corrected for multiple scattering within this limit. Applicability of the algorithm to field samples of varied composition was enhanced by using a large number of spectra and a range of cell types in algorithm development. Optical oceanography, Physical oceanography, Absorption, Scattering.
375 citations
Posted Content•
TL;DR: In this article, the authors examined the relation between managerial ownership and the probability of being a target firm, and the impact of managerial ownership on target shareholder returns, and found that targets have lower managerial ownership than either their industry counterparts or randomly selected nontargets.
Abstract: This paper examines the relation between managerial ownership and the probability of being a target firm, and the impact of managerial ownership on target shareholder returns. The paper finds that targets have lower managerial ownership than either their industry counterparts or randomly selected nontargets. Managerial ownership is significantly lower in contested compared to uncontested offers, and in unsuccessful compared to successful cases. Managerial ownership is significantly related to abnormal returns in contested cases that are ultimately successful. The results are consistent with a positive impact of managerial ownership where it is used to negotiate, but not ultimately block, an acquisition.
305 citations
TL;DR: Results show that the trajectories of development are very similar for Spanish- and English-speaking children in this age range, that children from varying social groups develop similarly, and that mail-in and personal interview administration techniques produce comparable results.
Abstract: This paper describes the early lexical development of a group of 328 normal Spanish-speaking children aged 0;8 to 2;7. First the development and structure of a new parent report instrument, Inventario del Desarollo de Habilidades Communicativas is described. Then five studies carried out with the instrument are presented. In the first study vocabulary development of Spanish-speaking infants and toddlers is compared to that of English-speaking infants and toddlers. The English data were gathered using a comparable parental report, the MacArthur Communicative Development Inventories. In the second study the general characteristics of Spanish language acquisition, and the effects of various demographic factors on that process, are examined. Study 3 examines the differential effects of three methods of collecting the data (mail-in, personal interview, and clinic waiting room administration). Studies 4 and 5 document the reliability and validity of the instrument. Results show that the trajectories of development are very similar for Spanish- and English-speaking children in this age range, that children from varying social groups develop similarly, and that mail-in and personal interview administration techniques produce comparable results. Inventories administered in a medical clinic waiting room, on the other hand, produced lower estimates of toddler vocabulary than the other two models.
248 citations
TL;DR: Methods for identification and control of dynamical systems by adalines, two-layer, and three-layer feedforward neural networks (FNNs) using generalized weight adaptation algorithms are discussed and the effect that the type of nonlinear activation functions present in the neurons and in the weight adaptation algorithm have on FNN system dynamics identification performance is investigated.
Abstract: Methods for identification and control of dynamical systems by adalines, two-layer, and three-layer feedforward neural networks (FNNs) using generalized weight adaptation algorithms are discussed. The FNNs considered contain odd nonlinear operators in both the neurons and the weight adaptation algorithms. Two application examples, each involving a nonlinear dynamical system, are considered. The first is identification of the system's forward and inverse dynamics. The second is control of the system using coordination of feedforward and feedback control combined with inverse system dynamics identification. Simulation results are used to verify the method's feasibility and to examine the effect of ENN parameter changes. Specifically the effect that the type of nonlinear activation functions present in the neurons and the type of nonlinear functions present in the weight adaptation algorithms have on FNN system dynamics identification performance is investigated. >
243 citations
TL;DR: Two self-report formats were found to have modest levels of reliability and validity with 4th grade children when administered in a classroom setting, highlighting the limitations of children's self-reports.
Abstract: This study evaluates the test-retest reliability and validity of self-report measures of physical activity that can be self-administered in classroom settings to 4th grade students. Four different self-report formats were tested on 66 students. To assess test-retest reliabilities, self-report measures were administered on two occasions, separated by a 3-day interval between Time 1 (Friday) and Time 2 (Monday). One-way model intraclass reliabilities ranged from .51 to .74. Three days of monitoring with the Caltrac accelerometer were used as the validity criterion. Only one of the three-weekly recalls, the Weekly Activity Checklist, was supported by significant validity correlations at both Time 1 (r = .34, p < .01) and Time 2 (r = .26, p < .05). The 1-day recall, Yesterday Activity Checklist, correlated significantly (r = .33, p < .01) with the previous day's Caltrac monitor score. Although two of the physical activity recall formats were found to be superior to two others, these data highlight th...
218 citations
TL;DR: In this article, the authors present a case study illustrating the interpretive possibilities of combining humour analysis with the study of paradox and ambiguity as a means to address everyday experience in organizations. But humor is built on a foundation of recognized contradiction, incongruity and incoherence, and it seems plausible that humour points to dis course capable of revealing the nature and substance of paradox, and ambiguity is a topic of increasing interest to students of organization.
Abstract: Assuming that humour is built on a foundation of recognized contradiction, incongruity and incoherence, then it seems plausible that humour points to dis course capable of revealing the nature and substance of paradox and ambiguity- a topic of increasing interest to students of organization. This paper presents the method and results of a case study illustrating the interpretive possibilities of combining humour analysis with the study of paradox and ambiguity as a means to address everyday experience in organizations. Results are interpreted as indicating a paradox of control and the ambiguity of problem and solution thinking.
TL;DR: In this article, the authors used time series data based on 24 countries to estimate the net effect of government coercion on two types of dissident activities: protest demonstrations and deaths from domestic group violence.
Abstract: The dynamic effect of government coercion on dissident activities has been a controversial issue. It is contended that this relationship is significantly altered when different control variables such as regime type, ideological orientation, and economic performance are employed. Time series data based on 24 countries is used to estimate the net effect of government coercion on two types of dissident activities: protest demonstrations and deaths from domestic group violence. It is shown that in democratic nations, government sanctions provoke a higher level of protest demonstrations. However, in nondemocratic countries, at the extreme, severe sanctions can impose an unbearable cost, resulting in an inverse relationship between sanctions and political deaths. The nature of the regime influences not only the dynamics of the relationship between government coercion and dissident activities, but also the qualitative character of opposition response.
TL;DR: A variable structure systems approach and a geometric approach to the analysis and synthesis of system zeros are employed in the synthesis of the proposed controllers.
Abstract: A class of variable structure output feedback controllers for uncertain dynamic systems with bounded uncertainties is proposed. No statistical information about the uncertain elements is assumed. A variable structure systems approach and a geometric approach to the analysis and synthesis of system zeros are employed in the synthesis of the proposed controllers. >
TL;DR: It is demonstrated that levels ofuanosine 3',5'-bispyrophosphate similar to those induced by amino acid starvation inhibit the rate of protein synthesis by 84-91%.
TL;DR: The authors conducted a four-day teaching experiment on complex additively-structured problems, which was followed by in-depth interviews of individual children to investigate children's difficulties in holding in mind at once situations in which one or more items played multiple roles.
Abstract: Six fifth-grade children participated in a four-day teaching experiment on complex additively-structured problems, which was followed by in-depth interviews of individual children. The teaching experiment was meant to investigate children's difficulties in holding in mind at once situations in which one or more items played multiple roles. Two important difficulties were identified: (1) distinguishing between “difference” as the result of subtracting and “difference” as the amount by which one quantity exceeded another; and (2) indirect evaluation of an additive comparison. Sources of these difficulties, along with pedagogical and curricular recommendations for addressing them, are discussed.
TL;DR: It is concluded that, under conditions of heightened expectations, the power of nonspecific effects far exceeds that commonly reported in the literature.
TL;DR: To establish population‐based data, with special emphasis on the effects of age, gender, and education, for eight, widely used neuropsychological tests in a community‐dwelling cohort of normal and cognitively impaired older adults.
Abstract: Objective: To establish population-based data, with special emphasis on the effects of age, gender, and education, for eight, widely used neuropsychological tests in a community-dwelling cohort of normal and cognitively impaired older adults.
Design: A population-based observational study.
Setting: Examinations were performed in a research clinic by specially trained staff during a 1988–1992 evaluation for osteoporosis.
Participants: 1,692 community-dwelling subjects, aged 55 to 94 years, who were members of the Rancho Bernardo Heart and Chronic Disease Study initiated in 1972. The mean age for men was 73.9 years (SD 9.3) and for women, 73.5 (SD 9.1).
Outcome measures: Eight neuropsychological tests were used to measure cognitive functions. Analysis of variance and post hoc contrasts were performed to determine the effects of age, gender, education, and their interactions on performance on these tests.
Results: Performance on all tests decreased progressively, without leveling off, from the youngest, age 55, to the oldest, age 94. Women performed better on verbal tasks and men on tests of visuospatial, visuoconceptual, and mental control functions. Performances of men on several tests declined more rapidly with advancing age than those of women. Both men and women with some college education performed better on most tests than men and women with high school educations, and the rate of decline with age was sometimes slower in the college-educated group. Only the savings score from the Visual Reproduction Test, which is a measure of rate of forgetting, and the scores of short-term recall derived from the Selective Reminding Test (Buschke-Fuld) were unaffected by educational attainment.
Conclusions: In a community-dwelling cohort, including normal and cognitively impaired elderly men and women, advancing age is accompanied by decline in cognitive functions as measured by neuropsychological tests. This decline is slower in women and in college-educated subjects. Two cognitive indices were unaffected by education, and these may be especially useful in cross-cultural studies.
TL;DR: Findings suggest that the old- old in general and old-old men in particular are especially vulnerable to psychological distress when losing friend support, and to lose friend support when experiencing psychological distress.
Abstract: In this study, the relationships among age, sex, friend support, and psychological distress are examined among elderly persons. Structural equation modeling and a longitudinal design are used to examine direct, indirect, and moderator (interaction) effects over a 22-month interval. Findings suggest that different causal processes operate among persons over the age of 70 (old-old) and those 50 to 70 years (young-old); the cross-lagged effects of friend support on distress and of distress on friend support are only observed in the older group. Compared to the young-old, the old-old receive less friend support at time 2 (T2) if they experienced psychological distress at time 1 (T1), and the old-old are more distressed at T2 if they received low levels of support at T1. As a result of this age interaction, the total effects of sex on distress and support at T2 are twice as large in the sample of old-old persons as in the sample of young-old persons. Such findings suggest that the old-old in general and old-old men in particular are especially vulnerable to psychological distress when losing friend support, and to lose friend support when experiencing psychological distress. Implications of these and other findings are discussed.
TL;DR: This chapter discusses the ultrastructural and physiological properties of the diverse muscle types of Drosophila melanogaster and how genetic studies permit an understanding of muscle cell determination, myofibril assembly, and protein isoform function.
Abstract: In this chapter we discuss the ultrastructural and physiological properties of the diverse muscle types of Drosophila melanogaster and how genetic studies permit an understanding of muscle cell determination, myofibril assembly, and protein isoform function.
TL;DR: The objective was to determine the effects of resistance training on muscular strength, body composition, and program adherence in active women over 60 years of age.
Abstract: Objective: To determine the effects of resistance training on muscular strength, body composition (percent fat and lean tissue mass), and program adherence in active women over 60 years of age.
Design: This study was designed as a stratified, randomized, non-blinded trial. Subjects were stratified into rank-ordered pairs by level of physical activity according to the Blair Seven-Day Recall, then randomly assigned into either a weight-training (WT, n = 18) or control (CON, n = 18) group.
Participants and Setting: Thirty-six women over the age of 60 (67.1 ± 1.5, x ± SE) were recruited from the San Diego community. All subjects had to be engaging in some form of aerobic exercise at least 3 days each week for a minimum of 6 months.
Measurements and Intervention: Subjects engaged in isotonic training 3 days/week on Polaris machines at a target intensity of 80% of the 1 repetition maximum (1 RM) for three sets of seven exercises selected to train major muscle groups of the trunk and upper and lower body. The 1 RM was re-tested every 6 weeks in WT and the workload adjusted to maintain target intensity. The 1 RM was tested at 0, 12, and 24 weeks in CON. Body fatness and lean tissue mass, excluding skeletal mass, were assessed at 0 and 24 weeks by dual energy radiography using a total body scan.
Results: Increases in muscle strength of the weight trainers were significant for all seven exercises (5%–65%), with the greatest gains in the shoulder and trunk muscles. Percent body fat of weight trainers decreased significantly (from 38.8% to 37.9%, P < 0.05), while lean tissue mass increased by 1.5 kg (P < 0.01). No changes in body composition were observed in control subjects. Overall program adherence was 83% (15 weight trainers and 15 control women completed the study). Monthly attendance averaged 86.8 ± 3.3%, with no incidence of injury during the training sessions.
Conclusions: These data indicate that heavy-resistance weight training is safe and enjoyable for older women and that meaningful gains in muscular strength and body composition can be made even in women who are already highly active.
TL;DR: In this paper, the authors evaluated multiple effects of a health-related physical education (PE) program for elementary school students, and found a trend for the children exposed to the PE intervention to have lower levels of body fat, but the differences were not significant.
Abstract: Project SPARK evaluates multiple effects of a health-related physical education (PE) program for elementary school students. Seven schools were randomly assigned to one of three conditions: usual PE or control, trained classroom teachers, or PE specialists. The intervention was implemented throughout the fourth and fifth grades. Data are available from one cohort of 550 children who were measured in the fall and spring of both grades. Adiposity was assessed by triceps and calf skinfolds, and body mass index (BMI) was also measured. Data at each measurement point were analyzed by ANOVAs, covarying for baseline values. At no measurement point were there significant group differences in total skinfold. At both fifth grade measurement points for boys and girls, however, there was a trend for the control group to have higher skinfold values than the two intervention groups. At the final measure, the difference between the highest and lowest groups was about 3 mm for girls and 2 mm for boys. BMIs were significantly lower at some measurement points for boys and girls, but this could be due to increased lean body mass in intervention students. After two years, there was a trend for the children exposed to the PE intervention to have lower levels of body fat, but the differences were not significant.
TL;DR: In this paper, the microbial biomass of seven arctic tundra soils was measured using both the chloroform fumigation-extraction procedure (biomass-C and -N) and the substrate-induced respiration method (BiomassC only) to test the suitability of these two methods for organic and mineral arctic soils.
Abstract: Sammary-The microbial biomass of seven arctic tundra soils was measured using both the chloroform fumigation-extraction procedure (biomass-C and -N) and the substrate-induced respiration method (biomass-C only) to test the suitability of these two methods for organic and mineral arctic soils. Results indicate that in general the two methods gave consistent microbial biomass-C measurements. Microbial biomass-C, estimated by the fumigation-extraction procedure (using & = 0.35) was highly correlated (r = 0.831, P < 0.001) with the microbial biomass-C values measured by the substrate-induced respiration technique across all soil types. Microbial biomass-N of the seven arctic soils measured by the fumigation-extraction procedure showed a higher linear correlation with the biomass-C values produced by the substrate-induced respiration procedure (r = 0.88) than those produced by the fumigation-extraction procedure (r = 0.69). This result seems to suggest that the fumigation+xtraction procedure works better for microbial biomass-N measurements than for biomass-C in these arctic soil conditions. The fumigation-extraction and substrate-induced respiration methods, developed to study mostly temperate agricultural soils, can be successfully applied to arctic tundra soils.
TL;DR: There are significant age-associated changes in chemosensory perception that have the potential to interact with dietary selection and nutrition in the elderly.
Abstract: The elderly person's perception of foods and food flavor is affected by age‐associated changes in the chemical senses (taste, smell, and trigeminal sensation). Both classic and modern psychophysical techniques have been applied to achieve some understanding of these changes. Taste threshold sensitivity declines with age; however, the magnitude of the decline and the degree to which taste qualities are differentially affected remains to be understood. Suprathreshold taste intensity perception is affected by age, but there is a differential effect of taste quality. Experiments with blended foods have indicated that both olfactory and taste deficits contribute to older people's difficulty with food identification. Experiments assessing threshold sensitivity, suprathreshold intensity, and suprathreshold identification have all demonstrated significant impairment in olfaction in old age. In fact, these effects are far greater than in the taste system. Patients with Alzheimer's disease show even greate...
TL;DR: It is hypothesized that macroalgae efficiently sequestered low concentrations of N and outcompeted the other groups, so that only when N supply exceeded macroalgal demand was N available to theother groups.
Abstract: The relative importance of nitrogen and phosphorus limitation in shallow coastal lagoons was tested in replicate microcosms which were inoculaied in summer with three algal groups and subjected to four levels of nutrient enrichment in five N : P ratios (20 treatments, n = 4). A subset of 12 treatments was repeated in spring. Algal groups were green macrophytes, phytoplankton, and benthic mats of cyanobacteria with associated epiphytes. Nutrients limited biomass when supply was less than the demand of the total community (supply < 0.270 mg N liter-l d-l). For the wide range of N and P treatments, N limitation was much more common than P in summer (14 of 20 treatments); differential limitation was not as clear in spring. Althoughbiomass was never directly controlled by P, there were indications that P supply was more important to the cyanobacterial mats, especially in spring. While N directly controlled the biomass of macroalgae, macroalgae controlled the biomass of mats and phytoplankton. From this we hypothesize that macroalgae efficiently sequestered low concentrations of N and outcompeted the other groups. Only when N supply exceeded macroalgal demand was N available to the other groups. The differences among algal groups and the temporal variation in N and P limitation help explain the conflicting evidence for nutrient limitation.
TL;DR: Active children appear to engage in a sufficient variety of activities to enhance multiple components of health-related physical fitness.
Abstract: • Objective —To examine the relationship between habitual physical activity and components of health-related physical fitness in children Design —Cross-sectional survey with correlational analysis Setting —Seven public elementary schools in a suburban southern California city Participants —Five hundred twenty-eight healthy fourth-grade children (274 boys and 254 girls), 85% of whom were non-Hispanic whites Ninety-eight percent of eligible students participated Interventions —None Measurements/Main Results —Results of six measures of physical activity in children (monitoring by accelerometer, parent report, and child self-reports of weekday activity, weekend activity, and summer involvement in activity classes and youth sports) were combined in a physical activity index This index of habitual physical activity was examined in relation to measures of five components of health-related fitness: the mile run, skin-fold tests, pull-ups, sit-ups, and the sit-and-reach test The physical activity index was significantly associated with all five fitness components The canonical correlation was 29 Conclusion —Active children appear to engage in a sufficient variety of activities to enhance multiple components of health-related fitness (AJDC 1993;147:890-896)
TL;DR: In this article, the authors investigate the knowledge about image formation exhibited by students following instruction in geometrical optics in an activity-based college physics course for prospective elementary teachers and find that their knowledge can be described as an intermediate state, a hybridization of pre-instruction knowledge and formal physics knowledge.
Abstract: This paper reports on a study that was designed to investigate the knowledge about image formation exhibited by students following instruction in geometrical optics in an activity-based college physics course for prospective elementary teachers. Students were interviewed individually, using several tasks involving simple apparatus (plane and curved mirrors, lenses, and prisms). The diagrams drawn by the students and the verbal comments they made provide evidence that their knowledge can be described as an intermediate state, a hybridization of preinstruction knowledge (which is dominated by a holistic conceptualization) and formal physics knowledge. We infer from our data the core concepts and main ideas of the postinstruction students' hybrid knowledge. Finally, by comparing preinstruction and formal physics conceptualizations of image formation we argue that a strong type of knowledge restructuring (in the sense of Carey, S., 1986: American Psychologist, 41, 1123-1130; Vosianou, S., & Brewer, W.F., 1987: Review of Educational Research, 57, 51-67) is required for students to acquire the latter.
TL;DR: The curriculum and inservice program equipped trained classroom teachers to provide significantly better classes than were provided by controls in terms of student activity engagement, lesson context, and active instructional behavior, though their classes did not match the quality of those taught by the physical education specialists.
Abstract: The primary responsibility for engaging children in opportunities to be physically active and learn physical skills rests with school physical education. This study evaluated the effects of a combined health-related curriculum and inservice program on the quantity and quality of elementary school physical education lessons. Seven schools (N = 28 fourth-grade classes) in one district were randomly assigned to one of three conditions: 10 classes were taught in their usual manner by classroom teachers (Control [CO]); 10 classes were taught by trained classroom teachers (TT) who received inservice training and, follow-up consultations; and 8 classes were taught by physical education specialists (PES) hired by the research project. Student activity level, curriculum context, and teacher behavior were directly observed and coded during a sample of 112 lessons over an 8-month period. Results indicated significant differences in both the frequency and mean length of classes (PES, 26.7 min; TT, 23.4 min; ...
TL;DR: In this article, the statistical relations between spectral vegetation indices (SVIs) derived from SPOT multi-spectral data and semi-arid shrub cover at the Jornada LTER site in New Mexico were assessed.
Abstract: We assessed the statistical relations between spectral vegetation indices (SVIs) derived from SPOT multi-spectral data and semi-arid shrub cover at the Jornada LTER site in New Mexico. Despite a limited range of shrub cover in the sample the analyses resulted in r2 values as high as 0.77. Greenness SVIs (e.g., Simple Ratio, NDVI, SAVI, PVI and an orthogonal Greenness index) were shown to be more sensitive to shrub type and phenology than brightness SVIs (e.g., green, red and near-infrared reflectances and a Brightness index). The results varied substantially with small-scale changes in plot size (60 m by 60 m to 100 m by 100 m) as a consequence of landscape heterogeneity. The results also indicated the potential for the spectral differentiation of shrub types, and shrubs from grass, using multi-temporal, multi-spectral analysis.
TL;DR: It is concluded that the ontogenetic criterion is not a reliable indicator of phylogenetic polarity and it is recommended that alternative classification schemes be pursued.