Search
Search Results
-
4291. [Article] Cover crop effects on root rot of sweet corn and soil properties
Root rot of sweet corn in western Oregon and Washington is a significant disease that can reduce yield of intolerant cultivars of processed sweet corn by fifty percent. Root rot is caused by a complex ...Citation Citation
- Title:
- Cover crop effects on root rot of sweet corn and soil properties
- Author:
- Miyazoe, Mikio
Root rot of sweet corn in western Oregon and Washington is a significant disease that can reduce yield of intolerant cultivars of processed sweet corn by fifty percent. Root rot is caused by a complex of soilborne organisms, including Drechslera sp., Phoma terrestris, and Pythium arrhenomanes. Processors have adopted tolerant cultivars but farmers continue to seek cultural management strategies that reduce inoculum potential. High rate manure and compost amendments (16.8 - 56.0 Mg ha⁻¹) suppress root rot of corn through general suppression but this practice is not agronomically viable. General suppression is typically associated with high rates of organic amendment and high microbial (FDA) activity. Processed vegetable farmers currently grow winter cover crops to improve soil and water quality and are interested in identifying cover crops that suppress root rot of corn and increase yield. High biomass cover crops can yield up to 12 Mg ha⁻¹ dry matter; this rate of organic amendment may or may not be sufficient to generate general suppression. However, specific cover crops, such as species and cultivars of crucifers and oats, have been shown to more suppressive than other cover crop species and cultivars against specific soilborne diseases. Oat is grown as a winter cover crop in the Willamette Valley and contains avenecin, a chemical that has been shown to have activity against pathogen propagules. In addition, in previous work in containers oat cover crops suppressed root rot of sweet corn. However, there is a concern that oat cover crops immobilize N and reduce corn yield. The objectives of this research were to 1) identify high biomass cover crops with agronomic potential for western Oregon processed vegetable cropping systems, 2) evaluate the impact of high biomass cover crops on root rot severity and yield of sweet corn, 3) determine whether there is a correlation between dry matter, soil microbial activity and root rot severity and 4) determine whether cover crops immobilize nitrogen and reduce corn yield. Research station field trials were conducted in 2003-04, 2004-05 and 2005-06 at the Oregon State University vegetable research farm in Corvallis, Oregon and an on-farm experiment was conducted in 2004-05 at Kenagy Family Farm in Albany, Oregon. Oat 'Saia' winter-killed in 2005-06 and mustard mix 'Caliente' winter-killed every winter except 2004-05, when winter temperatures never dropped below -7 °C. Rape 'Dwarf Essex', mustard 'Braco', and arugula are reliably winter-hardy. All mustard cover crop species are susceptible to white mold caused by Sclerotinia sclerotiorum, causal agent of white mold of snap bean. Oat (Avena sativa) is susceptible to barley yellow dwarf virus (BYDV), an important pathogen of grass seed crops. Mustard cover crops could contaminate cruciferous seed crops. All of the cover crop species evaluated demonstrated some potential to suppress root rot of corn. Oat 'Saia' was the most consistently suppressive; it suppressed root rot in 4 of 6 experiments. Sudangrass was suppressive in the only year it was evaluated as well as in container experiments in previous work. In general, cover crops increased or had no impact on shoot and root dry matter in greenhouse bioassays. There was only one significant cover crop treatment effect on yield; in 2006, the oat treatment increased yield by 11.6% compared to the fallow. Overall, cover crop aboveground dry matter (DM) ranged from 4.2 Mg ha⁻¹ (summer R 2003) to 12.2 Mg ha⁻¹ (winter O 2004). Overall, there was a significant relationship between cover crop DM and radicle rot severity in greenhouse bioassay but not in field experiment. Cover crop treatments consistently increased soil microbial activity. Overall, there was a significant negative correlation between microbial activity and root rot severity in greenhouse bioassays early after cover crop incorporation, but the correlation weakened over time and ultimately was lost by about 80 days after incorporation. The C:N of oat and rape residues was 51 and 21, respectively. Soil nitrogen was immobilized by both the oat and rape cover crops, but oat immobilized more N than rape. Corn grown in the oat treatment soils had lower SPAD values, but it is not clear whether foliar N was sufficiently low to reduce yield potential. There was no consistent trend in above- or below-ground corn dry matter after oat incorporation over the three years. In 2006, the oat treatment had no significant effect on corn DM but increased yield by 11.1%. More work is required to better understand the impact of oat cover crop N immobilization on corn N status and yield. Oat 'Saia' has the potential to suppress root rot of sweet corn and maintain or increase corn productivity. However, this oat cultivar is not reliably winter-hardy and is susceptible to BYDV. Future research should screen Avena species and/or cultivars for improved winter hardiness, BYDV resistance, and root rot suppressive potential.
-
Detailed geologic mapping in the Mormon Mountains and new geophysical data provide significant insight into contractional and extensional tectonics in southern Nevada, southwest Utah, and northwest Arizona. ...
Citation Citation
- Title:
- Structure of the southern Mormon Mountains, Clark County, Nevada and regional structural synthesis : fold-thrust and basin-range structure in southern Nevada, southwest Utah, and northwest Arizona
- Author:
- Carpenter, James Anthony
Detailed geologic mapping in the Mormon Mountains and new geophysical data provide significant insight into contractional and extensional tectonics in southern Nevada, southwest Utah, and northwest Arizona. The rocks in the region were complexly deformed during two distinct tectonic episodes. Numerous interrelated events occurred within each episode. The first tectonic episode, related to the Sevier orogeny, was characterized by east-west crustal shortening which culminated in thin-skinned decollement style folding and thrusting during the Cretaceous. The Virgin-Beaver Dam Mountains anticline, a Laramide-type basement-involved uplift, represents the only thick-skinned contractional structure in the region. The second tectonic episode, related to basin-range rifting, was characterized by east-west crustal extension which was accommodated by high-angle normal faults, with dips averaging 60 degrees, in the brittle upper crust. In this area, basin-range rifting initiated in the Oligocene and continued to Recent time. Relations in the North Muddy Mountains in southern Nevada suggest that the Muddy Mountain thrust sheet advanced and overrode the Weiser syncline during the Cenomanian and may have continued to advance in Turonian time. In the southern Mormon Mountains, the Cambrian Bonanza King Formation lies in the hanging wall flat position in thrust contact with the overturned Petrified Forest Member of the Triassic Chinle Formation at the footwall ramp. The thrust sheet advanced eastward more than 30 km from the place of origin. Thrust imbrication, and probably the formation of hanging wall horses, likely occurred as the Muddy Mountain thrust sheet encountered and ascended up the footwall ramp zone (composed largely of competent carbonate rocks) where slices of the thrust sheet (hanging wall horses) splayed of f and accreted to the footwall ramp zone. A detailed retrodeformable (balanced) regional structure section suggests that fold-thrust shortening at the latitude of the Mormon Mountains is a minimum of about 26%. Extension-related structures overprint older fold-thrust structures in the Mormon Mountains. The west-plunging east-trending Candy Peak syncline is one of a family of fold structures related to basin-range rifting. The syncline formed in pre-Miocene time in association with the northeast-striking Reber Mountain normal fault directly north and the northeast-striking Dry Canyon right-lateral strike-slip fault directly south. The Tortoise Flat synform, which lies southeast of the Dry Canyon fault, developed in Miocene and possibly Pliocene time by right-lateral flexure of early Miocene Horse Spring beds as a result of drag associated with the Dry Canyon fault. The Dry Canyon fault and the Tortoise Flat synform are interpreted to be part of the right-lateral Moapa Peak-Reber Mountain shear zone system in the southern Mormon Mountains. Therefore, the time of formation of the Moapa Peak-Reber Mountain shear zone system is pre-Miocene to possibly Pliocene. The shear zone system formed in response to different amounts of west-directed extension-related movement of the hanging wall block of the high-angle Virgin Beaver Dam Mountains fault, which initiated in the Oligocene. From this, the timing of the Moapa Peak-Reber Mountain shear zone, system is interpreted as Oligocene to Miocene, and possibly Pliocene. The interpretation of 261 km of seismic reflection sections suggests that large-displacement high-angle normal faults, typically with 60 degrees of dip, control horst and graben structure and accommodate extension by simple shear in the upper brittle crust. Such faults likely extend to depths of 15 to 18 km. Below this depth extension is thought to be accommodated by penetrative ductile deformation. A detailed retrodeformable (balanced) regional structure section suggests that basin-range extension at the latitude of the Mormon Mountains is about 17%. The Virgin-Beaver Dam Mountains high-angle normal fault is a large-displacement master fault in the area, having more than 8,000 in of normal vertical separation at the latitude of the Virgin Valley basin depocenter. Miocene doming and uplift of the Mormon Mountains occurred in response to displacement on the Virgin-Beaver Dam Mountains fault. The Virgin Valley basin formed as the hanging wall block downdropped, and the Mormon Mountains dome formed by relative uplift at the opposite end of the hanging wall block. Half-grabens, and tilted, folded, and faulted range blocks characterize basin-range crustal structure. Depositional growth relations are interpreted in basins from fanning-upward reflector geometry, and the wedge-shape of Oligocene to Recent syntectonic basin-fill sediments. Non-overlapping opposing east- and west-tilted half-grabens compose the Meadow Valley-California Wash basin. Seismic sections, gravity data, well data, and geologic mapping demonstrate that the Mormon Peak, Tule Springs Hills, and Beaver Dam/Castle Cliff "detachments," which were thought to be rooted low-angle normal faults, do not exist. The Mormon Peak and Beaver Dam/Castle Cliff low-angle normal faults are denudational fault planes below gravity slid masses. The widely distributed translocated Paleozoic blocks, which were thought to be remnant pieces of large hanging wall sheets ("extensional allochthons"), are disjunct rootless gravity slide blocks of minor tectonic significance. A large number of these rootless slide blocks lie on Pliocene and Quaternary basin-fill deposits. The Muddy Mountain-Tule Springs thrust, of Sevier age, was not reactivated as a crustal penetrating Tule Springs Hills low-angle normal fault, but is affected by small-scale gravity slide features. Rootless gravity slide blocks, secondary features to high-angle normal faults, commonly occur from instability as a result of the loss of lateral support induced by block faulting and the associated erosion of range blocks.
-
4293. [Article] Awareness of Aging in Taiwan and the United States : An Examination of Ageism among College Students using Stereotypes and Future Self-views
Ageism in the context of global population aging could lead to increasing human and economic costs. Age stereotypes tend to be negative (Hummert, 1990) and ubiquitous (Nelson, 2002) there are a variety ...Citation Citation
- Title:
- Awareness of Aging in Taiwan and the United States : An Examination of Ageism among College Students using Stereotypes and Future Self-views
- Author:
- Allen, Pamela M.
Ageism in the context of global population aging could lead to increasing human and economic costs. Age stereotypes tend to be negative (Hummert, 1990) and ubiquitous (Nelson, 2002) there are a variety of well documented detrimental consequences of negative age stereotypes on older adults' physical, cognitive and psychological outcomes (Hummert, 2011; Levy, 2009; Hess et al., 2003). This contributes to a toxic social environment for older people. The issue is of growing importance especially in Asia, where most of today's older people reside (United Nations, 2012) and where ageism appears to be on the rise despite traditional predictions that cultural collectivism and filial piety should protect against negative stereotypes (North & Fiske, 2015). Ageism is proposed by stereotype embodiment theory (Levy, 2009) to be driven by a lifespan process by which beliefs about aging are internalized from the sociocultural context of the individual beginning in childhood. In addition, age stereotypes and self-views related to aging assimilate such that age stereotypes also become internalized into one's self-view. Together, age stereotypes and self-views are components of one's overall subjective awareness of aging (AoA), an "integral psychological process or condition of the aging self" representing one's sense of having grown older (Diehl et al., 2014, p. 2). Depending on whether AoA is positive or negative it functions to enhance or constrict developmental opportunity throughout adult development, respectively. In early adulthood, a period characterized by identity consolidation (Côté, 2009; Erikson, 1968) and a developing future time orientation (Nurmi, 1991), age stereotypes stand to be internalized into one’s future oriented self-concept. Internalization of negative age stereotypes into young adults' future self-views (of one's self in old age) matters because it could give rise to negative AoA early in adulthood and developmental trajectories constraining healthy aging later in life. The cross-cultural ageism research in Western and Eastern societies has assessed stereotypes only and there has been little attention to future self-views (Markus & Nurius, 1986), developmental influences such as experiences with older people (Hagestad & Uhlenberg, 2005), or processes such as internalization by which negative stereotypes can become self-relevant (Levy, 2009). Conversely, the extant work examining internalization of age stereotypes into future self-views as of yet offers little insight into cultural or developmental factors for the processes of internalization (e.g., Kornadt & Rothermund, 2012). Therefore in this dissertation I draw on stereotype embodiment theory (Levy, 2009) and the Awareness of Aging model (Diehl et al., 2014), to examine the positivity of age stereotypes and future self-views among young adults in the U.S. and Taiwan. Data from the Cross-Cultural Perceptions of Aging Study were used to quantitatively measure experiential variables as well as the degree of positivity of age stereotypes and future self-views among 942 American and 659 Taiwanese college students using the Taiwanese developed Older Person Scale (OPS; Lu & Kao, 2009). The dissertation adapted the OPS for first time use in English before using it to examine how cultural context, personal experiences with older adults related to age segregation, and gender impact the positivity of age stereotypes and future self-views cross-culturally. Multiple group confirmatory factor analysis established partial scalar cross-cultural measurement invariance of 15-item and 17-item versions of the scale for measuring age stereotypes and future self-views, respectively. Results showed a four factor structure of the scale reflecting the domains of 1) physical abilities and appearance, 2) psychological and cognitive abilities, 3) interpersonal relationships and social engagement, and 4) employment and financial security. Content analyses of open ended descriptors of age stereotypes and future self-views among American college students provided a check on the assumption that the OPS captures content of these constructs in the population of American college students. Due to the superior psychometric properties of the OPS for measurement of the social domain, and relevance of this domain for experiences of intergenerational contact, the primary research questions were addressed with respect to the social domain. Results of moderated mediation modeling showed that, as hypothesized (hypothesis 1), Taiwanese participants exhibited less positivity in stereotypes and self-views in the psychological and social domains but not the physical or employment domains. Contrary to the expectation, Taiwanese age stereotypes were better characterized as slightly positive or ambivalent rather than negative. As predicted by hypothesis 2, females and those reporting regular experience of contact with older adults expressed more positivity in age stereotypes and future self-views in the social domain across cultural contexts. In support of hypothesis 3, age stereotypes mediated the association of 1) cultural context, and 2) contact frequency to the positivity of future self-views in the social domain. Exploratory results indicated that the strength of indirect effects did not vary significantly across cultural contexts or gender. Based on culture- and gender-based differences in interdependence of self-construals (Cross & Madson, 1997; Markus & Nurius, 1986), I hypothesize that Taiwanese students and American women would exhibit stronger association of age stereotypes to future self-views (i.e., internalization) than American men (hypothesis 4). Taiwanese and American women were found to have among the strongest internalization, but, unexpectedly, American men exhibited equal internalization and Taiwanese men exhibited the weakest internalization. A fifth hypothesis predicting that age integration (i.e., contact with both kin and non-kin older people) moderates the association of contact frequency with age stereotypes was unable to be tested due to an unbalanced response distribution on the relevant variable. Results of this dissertation reinforce the relevance of age stereotypes for future self-views among young adults and speak to the appropriateness of tailoring ageism-focused programs, policies, trainings or educational efforts to the individual or the cultural context.
-
4294. [Article] Constraints to urban park visitation: Conceptual connections and spatial attributes for traditionally well-served and underserved residents
Connecting with nature is associated with social, physical, and emotional benefits such as stress relief, improved physical health, and lower crime. Parks and other natural areas offer spaces in which ...Citation Citation
- Title:
- Constraints to urban park visitation: Conceptual connections and spatial attributes for traditionally well-served and underserved residents
- Author:
- Rushing, Jaclyn R.
Connecting with nature is associated with social, physical, and emotional benefits such as stress relief, improved physical health, and lower crime. Parks and other natural areas offer spaces in which to connect with nature and reap these and other benefits (e.g., family bonding, social events, learning). Despite increasing populations of racial and ethnic minorities in the United States of America, these groups are underrepresented in many outdoor recreation activities and in visitation to many parks and other protected areas. This underrepresentation and other attributes of park visitation can be partially explained through the theoretical lens of constraints to recreation. Constraints are factors that limit participation, affect leisure preferences, and / or reduce enjoyment and satisfaction with recreation experiences. Examples of constraints include inability to afford park fees, fear of crime in parks, and lack of available leisure time. This thesis contains two standalone articles focusing on resident constraints to visiting urban parks and other natural areas in the Portland, Oregon (USA) metropolitan region. These articles examine: (a) the most common constraints to visiting these parks and natural areas, and whether these constraints vary between traditionally well-served (i.e., white majority residents) and underserved (i.e., ethnic and racial minorities) populations; (b) relationships among constraints, park visitation, and place attachment for both of these groups of residents; and (c) how constraints groups, different types of constraints, and resident characteristics (e.g., minorities) are distributed spatially across this metropolitan region. Data were obtained from mail and online questionnaires completed by two samples of residents in Clackamas, Multnomah, and Washington counties: (a) a proportionate random sample of residents mostly targeting the following groups: African Americans / Blacks, American Indians, Asians, Hispanics / Latinos, Middle Eastern peoples, and Slavic / Eastern European peoples (i.e., probability sample); and (b) a convenience sample of Opt-In panel members (i.e., nonprobability sample). Questionnaires were completed by a total of 3,328 residents across these samples, and the data were weighted by the most recent Census based on county, age, sex (male, female), and education to be representative of adult residents in this region. Race and other demographics were consistent with the Census after weighting. Results of the first article showed that the primary constraints to visiting parks and natural areas in this urban region were being too busy to visit, limited knowledge about Metro parks, and lack of access to these places (Metro parks are managed by Metro, which is the main regional government for Clackamas, Multnomah, and Washington counties). There were no differences in these constraints and most other constraints between traditionally underserved and well-served populations. Traditionally underserved residents, however, were significantly more constrained than the well-served residents were by race and cultural issues at parks, as well as lack of facilities and services at Metro parks. Traditionally well-served residents visited all parks and natural areas in the region significantly more often than did the underserved residents, but there were no differences in visitation to Metro parks or their favorite park. There were also no differences between the two groups in their attachment to their favorite park. Constraints and visitation explained 15% of the variance in attachment for well-served residents and 38% for underserved residents, and constraints explained 4% of the variance in visitation for well-served residents and 26% for underserved residents. The strongest negative predictor of attachment for well-served residents was Metro parks are not the best places, followed by limited access to these places and disinterest in visiting parks and natural areas. The strongest positive predictor for well-served resident attachment was frequency of visitation, followed by race and cultural issues at Metro parks, and lack of facilities and services in these areas. For underserved residents, the strongest negative predictor of attachment was costs followed by Metro parks are not the best places and limited knowledge about these places. Positive predictors of attachment for these residents included frequency of visitation and lack of facilities and services at Metro parks. The only predictor of visitation to their favorite park for well-served residents was fear of visiting other areas (positive relationship), whereas visitation for underserved residents was negatively associated with limited access to Metro parks and positively associated with costs of visiting other areas. The second article used a Geographic Information System (GIS) and hot spot analysis of the survey data to determine any spatial patterns in constraints groups, different types of constraints, and resident characteristics (e.g., minorities). Results revealed two major trends: (a) in the northeast area of the region, there is a clustering of minority residents overlapping with the most constrained hot spots and these residents were most affected by constraints associated with health and lack of recreation partners; and (b) residents in the southwest area of the region were most affected by constraints associated with limited knowledge and access to parks. Specific implications of these results for both management and research are discussed in this thesis. In general, however, these results may inform local agency objectives associated with reaching and engaging various populations, including ethnic and racial minorities. These findings also contribute to the literature by exploring relationships among constraints, park visitation, and attachment between traditionally well-served and underserved populations, and also by applying a GIS analysis of survey data to understand spatial aspects of constraints for each of these populations.
-
4295. [Article] Optimizing map projection selection for world maps and web maps
The selection process for map projections is a mystery to many mapmakers and GIS users. Map projections ought to be selected based on the map’s geographic extent and the required distortion properties, ...Citation Citation
- Title:
- Optimizing map projection selection for world maps and web maps
- Author:
- Šavrič, Bojan
The selection process for map projections is a mystery to many mapmakers and GIS users. Map projections ought to be selected based on the map’s geographic extent and the required distortion properties, with the goal of minimizing the distortion of the mapped area. Despite some available selection guidelines, the selection of map projections is not yet automated. Automated selection would help mapmakers and GIS users to better select a projection for their map. The overall goal of this dissertation is to take a step towards this automation and explore user preferences with an objective to provide additional criteria for selecting world map projections. An additional goal is to optimize automatic map projection selection for web maps. The results presented in this work are mathematical models (new map projections for world maps, polynomial equations for selecting standard parallels) and new selection criteria for world maps. They improve our knowledge about map projection selection for world maps and web maps. As a result of the research presented in this doctoral dissertation, we know more about the map projection preferences of map-readers and have improved techniques for adapting map projections for scalable web maps and GIS software. Altogether, four concrete research questions were addressed. The first research question explores user preferences for world map projections. Many small-scale map projections exist and they have different shapes and distortion characteristics. World map projections are mainly chosen based on their distortion properties and the personal preferences of cartographers. Very little is known about the map projection preferences of map-readers; only two studies have addressed this question so far. This dissertation presents a user study among map-readers and trained cartographers that tests their preferences for world map projections. The paired comparison test of nine commonly used map projections reveals that the map-readers in our study prefer the Robinson and Plate Carrée projections, followed by the Winkel Tripel, Eckert IV, and Mollweide projections. The Mercator and Wagner VII projections come in sixth and seventh place, and the least preferred are two interrupted projections, the interrupted Mollweide and the interrupted Goode Homolosine. Separate binominal tests indicate that map-readers involved in the study seem to like projections with straight rather than curved parallels, and meridians with elliptical rather than sinusoidal shapes. The results indicate that map-readers prefer projections that represent poles as lines to projections that show poles as protruding edges, but there is no clear preference for pole lines in general. The trained cartographers involved in this study have similar preferences, but they prefer pole lines to represent the poles, and they select the Plate Carrée and Mercator projections less frequently than the other participants. The second research question introduces the polynomial equations for the Natural Earth II projection and tests user preferences for its graticule characteristics. The Natural Earth II projection is a new compromise pseudocylindrical projection for world maps. It has a unique shape compared to most other pseudocylindrical projections. At high latitudes, the meridians bend steeply toward short pole lines resulting in a map with highly rounded corners that resembles an elongated globe. Its distortion properties are similar to most other established world map projections. The projection equation consists of simple polynomials. A user study evaluated whether map-readers prefer Natural Earth II to similar compromise projections. The 355 participating general map- readers rated the Natural Earth II projection lower than the Robinson and Natural Earth projections, but higher than the Wagner VI, Kavrayskiy VII, and Wagner II projections. The third question examines how Wagner's transformation method can be used for improving map projections for scalable web maps, and its integration into the adaptive composite map projections schema. The adaptive composite map projections schema, invented by Bernhard Jenny, changes the projection to the geographic area shown on a map. It is meant as a replacement for the commonly used web Mercator projection, which grossly distorts areas when representing the entire world. The original equal-area version of the adaptive composite map projections schema uses the Lambert azimuthal projection for regional maps, and three alternative projections for world maps. In this dissertation, it is explored how the adaptive composite map projections schema can include a variety of other equal-area projections when the transformation between the Lambert azimuthal and the world projections uses Wagner's method. In order to select the most suitable pseudocylindrical projection, the distortion characteristics of a pseudocylindrical projection family were analyzed, and a user study among experts in the area of map projections was carried out. Based on the results of the distortion analysis and the user study, a new pseudocylindrical projection is recommended for extending the adaptive composite map projections schema. The new projection is equal-area throughout the transformation to the Lambert azimuthal projection, has better distortion characteristics than small-scale projections currently included in the original adaptive composite map projections schema, and aligns with map-readers' preferences for world map projections. The last research question explores how the selection of the standard parallels of conic projections can be automated. Conic map projections are appropriate for mapping regions at medium and large scales with east-west extents at intermediate latitudes. Conic projections are appropriate for these cases because they show the mapped area with less distortion than other projections. In order to minimize the distortion of the mapped area, the two standard parallels of conic projections need to be selected carefully. Rules of thumb exist for placing the standard parallels based on the width-to- height ratio of the map. These rules of thumb are simple to apply, but do not result in maps with minimum distortion. There also exist more sophisticated methods that determine standard parallels such that distortion in the mapped area is minimized. These methods are computationally expensive and cannot be used for real-time web mapping and GIS applications where the projection is adjusted automatically to the displayed area. This article presents a polynomial model that quickly provides the standard parallels for the three most common conic map projections: the Albers equal- area, the Lambert conformal, and the equidistant conic projection. The model defines the standard parallels with polynomial expressions based on the spatial extent of the mapped area. The spatial extent is defined by the length of the mapped central meridian segment, the central latitude of the displayed area, and the width-to-height ratio of the map. The polynomial model was derived from 3825 maps--each with a different spatial extent and computationally determined standard parallels that minimize the mean scale distortion index. The resulting model is computationally simple and can be used for the automatic selection of the standard parallels of conic map projections in GIS software and web mapping applications.
-
4296. [Article] A comparison of social class differences in adolescents' self-disclosure, parent-cathexis and self-cathexis
The purpose of this study was to investigate the differences between middle- and lower-class adolescents and the extent of their self-disclosure to their mothers and their fathers; and their feelings both ...Citation Citation
- Title:
- A comparison of social class differences in adolescents' self-disclosure, parent-cathexis and self-cathexis
- Author:
- Larsen, George Robert
The purpose of this study was to investigate the differences between middle- and lower-class adolescents and the extent of their self-disclosure to their mothers and their fathers; and their feelings both positive and negative toward their parents and themselves. The subjects consisted of 50 middle-class and 50 lower-class adolescents who were randomly selected from 297 sophomores and juniors attending the same high school in a rural town in Oregon. Hollingshead's Index of Social Position (1958), which uses the occupation and education of the father as criteria for social class, was used to classify the adolescents by social class. Sex comparisons were also analyzed for differences between the middle- and lower-class adolescents. In attempting to realize this purpose, two major hypotheses were tested: Hypothesis 1: There are no differences between these middle-class and lower-class adolescents in the extent of self-disclosure to their parents. Hypothesis 2: There are no differences between these middle-class and lower-class adolescent's in the extent of positive and negative feelings toward their parents and themselves. The extent of self-disclosure was measured by Jourard's Self-disclosure Questionnaire (1964). This 60 item instrument which permits the subjects to indicate the extent to which they are willing to talk to another person about themselves on the following six categories: A attitudes and opinions, B tastes and interests, C work or studies, D money, E personality, and F body. Total scores from the questionnaire were used in testing Hypothesis 1. The results indicated that the null hypothesis could not be rejected. Comparison of middle- and lower-class males and middle- and lower-class females also did not indicate any significant differences on total scores from the Self-disclosure Questionnaire. The extent of the adolescents' positive and negative feelings toward their parents and themselves was measured by the use of Jourard's Cathexis Questionnaire. This instrument consists of 40 personality traits such as: sense of humor, philosophy of life, temper, and happiness. Total scores from the questionnaire were used in the test of Hypothesis 2. Once again, the results of the test indicated that the null hypothesis could not be rejected. In addition analysis was made of differences between middle- and lower-class males and middle- and lower-class females on total scores from the Cathexis Questionnaire for mothers, fathers and themselves. No significant differences were found for the social class differences for the middle- and lower-class males and females. The items within each questionnaire were then analyzed for significant differences between the middle- and lower-class adolescents. To test for significant differences between social classes for each item within the questionnaires, Chi Square and the Kolmogrov- Smirnov Test were used. Sixteen of the 60 items on the Self-disclosure Questionnaire were found to be significantly different between the middle- and lower-class adolescents, with the middle-class adolescents talking more extensively to their parents than did the lower-class adolescents. More specifically five items were significantly different for both mothers and fathers which were: attitudes on drinking, feelings about how work is appreciated, feelings about people at work, trouble controlling feelings, being attractive to the opposite sex or not. While these five items were significant for both mothers and fathers the following eight items were of significance for mothers: attitudes on racial integration, tastes in music, style of house, how much money is made, to whom money is owed, amount in savings, aspects of personality that are disliked, and feelings about one's appearance in the past. The following three items were significant for fathers: tastes in food, source of income, and ideals of overall appearance. In addition analysis of differences between middle- and lower-class males and females on the items within the Self-disclosure Questionnaire with the lower-class adolescent indicating no self-disclosure in contrast to the middle-class adolescents extensive self-disclosure. Slightly more items were significantly different on self-disclosure to the parent of the same sex than to the parent of the opposite sex. The items of significance for males to fathers were: religion, food, social gatherings, feelings about people at work, and adequacy in sexual behavior. The items of significance for females to mothers were: style of house, present work, ambitions and goals, choice of a career, people at work, things that makes one furious, and adequacy in sexual behavior. The items of significance for the males to mothers were: appreciation of work, amount of savings, and being attractive to the opposite sex. The items of significance for the females to their fathers were: how much money is made and trouble controlling feelings. For the Cathexis Questionnaire there were three target persons: mother, father, and self. Only four of the 40 items in this questionnaire were significantly different between middle- and lower-class adolescents. The lower-class adolescents indicated negative feelings toward their fathers and themselves in contrast to the positive feelings expressed by the middle-class adolescents. Of the four items three were for fathers' general knowledge, intelligence level, and philosophy of life. The only significant item for the adolescents' feelings about themselves was their ability to control emotions. An additional comparison was made for differences between the middle- and lower-class males and females for feelings about their mothers, fathers and themselves. There were only two significant items for the sex comparisons for the items from the Cathexis Questionnaire. The lower-class males indicated negative feelings toward their fathers' general knowledge in contrast to the positive feelings of the middle-class males. The lower-class females indicated negative feelings for their fathers' intelligence level in contrast to the positive feelings of the middle-class females. An extension of the analysis of the differences between the extreme ends of the social class continuum was done by going back to the original 297 subjects and taking all of those in Classes I and II (N = 20) and all of those in Class V (N = 23). The two hypotheses were again tested by using the Self-disclosure and Cathexis Questionnaires. Total scores from the two questionnaires were used in the test of Hypothesis 1 and 2. The results of the t-test indicated that the null hypotheses could not be rejected, for both Hypothesis 1 and 2. The sex comparisons for the two hypotheses also indicated no significant differences on total scores from the two questionnaires. The analysis of the differences in the extent of self-disclosure between the extreme ends of the social class continuum provided a pattern which was the reverse for the random sample of middle- and lower-class adolescents. For the random sample there were more items of significant difference for mothers than for fathers, while there were more items of significant difference for fathers than for mothers for the extreme ends of the social class continuum. The lower socio-economic adolescents indicated no self-disclosure for the significant items in contrast to the upper socio-economic adolescents' extensive self-disclosure to their parents. The three items which were significantly different on self-disclosure to mothers were: attitudes toward other religious groups, satisfaction from present work, and who owes me money. The nine items which were significantly different on self-disclosure to fathers were: religion, standards of beauty, tastes in food, present work, ambitions and goals, who owes me money, different parts of the body, physical measurements, and adequate sexual behavior. The analysis of the differences in the extent of self-disclosure between the males and females of the upper and lower extremes of the social class continuum showed no significant difference. The analysis of the differences between the extreme ends of the social class continuum on the items within the Cathexis Questionnaire indicated one item for mothers and six items for fathers. For all of the items the lower socio-economic adolescents indicated negative feelings in contrast to the positive feelings of the upper socio-economic adolescents. The one significant item for feelings about mothers was her general knowledge. The six significant items for feelings about fathers were his: general knowledge, intelligence level, capacity to work, ability to meet new people, and business sense. The sex comparisons of the extreme ends of the social class continuum of the items within the Cathexis Questionnaire found two items of significant differences. The lower socio-economic females indicated negative feelings about fathers' general knowledge and intelligence level, while the upper socio-economic females indicated positive feelings on these items. The items within the questionnaires which indicated significant differences agreed with the literature on social class which suggests that there is more communication between middle-class parents and their children than for lower-class parents and their children, and that the lower-class adolescents report more negative feelings toward their parents than do the middle-class adolescents. The findings of this study suggest the necessity of additional studies of social class differences in rural settings and comparisons of rural and urban samples which use the same criteria for measuring social class and which use the same instruments for measuring differences among the social classes.
-
4297. [Article] Implications of cougar prey selection and demography on population dynamics of elk in northeast Oregon
Mule deer (Odocoileus hemionus hemionus) and Rocky Mountain elk (Cervus canadensis nelsoni; hereafter elk) populations in northeast Oregon have declined in the past 10 to 20 years. Concurrent with these ...Citation Citation
- Title:
- Implications of cougar prey selection and demography on population dynamics of elk in northeast Oregon
- Author:
- Clark, Darren A.
Mule deer (Odocoileus hemionus hemionus) and Rocky Mountain elk (Cervus canadensis nelsoni; hereafter elk) populations in northeast Oregon have declined in the past 10 to 20 years. Concurrent with these declines, cougar (Puma concolor) populations have apparently increased, leading to speculation that predation by cougars may be responsible for declining ungulate populations. However, empirical data on cougar diets, kill rates, and prey selection are lacking to support this speculation. Furthermore, the common assumption that cougar populations have increased in northeast Oregon may not be well founded because cougar populations in other areas within the Pacific Northwest region have declined in recent years. My primary research objectives were to (1) estimate kill rates and prey selection by cougars in northeast Oregon, (2) document causes of mortality and estimate survival rates for cougars, (3) estimate population growth rates of cougars in northeast Oregon and simulate the effects of hypothetical lethal control efforts on the cougar population, and (4) investigate the relative influence of top-down, bottom-up, and climatic factors for limiting population growth rates of elk in northeast Oregon. Results from my research will help guide cougar and elk management in northeast Oregon and provide a framework for assessing relative effects of top-down, bottom-up, and abiotic factors on population growth rates of ungulates in this and other areas. I implemented a 3-year study in northeast Oregon to investigate diets, kill rates, and prey selection of cougars in a multiple-prey system to better understand mechanisms by which cougars may influence ungulate populations. During my research, 25 adult cougars were captured and fitted with Global Positioning System (GPS) collars to identify kill sites. I monitored predation sequences of these cougars for 7,642 days and located the remains of 1,213 prey items killed by cougars. Cougars killed ungulates at an average rate of 1.03 per week (95% CI = 0.92 – 1.14); however, ungulate kill rates were variable and influenced by the season and demographic classification of cougars. Cougars killed ungulates 1.55 (95% CI = 1.47 – 1.66) times more frequently during summer (May-Oct) than during winter (Nov-Apr), but killed similar amounts of ungulate biomass (8.05 kg/day; 95% CI = 6.74 – 9.35) throughout the year. Cougars killed ungulates more frequently in summer because juvenile ungulates comprised most of the diet and were smaller on average than ungulate prey killed in winter. Female cougars with kittens killed more frequently (kills/day) than males or solitary females. After accounting for the additional biomass of kittens in cougar family groups, male cougars killed on average more biomass of ungulate prey per day than did females (R = 0.41, P < 0.001), and female cougars killed more biomass of prey per day as a function of the number and age of their kittens (R = 0.60, P < 0.001). Patterns of prey selection were influenced by season and demographic classification of cougars. Female cougars selected elk calves during summer and deer fawns during winter. In contrast, male cougars selected elk calves and yearling elk during summer and elk calves during winter. My results strongly supported the hypothesis that cougar predation is influenced by season, gender, and reproductive status of the cougar and these patterns in cougar predation may be generalizable among ecosystems. The observed selection for juvenile elk and deer suggested a possible mechanism by which cougars could negatively affect population growth rates of ungulates. I investigated survival and documented causes of mortality for radio-collared cougars at 3 study areas in Oregon during 1989 – 2011. Mortality due to hunter harvest was the most common cause of death for cougars in the Catherine Creek study area and the study area combining Wenaha, Sled Springs, and Mt. Emily Wildlife Management Units (WSM study area) in northeast Oregon. In contrast, natural mortality was the most common cause of death for cougars in the Jackson Creek study area in southwest Oregon. Annual survival rates of adult males were lowest at Catherine Creek when it was legal to hunt cougars with dogs (Ŝ = 0.57), but increased following the prohibition of this hunting practice (Ŝ = 0.86). This latter survival rate was similar to those observed at Jackson Creek (Ŝ = 0.78) and WSM (Ŝ = 0.82). Regardless of whether hunting of cougars with dogs was permitted, annual survival rates of adult females were similar among study areas (Catherine Creek Ŝ = 0.86; WSM Ŝ = 0.85; Jackson Creek Ŝ = 0.85). I did not document an effect of age on cougar survival rates in the Catherine Creek study area, which I attributed to selective harvest of prime-aged, male cougars when it was legal to hunt cougars with dogs. In contrast, I observed an effect of age on annual survival in both the WSM and Jackson Creek study areas. These results indicate that sub-adult males had significantly lower survival rates than sub-adult females, but survival rates of males and females were similar by age 4 or 5 years. My results suggest that survival rates of cougars in areas where hunting cougars with dogs is illegal should be substantially higher than areas where use of dogs is legal. I used estimates of cougar vital rates from empirical data collected in northeast Oregon to parameterize a Leslie projection matrix model to estimate deterministic and stochastic population growth rates of cougars in northeast Oregon when hunting cougars with dogs was legal (1989 - 1994) and illegal (2002 - 2011). A model cougar population in northeast Oregon that was hunted with dogs increased at a mean stochastic growth rate of 21% per year (λ[subscript s] = 1.21). Similarly, I found that a model cougar population that was subjected to hunting without dogs increased at a rate of 17% per year (λ[subscript s] = 1.17). Given that hunting cougars with dogs typically results in increased harvest and reduced survival rates of cougars, it was unexpected that the cougar population subjected to hunting with dogs was increasing at a faster rate than one that was not hunted with dogs. However, cougar populations in Oregon were subjected to low harvest rates when hunting cougars with dogs was legal and harvest was male biased. This resulted in high survival rates of female cougars and correspondingly high population growth rates. The Oregon Cougar Management Plan allows the Oregon Department of Fish and Wildlife to administratively reduce cougar populations to benefit ungulate populations, reduce human-cougar conflicts, and limit livestock depredation. Consequently, I was interested in modeling the effects of a hypothetical lethal control effort on a local cougar population. Using empirically-derived vital rates and a deterministic Leslie matrix model, I found that the proportion of the cougar population that would need to be removed annually to achieve a 50% population reduction within 3 years was 28% assuming a closed population, and 48% assuming maximum immigration rates into the population. Using a stochastic Leslie matrix model, I also determined that the model cougar population would likely return to its pre-removal size in 6 years assuming a closed population, and 2 years assuming maximum immigration rates. These model results indicate that current management practices and harvest regulations, combined with short-term, intensive, and localized population reductions, are unlikely to negatively affect the short-term viability of cougar populations in northeast Oregon. However, at this time, it is not known if intensive lethal control efforts funded by state agencies will be cost-effective (i.e., increased sales of tags to hunt deer and elk will offset the costs of control efforts). Further research is needed to investigate the cost-effectiveness of cougar control efforts in Oregon. I developed a Leslie matrix population model, parameterized with empirically-derived vital rates for elk in northeast Oregon, to investigate the relative influence on elk population growth rates of (1) survival and pregnancy, and (2) top-down, bottom-up, and climatic variables. I then estimated the effect of varying the strength of top-down factors on growth rates of elk populations. Growth rates of the model elk population were most sensitive to changes in adult female survival, but due to the inherent empirical variation in juvenile survival rates explained the overwhelming majority of variation in model population growth rates (r² = 0.92). Harvest of female elk had a strong negative effect on model population growth rates of elk (r² = 0.63). An index of cougar density was inversely related to population growth rates of elk in my model (r² = 0.38). A delay in mean date of birth was associated with reduced juvenile survival, but this had a minimal effect on population growth rates in my model (r² = 0.06). Climatic variables, which were used as surrogates for nutritional condition of females, had minimal effects on population growth rates. Likewise, elk density had almost no effect on population growth rates (r² = 0.002). The results of my model provided a novel finding that cougars can be a strong limiting factor on elk populations. Wildlife managers should consider the potential top-down effects of cougars and other predators as a limiting factor on elk populations.