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7251. [Article] Criteria for selection and management in the swine breeding herd
Oregon State University swine herd records of four genetic groups were analyzed to determine: (1) the association of occurrence of a small litter (≤ 7) at birth with size of subsequent litters for gilts ...Citation Citation
- Title:
- Criteria for selection and management in the swine breeding herd
- Author:
- Page, Edward Bryce
Oregon State University swine herd records of four genetic groups were analyzed to determine: (1) the association of occurrence of a small litter (≤ 7) at birth with size of subsequent litters for gilts and sows, separately; (2) the effect of parity, genetic background and litter size on mean birth weight and mean number weaned; and (3) the effect of same-day weaning of dams to achieve contiguity of farrowing and increase neonatal pig survival by transferring pigs from excessively large litters to smaller ones. Analysis of differences for size of subsequent litters between first parity dams that had farrowed small (≤7) and non-small (> 7) litters showed differences (P < 0.023) between the means of 9.64 pigs born alive and 10.27 pigs born alive in the two groups respectively. Correlation and regression coefficients for litters subsequent to first parity non-small litters were 0.19 (P < 0.01) and 0.32 Mean number weaned in litters of 8, 9, 10, and 11 were 6.71, 7.25, 8.16 and 8.74 pigs respectively. These means were different (P < 0. 005). Differences in genetic background, parity and effects of interactions were nonsignificant within constant litter size at birth. Increases in mean number weaned with increasing litter size indicate that the number surviving is associated with number born and neonatal management. Neither genetic background nor parity appear to have effects on maternal performance in the population used when litter size at birth is held constant. Assembling sow records to simulate 5, 10, 15 or 20 sows weaned at the same time resulted in farrowings occurring contiguously enough to permit transfers of pigs from litters larger than 12. The total number of pigs at birth in excess of 12 per dam was 11, 1 and 0 respectively for dam groups of 5, 10 and 15. The mean range in time from first to final farrowing was 4.68, 6.45, 8.86 and 10.60 days for groups of 5, 10, 15 and 20 dams respectively. These data indicate that increasing the number of dams weaned on the same day results in increased opportunity to transfer pigs from excessively large litters to smaller ones. The increase in size of dam groups also increases the efficiency of utilization of labor and facilities at farrowing by increasing the average number of farrowings from one per day for groups of five dams to two per day for groups of 20 dams. (P < 0.002) respectively; correlation and regression coefficients for litters subsequent to first parity small litters were small and not significant. Mean litter size of all gilts was 9. 15 live pigs at birth, which is 0.49 of a pig less than the mean of litters subsequent to small litters. Thus, in this population, culling based on a small first parity litter would result in decreasing the mean number born alive in the next farrowing. Also, there would be added expense associated with raising the replacement to breeding age. Mean pig weight was significantly different (P < 0.005) between litters from gilts vs sows; birth weights were 2.72 and 2.91 lbs respectively. Differences (P < 0.01) in mean birth weights were found among litters of 8, 9, 10, and 11; the means were 2.87, 2. 93, 2.75, and 2.70 lbs respectively. No significant differences were found among genetic background groups or for effects of interaction. These results indicate that sows on the average farrow slightly heavier pigs than gilts in litters of the same size and, as litter size increases, the mean birth weight decreases but numbers weaned continue to increase with increasing numbers born alive. Lack of significant difference of birth weights among genetic groups indicates that other factors, such as number in litter and parity, rather than genetic influences are responsible for differences in average pig birth weight.
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7252. [Article] Women's studies : a new program for the community college
The purpose of this study was to present the new women's studies program for the community college. The study advocated consciousness raising for females at all levels of public instruction, but this paper ...Citation Citation
- Title:
- Women's studies : a new program for the community college
- Author:
- Goltra, Raylene Denise
The purpose of this study was to present the new women's studies program for the community college. The study advocated consciousness raising for females at all levels of public instruction, but this paper was limited to the community college. The program outlined would seek to help women to assume a more equal position in American society. The initial phase of the study sought to prove that women are second class citizens in America. For example: women hold none of the presidencies in the top 100 United States business firms. There are no, women governors, nor attorney generals in all the 50 states, In addition, state legislatures across the country comprise approximately 7,000 positions. Only 300 of these positions are held by women. On the federal level, the Senate is an all-male club. In the House of Representatives only Edith Greene of Oregon holds any really important committee power. In the working world, women in blue collar positions face grave problems of overt discrimination, They are often paid less, denied advancement, refused maternity leaves, and are usually the last hired and the first fired. In the professional world, women have made scant headway in the last 30 years. In medicine, fewer women are accepted now than in the 1920's. In the legal profession, upward mobility is almost nil. Barely one percent of all the nation's judges are women. In education, women are abundant on the teaching staffs in, elementary and secondary schools. However, they are rarely promoted to the principal level. Women are also well represented on community college teaching staffs, but almost never rise to upper echelon administrative positions, In higher education, the problem is even more severe. Women encounter blatant discrimination in graduate school, the first pre-requisite to higher education teaching and administration, The number of women holding associate and full professorships in American universities are almost non-existent, Some of the sociological effects of "keeping women in their place" can be seen in the rising rates of females involved in: child abuse, drug usage, desertion, divorce, and suicide. Another major problem is that the number of families headed by women continues to grow. Many of these families exist in poverty. The second phase of the study explored the traditional areas of societal leadership, to ascertain what they were doing to alter these conditions. The groups under investigation were all the major Christian denominations and Judaism. Next studied were labor unions with 30 percent or more female members. Professional and fraternal organizations were also queried. It was concluded that none of these organizations had any structured plan to alter the existing situation for women. The writer then accepted the proposition that the greatest existing societal change agent was the public school system, specifically for this study, the community college. The final phase of the study concerned a detailed plan for the aforementioned new program. Several existing community college women's programs were profiled. Their relative strengths and weaknesses were explored. The major flaw noted in many of these programs was their insistance upon separatism, a "women only" policy, The program envisioned in this paper decries the concept of separatism. Its guiding principle is the creation of greater understanding between people. All classes would comprise both male and female students. Women can hope to alter their position in society very little if they exclude men from this kind of program. The latter group needs to gain more sensitivity to the problem, not increased hostility, which would be the result of exclusion. This new program would be under a Special Programs Director who would also be responsible for courses aimed at others with societal problems such as: ethnic minorities, the handicapped, and the aged. Interaction of all these groups with each other and the rest of the student body would be stressed. The program would offer women awareness courses, vocational training, job placement, group therapy, community activity, and competent, low cost, child care. Finally, the study endeavored to prove that the program could be initiated on almost any campus using the existing facilities and, in many cases, existing personnel.
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7253. [Article] Sequential isotopic analysis to characterize ontogenetic shifts and growth dynamics of loggerhead sea turtles (Caretta caretta)
Ontogenetic niche theory predicts that as organisms grow they make size-specific changes in habitat use and diet to optimize growth and survival. A variety of factors contribute to growth and survival ...Citation Citation
- Title:
- Sequential isotopic analysis to characterize ontogenetic shifts and growth dynamics of loggerhead sea turtles (Caretta caretta)
- Author:
- Ramirez, Matthew D.
Ontogenetic niche theory predicts that as organisms grow they make size-specific changes in habitat use and diet to optimize growth and survival. A variety of factors contribute to growth and survival in different habitats, ultimately leading to variation in life history that can affect population dynamics. An understanding of the variation in timing of habitat shifts and fidelity to those habitats is critical for population dynamics modeling and evaluation of conservation strategies, especially for species whose population vital rates are sensitive to changes in growth and survival of critical life stages, such as the loggerhead sea turtle (Caretta caretta). Isotopic analysis of sequentially deposited structures, such as sea turtle humerus bone, provides a means of studying intraspecific life history variation. I sequentially analyzed the annual humerus bone growth increments of 84 juvenile loggerhead sea turtles for stable isotopes (δ¹³C, δ¹⁵N) to reconstruct the diet and habitat use histories of turtles undergoing an oceanic-to-neritic ontogenetic shift. I also used skeletochronological methods to evaluate the growth dynamics surrounding this transition. Generated isotopic transects were used to classify individuals into alternative life history pattern groups and were combined with body size and growth data obtained from skeletal analyses to evaluate differences in the duration, timing, and growth dynamics of ontogenetic shifts. Sea turtles that displayed increases in nitrogen stable isotope ratios (δ¹⁵N) greater than 3.0‰ over one or more years were presumed to have transitioned from oceanic to neritic diets and/or habitats based on oceanic and neritic prey isotopic information collected from the literature, and were classified into one of two life history pattern groups: discrete shifters (n = 23) completed this transition within year, while facultative shifters (n = 16) completed this transition in up to eight years. As differences in isotopic values between neritic and oceanic prey are most likely driven by differences in isotopic baselines, I propose the gradual increases in δ¹⁵N values within facultative shifters over multiple years is indicative of foraging in both oceanic and neritic habitats within growth years. Size-at-transition between habitats was similar between discrete shifters (55.1 ± 7.6 cm straightline carapace length, SCL) and facultative shifters (52.8 ± 6.9 cm SCL). Growth variance was higher for facultative shifters versus discrete shifters. Yet, mean size at transition, size-at-age relationships, and mean increment-specific growth rates were similar between turtles with alternative life history patterns. Annual growth rates generally peaked within one year of transition (31/38 of turtles), providing support for a short-term (i.e., 1-2 year) ontogenetic shift-associated growth advantage. However, there was considerable variation in the timing of maximal growth rate among turtles with some individuals exhibiting maximal growth in years prior to the ontogenetic shift (14/38 turtles). The lack of substantial differences in the timing of transition and growth dynamics between discrete and facultative shifters likely limits the influence of these alternative life history patterns on time to sexual maturity in this species, though differences in habitat-specific survival probabilities could affect loggerhead population dynamics. This study demonstrates the value of paired isotopic and skeletal analyses to the study of long-term sea turtle life history variation and its affect on growth.
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This investigation consisted of two parts: A. stability, B. bioavailability of vitamin B₆ in wheat. Three variables; whole wheat flour (WHW), white flour (W) and W enriched with vitamin B₆ (WB₆) were tested. Stability ...
Citation Citation
- Title:
- Vitamin B₆ enrichment of wheat flour : stability and bioavailability
- Author:
- Perera, Anne Doloras
This investigation consisted of two parts: A. stability, B. bioavailability of vitamin B₆ in wheat. Three variables; whole wheat flour (WHW), white flour (W) and W enriched with vitamin B₆ (WB₆) were tested. Stability of vitamin B₆ during bread making and storage of bread and flour was determined. Bread was prepared from the three types of flour under commercial and home conditions. Two methods, straight dough and sponge dough for bread making were compared under home conditions. Vitamin B₆ content of dough before fermentation, after proofing and of bread was determined by a microbiological method. The WB₆ dough prepared using the sponge dough method showed a significant increase in the vitamin B₆ content during fermentation (P < 0.05). A significant baking loss of 10-15% was observed in the WHW and W breads prepared under commercial conditions (P < 0.05), and of 5-12% in WHW, WB₆ (P < 0.01) and W (P < 0.05) breads made using the sponge dough method. Storage stability of vitamin B₆ was determined in the comb mercially prepared WB₆ bread and all purpose flour enriched with vitamin B₆. There was no significant change in vitamin B₆ levels in the bread stored under frozen and refrigerated conditions for seven and four weeks, respectively. However, a significant drop of 10% was observed in the vitamin B₆ content of the bread after three days of storage at room temperature (P < 0.01). Vitamin B₆ content of the WB₆ flour did not change when stored over a period of 26 weeks at room temperature. Bioavailability of vitamin B₆ was studied in nine men, age 21-33 years. Each week one of the three types of bread, WHW (570 g), WB₆ (600 g) and W (600 g) was fed daily to each subject using a 3X3 Latin square design. The WHW, WB₆ and W bread supplied 1.20, 1.18 and 0.35 mg of vitamin B₆, respectively, while 0.38 mg was supplied by the constant diet. The daily vitamin B₆ intake was set at 1.5 mg, of which approximately 3/4 was supplied from WHW or WB₆ bread. During the period when W bread was consumed, the subjects also received an oral dose of 0.81 mg of vitamin B₆ in order to maintain a constant daily intake throughout the study. The predominant form of vitamin B₆ in the diets was found to be pyridoxine. Twenty-four hour urines, daily fecal collections and fasting blood samples three days per week were analyzed for vitamin B₆ and its metabolites, using microbiological, chromatographic and fluorometric techniques. The fecal vitamin B₆ level was significantly higher when WHW bread was fed as compared to when WB₆ or W bread was fed (P < 0.01). There was no significant difference in the urinary excretion of total and free vitamin B₆ in relation to the type of bread. The predominant form of vitamin B₆ in urine was found to be pyridoxal. The urinary 4-pyridoxic acid content was significantly lower when the diet was based on WHW bread as compared to WB₆ or W bread (P < 0.01). The percentage of the daily intake of vitamin B₆ accounted for by the excretory products analyzed in this study was 91.6 when WHW bread was fed. The corresponding percentages when WB₆ and W breads were fed were 81.5 and 79.8, respectively. The plasma vitamin B₆ and pyridoxal phosphate levels were slightly lower when WHW bread was consumed as compared to WB₆ or W bread. These data suggest that vitamin B₆ was not as available from WHW bread as from WB₆ and W bread. The availability of vitamin B₆ from WB₆ and W bread as determined in the present study was similar. For the populations who are dependent on refined wheat products, enrichment of flour with vitamin B₆ will be of advantage. However, enrichment of refined wheat products cannot replace completely the benefits of consuming whole wheat products.
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7255. [Article] An analysis of a population of snowshoe hares, Lepus americanus washingtonii Baird, in western Oregon
The ecology of a population of snowshoe hares, Lepus americanus washingtonii, was studied in western Oregon from 1960 to 1962. Objectives were to obtain information to control hares, which frequently cause ...Citation Citation
- Title:
- An analysis of a population of snowshoe hares, Lepus americanus washingtonii Baird, in western Oregon
- Author:
- Black, Hugh C., 1941-
The ecology of a population of snowshoe hares, Lepus americanus washingtonii, was studied in western Oregon from 1960 to 1962. Objectives were to obtain information to control hares, which frequently cause damage to coniferous reproduction in the region, and to compare the life history of this little-studied subspecies with others. The study area was located on cut-over forest land at 2900-foot elevation in the western Cascades. The climate is characterized by heavy precipitation in winter and summer drought. Snowfall is slight. Sixty-four live-traps were located in a square grid of 8 rows of 8 traps each, at spacings of approximately 100 and 200 feet. Half the traps were located on a recently clear-cut area and half in young-growth western hemlock and Douglas-fir. Traps usually were set for three successive days at monthly intervals. Trapped hares were marked and released on the main study area, and hares from nearby areas were removed for necropsy. In all, 207 hares were caught 889 times on the trapping grid during the 18-month study. One-third of hares tagged and released were not recaught, but the remainder were recaught one or more times. Trapping success varied from 3.6 to 44.4 percent. Principle factors influencing movements of hares, trapping success, and distribution of catches were vegetative structure, weather, and differing behavior of adults. Estimates of numbers of hares were computed from live-trapping data by the recapture, and the calendar-graph methods. Both methods indicated comparable trends in the population. Estimates of hares on the area trapped ranged from 41 in March to 136 in August. Estimated density of hares was 1.6 per acre at start of trapping in October. Density was nearly doubled to about 3.0 hares per acre in late summer. Most adult females on the area studied had two or three litters a year, averaging three young per litter. First litters were born in May and last litters in August. Most juveniles approached maximum size by four months. Mean total length of adults of both sexes was greater than that of subadults. Foot and total length of adult females were greater than in adult males. Mean weight of adult males in winter was 40.6 ounces and of females, 43.4 ounces. Subadults and adults weighed slightly less in early winter than in late fall. Sex ratio of 205 adult and juvenile hares was 80 females to 100 males; ratio of 84 young juveniles tagged during the summer was 87 females to 100 males. Juveniles tagged (154) exceeded adults tagged (51) by a ratio of 3:1. Weighted mean range-size of adult hares caught three or more times as computed by the inclusive-boundary-strip, and circular-bivariant-distribution methods was 5.76 and 10.15 acres for males; 3.30 and 7.80 acres for females. Mean home range of juveniles was comparable to the range of adult females. Distribution of catches of hares repeatedly caught and tracking of toe-clipped hares showed that trap-revealed ranges are related to true ranges and that ranges of most adults are fairly stable. A tendency towards farther ranging and linearity of movements was shown by some hares in winter. Location and use of forms are described. Signs of feeding showed that hares fed on conifers and shrubs in winter and herbaceous vegetation in summer. Young juvenile hares "disappeared" from the population at a high rate. Probability of their survival from birth to the first breeding season was less than 0.18. Crude survival rate of all hares was 0.73. Neither disease nor parasitism constituted serious decimating factors, and pathology of 74 hares necropsied was normal. Predation was the most important source of mortality among hares of all ages. Symptoms of "trap sickness" were shown, mainly in winter, by 29 of 207 hares. The following parasites were found in 50 necropsied hares, and 207 hares examined for ticks and fleas: Protozoa, Eimeria stiedae; Cestoda, Mosgovoyia pectinata americana, and Taenia pisiformis; Nematoda, Trichostrongylus affinis, and Nematodirus triangularis; Acarina, Haemphysalis leporis-palustris; and Siphonaptera, Cediopsyllus simplex and Hoplopsyllus affinis.
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Five experiments were conducted with commercial broilers to study the effects of feeding yellow pea (Pisum sativum L. var. Miranda) diets with and without supplementation. Mean body weights and feed conversion ...
Citation Citation
- Title:
- Studies on the effects of feeding yellow pea (Pisum sativum L. var. Miranda) diets with and without supplementation to commercial broiler chickens
- Author:
- Kulkarni, Gururaj Bhimrao
Five experiments were conducted with commercial broilers to study the effects of feeding yellow pea (Pisum sativum L. var. Miranda) diets with and without supplementation. Mean body weights and feed conversion for broilers fed 0, 25, 50 and 65% of soybean crude protein (CP) substituted with yellow pea (YP) protein were not significantly different among the dietary treatments at 4-weeks of age (WOA). At the end of 7 WOA broilers fed 50 and 65% YP diets had significantly lower mean male, female and combined sex body weights than broilers fed the 0 (C-S) and 25% YP diet. Feed conversion for broilers fed the 65% YP diets was significantly higher than for broilers fed the 0 (C-S), 25 and 50% YP diets (Experiment 1). Commercial broiler chicks grown in cages with raised wire floors from day-old to 4 WOA (Experiment 2) and from day-old to 7 WOA (Experiment 3) were fed YP diet without and with supplementation of either choline (.12%) or a dl-methionine (.4%) or a combination of the two. Autoclaved YP was also fed which represented 50% of the CP from soybean meal. Feeding diets containing 25 and 50% YP did not significantly depress either growth rate or improve feed utilization when compared to broilers fed the 0% YP diet. Supplementation of choline (.12%) or dl-methionine (.4%) or the combination of the two to 50% YP diet and feeding autoclaved 50% unsupplemented YP diet did not significantly improve performance. Broiler chicks were reared on litter floors (Experiment 4) and fed diets containing 0, 25 and 50% YP and 50% YP diets with supplemental 1-tryptophan (.045%) to 7 WOA. At 4 and 7 weeks, significant improvements in mean male body weights were observed with supplemental 1-tryptophan to the 50% YP diet then with the unsupplemented 50% YP diet. No significant difference was observed in combined body weights, mean female body weights and feed conversion at 4 and 7 WOA among broilers fed 50% YP with and without 1-tryptophan supplementation. Performance of broilers fed 0 and 25% YP diets were not significantly different at 4 and 7 WOA. Supplementations of either 1-tryptophan (.01%) or 1-threonine (.03%.) or 1-lysine (.1%) or combinations of two or three amino acids to 50% YP diets were carried out (Experiment 5). At 4 WOA, supplementation of tryptophan and threonine to 50% YP diet significantly improved body weight more than did the unsupplemented 50% YP diet. Supplementations of either tryptophan or threonine to 50% YP diets did not produce significant differences in mean body weights than the 25% YP diet. Lower body weight was observed with lysine supplementation than with other dietary treatments at 4 WOA. At 7 WOA, supplementation of threonine alone or combination of threonine and tryptophan to 50% YP diets produced comparable growth performance with that of broilers fed 0% and 25% YP diets. Lysine supplementation to the 50% YP diet produced lower body weights than the other dietary treatments. No significant differences in body weights were observed among the broilers fed the 50% YP diets supplemented with tryptophan alone or a combination of either lysine with tryptophan or threonine or all three amino acids when compared with 50% YP diet. Feed conversion was not significantly different among the dietary treatments at 4 and 7 WOA. Feeding of 25% YP diet was not detrimental to broiler growth and feed conversion. Supplementation of either tryptophan or threonine or the combination of the two to the 50% YP diet improved body weights. However, lysine, methionine and choline supplementations did not improve broiler performances.
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Metabolic syndrome (MetS) and abdominal obesity (AbOb) increase the risk of developing cardiovascular disease and diabetes. Energy restriction (ER), highprotein (PRO) intake and high-intensity interval ...
Citation Citation
- Title:
- Changes in body composition and metabolic syndrome risk factors : response to energy-restriction, protein intake, and high intensity interval training
- Author:
- Pilolla, Kari D.
Metabolic syndrome (MetS) and abdominal obesity (AbOb) increase the risk of developing cardiovascular disease and diabetes. Energy restriction (ER), highprotein (PRO) intake and high-intensity interval training (HIT) can independently improve MetS and AbOb. However, ER reduces metabolically active lean body mass (LBM) in addition to body fat (BF). Purpose: To determine the effects of a 16-wk ER diet with 2 levels of PRO (15% or 25% of energy), plus HIT, on MetS risk factors, AbOb, and body composition in women. Methods: Sedentary, premenopausal women (age=35±10y) with AbOb (waist circumference [WC] ≥80cm) were randomized to a 16-wk ER diet (-300kcals/d) with 15% (15PRO; n=17) or 25% (25PRO; n=18) of energy from PRO, plus 45min/d, 3d/wk HIT and 45min/d, 2d/wk continuous moderate-intensity exercise (CME) (-200kcals/d). Diet and physical activity (PA) were assessed using 4-d weighed food and PA records, respectively; diet and exercise compliance were assessed monthly with multiple-pass 24-h recalls and weekly tracking logs. Body weight (BW), WC, DXA-assessed body composition (BF [%], BF [kg], trunk fat [kg], and LBM [kg]), blood lipids (total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C], triglycerides [TG]), glycemic markers (fasting plasma glucose [FPG], insulin, and homeostatic model assessment for insulin resistance [HOMA-IR], beta cell function [HOMA-%β] and insulin sensitivity [HOMA-%S]) and resting blood pressure (BP) (systolic BP [SBP]; diastolic BP [DBP]) were assessed pre/post-intervention. Repeated measures analysis of variance and two sample t-tests were used at analyze the date. Results are reported as means±standard deviations. Results: There were significant time, but not group, differences in BW (-5.1±2.6kg, p=0.0141), WC (- 7.3±3.6cm, p<0.0001), TC (-18.1±17.4mg/dL, p<0.0001), LDL-C (12.2± 16.2mg/dL, p<0.0001), TG (-25.3±56.2mg/dL, p=0.0064), insulin (-2.1±4.2mg/dL, p=0.0048), HOMA-IR (-0.2±0.5, p=0.0062), HOMA-%β (-12.1±35.2%, p=0.0497), HOMA-%S (28.5±78.4%, p=0.0357), and SBP (-3±9mmHg, p=0.214). There were significant group x time differences in DBP (15PRO=-5±8mmHg, 25PRO=- 2±8mmHg; p=0.0024). There were no time or group differences in FPG or HDLC. There were significant time, but not group, effects on changes in BW (-5.1kg± 2.6, p<0.0001), BF (-3.3±1.6%, p<0.0001), and LBM (-0.6kg±1.5, p=0.0283). The 15PRO group lost more absolute whole BF (-5.2kg vs. -3.9kg, p=0.0355) and trunk fat (-3.1kg vs. -2.2kg) vs. the 25PRO group. Conclusion: Both diets significantly improved BW, AbOb, MetS risk factors, glycemic control, and BF (%); LBM (kg) loss was similar in both groups. Compared to the 15PRO diet had significantly greater absolute BF-kg and trunk fat-kg losses. Increased PRO intake did not improve AbOb or MetS risk beyond ER and HIT/CME. The impact of HIT/CME and the greater (-1.3kg) changes in BW in the 15PRO group may have contributed significantly to the changes in absolute BF and trunk fat. More research is needed to separate the impact of HIT/CME and weight loss from the impact of PRO during ER.
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7258. [Article] Interactions between ecosystem nitrogen and bedrock control long-term calcium sources in Oregon Coast Range forests
Ecosystem nitrogen (N) supply strongly influences the availability and cycling of other essential nutrients in temperate forests, especially calcium (Ca). Short-term additions of N that exceed ecosystem ...Citation Citation
- Title:
- Interactions between ecosystem nitrogen and bedrock control long-term calcium sources in Oregon Coast Range forests
- Author:
- Hynicka, Justin D.
Ecosystem nitrogen (N) supply strongly influences the availability and cycling of other essential nutrients in temperate forests, especially calcium (Ca). Short-term additions of N that exceed ecosystem demands often increase dissolved nitrate fluxes and decrease soil pH, which can stimulate soil Ca loss. However, the long-term effects of high N supply on ecosystem Ca availability are more difficult to determine, and may depend on the Ca content of bedrock and mineral soils. To address this, we examined major and trace element concentrations and ⁸⁷Sr/⁸⁶Sr ratios that trace Ca sources in precipitation, foliage, soil pools, and bedrock at 24 forested sites in the Oregon Coast Range having a wide, natural range of soil N (0.16 - 0.97 % N, 0-10 cm) on contrasting basaltic and sedimentary bedrock. Using a suite of 17 site properties, we also evaluated whether soil N variation across sites was related to the five major state-factors of soil and ecosystem development: climate, organisms, topography, parent material, and time. We found that as soil N increased across sites, its ¹⁵N/¹⁴N ratio declined towards atmospheric values, suggesting that soil N variation reflects a biotic legacy of symbiotic N fixation inputs. In contrast, soil N variation was unrelated to 17 other metrics of soil forming factors that represented climate (mean annual precipitation, mean annual temperature, and distance from the coast), topography (slope, soil depth, and abundance of coarse rock fragments), parent material (within bedrock type bulk and 1 M HNO₃ leachable rock Ca chemistry), and proxies of soil age (Hurst's redness rating, effective cation exchange capacity, Ca in non-exchangeable soil residues, chemical index of alteration, weathering index of Parker, Ca in coarse soil fragments, and soil Ca loss relative to bedrock). These analyses highlight symbiotic N-fixing red alder as a keystone organismal state-factor that produces a wide range of soil N accumulation in coastal Oregon forests. Strontium isotopes (⁸⁷Sr/⁸⁶Sr) and other geochemical analyses indicate that long-term Ca sources in foliage and exchangeable soil pools in Oregon Coast Range forests depend on an interactive effect between N availability and bedrock. Basaltic rocks contained nearly 20-times more Ca than sedimentary rocks across our sites, and this difference was reflected in Sr-isotope partitioning of base cation sources. Atmospheric sources dominated plant and soil pools in forests overlying Ca-poor sedimentary rock, regardless of variation in soil N, indicating extremely limited capacity of weathering to support forest Ca demands. In contrast, forests overlying basaltic rock obtained as much as 80% of Ca from rock weathering in low N sites, yet relied to a greater extent on atmospheric Ca as soil N increased, with less than 10% of Ca from rock weathering at sites with the highest soil N. Surprisingly, differences in fresh rock Ca content and base cation sources between sedimentary and basaltic sites was not reflected in ecosystem Ca availability, and instead increasing soil N caused similar declines in foliar and exchangeable Ca across both rock types. This illustrates that nutrient pool sizes do not necessarily reflect long-term nutrient supply, and highlights how coupled biogeochemical cycles within ecosystems can regulate nutrient loss and supply to biota. Broadly, our results highlight how interactions between biological and geologic factors can influence base cation sources in forest ecosystems. The sustainability of base cation supplies to forests may therefore depend greatly on variation in bedrock weathering at low N sites, yet converge to depend on atmospheric inputs in sites that receive high N loading from biological fixation or anthropogenic deposition.
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7259. [Article] Fault behavior over geomorphic time scales in the Pakistan Himalaya, Kashmir Himalaya, and California
The state of the knowledge for fault behavior in the northwest Himalaya and California varies dramatically. In the Pakistan and Kashmir Himalaya, few data constrain the role that individual active faults ...Citation Citation
- Title:
- Fault behavior over geomorphic time scales in the Pakistan Himalaya, Kashmir Himalaya, and California
- Author:
- Madugo, Christopher Lee Madden
The state of the knowledge for fault behavior in the northwest Himalaya and California varies dramatically. In the Pakistan and Kashmir Himalaya, few data constrain the role that individual active faults play in accommodating Indo-Eurasian convergence and the relative earthquake hazard across the region. By contrast, the San Andreas fault in California is one of the best-studied fault systems in the world, although seismic hazard models have yet to incorporate certain available geologic data, such as measurements of slip-in-the-last-event. This dissertation addresses the sparsity of earthquake hazard data in the northwest Himalaya, and the problem of how best to utilize available data in hazard models for California by (1) Providing the first quantitative constraints on the latest Pleistocene slip rate and earthquake potential for the thrust front Pakistan; (2) Characterizing the rate and style of upper plate faulting in Kashmir over geomorphic (10⁴ year) time scales; and (3) Creating a standardized database of fault offsets to help test time-dependent and time-independent seismic hazard models for the Uniform California Rupture Forecast. The Himalayan thrust front in Pakistan is defined by the Salt Range thrust (SRT), the up-dip extension of the plate boundary décollement, the Main Himalayan thrust (MHT). We constrain the convergence rate across the SRT by determining the slip rate for the Kalabagh fault (KF), a tear fault that is linked with the SRT at depth. Based on the age and offset of two alluvial fan apexes from their source canyons, we estimate a slip rate of between 9 and 27 mm/yr (~12-17 mm/yr best estimate) for the KF-SRT fault system. This rate matches well with the geodetically-constrained creep rate for the MHT at depth, suggesting the entire slip budget for the Pakistan Himalaya is accommodated at the thrust front. Because the SRT is cored by salt, the earthquake potential for the fault is inferred to be low, although evidence for seismogenic Holocene rupture on the Kalabagh fault, which is also locally lined with salt, suggests that the frontal fault ruptures in plate boundary earthquakes on the MHT. The primary implications of these findings are that convergence in the Pakistan Himalaya is focused at the thrust front rather than distributed between different faults across the plate boundary. In the Kashmir Himalaya, multiple active faults along the plate boundary suggest that Indo-Eurasian convergence is partitioned between the thrust front and faults to the north. To test how much deformation occurs within the overriding plate, we characterized deformation for the Balapora fault, a high-angle reverse fault on the southwest side of the Kashmir Valley. Based on dated offset stream terraces and alluvial fans, the slip rate for the Balapora fault is consistently between 0.3 and 0.5 mm/yr over time scales varying by an order magnitude between about 40 ka and 400 ka. These slip rates translate to shortening rates of 0.1 mm/yr, or less than 1% of the convergence rate across the Kashmir Himalaya. Earthquake recurrence for the Balapora fault is several thousand years, which is consistent with the low slip rate for the fault. The inference is thus that, the majority of convergence in the Kashmir Himalaya is accommodated near the thrust front, as in the Pakistan Himalaya. For California, a new database was created from thousands of measurements of slip resulting from one or more historical to prehistoric earthquakes for use in seismic hazard models. A new rating scheme characterizes the quality of the offsets. Multiple methods to estimate slip during the last event, average slip and slip-per-event are used to analyze the data. These data provide a first order check for models of earthquake behavior. With the advent of high resolution topographic datasets such as LiDAR, the new methodology serves as a template for inclusion of rapidly-accumulating topographic and paleoseismic data in California as well as to regions such as the Himalayan front, as those types of data are adopted.
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7260. [Article] Augmenting and interpreting ice core greenhouse gas records
The three studies that comprise this dissertation seek to answer significant questions in paleoclimatology through unconventional applications of ice core greenhouse gas data. These studies involve different ...Citation Citation
- Title:
- Augmenting and interpreting ice core greenhouse gas records
- Author:
- Rosen, Julia L
The three studies that comprise this dissertation seek to answer significant questions in paleoclimatology through unconventional applications of ice core greenhouse gas data. These studies involve different gases and span the interval of time between the Last Glacial Maximum and the Industrial Revolution, but are united by their nontraditional use of greenhouse gases and their attempt to realize the potential for greenhouse gases to reveal important information about Earth’s climate. Ever since their discovery, the abrupt climate changes of the last glacial period known as Dansgaard-Oeschger (D-O) events have proved challenging to explain. The dominant hypothesis involves periodic freshwater discharges into the North Atlantic, which may regulate the strength of the Meridional Overturning Circulation (MOC) and its role in transporting heat to high latitudes. These events were not restricted to the North Atlantic, and can also be recognized in paleoclimate archives around the world. However, numerous uncertainties surrounding the mechanism behind D-O events remain, including how they are communicated to low latitudes and whether other hypotheses can be definitively ruled out. To constrain the mechanism behind abrupt climate changes, we investigate the phasing of climate changes in high- and low-latitude regions at the Bølling Transition, the penultimate abrupt warming event of the last glacial period. We use methane and the ¹⁵N/¹⁴N ratio of N₂ from the North Greenland Eemian (NEEM) ice core, which serve as proxies for tropical climate and Greenland temperature, respectively. We find that these gases change synchronously in the ice core record, and use a firn air model together with a Monte Carlo approach to constrain the phase lag to within several decades. Our results indicate that the mechanism behind the Bølling Transition was capable of rapidly transmitting the climate signal across the planet in a matter of years, and must therefore involve components of the climate system that are suitably reactive. The glacial-interglacial change in atmospheric methane concentrations revealed in ice core records has spurred a decade of debate about its cause. The most likely explanations involve dramatic changes in methane emissions, which originate from both high- and low-latitude wetlands. One method of investigating the changing latitudinal distribution of methane sources is to quantify the difference in methane concentrations between Greenland and Antarctica, which changes in proportion to the fraction of methane produced at high northern latitudes. Previous attempts to determine the methane interpolar difference (IPD) abound, but many have been hampered by complications in synchronizing bipolar ice core records and analytical uncertainties. We present the first continuous estimate of the methane IPD across the termination using high-resolution methane data from the NEEM and West Antarctic Ice Sheet (WAIS) Divide ice cores. Our results reveal the dominant role of tropical sources in driving abrupt changes in atmospheric methane concentrations, and show that boreal methane sources were surprisingly insensitive to dramatic climate changes. We hypothesize that changes in Northern Hemisphere snow and ice cover exerted strong control over tropical methane emissions, while gradually increasing solar insolation and land area allowed boreal sources to grow during the termination. We also investigate the IPD across the major climate transitions of the termination, and during four centennial-scale methane variations, and find opposing trends in boreal and tropical source strengths during these transient events. We propose that temporary decoupling of the locus of interhemispheric mixing, the position of the Intertropical Convergence Zone, and tropical precipitation may explain these results. Atmospheric concentrations of nitrous oxide (N₂O) have risen by ~20% from preindustrial to modern times, but the cause of this increase is not fully understood. The change has been previously attributed to various agricultural activities which perturb microbial processes in soils, but exactly how remains an outstanding question with important implications for future mitigation of N₂O emissions. We present the first measurements of the isotopomers of tropospheric N₂O over the interval from 1450 to 1920 CE. Our results confirm that the preindustrial atmosphere was enriched in all isotopes relative to the modern atmosphere. Furthermore, we estimate that the net anthropogenic source of nitrous oxide must be depleted in all heavy isotopes and have a strong site preference, consistent with a strong role for agricultural emissions and characteristic of N₂O derived from nitrification. We also find a large oscillation in the site preference of the ¹⁵N in N₂O during the Little Ice Age between 1500 and 1700 CE. We hypothesize that this excursion may be due to changing climate conditions that led to an increase in the amount of N₂O produced by nitrification vs. denitrification.