Browsing by Subject "recovery"
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Item Agriculture, technology, and conflict(2009-05-15) Zilverberg, Cody JohnConflict and agriculture have a long, shared history. The purpose of this research is to look at the relationships between agriculture, agricultural technologies, and conflict during current and recent conflicts, large scale and localized. Agriculture and its related technologies are often affected by conflict, but rarely acknowledged as a cause or solution to conflict. Literature reviews in six topic areas illustrate various facets of the relationship between agriculture and conflict. Research conducted in Santa Cruz del Quich?, Guatemala illustrates the ways farmers were impacted by the country?s civil war. It also examines farmer survival strategies during the war, and reveals the presence of minor localized conflict over water resources. Conflict over land is not a major concern at present. Market access for inputs and outputs are shown to have been a problem for a number of farmers during the civil war. The poverty of Santa Cruz farmers indicates that much could be gained by rural development. Research is unable to support the hypotheses that agricultural technologies have prevented or caused conflict in Santa Cruz del Quich?, or that they have played a large role in recovery from the country?s civil war. The author recommends that future research be undertaken in regions with a diverse set of agricultural technologies, and/or a recent history of significant technological change in agriculture. Policy recommendations include providing secure access to markets during war time, increasing capacity for home-based rural production, and continuing research into resilient crops. Finally, the author suggests that the responsible decision to develop, adopt, or introduce an agricultural technology must take into account the social consequences of that decision, including how the new technology may alleviate or contribute to conflict.Item Blocked and recovered memories of affective, distinctive, and neutral paragraphs(2009-05-15) Corbisier, Barbara LynnHighly affective memories have been thought to be longer lasting and more detailed than other memories, and many experimental results have supported this assertion. The apparent robustness of these memories, however, may result from their high distinctiveness, rather than their emotional content. Two experiments tested free and cued recall for negative affect, distinctive, and neutral paragraphs. Experiment 1 compared neutral and negative affect paragraphs using a blocked and recovered memory technique. Affective paragraphs were remembered significantly better than neutral paragraphs in free recall of paragraph titles, regardless of condition. Details of neutral paragraphs were remembered significantly better than affective paragraphs, regardless of condition. No recovery effect was found. Experiment 2 compared distinctive and neutral paragraphs using the same technique. Free recall of paragraph titles did not differ between paragraph types. Neutral paragraphs were remembered better than distinctive paragraphs in cued recall, regardless of condition. Participants remembered significantly more with cued recall, and significantly more in the forget condition, and distinctive paragraphs were subject to a much greater forgetting effect than neutral paragraphs. It is unclear why a robust forgetting effect, using these stimuli, was not found. Consistent with previous literature, affective stimuli were remembered well, but inconsistently, distinctive stimuli were not. These results provide support for the claim that negative affect memories are more robust than other memories. This may result from their inherent emotional content as opposed to their being distinctive in some way.Item Characterization of Fatigue Cracking and Healing of Asphalt Mixtures(2012-07-16) Luo, XueFatigue cracking is one of the most common distresses of asphalt pavements, whereas healing is a counter process to cracking which alleviates cracking damage and extends fatigue life of asphalt pavements. Most of existing methods to characterize fatigue cracking and healing are generally empirical or phenomenological in nature, which does not satisfy the need to develop mechanistic-based pavement design methods. The objective of this study is to characterize fatigue cracking and healing of asphalt mixtures using an energy-based mechanistic approach. A controlled-strain repeated direct tension (RDT) test is selected to generate both fatigue cracking and permanent deformation in an asphalt mixture specimen. Fatigue cracking is separated from permanent deformation from a mechanical viewpoint. The development of fatigue cracking is described by the evolution of the damage density and the increase of the average crack size with the increase of loading cycles. A creep and step-loading recovery (CSR) test is designed to measure the internal stress in the recovery phase of an asphalt mixture specimen. The internal stress and the strain measured in the recovery phase are used to conduct the mechanistic analysis of recovery and healing of the asphalt mixture specimen. Then healing is described using the decrease of the damage density and average crack size with time. Different types of asphalt mixtures produce distinctly different fatigue cracking and healing characteristics. The effect of mixture composition, temperature, and aging are evaluated using the approach above. The entire series of tests for fatigue, permanent deformation and healing can be completed in one day, with the healing part requiring only a matter of minutes. The methods proposed in this study characterize fatigue cracking and healing of asphalt mixtures using its essential cause and effect relationship.Item Characterization of the Bone Loss and Recovery Response at the Distal Femur Metaphysis of the Adult Male Hindlimb Unloaded Rat(2012-02-14) Davis, Joshua MorganExtended periods of mechanical unloading are known to be detrimental to bone health. Astronauts who spend months in microgravity aboard the International Space Station (ISS) are at particular risk. It is anticipated that NASA will not drastically increase the size of the astronaut corps, and this will mean increased likelihood of repeat missions for more astronauts. Thus, it is important to better understand the effects that prolonged, multiple bouts of unloading have on bone. This study utilized the hindlimb unloaded (HU) rat model to examine bone loss and recovery for single and double unloading bouts. Adult male Sprague-Dawley rats (6 months old) were randomized into the following groups: baseline (sacrificed at 6 months), 1HU7 (unloaded for 1 month, weight-bearing recovery for 3 months), 2HU10 (unloaded for 1 month, recovered for 2 months, unloaded for another month, and then recovered 2 months), 1HU10 (normal cage activity until 1 month HU ending at month 10, 2 month recovery followed), and aging controls (remained ambulatory throughout experiment). Every month (28 days), animals were terminated and the left femurs were excised, resulting in n=15 per group for each time point. Mineral and geometric properties were measured using peripheral quantitative computed tomography (pQCT) at the distal femur metaphysis, and quasi-static reduced platen compression (RPC) was used to estimate the mechanical properties of cancellous bone. Strength indices based on pQCT parameters were calculated as predictors of mechanical properties. Bone mass properties decreased due to HU and recovered within 2-3 months post-HU. A combination of increased periosteal apposition and endocortical resorption also occurred during HU. The initial HU bout suppressed normal age-related increases in mechanical properties and recovered within 1-2 months. Cancellous compressive strength index (CSI) most closely matched changes in mechanical properties. A second HU bout after two months recovery had a less detrimental effect on pQCT parameters but a greater negative impact on mechanical properties, when compared to pre-HU values. The opposite is true for mechanical properties if loss is characterized relative to aging controls. Recovery after the second HU period did not appear to be significantly affected by a previous bout of HU.Item Effects of post-stroke depression on cognitive and linguistic recovery(2010-05) Amoroso, Jill; Harris, Joyce L.; Marquardt, Thomas P.The aim of this paper is to explore the relationship between functional recovery from stroke and depression. Stroke leads to depression both directly (through the location of the lesion) and indirectly (through decreased functional status and aphasia secondary to stroke). Consequently, depression may limit functional recovery and recovery from aphasia. The relationship between decreased functional status post-stroke and depression appears to be bidirectional and mutually-reinforcing (decreased functional status leads to depression and depression limits functional recovery). Similarly, the relationship between aphasia recovery and depression is likely bidirectional and mutually reinforcing. Antidepressants may be useful in disrupting these relationships and thereby improving functional recovery from stroke.Item Forecasting Recovery Opportunities for the Red-cockaded Woodpecker on Private Lands in Eastern North Carolina Using a Spatial Model of Tree Age(2014-11-21) Dube, Amanda MCurrently, recovery efforts for the federally endangered red-cockaded woodpecker (RCW; Picoides borealis) primarily occur on public lands throughout the Southeast, where proven management practices ensure availability of mature, open pine savannahs able to support populations. Many populations on public lands are approaching carrying capacity, suggesting RCW management on private lands will become increasingly important to achieve recovery goals. Recovery on private lands will involve developing recruitment clusters through management practices that produce sufficient quality and spatial aggregation of trees age 60 or older to provide nesting habitat, and trees age 30 or older to provide foraging habitat, as outlined in the U.S. Fish and Wildlife Service (USFWS) Recovery Plan. In this analysis, relationships between tree age, canopy height, and site index were applied to land cover, LiDAR-derived canopy height, and expected site index data in a geographic information system (GIS) to produce a tree age model for pines on private lands in eastern North Carolina. Modeling provided a means to spatially and temporally identify recovery opportunities over the next 10 to 40 years, predict locations for potential recruitment clusters within the next 10 years, and assess connectivity between potential recruitment clusters. Depending on predominant species, modeling produced acceptable estimates for tree age and suitability timeframes for 69-95% and 85-92% of surveyed parcels, respectively, compared to expected age and suitability timeframes derived from field-collected diameter at breast height (DBH). Over 90% of existing RCW clusters on public lands were modeled to contain trees age 40 or older, suggesting age was underestimated in some cases. Results indicate almost 80% of existing pines will remain too young over the next 10 years to support RCW cavity trees. However, over 3,000 potential recruitment cluster sites were identified. These could contribute to increased carrying capacity by providing habitat for potential breeding groups, and create links between existing populations. The prevalence of young pines suggests more opportunities to create RCW recruitment clusters will become available over time with proper habitat and population management. Modeling such as done in this study can serve as a valuable conservation planning tool to guide recovery efforts over space and time.Item Generalized Correlations to Estimate Oil Recovery and Pore Volumes Injected in Waterflooding Projects(2012-02-14) Espinel Diaz, Arnaldo LeopoldoWhen estimating a waterflood performance and ultimate recovery, practitioners usually prepare a plot of log of water-oil ratio vs. cumulative production or recovery factor and extrapolate the linear section of the curve to a pre-established economic limit of water production. Following this practice, engineers take the risk of overestimating oil production and/or underestimating water production if the economic limit is optimistic. Engineers would be able to avoid that risk if they knew where the linear portion of the curve finishes. We called this linear portion the "straight-line zone" of simply SLZ. In this research, we studied that ?straight-line zone? and determined its boundaries (beginning and end) numerically using mathematics rules. We developed a new procedure and empirical correlations to predict oil recovery factor at any water/oil ratio. The approach uses the fundamental concepts of fluid displacement under Buckley-Leverett fractional flow theory, reservoir simulation, and statistical analysis from multivariate linear regression. We used commercial spreadsheet software, the Statistical Analysis Software, a commercial numerical reservoir simulator, and Visual Basic Application software. We determined generalized correlations to determine the beginning, end, slope, and intercept of this line as a function of rock and fluid properties, such as endpoints of relative permeability curves, connate water saturation, residual oil saturation, mobility ratio, and the Dykstra-Parsons coefficient. Characterizing the SLZ allows us to estimate the corresponding recovery factor and pore volumes injected at any water-oil ratio through the length of the SLZ . The SLZ is always present in the plot of log of water-oil ratio vs. cumulative production or recovery factor, and its properties can be predicted. Results were correlated in terms of the Dykstra-Parsons coefficient and mobility ratio. Using our correlations, practitioners can estimate the end of the SLZ without the risk of overestimating reserves and underestimating water production. Our procedure is also a helpful tool for forecasting and diagnosing waterfloods when a detailed reservoir simulation model is not available.Item Public Housing after Hurricane, Urban Renewal or Removal? The Case Studies of Beaumont and Galveston, Texas.(2013-05-01) Tran, Tho Ngo DucDecent housing is a goal for many people not only in the United States but elsewhere in the world. A house becomes the symbol of family spirit whether it is a single-family or multiple-family home. Public housing in the United States is housing of ?last resort,? for families whose incomes do not allow them to find housing in the private market. Yet, many studies focusing on public housing find a host of social issues plaguing these units. The US Government has initiated various programs to improve the quality of public housing as well as the living condition of local resident through agenda of Department of Housing and Urban Development (HUD). HOPE VI is one of the major programs that focuses on distressed public housing. This program funds local government and housing authority in order to revitalized or rebuild public housing. This program has been very successful in providing high-quality housing for public housing residents. However, as any type of construction, housing usually received great damage when natural disaster happening. It can be partly damaged or completely destroyed due to the direct and indirect effects of disaster. Public housing, like most affordable housing, is often built in highly vulnerable areas, such as floodplains or other low-lying areas. When disasters such as hurricanes strike, housing located in these areas is likely to receive the greatest damage and recovery may be slower. This study looks at the case study of public housing in Galveston and Beaumont after Hurricane Ike (2008) and Rita (2005). After Hurricane Rita in 2005, Beaumont has rebuilt some public housing development with a HOPE VI grant awarded in 2007. These areas have successfully rebuilt through the cooperation of housing authority, local government, local residents, and developers. In contrast, Galveston could not reach agreement about the destiny of public housing after Hurricane Ike in 2008. This story becomes more serious when HUD announced that if Galveston cannot rebuild public housing in disaster area, they must refund the money to the federal Government. These two cities provide a comparative case study of the rebuilding of public housing after disaster, where on one successfully rebuilt while other did not. By looking at the secondary data sources, this research analyzes the situation of these places in different period: before the Hurricane, when the Hurricane happened, and after the Hurricane. The paper will address the similarities as well as differences between two case studies in term of historical profile, demography, public housing program characteristics, damage, and recovery. Besides, economic change after hurricane approached is addressed. The housing situation will be further analyzed in Galveston to clearly show the obstacles in which this city coped with. Finally, the study will conclude by suggesting some implications for theory, housing policy, management, and further research.Item The Effect of Dietary Starch Concentration on Glycogen Replenishment in Performance Horses(2013-12-12) Vonderohe, CaitlinFour Quarter Horses (2 to 3 yr; 401 to 432 kg BW) were used in a simple crossover design for a 49-d study to determine the effect of dietary starch levels on post-exercise glycogen replenishment. Horses were fed either high starch (HS) or low starch (LS) concentrates at 0.75% BW/d plus l.0% BW/d Coastal Bermudagrass hay for 14 d, and then worked to fatigue in a standardized exercise test (SET). After a 14-d washout period, horses were switched to the opposite diet for 14 d and then again performed the SET. The LS and HS concentrates were commercially available feeds. Total diets provided an average of 997.6 g of starch and 553.7 g of starch/d in the HS and LS diets, respectively. Throughout the trial, horses were lightly exercised for 30 min, 3 d/wk. The SET consisted of a 30-min warm-up period at a brisk trot in a panel exerciser, followed by 27 min of gradually ascending high-intensity work on a treadmill. Skeletal muscle biopsies were taken from the biceps femoris at rest, immediately after the SET, and again at 6-, 24- and 48-h post-exercise. Samples were flash frozen in liquid nitrogen and stored at -80?C until analysis for later muscle glycogen concentration using a commercial kit. Venous blood samples were taken at rest, immediately post exercise and every 15 min for 3 h post-exercise. Blood samples were analyzed for lactate, glucose, total protein and Ca concentration. Data were analyzed using Proc Mixed (SAS) procedure with main effects of sample time, horse, period, trt and time x trt interaction. Horses on the HS diet had a higher muscle glycogen concentration (P <0.05) at 48 h post exercise than the LS horses (18.1 vs. 10.6 ?g/mg wet wt). At 6 h, HS horses had a more rapid rate of repletion, as observed by the higher glycogen concentration (P<0.05) compared to the immediate post-exercise samples (15.4 vs. 7.9 ?g/mg wet wt); whereas, the LS horses did not return to normal levels until 24 h post SET. Results indicated that horses on the LS diet, which is representative of low-starch feeding programs commonly observed in the industry, replenish their skeletal muscle glycogen slower than horses on the HS diet. Based on this study, performance horses undergoing multiple bouts of intense exercise may benefit physiologically from receiving diets that contain more than 553.7 g of starch/day.Item Two Essays in Asset-Pricing(2012-10-19) Petkevich, AlexeyPast research documents a positive link between momentum and firm-level default risk, yet this anomaly is not connected to default risk at the macro level. Namely, there is no documented momentum during recessions, when default is higher on average. In the first essay, "Momentum and Aggregate Default Risk," we attempt to resolve this puzzle by analyzing momentum pro ts over time, conditional on both business cycles and unexpected changes in aggregate default risk. First, we show that momentum is driven by shocks to aggregate default, rather than general economic conditions such as expansions and recessions. Using the Fama and MacBeth procedure, we find that a conditional default shock factor is priced and can explain a large portion of the total momentum returns. Second, we provide a risk-based explanation for this anomaly by linking the returns of momentum portfolios to shareholder recovery during financial distress. We find that losers have higher recovery (i.e., shareholders have high bargaining power) on average, and, as a result, have relatively lower risk in high default states of the world. Therefore, loser stocks have a lower risk premium and lower expected returns in worsening aggregate default conditions, leading to the observed momentum. This effect is more pronounced among stocks of firms with low credit ratings. Our results help to reconcile the seemingly contradictory evidence documented by previous studies and o er a rational explanation for the momentum anomaly. In the second essay, "Sources of Momentum in Bonds," we study the relationship between momentum in bond returns and aggregate default. We document that momentum in corporate bonds occurs mainly during periods of high default shocks and is driven by losers. Supporting this result, we find that conditional default risk is priced in the cross-section of corporate bond portfolios. Motivated by these findings, we develop a theoretical model connecting bond momentum returns to the ability of bondholders to recover value in financial distress. Specifically, we find that losers have relatively higher recovery potential and, therefore, become less risky when high default shocks occur. Thus, losers have lower expected returns in high default shocks, leading to the observed conditional momentum. Further, US government bonds, with default risk approaching zero, feature no momentum, however this anomaly prevails in sovereign bonds with positive default risk, consistent with our main results.