No / The regulation of linearized multivariable system models, following input set point and load disturbance changes, is considered. An inner and outer closed-loop control strategy is outlined, enabling targeted recovery rates, offset attenuation and low steady state interaction to be achieved. Proportional control and passive network compensation alone are employed. Gain ratio selection and outer loop tuning are exercised, ensuring thereby the confinement of output perturbations to low-frequency load disturbances and reference input changes. Application studies are presented for purposes of comparison.

We sampled forest stands in upland forests of the Southeastern US along a chronosequence of a replicated successional forest sere (1, 6, 10, 25, and 80 years) to elucidate the temporal changes in soil spatial heterogeneity. Samples were collected from loblolly pine plantations representing reorganization through aggradation phases of succession, and from one set of oak-hickory stands to signify the steady-state phase of the model. These trends are characterized and compared to a conceptual model of pattern dynamics. Variability in soil properties (NO3, NH4, pH, Total N, Total C) and forest floor litter at scales relevant to individual plants was quantified using univariate and geostatistical procedures. Global variation (using both coefficient of variation and standard deviation), patch size and proportion of spatially structured variation were examined for individual variables at each successional stage. These patterns were also averaged to produce a generalized model of spatial heterogeneity change during succession. Individual variables often showed differing patterns. However, when patterns from individual variables were averaged, overall patterns emerged. Early in succession global variability was largest and patch sizes were smallest. As succession progressed, trends in the data showed that global variability decreased and patch sizes increased to the middle stage of succession. Both of these trends fit our conceptual model of pattern dynamics. However, the slopes in these trends were not significant at alpha=0.05. / Master of Science

No description available.

The southern Appalachian forests of the United States are undergoing changes due to the death of hemlock trees attacked by the hemlock wooly adelgid. This paper addresses the management impacts of Rhododendron maximum removal in the riparian and upslope areas previously occupied by hemlock. This study measured the consequences macroinvertebrates faced due to riparian Rhododendron removal from 300 m reaches of two low order streams. Two additional low order streams served as reference sites for the experiment. The stream macroinvertebrate communities were assessed using a before-after controlled impact model comparing communities between fall 2014 to those from fall 2015 and from spring 2015 to spring 2016. Macroinvertebrate collections consisted of 288 samples with a total of 61,056 individuals. There was a significant increase in collector-gathers in both removal sites, mostly from increases in Ephemerellidae and Chironomidae. There was also a significant decrease in filter feeding organisms in the removal reaches. Traits analysis also revealed that several traits that are shared by collector gathers also increased, e.g., short life cycles that are related to the increase in Chironomidae. Using Nonmetric Multidimensional Scaling (NMDS) and permutational MANOVA significant annual differences in macroinvertebrates were found in all of the stream reaches during both seasons. However, the trait based NMDS and permutational MANOVA found significant change only in one removal site between fall collections based on traits. These finding are consistent with findings from logging and other riparian removal projects; suggesting that the short-term impacts of selective Rhododendron removal on benthic macroinvertebrates are comparable to that of logging activity. / Master of Science / The southern Appalachian forests of the United States are undergoing changes due to the death of hemlock trees attacked by the hemlock wooly adelgid. This paper addresses the management of Rhododendron removal in the riparian and upslope areas previously occupied by hemlock. This study investigates the consequences stream insects face due to near stream Rhododendron removal from 300 m section of two small streams. Two similarly sized streams served as reference sites for the experiment. The stream insect communities were assessed using a before-after controlled impact model comparing collections from the fall 2014 to those from fall 2015 and from spring 2015 to spring 2016. Insect collections consisted of 288 samples with a total of 61,056 individual insects. There was a significant increase in generalist feeding insects in both removal sites, mostly from increases in common mayflies and small non-biting midges. Analysis of insect attributes also revealed that attributes shared by generalist feeding insects also increase, e.g., short life cycles that are related to the increase in nonbiting midges. Looking at the insect communities we found annual changes in all of the stream reaches during both seasons. However, analysis of insect attributes found significant change only in one removal site between the fall collections. These finding are consistent with findings from logging and other riparian removal projects; suggesting that the short-term impacts of selective Rhododendron removal on stream insects are comparable to that of near stream logging activity.

Much of the biodiversity in a forest comes from the understory vegetation. However, centuries of fire suppression in the western United States have made human-implemented disturbance necessary for reinstating natural disturbance cycles. However, the mechanical thinning and prescribed burning treatments used by land managers may differentially affect the response of the understory community. This study aimed to compare how prescribed fire and mechanical thinning treatments, with the size and severity of those treatments, affect understory plant communities in aspen-conifer forests over time. We sampled the understory community in burned, mechanically thinned, and untreated forest stands one, three, or five years post-treatment. Within these treatment areas, we measured understory cover, species richness, and leaf area index in belt transects, and we calculated species diversity and non-native cover for each transect. Understory cover increased in burn and mechanical treatments over time and was significantly higher in burned treatments than in untreated stands five years after treatments. Additionally, understory cover was highest in large, low-severity fires. Species richness also increased in burned areas as time since treatment increased. Species richness and species diversity positively correlated with canopy openness in untreated plots, while the cover of non-native species positively correlated with fire severity. Large, lower-severity burns had the most significant positive impact on understory plant communities, but these impacts may take time to become apparent.

No description available.

The objective of this study was to determine the effects race, sex and sleep disturbance have on the severity of Parkinson’s disease as assessed by the Hoehn Yahr (HY) score in both the medicated (ON) and non-medicated (OFF) states. The potentially confounding variables of age, time in years from the onset of symptoms to database entry, and education were taken into account. Secondary analysis was also conducted to determine how the non-motor symptoms of dementia, hallucinations and autonomic dysfunction impacted Hoehn Yahr ON and OFF scores. This study used the statistical techniques of the Student’s t-test, ANOVA, Tukey-Kramer test, univariate linear regression, and multivariate regression. The t-tests and ANOVA test revealed that there was no significant differences in mean HY ON and OFF scores between the sexes, patients with and without sleep disturbance, and between the different races analyzed in this study. Patients with and without sleep disturbance did show significantly higher HY ON scores as compared to HY OFF scores, which is peculiar as this finding suggests that these patients are not responding to their medication. The univariate linear regression models did show, however, that time in years from the onset of symptoms to database entry did significantly impact both HY ON and OFF scores, whereas age is only shown to have a significant impact on HY OFF scores. Additionally, the univariate linear regression model analyzing the association between education and HY OFF scores showed that having some high school education, but not receiving a degree, was associated with an increase in HY OFF scores. Several multivariate linear regression models where built to assess the impact different predictor variables had on HY ON and HY OFF scores. The first two multivariate models used the predictor variables of age, race, and time in years from the onset of symptoms until database entry. These models showed that only time in years from the onset of symptoms until database entry impacted HY ON scores, whereas all three of these predictor variables impacted HY OFF scores. Two additional multivariate linear regression models were built to assess how age, race, time in years from the onset of symptoms until database entry, dementia, autonomic dysfunction and hallucinations all impacted HY ON and OFF scores. These models revealed that all of these predictors, when taken together, significantly impacted HY OFF scores, but not HY ON scores. Finally a scatter plot was made comparing HY ON and HY OFF scores. A LOWESS scatter plot smooth line was also superimposed on top of this plot to show the overall trend these scores had on one another. This scatter plot was interesting because it suggested that there were two spate groups of patients contained in this database, those that responded well to medication and those that did not. Overall, this study showed that age, time in years from the onset of symptoms until database entry, education and race impacted HY OFF scores. Furthermore, the analysis indicated that patients who were asked about sleep disturbance did not appear to be responding to medication. There are several limitations to this study, however, with the most important being missing data and the cross-sectional design. Missing data prevented sleep disturbance from being thoroughly analyzed and the cross-sectional design does not allow for any causal relationships to be determined.

Research has shown that sleep disturbance (e.g., sleep latency, wakefulness after sleep onset [WASO]) negatively affects physical, emotional, and mental health. For many adults, the postpartum period is one that is particularly highlighted by sleep disturbance and fatigue. Postpartum mothers are also more vulnerable to psychiatric disorders such as depression. We sought to investigate whether the number of children and presence of an infant predicted clinically significant sleep disturbance, and subsequently, depressive symptoms, for both mothers and fathers. We found that having an infant was significantly associated with increased wife WASO, which in turn was associated with increased depressive symptoms for wives. Further, husband WASO was associated with decreased wife WASO which was similarly associated with decreased depressive symptoms for wives. Thus, by helping with nighttime care so that mothers can get more sleep fathers can greatly contribute to the physical and emotional health of mothers.

<p>The main cause of environmental disturbance in the Fennoscandian boreal forests today is forestry. Natural disturbances are important to maintain diversity, but anthropogenic disturbance, such as forestry, differs in many ways from the natural ones. Forestry is a big industry in Sweden and only a small remnant of old-growth forest is left. Several studies have shown an initial decrease in e.g. dragonfly diversity a few years after logging, followed by an increase up to numbers comparable with the original species number. In this study I examined whether the new, quite diverse, species composition is similar to the one present before the logging or if some species are disappearing and are replaced with other, maybe opportunistic species. Other factors such as ongoing changes in climate also will be considered. A resampling of 34 (and an additional 4) lakes that also were sampled in 1996-97 was done during summer of 2006. Analyses of data from the two sampling occasions were done. I found that even if the diversity is just temporarily affected (or not affected at all), it is not always the same species involved. This means that the diversity in a single lake can appear to be high, but the total diversity in Sweden, or Scandinavia, is declining. I also found some interesting new species for the area, such as Nehalennia speciosa, Sympecma fusca and Aeshna mixta.</p>

Red spruce is a shade-tolerant conifer whose distribution and abundance reflect Quaternary climate history as well as natural and anthropogenic disturbances. This species once extended further south than its present localities, because of natural and anthropogenic disturbances such as logging, windthrow, and fire. Little is known about the disturbance regime of this species, because long term stand dynamics are difficult to obtain. This-long lived species is hypothesized to be suffering a decline in radial growth, density and abundance at the present time. Recent research suggests pollution, biotic stresses, climate change and natural stand dynamics are the driving forces behind these decreases. The purpose of this study is to investigate the influence of fire in a mesic ecosystem, specifically a high-elevation red spruce (Picea rubens Sarg.) forest on Whitetop Mountain in the southern Appalachian Mountains. Six plots were established in a high elevation red spruce stand to characterize the stand composition. Tree ring data were collected to investigate radial growth relations to inter-annual climatic variability and cross-sections were used to investigate fire history. Red spruce continued to establish throughout the 19th century until a severe fire occurred in 1919 and caused a new cohort of yellow birch (Betula alleghaniensis Britt.) to establish within the stand. Logging and fire caused high mortality in the stand, yet many spruce remain that outdate the past disturbances. Red spruce saplings continue to persist in the stand, showing regeneration despite the abundant hardwoods. Moisture was the main contributing factor to red spruce growth in the dendroclimatic analysis. Red spruce radial growth was significantly correlated to high precipitation and low temperatures of the previous growing season, which is similar to recent research results. This study collaborates the current literature on red spruce growth along with the results found here in creating a model to represent the growth characteristics of red spruce when inter-mixed with hardwoods after a severe disturbance.