No description available.

The hemlock woolly adelgid (HWA), Adelges tsugae Annand, (Hemiptera: Adelgidae) is an invasive species in the eastern United States and Canada. This scale-like insect feeds on the xylem ray parenchyma cells of eastern hemlock, Tsuga canadensis (L.) Carrière, (Pinales: Pinaceae) and Carolina hemlock, Tsuga caroliniana Englem., resulting in multiple physical and physiological symptoms, all of which commonly leads to tree mortality within 4 to 10 years. Currently, HWA has spread throughout most of the eastern hemlock range and all of the range of Carolina hemlock and threatens the forest ecosystems they serve. In its introduced range, there are no natural enemies specialized to feed on HWA and suppress HWA populations below damaging levels. In the urban environment and at some public locations, the use of chemicals, such as imidacloprid, have been used to temporarily protect hemlocks, however; this does not provide a permanent solution. In the 1990's a classical biological control program for HWA was created with the goal to suppress HWA populations below damaging levels to reduce tree mortality, and to reduce the negative effects associated with the loss of either hemlock species. Presently, four predators have become the main focus of this program: Laricobius nigrinus Fender, Laricobius osakensis Shiyake and Montgomery (Coleoptera: Derodontidae), Leucotaraxis argenticollis (Zetterstedt), and Leucotaraxis piniperda (Malloch) (Diptera: Chamaemyiidae). Throughout the eastern US, La. nigrinus has established populations and expanded its distribution beyond where it has been released. Although it has successfully established and continues to spread, its effect on eastern hemlock health has been unknown. A 1-year study, carried out in 2021, revealed that La. nigrinus predation on the sistens generation not only reduced the sistens generation, but also had a similar net photosynthetic rate to the negative control on 1-2 year old shoot growth. In addition, significantly more shoots were produced for treatment branches with the highest La. nigrinus density. This also led to a significantly reduced aestivating sistens density compared to the no predator treatment. However, predation was insufficient to reduce HWA populations below the suggested damaging threshold of eastern hemlock (< 4 HWA/cm), suggesting that additional predators would be needed. Recently, the western strain of Le. argenticollis had been released in the eastern US. However, its phenology in the eastern US was unknown. A 2-year study, from 2021-2023, revealed that Le. argenticollis eggs and larvae were present when both generations of HWA adults with eggs and HWA nymphs were present. In addition, Le. argenticollis was capable of completing development in NY and VA, showing promise that this species could establish populations in the eastern US. Timing the adult fly releases into cages at the time when sistens were producing eggs resulted in Le. argenticollis phenology to synchronize well with HWA phenology at both locations, thus providing additional support for its release in the eastern US. Another 2-year study conducted in 2021-2022, at five locations (MD, NC, PA, TN, and VA), sought to determine how the predation of La. nigrinus and Le. piniperda, alone and together, would impact the sistens and progrediens generations, as well as how their predation would affect the aestivating sistens density and new shoot growth production. From this study, La. osakensis was found as the dominant Laricobius species present at the TN site, and similarly to La. nigrinus, reduced intact ovisac density in. This provided a small preview in La. osakensis capabilities and how this predator may be impacting HWA populations at locations where it has established. In order to assess Le. piniperda's impact on the progrediens generation, mesh cages were applied to treatment branches at each site. The study found that Le. piniperda could reproduce at all field sites and that the percentage of disturbed progrediens was significantly higher for treatments with Le. piniperda present at all field sites, except at PA in 2022. However, the affect of both of these predators on the aestivating sistens density and eastern hemlock health was inconclusive. In addition, the percentage of new shoot growth was highly variable among treatments at all field sites, and there was no treatment effect on the mean length of new shoot growth produced at all field sites. The results of this study suggests that in order to fully understand the affects of these predators on HWA populations and on hemlock tree health, longer term studies should be conducted. However, this study does provide some insight on the capabilities of these predators in the short term and supports the continued release and redistribution of these predators. / Doctor of Philosophy / The hemlock woolly adelgid (HWA), is an invasive species in the eastern United States and in Canada. This small scale-like insect was introduced likely on nursery stock material from southern Japan and was first discovered in the eastern US in 1951 in Richmond, Virginia. Two generations of HWA occur each year known as the sistens and progrediens; both reproduce without males. This insect feeds on eastern hemlock and Carolina hemlock, and since its discovery has spread through most of their range. While this insect feeds, it weakens the tree, eventually causing tree death. In eastern North America, eastern hemlock is one of the major tree species in the forest and provides a unique habitat for various mammals, birds, fish, and invertebrate species. To protect this habitat, multiple management strategies have been developed. The two main management strategies that are in use are the use of pesticides and the release of predators of HWA. Pesticides have been useful in the urban environment and in parks and forests, but they only last for a short time and can lead to negative affects to the environment. Since the 1990's, the release of insect predators originally found in the native range of HWA, has occurred with the goal of predator establishment, to lower HWA populations, and to lower hemlock tree death in the eastern US. Four small insect predators have been the main focus of this program: Laricobius nigrinus, Laricobius osakensis, Leucotaraxis argenticollis, and Leucotaraxis piniperda. So far La. nigrinus and La. osakensis have populations at multiple locations throughout the eastern US, and a low number of sites have been recently found for Le. argenticollis and Le. piniperda. Past studies have indicated that La. nigrinus has a significant impact to the sistens generation of HWA, but its affect to eastern hemlock health has been unclear. A 1-yr study conducted in VA in 2021, released La. nigrinus adults into mesh cages, with two different population sizes of beetles, to determine if La. nigrinus predation on HWA populations lead to an indirect effect on eastern hemlock health at the branch level. Results confirmed that La. nigrinus had a significant impact to the sistens generation of HWA. Photosynthesis of branches with La. nigrinus, in June, was similar to the photosynthesis of the negative control branches, which started with a lower number of sistens present on the branch at the beginning of the study. Suggesting that branches with La. nigrinus may be healthier compared to branches without La. nigrinus. Laricobius nigrinus predation also significantly reduced the number of aestivating sistens on new shoot growth, but not below damaging levels (< 4 HWA/cm). This suggested that additional predators may be needed to target the progrediens generation of HWA so that HWA populations do not return to damaging levels after La. nigrinus predation. To learn more about the potential for Le. argenticollis to survive and reproduce in the eastern US, a 2-yr study was conducted in 2021 – 2023, to determine when different life stages of Le. argenticollis could occur in NY and VA. Results revealed that Le. argenticollis was able to reproduce in the mesh cages and complete its life cycle. In addition, Le. argenticollis eggs and larvae were present at the time when HWA adults were producing eggs and when HWA nymphs were present for both generations of HWA. These results provide insight on Le. argenticollis life cycle and shows that Le. argenticollis has a good chance in surviving throughout the eastern US. A 2-yr study at five locations in the eastern US (MD, NC, PA, TN, and VA), tried to combine two predators, La. nigrinus and Le. piniperda, to determine if their combined impact would be sufficient to reduce HWA populations and affect eastern hemlock tree health. Three assessments were conducted each year to determine the impacts of La. nigrinus and Le. piniperda on HWA populations and on eastern hemlock shoot growth production as a representation of tree health. Results confirmed that La. nigrinus significantly reduced the sistens generation at all locations, except at TN. At the TN site, La. osakensis was found to be the main predator of the sistens generation and had a similar affect on the sistens generation as La. nigrinus. Leucotaraxis piniperda was able to reproduce at all locations and also had a significant affect on progrediens ovisacs at four of the locations in 2021 (MD, NC, PA, and VA) and at three of the locations in 2022 (MD, NC, and VA). However, the results on the number of aestivating sistens on new shoot growth and eastern hemlock health were inconclusive. Therefore, it is unclear as to how the presence of both of these predators' affect eastern hemlock health. A long term study may be needed in order to understand the relationship between these predators and their indirect affect to eastern hemlock health.

The hemlock woolly adelgid (HWA) (Adelges tsugae [Annand]) (Hemiptera: Adelgidae) is a non-native lethal pest to eastern hemlock (Tsuga canadensis [L.] (Pinales: Pinaceae), and Carolina hemlock (Tsuga caroliniana [Engelmann]) (Pinales: Pinaceae). In the early 2000's, a robust biological control initiative using Laricobius spp. (Insecta: Coleoptera) was launched with the goal of decreasing HWA's impact to hemlock and the associated ecosystems on landscape level. Since then, two Laricobius agents, Laricobius nigrinus Fender (Coleoptera: Derodontidae) and Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae) have been evaluated, approved, and released. The production and subsequent release of these agents has largely occurred through mass rearing efforts by Virginia Tech. A descriptive analysis of these rearing and release data over the past 16 years at Virginia Tech revealed that the mass production of these agents has been consistently limited by: 1) excessively high rates of subterranean mortality and 2) early subterranean emergence. Very little is known about the subterranean life cycle of these species in the field in terms of survivorship and timing of emergence. Additionally, the thermal limits and rates of development are unknown for L. osakensis and were thus further investigated. In 2019, surveys within the urban environment in two counties in southwest Virginia were conducted to determine if these agents have dispersed from their original release location. Laricobius nigrinus was documented to have established outside of release sites in 100 and 75% of the surveyed grids containing HWA infested hemlocks. The establishments of these species in easily accessible locations allowed for the use of field-caught larvae, in addition to laboratory-produced larvae, for experiments. Experiments were conducted in 2019-2020 to determine the overall subterranean survivorship in relation to site condition, differences in survivorship between field-caught vs. laboratory-reared, and the seasonal timing of emergence. We found that the average field subterranean survivorship (17.1 ± 0.4%) was significantly less than the historical production of these agents in the laboratory (37.5 ± 13.6%). We found that as soil pH and organic matter depth increased, survivorship decreased. While the majority of emergence occurred as expected in the fall, a surprising amount of emergence also occurred in spring and summer. The rate of development and the minimum threshold temperature for each life stage were determined through constant temperature experiments, and were used in the construction of a phenological forecast model. Laricobius osakensis minimum threshold temperature (3.6°) from egg to adult was similar to that of other Laricobius spp., but completed development at higher a constant temperature (22°C). Our results suggest L. osakensis can handle the same colder climates as L. nigrinus, but may be better adapted for warmer locations than L. nigrinus. Laboratory rearing, establishment, subterranean survivorship, and thermal requirements of Laricobius spp. (Coleoptera: Derodontidae), biological control agents released for Adelges tsugae (Hemiptera: Adelgidae) / Doctor of Philosophy / Eastern and Carolina hemlocks are long lived, shade tolerant evergreen tree species that support a unique ecological assemblage of plants and animals. However, following the accidental introduction of a highly invasive aphid-like insect pest first found in the 1950s, known as the hemlock woolly adelgid (HWA), significant mortality of hemlocks in the eastern U.S. was eventually observed. In order to mitigate this pest's impact and to prevent the further collapse of this unique ecological system, a robust management program was initiated. Today, the primary management strategy to reduce HWA's deleterious effects is through the use of chemical and biological treatments. Biological treatments in the form of insect biological control agents, have focused on the use of two closely related beetle species in the genus Laricobius spp. These species were imported from their respective native ranges, biologically evaluated, and approved for release by federal and state agencies. Since then, the beetles have been mass-produced by multiple governmental and academic agencies and released on infested landscape on mostly public land. Key aspects of these species' biology in terms of their population patterns, development, distribution capabilities, and potential supplementary diet remains unknown. Therefore, investigations into these aforementioned aspects were conducted from 2018-2021 in both laboratory and field experiments. In order to supply beetle larvae for field experiments and to better understand how well these predatory beetles were establishing across the landscape, we investigated heavily urbanized areas for their presence. We found that L. nigrinus was established outside of release locations, in 100 and 75% of the surveyed grids containing HWA in southwest Virginia. Laricobius spp. spend a significant amount of their lives in a presumed dormant state beneath the soil during the summer months. Observations over the past 17 yrs. of rearing Laricobius spp. revealed relatively high rates of subterranean mortality and subterranean early emergence, both of which are substantial mortality factors. Through field experiments, the survivorship of these beneficial beetles was found to be 17.1 ± 0.4% and their seasonal emergence was not limited to fall.Comparing the average survivorship from our field study (17.1 ± 0.4% ) to that of the past 17 yrs. of laboratory production (37.5 ± 13.6%), there was significantly less survivorship. The developmental and phenological biology of one of the two Laricobius spp., L. osakensis was determined and found to be similar to that of other beetles. However, L. osakensis was able to complete development at 22°C, the highest developmental temperature recorded for any Laricobius spp. The similar phenological biology of these two predators will allow for precise larval sampling as a metric for establishment. Results and conclusions from these data have provided further knowledge to scientists, land managers, and public stakeholders regarding the benefits of Laricobius spp.

The insecticide imidacloprid, has been found to be highly effective in suppressing hemlock woolly adelgid, Adelges tsugae. Laricobius nigrinus is a predatory beetle released as a biological control of adelgids in the eastern U.S. This project was designed to develop a pest management strategy that utilizes both tactics concurrently within the same site. It will assess the efficiency of this strategy in reducing HWA populations and improving the health of hemlock forests. The project was started in 2010 and data were collected annually through 2016. The project spanned three sites in three different states (KY, WV, and TN). Results show that tree health has generally declined across all sites for each year. HWA population index values are highly variable and are more strongly influenced by the occurrence of low winter temperatures than by treatment effect. Cross-correlation analysis of tree health and HWA population, revealed characteristics of their temporal relationship. In two of the three sites, tree health lagged up to three years behind changes in HWA population, and HWA populations lagged approximately one year behind changes in tree health. L. nigrinus did not establish at any site as of 2016. The lack of sustained recovery of the beetle may be attributable to the occurrence of extremely cold temperatures during the winters of 2014 and 2015 which produced subsequent crashes in the HWA population at two of the three sites. In TN, the L. nigrinus population may have never established due to a decline in the HWA population shortly after release. / Master of Science in Life Sciences / The insecticide imidacloprid, has been found to be highly effective in suppressing hemlock woolly adelgid, <i>Adelges tsugae. Laricobius nigrinus</i> is a predatory beetle released as a biological control of adelgids in the eastern U.S. This project was designed to develop a pest management strategy that utilizes both tactics concurrently within the same site. It will assess the efficiency of this strategy in reducing HWA populations and improving the health of hemlock forests. The project was started in 2010 and data were collected annually through 2016. The project spanned three sites in three different states (KY, WV, and TN). Results show that tree health has generally declined across all sites for each year. HWA population index values are highly variable and are more strongly influenced by the occurrence of low winter temperatures than by treatment effect. Cross-correlation analysis of tree health and HWA population, revealed characteristics of their temporal relationship. In two of the three sites, tree health lagged up to three years behind changes in HWA population, and HWA populations lagged approximately one year behind changes in tree health. <i>L. nigrinus</i> did not establish at any site as of 2016. The lack of sustained recovery of the beetle may be attributable to the occurrence of extremely cold temperatures during the winters of 2014 and 2015 which produced subsequent crashes in the HWA population at two of the three sites. In TN, the <i>L. nigrinus</i> population may have never established due to a decline in the HWA population shortly after release.

Ce travail de thèse s'inscrit dans la thématique de la pollution particulaire de l'air intérieur et concerne plus particulièrement les phénomènes de remise en suspension liés à l'impact, au niveau du sol, des pas d'une personne qui marche sur un plancher chargé en particules. La première partie présente un état de l'art des connaissances de la pollution particulaire. Les différents paramètres expérimentaux qui influencent la remise en suspension des particules ainsi que les coefficients utilisés pour la quantification du phénomène sont recensés. Les différentes perturbations mécaniques et aérodynamiques générées lors de l'impact d'un pied avec le sol pendant la marche d'une personne sont présentées et comparées. Nous terminons la première partie par une présentation des différents modèles de remise en suspension des particules émanant d'une surface. La seconde partie est consacrée à la présentation de la maquette qui a été mise au point au laboratoire LaSIE à La Rochelle afin d'étudier le dépôt et la remise en suspension des particules par un simulateur mécanique du pas humain depuis un sol chargé en particules. Cette étude a permis de classer les différents types de surfaces utilisées dans le bâtiment en fonction de leurs émissions en particules après l'impact mécanique d'un solide. La troisième partie du travail consiste à mesurer les vitesses de l'écoulement de l'air généré par un simulateur mécanique automatisé du pas humain en différents emplacements. Les mesures de la vitesse ont été effectuées par trois types de méthodes largement utilisées dans le domaine de la mécanique des fluides : deux méthodes de Vélocimétrie Laser (Vélocimétrie par Image des particules et Vélocimétrie Laser Doppler), mais également une méthode d’Anémométrie à Fil Chaud. Ces mesures nous ont permis de trouver la zone de forte vitesse qui correspond à la zone où nous avons une remise en suspension importante. Nous avons également étudié l'influence de l'état de la surface sur les vitesses de l'écoulement générées à proximité du sol suite au mouvement du simulateur mécanique. Ces mesures ont mis en évidence que l'influence de la rugosité de la surface sur la vitesse de l'écoulement généré par le pas est marginale. Finalement, nous avons étudié analytiquement le détachement des particules en utilisant un modèle basé sur le bilan des moments de forces. Des perspectives à la fois sur l'amélioration des deux maquettes mises en place au LaSIE et à l'ERM, ainsi que le développement d'un code numérique pour simuler le pas humain sont présentées et argumentées en conclusion. / This thesis work is part of indoor air particle pollution theme and more particularly the phenomenon of walking-induced particle resuspension. The first part presents a state of the art knowledge of particulate pollution. The different experimental parameters that influence the particles resuspension, as well as the coefficients used for the phenomenon quantification, are identified. The various mechanical and aerodynamic disturbances generated during person walking are presented and compared. We end the first part with a presentation of the different particles resuspension models. The second part is dedicated to present the experiment made on a small scale model developed at the LaSIE laboratory in La Rochelle to study particles deposition and resuspension by amechanical simulator of the human step from a particle-laden soil. This study classified the different types of surfaces used in the building according to their particulate emissions after the mechanical simulator impact. The third part of the work consists of measuring the airflow velocities generated by an automated mechanical simulator of the human footstep at different locations. The velocity measurements have been done in the Royal Military Academy at Brussels (RMA) by three types of methods widely used in the field of fluid mechanics : two methods of Laser Velocimetry (Particle Image Velocimetry and Laser Doppler Velocimetry), but also a method of Wire Anemometry. These measurements allowed us to find the high-speed zone that corresponds to the area where we have a significant resuspension. We also studied the influence the surface roughness on the flow velocities generated near the ground following the movement of the mechanical simulator. We have shown that the influence of the surface roughness on the speed of the flow generated by the pitch is marginal. Finally, we analytically studied the detachment of particles using a model based on the momentum balance. Perspectives on both the improvement of the two models set up in LaSIE and the RMA, as well as the development of a numerical code to simulate the human step, are presented and argued in conclusion.

Ces travaux concernent l'étude expérimentale e analytique de la turbulence en phase de développement dans les fluides hétérogènes à densité et à viscosité variable. Ils font appel à des outils de diagnostics expérimentaux (anémométrie à fil chaud, technique de diffusion Rayleigh, Vélocimétrie Doppler Laser), et au formalisme des équations de Navier-Stockes à viscosité variable. L'innovation porte sur l'indépendance de la mesure de la vitesse. Après sa validation, la plate-forme expérimentale est exploitée pour l'étude comparative d'un jet de propane émergeant dans un milieu air-néon, à viscosité et densité variable, avec un jet d'air classique, à même quantité de mouvement injectée initialement. Ce travail se poursuit ensuite par un approfondissement des propriétés dans le champ proche, complétés par une approche analytique à partir des réécritures des équations de Navier-Stokes à viscosité variable.

Ces travaux concernent l'étude expérimentale e analytique de la turbulence en phase de développement dans les fluides hétérogènes à densité et à viscosité variable. Ils font appel à des outils de diagnostics expérimentaux (anémométrie à fil chaud, technique de diffusion Rayleigh, Vélocimétrie Doppler Laser), et au formalisme des équations de Navier-Stockes à viscosité variable. L'innovation porte sur l'indépendance de la mesure de la vitesse. Après sa validation, la plate-forme expérimentale est exploitée pour l'étude comparative d'un jet de propane émergeant dans un milieu air-néon, à viscosité et densité variable, avec un jet d'air classique, à même quantité de mouvement injectée initialement. Ce travail se poursuit ensuite par un approfondissement des propriétés dans le champ proche, complétés par une approche analytique à partir des réécritures des équations de Navier-Stokes à viscosité variable. / This work is devoted to the study of the undeveloped turbulence in heterogeneus gaseus mixtures, using experimental tools (Hot-wire Anemometry, Rayleigh Light Scattering, Laser Doppler Velocimetry) and analytical methods (variable-viscosity Navier Stokes equations). A new technique combining HWA and RLS is first adapted to reliabily measure the fluctuating velocity and concentration fields in variable-viscosity flows (herein, a propane-air mixture). A variable-viscosity round jet (propane emerging into an air-neon mixture) is characterized and compared with a turbulent air jet discharging into still air, at the same initial jet momentum. An analytical work is further performed with a particular focus on the jet axis, based on the Navier-Stokes equations including variable viscosity to support the experiments. It is shown that the kinetic energy dissipation rate is enhanced by several additional terms, particularly involving 'viscosity-velocity' correlations.

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In this research oriented master’s thesis we have proposed a future vision of ITS (Intelligent Transport Systems) by utilizing the novel concept of HWA (Heterogeneous Wireless Access). Our proposal is backed by the investigation of the results of experiments conducted at CERES (Centre for Research on Embedded Systems), Halmstad University, Sweden to evaluate the quality of communication for V2V and V2I by using the IEEE 802.11p standard. We have also identified the expected scenarios with need of any other communication technology in replacement of IEEE 802.11p for V2V and V2I communication. We have also investigated the relevant research projects, experiments and their results on the basis of predefined constraints. In the investigated research projects the concept of HWA has been correlated with our proposal of HWA for ITS. We have identified that for smooth integration of any communication technology with IEEE 802.11p, an efficient and smart vertical handover protocol or method will be required. We have presented a blue print of a custom designed vertical handover technique which can be implemented for future ITS with further enhancements and experimental evaluations. We have also evaluated the worst case scenarios to assess the suitability of the HWA for the ITS. We proposed few solutions based on the evaluation of communication scenarios for the integration of IEEE 802.11p with other wireless communication technologies. Finally we have provided some conclusions and suggested future researches which must be conducted to realize the dream of ITS with support of HWA.

Porter¡¦s (1990) Four Stages of National Competitive Development are: factor-driven, investment-driven, innovation-driven and wealth-driven. At last stage, the drivers of social development come from the desire to upgrade living quality and pursue the goal of entertainment, leisure, enjoyment, and beauty. In the background, every country begins to emphasize on knowledge economics and creative economics. As well as Taiwan, government brings up two tern plan of culture and creative industries. The first tern stresses on promoting artistic appreciation to enrich the facilities of industrial park. Next, the second tern accents on combinations from different business sectors/fields and culture clusters. Five greatest of culture and creative parks always at the stage of drawing land ownership and building hardware infrastructures in five years. Hwa Shun Cultural and Creative Industrial Park is set on the golden area in Taipei and finally bidden the fifteen-year ownership of ROT (Refurbish-Operate-Transfer) by Taiwan Culture and Creative Company and introduced to the business model. Be the first mover of culture an d creative parks in Taiwan, the experiences of Hwa Shun is definitely important no matter It would success or lose. In this essay, the writer trys to modify Porter¡¦s diamond model(1996,1999) according to the characteristic of culture and creative industries, and pick the Beijing 798 Artistic Village, and Korea Paju Bookcity plus Heiry Artistic Village as the success case to discuss the essential elements of culture and creative clusters. Finally benchmarks the key points to Hwa Shun, and discusses the role of government and the problem of promoting culture and creative industrials in Taiwan. Above all, this essay indicates the interaction between the core of creation and environment, plus the good corporate situation between creative workers and A-style talent are the most important cluster factors. To go a step further, it needs lot of fund and infrastructures to become a industry, in the meantime, how to set up a good evaluated system to inject fund into culture and creative industries through accumulated knowledge is a key point. Otherwise, mass media is other culture and creative industries¡¦ channel, it always has a long and complicated supply chain, and an integrated supply chain can reduce cost effectively and encourage knowledge circulation through cluster effect, therefore be the one that government can nurture strenuously. In demand part, this essay based on three factors of artistic appreciation including culture participation, culture opportunity, and culture consumption to analysis consumers, according to this view, mass population are easier possess capacity to be engaged in culture campaign and really result in consumption. A proper feedback system and platform would benefit cash and resources inflow and support more creative works in experiment step keep creating, and furthermore provide excellent products by means of A-style peoples¡¦ cooperation, finally gain the mass population¡¦s identification and increase culture participation and culture consumption.