Direct computations of a synthetic jet actuator

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Synthetic jet actuators have previously been defined as having potential use in both internal and external aerodynamic applications. The formation of a jet flow perpendicular to the surface of an aerofoil or in a duct of diffuser has a range of potential flow control benefits. These benefits can include both laminar to turbulent transition control, which is associated with a drag reduction in aerodynamic applications. The formation and development of zero-net-mass-flux synthetic jets are investigated using highly accurate numerical methods associated with the methodology of Direct Numerical Simulation (DNS). Jet formation is characterised by an oscillating streamwise jet centreline velocity, showing net momentum flux away from the jet orifice. This momentum flux away from the orifice takes the form of a series of vortex structures, often referred to as a vortex train. Numerical simulations of the synthetic jet actuator consist of a modified oscillating velocity profile applied to a wall boundary. The Reynolds numbers used vary from 85 ≤ Re ≤ 300. A complete numerical study of both axisymmetric and fully three-dimensional jet flow is performed. A parametric axisymmetric simulation is carried out in order to study the formation criterion and evolution of zero-net-mass-flux synthetic jets under variations in actuator input parameters. From the results of these simulations the conditions necessary for the formation of the synthetic jet along with the input parameters that provide an optimal jet output are deduced. Jet optimisation is defined by the mass flow, vortex strength and longevity of the vortex train as it travels downstream. Further investigations are carried out on a fully three-dimensional DNS version of the optimised axisymmetric case. Comparisons between the jet evolution and flow-field structures present in both the axisymmetric and three-dimensional configurations are made. This thesis examines the vortex structures, the jet centreline velocities along with time dependent and time averaged results in order to deduce and visualise the effects of the input parameters on the jet formation and performance. The results attained on altering the oscillation frequency of the jet actuator indicated that synthetic jets with zero mean velocity at the inflow behave significantly differently from jets with non-zero mean velocity at the inflow. A study into the evolution and formation of the train of vortex structures associated with the formation of a synthetic jet is performed. This study is accompanied with a series of time averaged results showing time dependent flow-field trends. The time history of the jet centreline velocity, showing the net momentum flux of the fluid away from the orifice of a fully developed synthetic jet, is analysed for both axisymmetric and three-dimensional cases. Differences in the fluid dynamics between the idealised axisymmetric configuration and the three-dimensional case have been identified, where three-dimensional effects are found to be important in the region near the jet nozzle exit. The effect of a disturbance introduced into the three-dimensional simulation in order to break its inherent symmetr around the jet centreline is examined by altering the input frequency of the disturbance. It was found that the effect of this relatively minor disturbance had a major effect on the jet flow field in the region adjacent to the orifice. The effect of which was deemed to be caused by discontinuities in the surface of the jet orifice due to manufacturing tolerances. Although the effects of these disturbances on the jet flow-field are large, they seem to have been neglected from numerical simulations to date. The effect of a synthetic jet on an imposed cross-streamwise velocity profile was examined. It was found that the synthetic jet flow-field resulted in a deformation of the velocity profile in the region downstream of the synthetic jet. It is suggested that this region of deformed flow could interact with coherent structures in a transitional boundary layer in order to delay flow transition to turbulence. The effect of varying the Strouhal number of a synthetic jet in a cross-flow is also analysed. It is clear from the results presented that, in the presence of a cross-flow velocity the Strouhal number effect on the synthetic jet flow field evolution, while dominant in a quiescent fluid is surpassed by the effect of the cross-flow

The service of the Scottish mercenary forces in Ireland, from 1565-1603, with an account of the mercenary system in Ireland and of its effect on Scottish history

CHAPTER ONE: The Background of relationship between Scottish and Irish affairs (to c.1565)CHAPTER TWO: The Scottish Mercenary Forces of Turlough Luineach O'Neil in Ulster, and the service of the Scots in Connacht (1565-1575.)CHAPTER THREE: The service of the Scots in Munster and Ulster, and in Connacht during the second and third Clanricarde Rebellions. (1575-1581).CHAPTER FOUR: The Effect of the Composition in Connacht, Perrott's Failure in Antrim, and the suspected Implication of the Court of King James VI. in Irish Affairs. (1581-1586.)CHAPTER FIVE: The Growth of the Earl of Tyrone's Disaffection, his intrigues with the Scots, the last internal rebellion in Connacht, and the reaction on Irish affairs of the activities of the MacLeans. (1586 -1594).CHAPTER SIX: The MacLean Intrigue, Secret Service Nork in the Isles, and the Abortive Expedition of 1595 (1594- 1595).CHAPTER SEVEN: The successes of the Irish in Rebellion, the English suspicion of King James in that regard, and the course of the MacLean-MacDonald Feud in the Isles. (1596- 1598.)CHAPTER EIGHT: Continued Success of the Irish, and the Project of Employing Scots in the Service of queen Elizabeth. (1598 -1599)CHAPTER NINE. The Defeat,of the Irish at Kinsale, the Efforts of King James on Elizabeth's behalf, and the movements of .the Clan Donald in Antrim, (1600 -1601)CHAPTER TEN: aftermath. (1602 -1603

James Fitzpiers Fitzgerald, Captain Thomas Lee, and the Problem of “Secret Traitors”: Conflicted Loyalties During the Nine Years’ War, 1594-1603

Existing evidence pertaining to Ireland’s Nine Years’ War (1594-1603) strongly lends itself to the impression that the majority of Old English Palesmen, at least those of higher social status, chose to support the English crown during this conflict rather than their co-religionist Gaelic Irish countrymen. Loyalties, however, were anything but straightforward and could depend on any number of cultural values, social concerns, and economic incentives. Nevertheless, James Fitzpiers Fitzgerald, a ‘Bastard Geraldine’ who served as sheriff of Kildare, seemed to have been driven by a genuine sense of duty to the English crown and establishment. With the outbreak of hostilities in the 1590s, Fitzpiers proved to be a devout crown servitor, risking life and limb to confront the English queen’s Irish enemies. But, in late 1598 he suddenly, and somewhat inexplicably, threw his lot in with Irish Confederacy, defying the government he had once championed. During the ensuing investigation, the Dublin administration accumulated much damning evidence against Fitzpiers, including a patriotic plea from rebel leader Hugh O’Neill which urged Fitzpiers to defend his Irish homeland from the oppressions of English Protestant rule. Yet, at the very same time, a counter case was made by Fitzpiers’ controversial English friend, Captain Thomas Lee, which argued that Fitzpiers’ actions were more loyal than anyone could have imagined. Through an examination of Fitzpiers’ perplexing case, this paper will explore the complicated nature of allegiances in 1590s Ireland and how loyalties were not always what they seemed

Francisella tularensis in the United States

Subpopulations A.I and A.II. of Francisella tularensis subsp. tularensis are associated with unique biotic and abiotic factors that maintain disease foci

Treatment as prevention: preparing the way

Potent antiretroviral therapy (ART) reduces mortality and morbidity in people living with HIV by reducing viral load and allowing their immune systems to recover. The reduction in viral load soon after starting ART has led to the hypothesis that early and widespread ART could prevent onward transmission and therefore eliminate the HIV epidemic in the long term. While several authors have argued that it is feasible to use HIV treatment as prevention (TasP), provided treatment is started sufficiently early, others have reasonably drawn attention to the many operational difficulties that will need to be overcome if the strategy is to succeed in reducing HIV transmission. Furthermore, international public health policy must be based on more than theoretical studies, no matter how appealing. Community randomized controlled trials provide the gold standard for testing the extent to which early treatment reduces incidence, but much still needs to be understood and the immediate need is for operational studies to explore the practical feasibility of this approach. Here, we examine some of the issues to be addressed, the obstacles to be overcome, and strategies that may be necessary if TasP is to be effective. Studies of this kind will provide valuable information for the design of large-scale trials, as well as essential information that will be needed if early treatment is to be incorporated into public health policy

Warming mediates the relationship between plant nutritional properties and herbivore functional responses

Quantifying the per capita effects of invasive alien species is crucial for assessing their ecological impact. A major challenge to risk assessment of invasive species was to understand the factors that cause per capita effects to vary in different ecological contexts, particularly in a warming world. By conducting functional response experiments, we estimated the per capita effects (attack rate and maximum feeding rate) of an invasive herbivorous snail, Pomacea canaliculata, toward ten host plant species. We tested whether variation in these effects is related to plant nutritional and physical properties (total N and dry matter content (DMC)) and examined how increasing temperature can shift these relationships. We observed stronger per capita effects (i.e., higher attack rate and maximum feeding rate) by the snail on plants with higher total N, but no direct relationship was found with DMC. A significant interaction effect of total N and DMC on the attack rate indicated that DMC probably adjusted the feeding indirectly. Warmer temperatures reduced correlations between snail functional responses and host plant nutritional properties (total N) by increasing maximum feeding rate for plants of low nutrition, but there was no such effect on attack rates. However, given the nonreplacement design used in our study, the nonsignificant effect of temperature on the attack rate should be caveated. Our result suggests that characterizing the per capita effects of herbivores using functional responses can reveal the mechanisms by which climate change may alter herbivore–plant interactions and, thus, the ecological impacts of introduced herbivores

Epithelial damage and tissue γδ T cells promote a unique tumor-protective IgE response

IgE is an ancient and conserved immunoglobulin isotype with potent immunological function. Nevertheless, the regulation of IgE responses remains an enigma, and evidence of a role for IgE in host defense is limited. Here we report that topical exposure to a common environmental DNA-damaging xenobiotic initiated stress surveillance by γδTCR+ intraepithelial lymphocytes that resulted in class switching to IgE in B cells and the accumulation of autoreactive IgE. High-throughput antibody sequencing revealed that γδ T cells shaped the IgE repertoire by supporting specific variable-diversity-joining (VDJ) rearrangements with unique characteristics of the complementarity-determining region CDRH3. This endogenous IgE response, via the IgE receptor FcεRI, provided protection against epithelial carcinogenesis, and expression of the gene encoding FcεRI in human squamous-cell carcinoma correlated with good disease prognosis. These data indicate a joint role for immunosurveillance by T cells and by B cells in epithelial tissues and suggest that IgE is part of the host defense against epithelial damage and tumor development

Structure and catalytic regulatory function of ubiquitin specific protease 11 N-terminal and ubiquitin-like domains

The ubiquitin specific protease 11 (USP11) is implicated in DNA repair, viral RNA replication, and TGFβ signaling. We report the first characterization of the USP11 domain architecture and its role in regulating the enzymatic activity. USP11 consists of an N-terminal "domain present in USPs" (DUSP) and "ubiquitin-like" (UBL) domain, together referred to as DU domains, and the catalytic domain harboring a second UBL domain. Crystal structures of the DU domains show a tandem arrangement with a shortened β-hairpin at the two-domain interface and altered surface characteristics compared to the homologues USP4 and USP15. A conserved VEVY motif is a signature feature at the two-domain interface that shapes a potential protein interaction site. Small angle X-ray scattering and gel filtration experiments are consistent with the USP11DU domains and full-length USP11 being monomeric. Unexpectedly, we reveal, through kinetic assays of a series of deletion mutants, that the catalytic activity of USP11 is not regulated through intramolecular autoinhibition or activation by the N-terminal DU or UBL domains. Moreover, ubiquitin chain cleavage assays with all eight linkages reveal a preference for Lys(63)-, Lys(6)-, Lys(33)-, and Lys(11)-linked chains over Lys(27)-, Lys(29)-, and Lys(48)-linked and linear chains consistent with USP11's function in DNA repair pathways that is mediated by the protease domain. Our data support a model whereby USP11 domains outside the catalytic core domain serve as protein interaction or trafficking modules rather than a direct regulatory function of the proteolytic activity. This highlights the diversity of USPs in substrate recognition and regulation of ubiquitin deconjugation

Factors that distinguish aggression towards animals from other antisocial behaviors: Evidence from a community sample

Animal cruelty is a form of passive and active aggression that is largely undocumented and unreported. Given that animals are voiceless victims, we have to rely on witnesses and frontline staff (e.g., veterinarians) to report incidents of abuse, which suggests the number of convicted animal abusers is an under‐representation of actual perpetrators. The primary aim of the current study was to identify the static and dynamic factors that distinguish animal abusers from non‐abuse offenders (i.e., individuals who self‐reported antisocial behavior, but not animal abuse), and non‐offenders (i.e., individuals who have not engaged in any antisocial behavior) in a community sample. The secondary aim was to identify the potential pathways that distinguish animal abuse perpetration from other types of antisocial behavior. Three hundred and eighty‐four participants took part in this retrospective, correlational study. We found that animal abusers share similar socio‐demographic characteristics to other offenders but are distinct in their exposure to animal harm/killing during childhood. Low animal‐oriented empathy and low self‐esteem distinguished animal abusers from non‐abuse offenders when controlling for confound variables and other psychological characteristics. We also found that low animal‐oriented empathy mediated the relationship between childhood exposure to animal killing and animal abuse perpetration, and that this relationship was stronger among participants with anger regulation issues. This is the first study to examine similarities and differences between animal abusers, non‐abuse offenders, and non‐offenders on socio‐demographic and psychological characteristics. The findings highlight potential treatment targets that are unique to animal abusers with implications for prevention and intervention strategies