Lean premixed combustors are highly susceptible to combustion instabilities, caused by the coupling between heat release fluctuations and combustor acoustics. In order to predict the conditions under which these instabilities occur and their limit cycle amplitudes, understanding of the amplitude dependent response of the flame to acoustic excitation is required. Extensive maps of the flame response were obtained as a function of perturbation amplitude, frequency, and flow velocity. These maps illustrated substantial nonlinearity in the perturbation velocity - heat release relationship, with complex topological dependencies that illustrate folds and kinks when plotted in frequency-amplitude-heat release space. A detailed analysis of phase locked OH PLIF images of acoustically excited swirl flames was used to identify the key controlling physical processes and qualitatively discuss their characteristics. The results illustrate that the flame response is not controlled by any single physical process but rather by several simultaneously occurring processes which are potentially competing, and whose relative significance depends upon forcing frequency, amplitude of excitation, and flame stabilization dynamics. An in-depth study on the effect of acoustic forcing on the turbulent flame properties was conducted in a turbulent Bunsen flame using PIV measurements. The results showed that the flame brush thickness and the local consumption speed were modulated in the presence of acoustic forcing. These results will not only be a useful input to help improve combustion dynamics predictions but will also help serve as validation data for models.

<p>The vitamin D metabolite 1,25(OH)2D3 has long been known to inhibit growth of prostate cancer cells and this mainly through a VDR-mediated pathway controlling target gene expression, resulting in cell cycle arrest, apoptosis and differentiation. Another major way in which 1,25(OH)2D3 inhibits cell growth in prostate cancer is via membrane-initiated steroid signalling, which triggers activation of signal cascades upon steroid binding to a receptor complex, leading to induction of genes regulating cell growth, proliferation and apoptosis. The main prostate cancer inhibiting membrane-initiated route is the TGFβ signalling pathway, elicited by the protein TGFβ. Two other important proteins downstream in this cascade are Smad2 and Smad3. In this study the early effects of 1,25(OH)2D3 on activated Smad2/3 levelsin PC-3 prostate cancer cells were examined. PC-3 cells were incubated for 3, 5, 10, 30 and 60 minutes as well as 38 hours both together with 1,25(OH)2D3 of the concentrations 10-10 and 10-7 M and without. Western Blots were then performed on supernatants from the cells treated followed by treatment of the membranes with primary antibodies against phosphorylated Smad2/3 C-terminal linker regions, alkaline phosphatase conjugated secondary antibodies and finally visualization with BCIP/ NBT tablets. As the downstream cascade protein JNK is a proposed activator of Smad2/3, this procedure was also repeated with a JNK inhibitor. This is a follow-up to an earlier study which examined the influence of 1,25(OH)2D3 on TGFβ levels using the same doses and time points and which found that 1,25(OH)2D3 initially lowered the level of active TGFβ, then increased it. The results of this study indicated a 1,25(OH)2D3 mediated induction of the same pattern in the levels of active Smad2 and 3, both with and without JNK inhibitor. The results did not indicate that 1,25(OH)2D3 activates the Smad2/3 C-terminal linker region via the JNK pathway.</p>

<p>The vitamin D metabolite 1,25(OH)2D3 has long been known to inhibit growth of prostate cancer cells and this mainly through a VDR-mediated pathway controlling target gene expression, resulting in cell cycle arrest, apoptosis and differentiation. Another major way inwhich 1,25(OH)2D3 inhibits cell growth in prostate cancer is via membrane-initiated steroid signalling, which triggers activation of signal cascades upon steroid binding to a receptor complex, leading to induction of genes regulating cell growth, proliferation and apoptosis. The main prostate cancer inhibiting membrane-initiated route is the TGFβ signalling pathway, elicited by the protein TGFβ. Another important protein downstream in this cascade is Smad2. In this study the early effects of 1,25(OH)2D3 on activated Smad2 levels in PC-3 prostate cancer cells were examined. PC-3 cells were incubated for 5, 10, 30 and 60 minutes as well as 24 and 40 hours both together with 1,25(OH)2D3 of the concentrations 10-10 and 107 M and without. An ELISA assay scanning for activated Smad2 was then performed on supernatants from both treated and untreated cells. This is a follow-up to an earlier study which examined the influence of 1,25(OH)2D3 on TGFβ levels using the same doses and similar time points and which found that 1,25(OH)2D3 initially lowered the level of active TGFβ, then increased it. The results of this study showed a statistically insignificant, time delayed 1,25(OH)2D3 mediated induction of the same pattern in the levels of active Smad2.</p> / Project Work in Biomedicine, Advanced Level, 7.5 ECTS

Thesis (D.Min.)--Dallas Theological Seminary, 2008. / Includes abstract. Description based on print version record. Includes bibliographical references (leaves 146-149).

Den produktiva skogsarealen i Sverige som är grandominerad utgörs av 9,5 miljoner ha(Skogsstyrelsen 2011). Varav knappt 0,2 miljoner ha står på torr mark (personlig kommunikation Göran Kämpe, 2015). Problematiken i södra Sverige är att gran planteras på allt för torra marker, eftersom att tall anses för osäkert pga av betestrycket av vilt.  I undersökningen utreds om och när tillväxten avtar för granen på torrare marker i sydöstra Sverige med hjälp av bestämning av ståndortsindex (SI).  Höjdtillväxten har, med hjälp av borrning/kapning på olika trädhöjder, rekonstruerats i granbestånd för en hel omloppstid. Detta har utförts på två olika lokaler där tall hade varit det naturliga valet och där granen bedöms lida av vattenbrist. Fokusområdet är ifall höjdtillväxten och SI avtar för granen på tall/torra marker under omloppstiden, som kan ses som en indikation på granknytning. Resultatet visar att granbestånden har ett betydligt högre ståndortindex i ungskogsfasen jämfört med när beståndet är äldre.  Under omloppstiden visar det sig att ståndortindexen ändrar sig vid två tillfällen under granbeståndets livslängd, eventuell vattenbrist uppstår. Bestämning av SI visade att bestånden motsvarade en G30 i ungskogsfasen men vid slutavverkning hade det sjunkit till en G24. / Today we know that 9,5 million hectares of productive forest land in Sweden consists of Norway spruce (Skogsstyrelsen 2011), of which almost 0.2 million hectares are standing on dry land with low moisture content (personal, communication Göran Kämpe, 2015). The problem today in southern Sweden is that Norway spruce is planted on arid lands, because that pine is considered unsafe due to damage on young plants done by wild animals. The study investigates if and when growth slows down for spruce on arid lands in south-eastern of Sweden, based on determination of a site index (SI) for a whole rotation. In order to determine SI, increment cores/cutting at different tree height has been conducted. It compares the height growth of spruce stands during the rotation period, on land where the pine had been the natural choice and where the spruce likely suffers from a water deficit. The focus area of this study is if height growth and SI declines with age as an indication of water deficit in older stands. The boundaries are the economic part. The result shows that the spruce stands had a considerably higher site index at an early age, compared when it reaches older ages. During the rotation period, it turns out that site index drops twice during the rotation period, when a possible water deficit occurs. Calculations of the site index show that SI of G30 in the young stand but at time for clear-felling, it drops to a G24.

Oxidation of organic species, in particular dicarboxylic and humic acids, was investigated in ice. Products were analyzed by Proton Transfer Reaction Mass Spectrometry, ion and gas chromatography, and a Total Organic Carbon analyzer. Photolysis of succinic acid with H2O2, an OH precursor, produced malonic acid and malic acid, illustrating that diacids are subject to photochemical degradation in ice. First-order decay rate constants were an order of magnitude higher at room temperature (~23 °C) than in ice (-20 °C). A smaller difference was observed for malonic acid, a more soluble diacid, suggesting that partial segregation of H2O2 and succinic acid during freezing played an important role in the kinetics. VOCs, likely to be aldehydes and ketones, were produced from ice containing humic acid through heterogeneous ozonolysis and photooxidation which was enhanced by NO3-, an OH precursor. VOCs also formed from ice made from deionized water, likely through oxidation of organic contaminants.

Biologically active 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) binds the vitamin D receptor (VDR) to exert its effect on target cells. VDR expression is found in a number of immune cells including professional antigen-presenting cells such as dendritic cells. It has been found that the actions of 1,25-(OH)2D3 on the immune system are mainly immunosuppressive. The cross-presentation pathway allows for exogenously derived antigens to be presented by pAPCs on MHC-I molecules to CD8+ T cells. CD8+ T cell activation results in the expansion of epitope-specific T cell populations that confer host protection. These epitopes can be organized into an immunodominance hierarchy. Previous work demonstrated that introducing LCMV-NP via the cross-priming pathway significantly alters the immunodominance hierarchy of a subsequent LCMV infection. Building upon these observations, our study assessed the effects of LCMV-NP cross priming in the presence of a single dose of 1,25-(OH)2D3. Treatment with 1,25-(OH)2D3 was found to have biological effects in our model system. In vitro pAPCs were demonstrated to up-regulate IL-10 and CYP24A1 mRNA, in addition to the transactivation of cellular VDR, as demonstrated by a relocalization to the nuclear region. Mice treated with 1,25-(OH)2D3 were found to produce up-regulated IL-10 and CYP24A1 transcripts. Expression of VDR was increased at both the transcript and protein level. Our results demonstrate that a single dose of 1,25-(OH)2D3 does not affect the cross-priming pathway in this system. Treatment with 1,25-(OH)2D3 did not influence the ability of differentiated pAPCs to phagocytose or cross-present exogenous antigen to epitope-specific CD8+ T cells. Furthermore, 1,25-(OH)2D3 did not alter cross-priming or the establishment of the LCMV immunodominance hierarchy in vivo. By confirming that 1,25-(OH)2D3 does not suppress cross-priming in our model, our study helps to expand the understanding of the immunomodulatory role of exogenous 1,25-(OH)2D3 on the outcome of virus infection. Collectively, our data supports the observation that the role of 1,25-(OH)2D3 in the immune system is not always associated with suppressive effects. / Thesis (Master, Microbiology & Immunology) -- Queen's University, 2011-08-29 14:53:18.766

No description available.

Vitamin D status is assessed with circulating 25-hydroxyvitamin D [25(OH)D]. As some evidence suggests that low vitamin D status adversely affects neonatal health, this project aimed to determine the association between cord blood 25(OH)D levels and preterm birth (PTB; <37 weeks gestation), low birthweight (LBW; <2500 grams) and small for gestational age (SGA; <10th percentile) and to examine the relationship between maternal 25(OH)D levels during the first trimester of pregnancy and fetal 25(OH)D levels at birth in a Canadian population. This nested case-control study used serums, questionnaires and chart reviews collected in Quebec City. Compared to 25(OH)D concentrations ≥75 nmol/L, concentrations 37.5-<75, 50-<75, and <75 nmol/L were associated with lower odds of LBW, PTB and an adverse neonatal composite outcome, and PTB as well as LBW, respectively. Maternal and neonatal 25(OH)D were correlated (r=0.23, p<0.01; adjusted r=0.46, p<0.01). This study contributes to evidence for identifying further policy and research directions.

Radiotherapy is the major curative therapy for carcinogesis. Identifying the effective species that induce DNA damage under ionizing radiation holds the key to improve and advance radiotherapy. In a cellular environment, most of the radiation energy is absorbed by water in the cell. Traditionally, the major radicals resulting from the radiolysis of water are thought to be the hydroxyl radical (OH) and the hydrated electron, whereas the (OH) radical is considered as the major contributor to radiation-induced DNA damage. With the birth of femtosecond time-resolved laser spectroscopy, the precursor to the hydrated electron, the so-called prehydrated electron, has been directly observed. The prehydrated electrons are the excited states of the well-known hydrated electron in nature. Very recently, it was pointed out that the prehydrated electron is a reactive species capable of causing lethal DNA double strand breaks. Thus the reductive DNA damage is proposed as a new molecular pathway for radiation-induced DNA damage. Therefore, the reaction dynamics of the prehydrated electron is of great interest to unravel the exact mechanism of radiation-induced DNA damage. In order to study the action of the prehydrated electron (epre???) in biologically relevant reactions, additional compounds need to be applied to regulate the prehydrated electrons. Such compounds are electron scavengers. In this thesis, the ultrafast electron transfer reaction of epre??? with an electron scavenger potassium nitrate was first investigated using our state-of-the-art femtosecond time-resolved pump-probe laser spectroscopy (fs-TRLS). Quantitative scavenging efficiency is successfully obtained by measuring the reaction rate constant, which is determined to be kpre = (0.75 ?? 0.5)??10^13 M^???1s^???1. This value is two-orders larger than the reaction rate constant of ehyd??? with potassium nitrate k =9.7??10^9 M^???1s^???1, confirming the high reactivity of epre???. Moreover, to comparing effectiveness of the reductive DNA damage induced by the prehydrated electron to the oxidative DNA damage induced by OH radicals, OH radical scavengers are used to quench OH radicals, leaving the prehydrated electron as the only active species. However, no studies have ever investigated the reactions between OH radical scavengers and the prehydrated electron. Here we performed the first quantitative study on the scavenging reactions of epre??? with the well-known OH radical scavengers, isopropanol and dimethyl sulfoxide (DMSO). We present the first evidence of such scavenging reactions and determine the reaction rate constants, which are measured to be k = 3.3 ?? 0.5??10^11 M^???1s^???1 and 8.7 ?? 0.5??10^11 M???1s???1 for isopropanol and DMSO in PBS buffer, respectively.These values are much higher than the reaction rate constants of isopropanol with OH radicals and DMSO with OH radicals (kisopropanol+OH = 2??10^9 M^???1s^???1 and kDMSO+OH = 7??10^9 M^???1s^???1). Furthermore, the OH radical is an important species produced from radiolysis of water. Knowing its reaction dynamics and kinetics can facilitate the comparison between the oxidative DNA damage induced by OH radicals and the reductive DNA damage by prehydrated electrons. By using an OH radical scavenger KSCN, we are able to directly observe the reaction dynamics of the OH radical. In addition, knowing the relative yield ratio of OH radicals and the epre??? (r = [OH]/[epre???]) is necessary for the comparison of the effectiveness of epre??? and OH radicals at inducing DNA damage. In our study, a quantitative analysis of the relative yield ratio r using an OH radical scavenger KSCN was obtained. The relative yield ratio is determined to be r = [OH]/[epre???] = 2.8 ?? 0.4. Incorporating this value into our recent studies on reductive DNA damage, we find that in terms of single-strand breaks and double-strand breaks yields per radical, an epre??? is nearly three times as effective as an OH at inducing DNA damage under irradiation. Overall, the results obtained from this thesis provide important information for future studies of epre??? action in biologically relevant reactions.