Infrared Laser-Induced Grating Techniques for Diagnostics in Reactive Flows

AbstractThe work presented in this thesis is mainly focused on the development andapplication of infrared laser-induced grating techniques in order to measure the gasphase temperature and species concentrations in reactive flows. The two techniquesused for this purpose are laser-induced grating spectroscopy (LIGS) and degeneratefour-wave mixing (DFWM). Their coherent nature allows to perform laser-baseddiagnostics in the infrared spectral region where fundamental ro-vibrationaltransitions of several combustion-related molecular species can be utilized.Gas phase temperature measurements has been performed with laser-inducedthermal grating spectroscopy, known as LITGS. The single-shot precision andaccuracy of mid-infrared LITGS was investigated in premixed CH4/H2/air flames atatmospheric pressure by probing the hot water absorption lines around 3.1 μm,resulting in a single-shot precision better than 1 % and an accuracy of 2.5 %.Furthermore, the technique has been applied in sooty premixed atmosphericC2H4/air flames. Besides the application of mid-IR LITGS, the alignment of thetechnique in terms of grating spacing, number of resolved oscillation peaks in theLITGS signal and its time characteristics has been investigated as well asmisalignment effects. Attention has also been paid to select absorption lines whichresults in thermalization and hence are present in a LITGS excitation spectrum. Inaddition to LITGS, laser-induced electrostrictive grating spectroscopy (LIEGS) wasinvestigated for possible application in harsh environments at temperatures up to700 K. This study was carried out in the spectral band of oxygen at 760 nm and fortwo different geometrical alignments of LIEGS/LITGS.Ammonia (NH3) and hydrogen cyanide (HCN) are two molecular species ofparticular interest in the thermochemical conversion of biomass, which havefundamental or combinational vibrational bands in the mid-IR. Hence, speciesconcentration measurements were carried out using mid-IR DFWM. A feasibilitystudy has been performed for application of DFWM for ammonia detection around2.3 μm. Moreover, DFWM was applied for HCN detection during thethermochemical conversion of straw pellets, where the HCN release history duringthe devolatilization stage was quantified at different flue gas temperatures

Un bilinguisme stable est-il possible à Iqaluit?

Many speakers of the Inuit language in Iqaluit (Nunavut) wish for an evolution of the current linguistic situation towards an ideal situation of stable bilingualism. However, efforts at promoting the Inuit language do not clearly challenge the dynamics of language loss in the capital of the territory. An inquiry about the role of literacy in the search for stable bilingualism allows for a better understanding of language choices among bilingual speakers. The attitudes of the speakers show that in order to strengthen intergenerational transmission one must take into account a tendency to marginalise Inuit language literacy in daily life.De nombreux locuteurs de la langue inuit à Iqaluit (Nunavut) expriment le désir que la situation linguistique évolue idéalement vers un bilinguisme stable. Néanmoins, les efforts de promotion de la langue inuit n’infléchissent pas nettement la dynamique de perte de la langue dans la capitale du territoire. Étudier le rôle de l’écriture dans la recherche de ce bilinguisme stable permet une meilleure compréhension des choix langagiers chez les locuteurs bilingues. Les attitudes des locuteurs montrent que pour consolider la transmission intergénérationnelle il faut prendre en compte une tendance à la marginalisation de l’écrit en langue inuit au quotidien

The small G-protein MglA connects the motility machinery to the bacterial actin cytoskeleton

Motility of Myxococcus xanthus cells is powered by two distinct engines: S-motility allows grouped cells movement and is driven by type IV pili (T4P) at the leading cell pole that use ATP for their function and pull the cell forward upon their retraction. Single cell movement is called gliding or A-motility and its AglQ/R/S engine is powered by proton-motive force and is incorporated at focal adhesion complexes in the cell. The control of motility and its direction is accomplished by cells rapidly switching their leading into lagging cell pole (cellular reversal), a process regulated by the small Ras-like G-protein MglA and its cognate GTPase activating protein (GAP) MglB. Using fluorescence microscopy it was previously shown that MglA localizes at the leading cell pole and MglB at the lagging cell pole and both proteins dynamically switch polarity during cellular reversal. Further, recent experiments showed that an A-motility protein AglZ, and A-motility engine AglQ/R/S localize at clusters distributed along the cell body that stay fixed relative to the substratum as the cell moves forming focal adhesion complexes (FACs). Based on the in vivo experiments it has been proposed that gliding motility machinery assembles at the leading cell pole and that it is guided by the cytoskeletal element to the lagging cell pole, where it disassembles. In this work we investigated the function of MglA during gliding motility. First, we demonstrate that MglA in its active state forms a focal adhesion cluster, which co-localizes with AglZ and AglQ, thus showing that active MglA is a component of the FACs. We show that MglA is essential for incorporation of AlgQ in the FACs, and that MglA GTPase cycle regulates the number of AglQ clusters. Further, we provide evidence that the GTPase negative MglA variant MglAQ82A leads to regularly reversing cells after movement of only one cell length, and that MglA GTPase cycle regulates the disassembly of the FACs at the lagging cell pole. Fluorescent YFP-MglAQ82A forms a focal adhesion cluster which appears to regularly oscillate between the poles, and causes the cell to move in a pendulum-like manner. Unlike wildtype MglA, MglAQ82A is insensitive to the GAP activity of MglB, and upon reaching the lagging cell pole where MglB localizes, it causes a cellular reversal by starting to oscillate in the opposite direction. The co-localizing YFP-MglAQ82A/AglZ-mCherry and YFP-MglAQ82A/AglQ-mCherry FAC also appear to continuously oscillate between the poles suggesting that the gliding motility machinery coupled to active MglA needs to be disassembled at the lagging cell pole by MglB GAP, and in this way allow uni-directional motility for distances longer than one cell length. Furthermore, in this work we demonstrate that active wt MglA and MglAQ82L variant interact directly with filament forming MreB actin homolog. Additionally, our results show that the formation and localization of FACs depend on intact MreB, thus indicating that MreB acts as a scaffold for the assembly of gliding motility machinery. The addition of antibiotics which inhibit peptidoglycan (PG) synthesis and reduce the dynamics of MreB in other bacteria did not inhibit single cell motility and did not cause mislocalization of MglA and AglQ. This strongly suggests that the major proposed function of MreB as a scaffold for PG elongation machinery is not coupled to its essential role during gliding motility in M. xanthus. Thus, we demonstrate that MreB is required for MglA, AglZ and AglQ localization at FACs during gliding, and this function of MreB is separable from its major proposed function in PG synthesis

Molecular aspects of WNT/Frizzled signalling in brain angiogenesis

The family of WNT lipoglycoproteins consists of 19 secreted proteins that are important for multiple cellular processes including cell proliferation, migration and fate. WNTs induce signalling cascades by binding the seven transmembrane receptors named Frizzleds (FZDs) classified as G protein-coupled receptors (GPCRs). Binding of WNT proteins to FZDs leads to the activation of either β-catenin-dependent and/or β-catenin–independent pathways. Mutations or misregulation in the WNT signalling components can cause severe developmental defects, and disorders such as cancer. During embryonic development WNT/FZD signalling is one of the key regulators of vascular development in the central nervous system (CNS). Ablation of the transcriptional activator β-catenin resulted in haemorrhage throughout the entire CNS. Moreover, deletion of one of the WNT receptors, FZD4, also exhibited vascular defects, which were mainly localised to the retina. In this thesis we investigated the process leading to CNS haemorrhage by creating a novel mouse model where β-catenin was inhibited. By overexpressing AXIN1, one of the major components of the β-catenin destruction complex, we could conclude that inhibition of β-catenin in CNS endothelium increased vessel regression and remodelling. Furthermore, we identified an extracellular matrix protein, ADAMTS-Like Protein 2 (ADAMTSL2), to be important for proper vascularisation of the brain. In addition, RNA sequencing data of the embryonic forebrain endothelial cells provided us with the FZD expression profile revealing that FZD4 and its close homolog FZD10 are present during early blood vessels development. Even though FZDs are classified as GPCRs, the question as to whether they can activate G proteins has been under the debate. Despite sequence homology indicating a structure similar to other classical GPCRs, the evidence that they can signal through G proteins has been limited due to a lack of pharmacological tools and robust read-out assays. Here, we show for the first time that the two WNT receptors, FZD4 and FZD10 belonging to the same FZD homology cluster, form inactive-state complexes with the Gα12/13 proteins. Moreover, we show that FZD4, the receptor previously connected to vascular malformations is able to induce Gα12/13-dependent recruitment of p115-RHOGEF, suggesting a novel FZD4/Gα12/13/RHO signalling axis. In addition, we demonstrate that FZD10 has a selective preference for Gα13 over other G protein family members. While FZD10 is able to activate β-catenin transcriptional activity in the presence of overexpressed LRP6, FZD10 triggers Gα12/13-dependent transcriptional activity of Yes Associated Protein 1 (YAP) and Tafazzin (TAZ) in the absence of its co-receptor. Furthermore, we confirm by in situ hybridisation that as indicated in the RNA sequencing data, FZD10 mRNA is indeed present in the developing CNS endothelium. Much like WNT/β-catenin signalling also Gα12/13 dependent signalling is crucial for proper vascular development. With that in mind and with the data presented in this thesis, I would like to propose a parallel route for WNT/FZD induced signalling during CNS vascular development, mediated through the Gα12/13 proteins

Hot Rocks Steakhouse

Miller and Roberts, Chautaugua, NY 14722https://digitalcommons.buffalostate.edu/chefstevemenus/1002/thumbnail.jp

An Analysis of Phatic Expressions Using Greetings & Salutations In English

Phatics expressions are vital in our day- to-day interactions with the society. They are intended to create  ties of union among the people who interact with each other in the form of minitalk. The aim of the study includes (1) the reasons why phatic expressions are important in English, (2) the way how the pathic expressions are classified, (3) what makes them different from interjections. The data used are the greetings and salutations commonly used in English by employing some references regarding phatic particles, words and phrases. This is a descriptive research approach by collecting secondary data, analysing and classified accurately. This is just a preliminary survey without deeply analysing the data. The writer describes the phatic expressions based on the observations and examples by Beare, Kenneth and Nordquist, Richard on thoughtco.com. The data show that the  beginning of a conversation, letter, email, or another form of communication, a salutation is a polite greeting, an expression of goodwill, or other sign of recognition. Salutation terms are an important part of a conversation to tell the other that we feel friendly toward them, and they are maybe the start of a longer conversation. The writer found that the phatics expressions are in the form of particles, words and phrases phatically. Based on the analysis it is concluded that the phatic pressions are purposed at strengthening solidarity and ties of union while interjections convey emotion and they are emotive while the phatic expressions are content-free and context-based.  Syntactically the phatic expressions can be positioned either in the beginning, in the middle or in the end of the sentences or utterances while the interjections are only put in the beginning.     &nbsp