Notch activates Wnt-4 signalling to control medio-lateral patterning of the pronephros

Previous studies have highlighted a role for the Notch signalling pathway during pronephrogenesis in the amphibian Xenopus laevis, and in nephron development in the mammalian metanephros, yet a mechanism for this function remains elusive. Here, we further the understanding of how Notch signalling patterns the early X. laevis pronephros anlagen, a function that might be conserved in mammalian nephron segmentation. Our results indicate that early phase pronephric Notch signalling patterns the medio-lateral axis of the dorso-anterior pronephros anlagen, permitting the glomus and tubules to develop in isolation. We show that this novel function acts through the Notch effector gene hrt1 by upregulating expression of wnt4. Wnt-4 then patterns the proximal pronephric anlagen to establish the specific compartments that span the medio-lateral axis. We also identified pronephric expression of lunatic fringe and radical fringe that is temporally and spatially appropriate for a role in regulating Notch signalling in the dorso-anterior region of the pronephros anlagen. On the basis of these results, along with data from previous publications, we propose a mechanism by which the Notch signalling pathway regulates a Wnt-4 function that patterns the proximal pronephric anlagen

Female perception of the annulment of marriage in the Catholic Church

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Inverse magnetic catalysis and regularization in the quark-meson model

Motivated by recent work on inverse magnetic catalysis at finite temperature, we study the quark-meson model using both dimensional regularization and a sharp cutoff. We calculate the critical temperature for the chiral transition as a function of the Yukawa coupling in the mean-field approximation varying the renormalization scale and the value of the ultraviolet cutoff. We show that the results depend sensitively on how one treats the fermionic vacuum fluctuations in the model and in particular on the regulator used. Finally, we explore a $B$-dependent transition temperature for the Polyakov loop potential $T_0(B)$ using the functional renormalization group. These results show that even arbitrary freedom in the function $T_0(B)$ does not allow for a decreasing chiral transition temperature as a function of $B$. This is in agreement with previous mean-field calculations.Comment: 13 pages, 5 figure

Chiral and deconfinement transitions in a magnetic background using the functional renormalization group with the Polyakov loop

We use the Polyakov loop coupled quark-meson model to approximate low energy QCD and present results for the chiral and deconfinement transitions in the presence of a constant magnetic background $B$ at finite temperature $T$ and baryon chemical potential $\mu_B$. We investigate effects of various gluoni potentials on the deconfinement transition with and without a fermionic backreaction at finite $B$. Additionally we investigate the effect of the Polyakov loop on the chiral phase transition, finding that magnetic catalysis at low $\mu_B$ is present, but weakened by the Polyakov loop.Comment: 17 pages and 8 figs. v2: added ref

Model studies of the chiral and deconfinement transitions in QCD

The Doctoral thesis of William Naylor. Gives the background of the three papers included, specifically introducing both the quark meson model and the NJL model, the basic formalism of thermal field theory, and functional renormalization group (including some details on numerically solving the FRG equation for the QM model).Comment: This is a Doctoral thesi

An investigation into how the cell cycle and the Notch signalling pathway regulate pronephrogenesis in Xenopus laevis

The connections between cell cycle exit and terminal differentiation remain poorly understood. Cyclin dependent Kinase Inhibitors (CKIs) provide a possible link between entry into the quiescent state and differentiation. The initial aim of this project was to further investigate if the CKI p27Xic1 could promote differentiation in addition to, and independently of, its well characterised cell cycle exit function. p27Xic1 has been shown to be involved in cell fate determination during gliogenesis, neurogenesis, myogenesis and cardiogenesis and many mammalian Cip/ Kip CKI homologues of p27Xic1 have been described as important regulators of cellular processes beyond control of cell division. We aimed to investigate these roles during development of the embryonic kidney, the pronephros. We discovered that p27Xic1 does not affect differentiation during pronephrogenesis, but instead controls pronephric organ size through its cell cycle exit function. In addition we identified a previously unrecognised role for the cell cycle exit function of p27Xic1 in allocation of the somites during paraxial mesoderm segmentation. Preliminary results had suggested p27Xic1 expression in the pronephros was under the control of the Notch signalling pathway. Over-expressing a constitutively active form of Notch, Notch-ICD, and a dominant negative form of the Delta ligand, DeltaSTU, showed that both mis-activation and suppression of Notch signalling inhibited p27Xic1 expression. However, when investigating the effects these overexpressions had on pronephros development, we identified novel results indicating the Notch signalling pathway, which has previously been implicated in pronephros development, is essential for the separation of the proximal lateral and medial pronephric mesoderms. This process we propose is mediated by the Notch signalling pathway through the establishment of a boundary between these two distinct populations of cells, permitting both compartments to develop in isolation. The results in this thesis suggest novel mechanisms by which cell division controls X. laevis segmentation and organ size and how the Notch signalling pathway is able to pattern the pronephros anlagen such that the different compartments of the mature pronephros are able to develop, and thus function

Non-classical photon streams using rephased amplified spontaneous emission

We present a fully quantum mechanical treatment of optically rephased photon echoes. These echoes exhibit noise due to amplified spontaneous emission, however this noise can be seen as a consequence of the entanglement between the atoms and the output light. With a rephasing pulse one can get an "echo" of the amplified spontaneous emission, leading to light with nonclassical correlations at points separated in time, which is of interest in the context of building wide bandwidth quantum repeaters. We also suggest a wideband version of DLCZ protocol based on the same ideas.Comment: 5 pages, 4 figures. Added section

Female perception of the annulment of marriage in the Catholic Church

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Experimental quantum teleportation over a high-loss free-space channel

We present a high-fidelity quantum teleportation experiment over a high-loss free-space channel between two laboratories. We teleported six states of three mutually unbiased bases and obtained an average state fidelity of 0.82(1), well beyond the classical limit of 2/3. With the obtained data, we tomographically reconstructed the process matrices of quantum teleportation. The free-space channel attenuation of 31 dB corresponds to the estimated attenuation regime for a down-link from a low-earth-orbit satellite to a ground station. We also discussed various important technical issues for future experiments, including the dark counts of single-photon detectors, coincidence-window width etc. Our experiment tested the limit of performing quantum teleportation with state-of-the-art resources. It is an important step towards future satellite-based quantum teleportation and paves the way for establishing a worldwide quantum communication network