The wavelength dependence of polarization in NGC 2023

NGC 2023 is a bright reflection nebula illuminated by the central star HD37903. At 2 microns the nebula is seen solely by reflected light from the central star but in the NIR there is excess radiation that is supposed to arise from thermal emission from a population of small grains (Sellgren, 1984). The unexpectedly high surface brightness at R and I wavelengths has led to the suggestion that even at these wavelengths there is a significant contribution from this thermal emission process (Witt, Schild, and Kraiman, 1984). If the nebula is seen by reflected starlight then this radiation will be linearly polarized. The level of polarization depends on the scattering geometry, grain size distribution, etc., and is typically 20 to 40 percent for nebulae such as NGC 1999 which is morphologically similar to NGC 2023. If, in any waveband, there is a contribution of radiation from emission processes this radiation will be unpolarized and will serve to dilute the scattered radiation to give a lower level of observed polarization. A study of the wavelength dependence of polarization in nebulae in which there may be thermal emission from grains will indicate the contribution from this process to the total luminosity. Polarization maps were produced in BVRI wavebands for the NGC 2023 nebulosity which confirm that at all wavelengths it is a reflection nebula illuminated by a central star. The wavelength dependence of polarization at representative points in the nebula and in a scatter plot of polarization in V and I wavebands at all points at which measurements are given. Results indicate that throughout the nebula there is a general trend for the level of polarization to increase with wavelength and that maximum levels of polarization occur at the longest wavelengths. No evidence is seen in the data for any significant contribution from the thermal emission from grains in the BVRI luminosity of NGC 2023

The development of amine-functionalised polymeric stars as dual-functional catalysts for polyurethane foam.

This Thesis explores the synthesis of amine-functionalised polymeric stars synthesised using Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerisation, and their applicability as dual functional catalysts for both the catalysis of polyurethane foam production, and for the deblocking of blocked isocyanates. Chapter 1 introduces polyurethane chemistry, and provides an in-depth summary of blocked isocyanates. Additionally, it introduces the RAFT polymerisation chemistry utilised for catalyst synthesis within this thesis. Chapter 2 investigates the use of RAFT polymerisation for the production of non-responsive crosslinked methacrylate polymeric stars. Evaluation of polymeric stars with different structural properties in the polyurethane foam formulation was carried out to assess the protection afforded to the catalytic amine when tethered within the star polymer. Chapter 3 utilises the RAFT synthesis of analogous acrylate based polymeric stars, the hydrolytic susceptibility of which is able to act as a model to those introduced in Chapter 2. Evaluation of the hydrolytic behaviour allowed for further probing of the effect of structural parameters on the protection of the amine. Chapter 4 describes the incorporation of responsive crosslinkers to produce stimuli responsive polymeric stars, including the incorporation of a furan-maleimide thermoresponsive crosslinker utilising Diels-Alder chemistry, in addition to a disulphide based crosslinker which is redox responsive. Chapter 5 explores the incorporation of a diisocyanate based crosslinker with a view towards the production of thermoresponsive polymeric stars using blocked isocyanate chemistries, and therefore minimising the addition of contaminants (e.g. other crosslinkers) to the polyurethane formulation. Chapter 6 discusses the determination of the deblocking temperature of isocyanates in order to understand any trends in the deblocking of both externally and internally blocked isocyanates, as well probing the effect of amines on the deblocking temperature. In the final Chapter, a summary of the work reported in Chapters 2- 6 is provided, with an outlook towards further applications of the polymeric stars reported in this thesis

Delivering mental healthcare to patients with a depressive disorder alongside a life-limiting illness

The concurrent assessment and treatment of mental health disorders and palliative illnesses is complex. Affective disorders are more prevalent in people who need palliative care. Identifying the most suitable place of care and multi-professional multidisciplinary teams to provide support can be challenging and bewildering for professionals and patients. Mental health clinicians may be left with a sense of therapeutic nihilism, while palliative care teams can feel limited by the mental health resources available for treating those living with significant physical and mental health needs. We discuss the fictional case of a gentleman with metastatic bowel cancer who has developed symptoms of depressive disorder and identify how taking a pragmatic patient-centred approach can offer a route through potential dilemmas when seeking to provide individualised care based on needs. We used lay person experience alongside our own experiences of novel mechanisms for cross-specialty working in order to direct psychiatric trainees' approaches to such cases

Spacetime as a quantum circuit

We propose that finite cutoff regions of holographic spacetimes represent quantum circuits that map between boundary states at different times and Wilsonian cutoffs, and that the complexity of those quantum circuits is given by the gravitational action. The optimal circuit minimizes the gravitational action. This is a generalization of both the “complexity equals volume” conjecture to unoptimized circuits, and path integral optimization to finite cutoffs. Using tools from holographic TT¯ , we find that surfaces of constant scalar curvature play a special role in optimizing quantum circuits. We also find an interesting connection of our proposal to kinematic space, and discuss possible circuit representations and gate counting interpretations of the gravitational action

Blocked isocyanates:from analytical and experimental considerations to non-polyurethane applications

In this review we aim to provide an introductory guide to blocked isocyanates, through discussion on different examples of blocking groups, along with experimental considerations for their application. The review brings together updated examples of functionalities used and places specific emphasis on the analytical techniques used for the determination of deblocking temperature, updating previous reviews with the newly applied technique of X-ray photoelectron spectroscopy (XPS). Additionally, we put forward a brief update on the use of blocked isocyanates for other non-traditional polyurethane based polymer applications. We also highlight the importance of matching the analytical technique to the application of the blocked isocyanate, with differences in material state and experimental parameters having a great impact on the deblocking temperature reported

Protection from arthritis and myositis in a mouse model of acute chikungunya virus disease by bindarit, an inhibitor of monocyte chemotactic protein-1 synthesis

Chikungunya virus (CHIKV) is associated with outbreaks of infectious rheumatic disease in humans. Using a mouse model of CHIKV arthritis and myositis, we show that tumor necrosis factor-α, interferon-γ, and monocyte chemotactic protein 1 (MCP-1) were dramatically induced in tissues from infected mice. The same factors were detected in the serum of patients with CHIKV-induced polyarthralgia and polyarthritis, with MCP-1 levels being particularly elevated. Bindarit (MCP inhibitor) treatment ameliorated CHIKV disease in mice. Histological analysis of muscle and joint tissues showed a reduction in inflammatory infiltrate in infectedmice treated with bindarit. These results suggest that bindarit may be useful in treating CHIKV-induced arthritides in humans.Facultad de Ciencias Exacta

Protection from arthritis and myositis in a mouse model of acute chikungunya virus disease by bindarit, an inhibitor of monocyte chemotactic protein-1 synthesis

Chikungunya virus (CHIKV) is associated with outbreaks of infectious rheumatic disease in humans. Using a mouse model of CHIKV arthritis and myositis, we show that tumor necrosis factor-α, interferon-γ, and monocyte chemotactic protein 1 (MCP-1) were dramatically induced in tissues from infected mice. The same factors were detected in the serum of patients with CHIKV-induced polyarthralgia and polyarthritis, with MCP-1 levels being particularly elevated. Bindarit (MCP inhibitor) treatment ameliorated CHIKV disease in mice. Histological analysis of muscle and joint tissues showed a reduction in inflammatory infiltrate in infectedmice treated with bindarit. These results suggest that bindarit may be useful in treating CHIKV-induced arthritides in humans.Facultad de Ciencias Exacta

Cost of holographic path integrals

We consider proposals for the cost of holographic path integrals. Gravitational path integrals within finite radial cutoff surfaces have a precise map to path integrals in $T\bar T$ deformed holographic CFTs. In Nielsen's geometric formulation cost is the length of a not-necessarily-geodesic path in a metric space of operators. Our cost proposals differ from holographic state complexity proposals in that (1) the boundary dual is cost, a quantity that can be `optimised' to state complexity, (2) the set of proposals is large: all functions on all bulk subregions of any co-dimension which satisfy the physical properties of cost, and (3) the proposals are by construction UV-finite. The optimal path integral that prepares a given state is that with minimal cost, and cost proposals which reduce to the CV and CV2.0 complexity conjectures when the path integral is optimised are found, while bounded cost proposals based on gravitational action are not found. Related to our analysis of gravitational action-based proposals, we study bulk hypersurfaces with a constant intrinsic curvature of a specific value and give a Lorentzian version of the Gauss-Bonnet theorem valid in the presence of conical singularities

Identification and characterization of a Ross River virus variant that grows persistently in macrophages, shows altered disease kinetics in a mouse model, and exhibits resistance to type I interferon

Alphaviruses, such as chikungunya virus, o'nyong-nyong virus, and Ross River virus (RRV), cause outbreaks of human rheumatic disease worldwide. RRV is a positive-sense single-stranded RNA virus endemic to Australia and Papua New Guinea. In this study, we sought to establish an in vitro model of RRV evolution in response to cellular antiviral defense mechanisms. RRV was able to establish persistent infection in activated macrophages, and a small-plaque variant (RRVPERS) was isolated after several weeks of culture. Nucleotide sequence analysis of RRV PERS found several nucleotide differences in the nonstructural protein (nsP) region of the RRV PERS genome. A point mutation was also detected in the E2 gene. Compared to the parent virus (RRV-T48), RRV PERS showed significantly enhanced resistance to beta interferon (IFN-β)-stimulated antiviral activity. RRV PERS infection of RAW 264.7 macrophages induced lower levels of IFN-β expression and production than infection with RRV-T48. RRV PERS was also able to inhibit type I IFN signaling. Mice infected with RRV PERS exhibited significantly enhanced disease severity and mortality compared to mice infected with RRV-T48. These results provide strong evidence that the cellular antiviral response can direct selective pressure for viral sequence evolution that impacts on virus fitness and sensitivity to alpha/beta IFN (IFN-α/β).Facultad de Ciencias Exacta