Time-Resolved Spectroscopy of Condensed Matter

Contains reports on three research projects.Joint Services Electronics Program (Contract DAAG29-78-C-0020)National Science Foundation (Grant DMR78-23555)National Science Foundation (Grant DMR76-80895

Stigma and the in(visible) perspectives and expectations of home oxygen therapy among people with chronic breathlessness syndrome: A qualitative study

© The Author(s) 2018. Background: Chronic breathlessness syndrome in the context of advancing disease is distressing for all concerned. Oxygen is commonly prescribed in this setting; however, little is known about the perspectives of breathless people who either are on oxygen or are yet to have it prescribed. Aim: To understand and describe the perspectives and experiences of breathless people towards oxygen use at home. Design: This qualitative study utilised an interpretive description approach using semi-structured interviews and thematic analysis. Setting/participants: A total of 19 people with chronic breathlessness syndrome living in South Australia participated in semi-structured interviews. Participants were divided into sub-groups according to whether they were chronically breathless and (1) not using home oxygen (n = 6), (2) using funded home oxygen for severe hypoxaemia (n = 7) and (3) using home oxygen for palliation outside of funding guidelines (n = 6). Results: Three main themes were identified: (1) managing distress and living with chronic breathlessness syndrome, with or without oxygen, requires a range of self-management strategies; (2) expectations of oxygen use: ‘Not as good as I thought it would be’; and (3) the stigma of using oxygen: the visible and invisible. Conclusion: People living with chronic breathlessness struggle daily with both the progression of the underlying disease and the distressing nature of the syndrome. While oxygen does provide benefit for some people, its use and the perceptions of its use are often associated with both the visible and invisible manifestations of stigma. Clinicians need to promote self-management strategies and give careful thought to the prescribing of home oxygen, especially outside the current funding guidelines

Pharmacovigilance in hospice/palliative care: Net effect of haloperidol for delirium

Introduction: Prescribing practice in hospice/palliative care is largely extrapolated from other areas of clinical practice, with few studies of net medication effects (benefits and harms) in hospice/palliative care to guide prescribing decisions. Hospice/palliative care patients differ in multiple ways from better studied participant groups, hence the applicability of studies in other participant groups is uncertain. Haloperidol, a butyrophenone derivative and dopamine antagonist, is commonly prescribed for nausea, vomiting, and delirium in hospice/palliative care. Its frequent use in delirium occurs despite little evidence of the effect of antipsychotics on the untreated course of delirium. The aim of this study was to examine the immediate and short-term clinical benefits and harms of haloperidol for delirium in hospice/palliative care patients. Method: A consecutive cohort of participants from 14 centers across four countries who had haloperidol commenced for delirium were recruited. Data were collected at three time points: baseline, 48 hours (clinical benefits), and day 10 (clinical harms). Investigators were also able to report clinical harms at any time up to 14 days after it was commenced. Results: Of the 119 participants included, the average dose was 2.1 mg per 24 hours; 42 of 106 (35.2%) reported benefit at 48 hours. Harm was reported in 14 of 119 (12%) at 10 days, the most frequent being somnolence (n=11) and urinary retention (n=6). Seven participants had their medication ceased due to harms (2 for somnolence and 2 for rigidity). Approximately half (55/119) were still being treated with haloperidol after 10 days. Conclusion: Overall, 1 in 3 participants gained net clinical benefit at 10 days. © Copyright 2013, Mary Ann Liebert, Inc. 2013

First order isotropic - smectic-A transition in liquid crystal-aerosil gels

The short-range order which remains when the isotropic to smectic-A transition is perturbed by a gel of silica nanoparticles (aerosils) has been studied using high-resolution synchrotron x-ray diffraction. The gels have been created \textit{in situ} in decylcyanobiphenyl (10CB), which has a strongly first-order isotropic to smectic-A transition. The effects are determined by detailed analysis of the temperature and gel density dependence of the smectic structure factor. In previous studies of the continuous nematic to smectic-A transition in a variety of thermotropic liquid crystals the aerosil gel appeared to pin, at random, the phase of the smectic density modulation. For the isotropic to smectic-A transition the same gel perturbation yields different results. The smectic correlation length decreases more slowly with increasing random field variance in good quantitative agreement with the effect of a random pinning field at a transition from a uniform phase directly to a phase with one-dimensional translational order. We thus compare the influence of random fields on a \textit{freezing} transition with and without an intervening orientationally ordered phase.Comment: 8 pages, 8 figure

A breakage kernel for use in population balance modelling of twin screw granulation

This paper presents a novel breakage kernel for use in population balance modelling for twin screw granulation (TSG) using mechanistic understanding in different screw elements. Breakage-isolated experiments are conducted using conveying and distributive mixing elements for a range of model formulations of widely different yield stresses. The breakage kernel, i.e. the selection and breakage functions, are mathematically formed based on the identification of the dominant breakage mechanisms of chipping and fragmentation in the conveying and distributive mixing elements, respectively, and the unique geometries of the two screw elements. A parametric study for the proposed breakage kernel is performed to identify the influential parameters on the breakage kernel. This is the first breakage model specifically developed for a TSG and incorporates a mechanistic understanding of several key parameters, particularly the role of screw geometry. The breakage model is well suited to population balance modelling framework for model-driven design of twin screw granulation

A lattice model for the kinetics of rupture of fluid bilayer membranes

We have constructed a model for the kinetics of rupture of membranes under tension, applying physical principles relevant to lipid bilayers held together by hydrophobic interactions. The membrane is characterized by the bulk compressibility (for expansion), the thickness of the hydrophobic part of the bilayer, the hydrophobicity and a parameter characterizing the tail rigidity of the lipids. The model is a lattice model which incorporates strain relaxation, and considers the nucleation of pores at constant area, constant temperature, and constant particle number. The particle number is conserved by allowing multiple occupancy of the sites. An equilibrium ``phase diagram'' is constructed as a function of temperature and strain with the total pore surface and distribution as the order parameters. A first order rupture line is found with increasing tension, and a continuous increase in proto-pore concentration with rising temperature till instability. The model explains current results on saturated and unsaturated PC lipid bilayers and thicker artificial bilayers made of diblock copolymers. Pore size distributions are presented for various values of area expansion and temperature, and the fractal dimension of the pore edge is evaluated.Comment: 15 pages, 8 figure

Dynamics of Weak First Order Phase Transitions

The dynamics of weak vs. strong first order phase transitions is investigated numerically for 2+1 dimensional scalar field models. It is argued that the change from a weak to a strong transition is itself a (second order) phase transition, with the order parameter being the equilibrium fractional population difference between the two phases at the critical temperature, and the control parameter being the coefficient of the cubic coupling in the free-energy density. The critical point is identified, and a power law controlling the relaxation dynamics at this point is obtained. Possible applications are briefly discussed.Comment: 11 pages, 4 figures in uuencoded compressed file (see instructions in main text), RevTeX, DART-HEP-94/0

Time-Resolved Spectroscopy of Condensed Matter

Contains reports on three research projects.Joint Services Electronics Program (Contract DAAG29-78-C-0020)Joint Services Electronics Program (Contract DAAG29-80-C-0104)National Science Foundation (Grant DMR78-23555)National Science Foundation (Grant DMR78-24185

Shear induced instabilities in layered liquids

Motivated by the experimentally observed shear-induced destabilization and reorientation of smectic A like systems, we consider an extended formulation of smectic A hydrodynamics. We include both, the smectic layering (via the layer displacement u and the layer normal p) and the director n of the underlying nematic order in our macroscopic hydrodynamic description and allow both directions to differ in non equilibrium situations. In an homeotropically aligned sample the nematic director does couple to an applied simple shear, whereas the smectic layering stays unchanged. This difference leads to a finite (but usually small) angle between n and p, which we find to be equivalent to an effective dilatation of the layers. This effective dilatation leads, above a certain threshold, to an undulation instability of the layers. We generalize our earlier approach [Rheol. Acta, vol.39(3), 15] and include the cross couplings with the velocity field and the order parameters for orientational and positional order and show how the order parameters interact with the undulation instability. We explore the influence of various material parameters on the instability. Comparing our results to recent experiments and molecular dynamic simulations, we find a good qualitative agreement.Comment: 15 pages, 12 figures, accepted for publication in PR

Europa's FUV auroral tail on Jupiter

peer reviewedaudience: researcher, professional, studentUltraviolet images of Jupiter's northern aurora obtained in 2005 confirm the existence of an electromagnetic interaction between Europa and the Jovian ionosphere. The auroral signature shows a two-component structure: a quasi-circular Europa spot, followed by a previously undetected faint tail emission trailing in the direction of corotation flow. The characteristic brightness for the auroral spot is similar to 14 +/- 1 kR above background, and approximately 7 +/- 1 kR for the tail. The spot's size is similar to 1100 km, magnetically mapping to an interaction region <= 15 Europa diameters. The auroral tail extends over similar to 5000 km, which maps along a region of at least 70 Europa diameters. The ultraviolet power emitted by both components varies from a fraction to several GW. The present study suggests auroral interaction at Europa similar to that at Io, but scaled-down by an order of magnitude, including a sub-corotating plasma plume in the geometrical wake of Europa