On Vertically Global, Horizontally Local Models for Astrophysical Disks

Disks with a barotropic equilibrium structure, for which the pressure is only a function of the density, rotate on cylinders in the presence of a gravitational potential, so that the angular frequency of such a disk is independent of height. Such disks with barotropic equilibria can be approximately modeled using the shearing box framework, representing a small disk volume with height-independent angular frequency. If the disk is in baroclinic equilibrium, the angular frequency does generally depend on height, and it is thus necessary to go beyond the standard shearing box approach. In this paper, we show that given a global disk model, it is possible to develop approximate models that are local in horizontal planes without an expansion in height with shearing-periodic boundary conditions. We refer to the resulting framework as the vertically global shearing box (VGSB). These models can be non-axisymmetric for globally barotropic equilibria but should be axisymmetric for globally baroclinic equilibria. We provide explicit equations for this VGSB which can be implemented in standard magnetohydrodynamic codes by generalizing the shearing-periodic boundary conditions to allow for a height-dependent angular frequency and shear rate. We also discuss the limitations that result from the radial approximations that are needed in order to impose height-dependent shearing periodic boundary conditions. We illustrate the potential of this framework by studying a vertical shear instability and examining the modes associated with the magnetorotational instability.Comment: 24 pages, 8 figures, updated to match published versio

RAGTIME THEN AND NOW: Composers and Audiences from the Ragtime Era to the Ragtime Revival

The works from ragtime\u27s revival era, including those by William Albright, William Bolcom, Eugene Kurtz, George Rochberg, and more recently Carter Pann, stand as some of the finest examples of ragtime composition. Yet these works were not generative of the ragtime age, but followed a lengthy drought of compositional interest in the ragtime style. Instead, they were the result of the amalgamation of formal and idiomatic gestures common to the ragtime style and of serious and extensive training in classical styles. In an effort to determine what distinguishes these works by the classical composers of the ragtime revival from the works of ragtime\u27s Big Three (Scott Joplin, Joseph Lamb and James Scott), this document explores seven representative pieces by the aforementioned composers in both analytical and historical contexts. Over the past forty years, articles devoted to ragtime, written by serious scholars with formal training in music theory or music history, demonstrate serious, albeit narrowly focused, efforts to study ragtime (primarily classic ragtime) in an intensive manner. This contrasts with enthusiastic ragtime aficionados, whose articles tend toward biography and superficial description of the music. Their work is as invaluable as it is staggeringly voluminous, but avoids the deeper problems of contextualizing ragtime against then-contemporary genres, understanding compositional shifts in possible correlation to its discrete (and continually evolving) audiences, and exploring the trajectory of the prioritizing of the elements of ragtime by active composers. By exploring audience taste, compositional elements, and historical context of the ragtime style over the past twelve decades, this study offers insight on what motivates composers to make the minute compositional decisions which, in accumulation, speak both to the genre in which they are writing and to their sovereignty as original thinkers in music

Student awareness of costs and benefits of educational decisions: effects of an information campaign

Many students appear to leave full-time education too soon, despite the possibility of high returns from further investment in their education. One contributory factor may be insufficient information about the potential consequences of their choices. We investigate students’ receptiveness to an information campaign about the costs and benefits of pursuing postcompulsory education. Our results show that students with higher expected net benefits from accessing information are more likely to avail themselves of the opportunity presented by our experiment. Their intention to stay on in post-16 education is strongly affected by the experiment, though not their intention to apply to university. Effects are heterogeneous by family background and gender

Cytotoxicity of adriamycin to tumour cells in vivo and in vitro.

Two mouse sarcomas have been used to assess the sensitivity to Adriamycin of tumour cells in vivo and in vitro. Both tumours were tissue-culture adapted so that cell survival could be assayed in vitro after treatment either in vivo or in vitro. For both tumours (WHFIB and CBSAF) cells were highly sensitive when treated in vitro yet very resistant to treatment in vivo, whether assayed by cell survival or regrowth delay. Cells from both tumours treated in vitro with Adriamycin immediately after excision were slightly more resistant than the cells maintained in vitro. However, this was not adequate to explain the marked discrepancy between in vivo resistance and in vitro sensitivity. The discrepancy was not due to a failure of drug delivery. Phase of cell growth was the factor was most significantly affecting chemosensitivity in vitro, plateau-phase cells being much more resistant than log-phase cells. Hypoxia was also an important factor leading to reduced chemosensitivity. Tumour diameter, in the range 2-8 mm, did not appear to be important

Spatially resolved investigation of the optical and structural properties of CuCl thin films on Si

CuCl thin films grown on (100) Si by thermal evaporation are studied by means of low temperature photoluminescence (PL) and reflectance spectroscopies. Spatially and wavelength resolved room temperature cathodoluminescence (CL) imaging of the surface of the CuCl samples in a scanning electron microscope (SEM) has also been performed. The reflectance spectra are modeled using a dielectric response function with various models involving dead layers and reflected waves in the thin film and the exciton-polariton structure obtained is compared to other studies of CuCl. The modeling is shown to match the experimental data quite well when a dead layer is included at the air/CuCl and CuCl/Si interfaces. Some inconsistencies between the CL spectra and those measured by PL and reflectance have been observed. The effects of changing the accelerating voltage of the probe from 10 keV to the range 1-5 keV to allow depth analysis of the CL are reported, in order to pinpoint the spatial origin of the CL emission within the thin film

The importance of appropriate diagnostics in prosthetic joint infection:letter to the editor of BMC musculoskeletal disorders

Assessment of a new diagnostic test must be performed against an acceptable and validated standard to allow comparison with other studies. We are concerned that the adoption of lower diagnostic criteria in this paper has contributed to an over-diagnosis of prosthetic joint infection and makes interpretation of the results difficult

Does local implantation of gentamicin impair renal function in patients undergoing surgery for chronic bone infection?

Background: The treatment of chronic bone infection often involves excision of dead bone and implantation of biomaterials which elute antibiotics. Gentamicin is a preferred drug for local delivery, but its systemic use carries a well-established risk of nephrotoxicity.  We aim to establish the risk of acute kidney injury (AKI) with local delivery in a ceramic carrier.Methods: 163 patients with Cierny-Mader type 3 or 4 chronic osteomyelitis had a single-stage operation including filling of the osseous defect with a calcium sulphate-hydroxyapatite carrier containing gentamicin. Mean gentamicin dosing was 191.3 mg (maximum 525 mg). Glomerular filtration rate (GFR) was calculated pre-operatively and during the first seven days post-operatively. Renal impairment was graded using the chronic kidney disease (CKD) staging system, and AKI was assessed using the RIFLE criteria.Results: 155 cases had adequate data to allow calculation of pre- and post-operative GFR. 7 had pre-existing renal disease. 70 patients (45.2%) had a temporary GFR drop post-operatively, with the greatest decrease occurring at a mean of 3.06 days following surgery. Twenty cases had a >10% decline in GFR, but 12 resolved within 7 days. 7 patients transiently fell into the “Risk” category according to RIFLE criteria, but no patient had a change consistent with “Injury”, “Failure” or “Loss” of renal function and none had clinical signs of new acute renal impairment post-operatively. Conclusions: Renal function is not significantly affected by local implantation of gentamicin up to 525 mg. The presence of pre-existing renal disease is not a contraindication to local gentamicin therapy.