Habent sua fata libelli: Aristotle's Categories in the first century BC

A re-examination of the question why, in the revival of interest, in the first century BC in Aristotle’s esoteric works, as opposed to his doctrines, the work Categories played so large a part. The answers suggested are that the work aroused interest just because it did not easily fit into the standard Hellenistic divisions of philosophy and their usual agendas, and that, more than Aristotle’s other works with the possible exception of the Metaphysics , it revealed aspects of Aristotle’s thought that had become unfamiliar during the Hellenistic period

Spectroscopy of Globular Clusters in the Sculptor Group Galaxies NGC 253 and NGC 55

We have obtained spectra for 103 published globular cluster candidates in the Sculptor Group galaxies NGC 253 and NGC 55. On the basis of radial velocities and digitized plate images, 14 globular clusters are identified in NGC 253 and one probable globular cluster is identified in NGC 55. The majority of the objects in the sample appear to be background galaxies. We have obtained and analysed COSMOS plate scans of NGC 253 and NGC 55 and use these along with the spectroscopically identified clusters to define new samples of globular cluster candidates in the two galaxies which should have reduced contamination.Comment: 11 pages, 9 postscript figures, accepted for publication in MNRA

Route finding as a consequence of a reduction in road capacity

The conditions for using a car in Brisbane, as elsewhere, have changed over the years. However, one of the same drivers as before is still there: That is, motorists' desire to make trips by driving in the way that is comfortable for them. The driver that is traffic congestion is also still widespread. This paper considers the driver of travel and transport that is habits. In particular, it considers the habits (including use of technology) which affect the choice of route when there is a reduction in road capacity. In this situation there may be initial confusion about what motorists should do and where they should go, in order to carry out their usual trips. The normal expectation of route choice is that a path between an origin and a destination will be selected (in advance) so as to minimize the distance and/or time required. A desire to avoid paying tolls is also an expected reaction. Less often discussed are the decisions that motorists make while driving about which roads to use as a result of their own perceptions of the traffic situation. This paper discusses a qualitative study of motorists affected by the reduction in road capacity that occurred on Epping Road after the Lane Cove Tunnel in Sydney was opened. It found a range of different bases for choice of route, depending on the motorists' attitudes, knowledge and existing habits. This can be used to explain why any chaos that occurs when a road is narrowed, is short-lived

S2P3-R (v1.0): a framework for efficient regional modelling of physical and biological structures and processes in shelf seas

An established one-dimensional (1-D) model of Shelf Sea Physics and Primary Production (S2P3) is adapted for flexible use in selected regional settings over selected periods of time. This Regional adaptation of S2P3, the S2P3-R framework (v1.0), can be efficiently used to investigate physical and biological phenomena in shelf seas that are strongly controlled by vertical processes. These include spring blooms that follow the onset of stratification, tidal mixing fronts that seasonally develop at boundaries between mixed and stratified water, and sub-surface chlorophyll maxima that persist throughout summer. While not representing 3-D processes, S2P3-R reveals the horizontal variation of the key 1-D (vertical) processes. S2P3-R should therefore only be used in regions where horizontal processes – including mean flows, eddy fluxes and internal tides – are known to exert a weak influence in comparison with vertical processes. In such cases, S2P3-R may be used as a highly versatile research tool, alongside more complex and computationally expensive models. In undergraduate oceanography modules and research projects, the model serves as an effective practical tool for linking theory and field observations. Three different regional configurations of S2P3-R are described, illustrating a range of diagnostics, evaluated where practical with observations. The model can be forced with daily meteorological variables for any selected year in the reanalysis era (1948 onwards). Example simulations illustrate the considerable extent of synoptic-to-interannual variability in the physics and biology of shelf seas. In discussion, the present limitations of S2P3-R are emphasised, and future developments are outlined

Detecting the Gravitational Redshift of Cluster Gas

We examine the gravitational redshift of radiation emitted from within the potential of a cluster. Spectral lines from the intracluster medium (ICM) are redshifted in proportion to the emission-weighted mean potential along the line of sight, amounting to approximately 50 km/s at a radius of 100 kpc/h, for a cluster dispersion of 1200 km/s. We show that the relative redshifts of different ionization states of metals in the ICM provide a unique probe of the three-dimensional matter distribution. An examination of the reported peculiar velocities of cD galaxies in well studied Abell clusters reveals they are typically redshifted by an average of $\sim +200$ km/s. This can be achieved by gravity with the addition of a steep central potential associated with the cD galaxy. Note that in general gravitational redshifts cause a small overestimate of the recessional velocities of clusters by an average of $\sim$ 20 km/s.Comment: 6 pages, 3 figures, accepted to the Astrophysical Journal Letter

Cost-effectiveness of left ventricular assist devices (LVADs) for patients with advanced heart failure : analysis of the British NHS Bridge to Transplant (BTT) program

Background: A previous cost-effectiveness analysis showed that bridge to transplant (BTT) with early design left ventricular assist devices (LVADs) for advanced heart failure was more expensive than medical management while appearing less beneficial. Older LVADs were pulsatile, but current second and third generation LVADs are continuous flow pumps. This study aimed to estimate comparative cost-effectiveness of BTT with durable implantable continuous flow LVADs compared to medical management in the British NHS. Methods and results: A semi-Markov multi-state economic model was built using NHS costs data and patient data in the British NHS Blood and Transplant Database (BTDB). Quality-adjusted life years (QALYs) and incremental costs per QALY were calculated for patients receiving LVADs compared to those receiving inotrope supported medical management. LVADs cost £80,569 ($127,887) at 2011 prices and delivered greater benefit than medical management. The estimated probabilistic incremental cost-effectiveness ratio (ICER) was £53,527 ($84,963)/QALY (95%CI: £31,802–£94,853; $50,479–$150,560) (over a lifetime horizon). Estimates were sensitive to choice of comparator population, relative likelihood of receiving a heart transplant, time to transplant, and LVAD costs. Reducing the device cost by 15% decreased the ICER to £50,106 ($79,533)/QALY. Conclusions: Durable implantable continuous flow LVADs deliver greater benefits at higher costs than medical management in Britain. At the current UK threshold of £20,000 to £30,000/QALY LVADs are not cost effective but the ICER now begins to approach that of an intervention for end of life care recently recommended by the British NHS. Cost-effectiveness estimates are hampered by the lack of randomized trials

Cost-effectiveness of left ventricular assist devices (LVADs) for patients with advanced heart failure : analysis of the British NHS Bridge to Transplant (BTT) program

Background: A previous cost-effectiveness analysis showed that bridge to transplant (BTT) with early design left ventricular assist devices (LVADs) for advanced heart failure was more expensive than medical management while appearing less beneficial. Older LVADs were pulsatile, but current second and third generation LVADs are continuous flow pumps. This study aimed to estimate comparative cost-effectiveness of BTT with durable implantable continuous flow LVADs compared to medical management in the British NHS. Methods and results: A semi-Markov multi-state economic model was built using NHS costs data and patient data in the British NHS Blood and Transplant Database (BTDB). Quality-adjusted life years (QALYs) and incremental costs per QALY were calculated for patients receiving LVADs compared to those receiving inotrope supported medical management. LVADs cost £80,569 ($127,887) at 2011 prices and delivered greater benefit than medical management. The estimated probabilistic incremental cost-effectiveness ratio (ICER) was £53,527 ($84,963)/QALY (95%CI: £31,802–£94,853; $50,479–$150,560) (over a lifetime horizon). Estimates were sensitive to choice of comparator population, relative likelihood of receiving a heart transplant, time to transplant, and LVAD costs. Reducing the device cost by 15% decreased the ICER to £50,106 ($79,533)/QALY. Conclusions: Durable implantable continuous flow LVADs deliver greater benefits at higher costs than medical management in Britain. At the current UK threshold of £20,000 to £30,000/QALY LVADs are not cost effective but the ICER now begins to approach that of an intervention for end of life care recently recommended by the British NHS. Cost-effectiveness estimates are hampered by the lack of randomized trials