Local Box Adjacency Algorithms for Cylindrical Algebraic Decompositions

AbstractWe describe new algorithms for determining the adjacencies between zero-dimensional cells and those one-dimensional cells that are sections (not sectors) in cylindrical algebraic decompositions (cad). Such adjacencies constitute a basis for determining all other cell adjacencies. Our new algorithms are local, being applicable to a specified 0D cell and the 1D cells described by specified polynomials. Particularly efficient algorithms are given for the 0D cells in spaces of dimensions two, three and four. Then an algorithm is given for a space of arbitrary dimension. This algorithm may on occasion report failure, but it can then be repeated with a modified isolating interval and a likelihood of success

A whole-body micro-CT scan library that captures the skeletal diversity of Lake Malawi cichlid fishes

Here we describe a dataset of freely available, readily processed, whole-body μCT-scans of 56 species (116 specimens) of Lake Malawi cichlid fishes that captures a considerable majority of the morphological variation present in this remarkable adaptive radiation. We contextualise the scanned specimens within a discussion of their respective ecomorphological groupings and suggest possible macroevolutionary studies that could be conducted with these data. In addition, we describe a methodology to efficiently μCT-scan (on average) 23 specimens per hour, limiting scanning time and alleviating the financial cost whilst maintaining high resolution. We demonstrate the utility of this method by reconstructing 3D models of multiple bones from multiple specimens within the dataset. We hope this dataset will enable further morphological study of this fascinating system and permit wider-scale comparisons with other cichlid adaptive radiations

GASP III. JO36: a case of multiple environmental effects at play?

The so-called jellyfish galaxies are objects exhibiting disturbed morphology, mostly in the form of tails of gas stripped from the main body of the galaxy. Several works have strongly suggested ram pressure stripping to be the mechanism driving this phenomenon. Here, we focus on one of these objects, drawn from a sample of optically selected jellyfish galaxies, and use it to validate SINOPSIS, the spectral fitting code that will be used for the analysis of the GASP (GAs Stripping Phenomena in galaxies with MUSE) survey, and study the spatial distribution and physical properties of gas and stellar populations in this galaxy. We compare the model spectra to those obtained with GANDALF, a code with similar features widely used to interpret the kinematic of stars and gas in galaxies from IFU data. We find that SINOPSIS can reproduce the pixel-by-pixel spectra of this galaxy at least as good as GANDALF does, providing reliable estimates of the underlying stellar absorption to properly correct the nebular gas emission. Using these results, we find strong evidences of a double effect of ram pressure exerted by the intracluster medium onto the gas of the galaxy. A moderate burst of star formation, dating between 20 and 500 Myr ago and involving the outer parts of the galaxy more strongly than the inner regions, was likely induced by a first interaction of the galaxy with the intracluster medium. Stripping by ram pressure, plus probable gas depletion due to star formation, contributed to create a truncated ionized gas disk. The presence of an extended stellar tail on only one side of the disk, points instead to another kind of process, likely a gravitational interaction by a fly-by or a close encounter with another galaxy in the cluster.Comment: ApJ in press, 26 pages, 18 figure

GASP IV: A muse view of extreme ram-pressure stripping in the plane of the sky: the case of jellyfish galaxy JO204

In the context of the GAs Stripping Phenomena in galaxies with Muse (GASP) survey, we present the characterization of JO204, a jellyfish galaxy in A957, a relatively low-mass cluster with $M=4.4 \times10^{14}M_\odot$. This galaxy shows a tail of ionized gas that extends up to 30 kpc from the main body in the opposite direction of the cluster center. No gas emission is detected in the galaxy outer disk, suggesting that gas stripping is proceeding outside-in. The stellar component is distributed as a regular disk galaxy; the stellar kinematics shows a symmetric rotation curve with a maximum radial velocity of 200km/s out to 20 kpc from the galaxy center. The radial velocity of the gas component in the central part of the disk follows the distribution of the stellar component; the gas kinematics in the tail retains the rotation of the galaxy disk, indicating that JO204 is moving at high speed in the intracluster medium. Both the emission and radial velocity maps of the gas and stellar components indicate ram-pressure as the most likely primary mechanism for gas stripping, as expected given that JO204 is close to the cluster center and it is likely at the first infall in the cluster. The spatially resolved star formation history of JO204 provides evidence that the onset of ram-pressure stripping occurred in the last 500 Myr, quenching the star formation activity in the outer disk, where the gas has been already completely stripped. Our conclusions are supported by a set of hydrodynamic simulations.Comment: accepted for publication in Ap

Vasoactive agents in acute mesenteric ischaemia in critical care. A systematic review

Acknowledgements With thanks to Helen Fulbright, PhD, MA, PGDip LIS, BA (Hons), MCLIP, Information Specialist, Royal College of Surgeons of England Library and Archives Team, for conducting the literature searchesPeer reviewedPublisher PD

Structural response of a compliant pipe-in-pipe under frictionless and frictional conditions of the seabed.

Pipe-in-Pipe (PIP) technology has been studied significantly owing to its superior performance in deep-water and high-pressure high temperature fields than conventional single pipe. The PIP system has excellent track record of mitigating flow assurance problems from subsea wells through maintenance of the fluid's temperature in the pipe. It has also been applied in marine environment where conventional single pipe cannot perform. However, owing to complex interaction and contact within the PIP system and seabed, the mechanism of load transfer and the stresses that developed due to pressure, temperature and combined loading has not been fully understood and quantified. Therefore, this study examined the effect of pressure, temperature and the combined loading on PIP systems for flat seabed subsea pipeline. Simulations are performed to examined frictional and frictionless conditions of the flat seabed on PIP system and individual results of inner pipe, insulation material and outer pipe are presented for each analysis. The analytical calculations are carried-out for determining the operating stresses in each component of the PIP system in view of its significance for the overall structural behaviour of the system and validation of the numerical model. The impact response of the inner pipe, insulation and the outer pipe based on pressure, temperature and the combination of both (pressure and temperature) and the resulting stress on each component of the PIP system are investigated and the result presented. Furthermore, results of axial, radial and hoop stresses for the individual loading condition and with coupled analysis corresponding to each simulation (Frictional and Frictionless seabed conditions) are found to be closely similar with percentage difference less than 5 except for the von Mises stress which give 5.3%. This interesting finding revealed that the friction force does not affect structural integrity of the PIP system compared to conventional - single pipeline assuming all other parameters remains constant. Moreover, the presence of the outer pipe and the insulation material enhanced the performance of the inner pipe. The numerical simulation predicts closely the impact response for pipe-in-pipe composite specimens under individual and combined loading conditions. Therefore, the results obtained will serve as a reference guide for designing, construction and operating PIP system in the future to develop unconventional challenging energy resources like High Pressure High Temperature fields