Automatic segmentation of liver using a topology adaptive snake

Most attempts at automatic segmentation of liver from computerised tomography images to date have relied on low-level segmentation techniques, such as thresholding and mathematical morphology, to obtain the basic liver structure. The derived boundary can then be smoothed or refined using more advanced methods. In this paper we present a method by which a topology adaptive active contour model, or snake, accurately segments liver tissue from CT images. The use of conventional snakes for liver segmentation is difficult due to the presence of other organs closely surrounding the liver. Our technique avoids this problem by adding an inflationary force to the basic snake equation, and initialising the snake inside the liver. Once the user has initialised the snake for one CT slice, the starting locations for other slices in a dataset are determined automatically from the center of gravity of the segmented area of previous slice. We present results from over 500 images, covering 4 different healthy datasets, and each liver slice is segmented in 2D before being compared to the equivalent segmentation performed by hand. Statistical analysis of the datasets shows that, in each case, there is no significant difference between the areas and the snake-segmented liver to the areas of hand segmented liver, here treated as the gold standard.</p

Automatic 3D segmentation of the liver from computed tomography images, a discrete deformable model approach

Automatic segmentation of the liver has the potential to assist in the diagnosis of disease, preparation for organ transplantation, and possibly assist in treatment planning. This paper presents initial results from work that extends on previous two-dimensional (2D) segmentation methods by implementing full three-dimensional (3D) liver segmentation, using a self-reparameterising discrete deformable model. This method overcomes many of the weaknesses inherent in 2D segmentation techniques, such as the inability to automatically segment separate lobes of the liver in each image slice, and sensitivity to individual-slice noise. Results are presented showing volumetric and overlap comparison of twelve automatically segmented livers with their corresponding manually segmented livers, which were treated as the gold standard for this study. © 2006 IEEE.</p

Influence of quenching and aging on residual stress in Al-Zn-Mg-Cu alloy 7449

The present investigation aims to quantify the size and distribution of residual stresses remaining in rectilinear aluminium forged alloy blocks after they had been partially and fully heat treated. Various quench conditions were used, including water at different temperatures and polyoxyethylene glycol in two concentrations. The influence of standard and novel aging procedures, including retrogression and reaging, has been determined. Residual stresses were characterised using X-ray and neutron diffraction. Residual stress magnitudes were found to vary significantly with rapidity of cooling from the solution treatment temperature, with the subsequent aging treatments having a much smaller effect. The influence of heat treatments on the mechanical properties of the alloy was predicted by means of quench factor analysis and measured using indentation hardness and tensile testing. Quench factor analysis is also used to predict the change in lattice parameter arising from different quench paths in the strain free reference samples d(0)

Novae in the SuperWASP data base

We present the results of trawling through the SuperWASP data base for classical and recurrent novae. We report light curves for a nova in eruption, and for classical novae and a recurrent nova in quiescence. For five objects in quiescence, we report periodicity, arising in most cases from orbital modulation of the light from the cool secondary star. The stability of the SuperWASP system means that these data have huge potential for the study not only of novae in eruption, but also of the long-term modulations of light during quiescence

Additional file 1: of Drivers of hibernation in the brown bear

Supplemental Figures and Tables. (DOCX 10538 kb

EU transport accident, incident and casualty databases: current status and future needs

Accident and casualty databases are an indispensable tool to allow for objective assessment of the transport safety problem, the identification of priority areas for action and for monitoring the effectiveness of countermeasures. Such databases at European Union level are needed to describe the current state of transport safety across the EU, to help define target levels of safety for each of the transport modes and to facilitate a data-led systems approach in defining strategies. The process of creating a range of common data sources necessary for the development and monitoring of the Common Transport Policy began in 1993. Progress has been achieved, especially for road transport, but for other modes basic kinds of data are lacking at EU-level. In order to allow meaningful analyses within each mode and comparison across the modes, further progress is needed. The purpose of this report is to review the progress made in the development of databases on accidents, casualties and exposure measures for each transport mode and, where gaps exist, to try to identify various options for EU action

SuperWASP-N extrasolar planet candidates from fields 06 < RA < 16

The Wide Angle Search for Planets (WASP) survey currently operates two installations, designated SuperWASP-N and SuperWASP-S, located in the Northern and Southern hemispheres, respectively. These installations are designed to provide high time-resolution photometry for the purpose of detecting transiting extrasolar planets, asteroids, and transient events. Here, we present results from a transit-hunting observing campaign using SuperWASP-N covering a right ascension (RA) range of 06h < RA < 16h. This paper represents the fifth and final in the series of transit candidates released from the 2004 observing season. In total, 729 335 stars from 33 fields were monitored with 130 566 having sufficient precision to be scanned for transit signatures. Using a robust transit detection algorithm and selection criteria, six stars were found to have events consistent with the signature of a transiting extrasolar planet based on the photometry, including the known transiting planet XO-1b. These transit candidates are presented here along with discussion of follow-up observations and the expected number of candidates in relation to the overall observing strategy

Infrared observations of the recurrent nova T Pyxidis: ancient dust basks in the warm glow of the 2011 outburst

We present Spitzer Space Telescope and Herschel Space Observatory infrared observations of the recurrent nova T Pyx during its 2011 eruption, complemented by ground-base optical-infrared photometry. We find that the eruption has heated dust in the pre-existing nebulosity associated with T Pyx. This is most likely interstellar dust swept up by T Pyx — either during previous eruptions or by a wind — rather than the accumulation of dust produced during eruptions

SuperWASP-N extrasolar planet candidates between 18 < RA < 21 h

The SuperWASP-I (Wide Angle Search for Planets-I) instrument observed 6.7 million stars between 8 and 15 mag from La Palma during the 2004 May-September season. Our transit-hunting algorithm selected 11 626 objects from the 184 442 stars within the RA (right ascension) range 18-21 h. We describe our thorough selection procedure whereby catalogue information is exploited along with careful study of the SuperWASP data to filter out, as far as possible, transit mimics. We have identified 35 candidates which we recommend for follow-up observations

The Temporal Development of Dust Formation and Destruction in Nova Sagittarii 2015#2 (V5668 SGR): A Panchromatic Study

We present 5–28 μm SOFIA FORECAST spectroscopy complemented by panchromatic X-ray through infrared observations of the CO nova V5668 Sgr documenting the formation and destruction of dust during ∼500 days following outburst. Dust condensation commenced by 82 days after outburst at a temperature of ∼1090 K. The condensation temperature indicates that the condensate was amorphous carbon. There was a gradual decrease of the grain size and dust mass during the recovery phase. Absolute parameter values given here are for an assumed distance of 1.2 kpc. We conclude that the maximum mass of dust produced was 1.2 × 10−7 Me if the dust was amorphous carbon. The average grain radius grew to a maximum of ∼2.9 μm at a temperature of ∼720 K around day 113 when the shell visual optical depth was τv ∼ 5.4. Maximum grain growth was followed by a period of grain destruction. X-rays were detected with Swift from day 95 to beyond day 500. The Swift X-ray count rate due to the hot white dwarf peaked around day 220, when its spectrum was that of a kT = 35 eV blackbody. The temperature, together with the supersoft X-ray turn-on and turn-off times, suggests a white dwarf mass of ∼1.1 Me. We show that the X-ray fluence was sufficient to destroy the dust. Our data show that the post-dust event X-ray brightening is not due to dust destruction, which certainly occurred, as the dust is optically thin to X-rays