1,059 research outputs found
GIFTed Demons: deformable image registration with local structure-preserving regularization using supervoxels for liver applications.
Deformable image registration, a key component of motion correction in medical imaging, needs to be efficient and provides plausible spatial transformations that reliably approximate biological aspects of complex human organ motion. Standard approaches, such as Demons registration, mostly use Gaussian regularization for organ motion, which, though computationally efficient, rule out their application to intrinsically more complex organ motions, such as sliding interfaces. We propose regularization of motion based on supervoxels, which provides an integrated discontinuity preserving prior for motions, such as sliding. More precisely, we replace Gaussian smoothing by fast, structure-preserving, guided filtering to provide efficient, locally adaptive regularization of the estimated displacement field. We illustrate the approach by applying it to estimate sliding motions at lung and liver interfaces on challenging four-dimensional computed tomography (CT) and dynamic contrast-enhanced magnetic resonance imaging datasets. The results show that guided filter-based regularization improves the accuracy of lung and liver motion correction as compared to Gaussian smoothing. Furthermore, our framework achieves state-of-the-art results on a publicly available CT liver dataset
Measurement of the Remaining In-Plane Polarization Transfer Coefficients for the 10-B(p,p') 10-B Reaction at 200 MeV
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Long-term surgical anaesthesia with isoflurane in human habituated Nile Crocodiles
A suitable long-term anaesthetic technique was required for implantation of physiological
sensors and telemetric devices in sub-adult Nile crocodiles (Crocodylus niloticus) to allow the
collection of physiological data. Five Nile crocodiles with a median body mass of 24 kg were
used. After manual capture, they were blindfolded and 0.2 mL (1 mg/mL) medetomidine was
administered intramuscularly in four of the animals which had an estimated body mass
between 20 kg and 30 kg. One crocodile with an estimated body mass of 50 kg received 0.5 mL.
For induction, 5 mL propofol (10 mg/mL) was injected intravenously into the occipital sinus.
Additional doses were given when required to ensure adequate anaesthesia. Anaesthesia
was maintained with 1.5% isoflurane. Ventilation was controlled. Local anaesthesia was
administered for surgical incision and external placement of the radio transmitter. Medetomidine
was antagonised with atipamezole at the end of surgery. Median heart rate during surgery
was 22 beats/min, at extubation 32 beats per min and 30 beats per min the following day at
the same body temperature as under anaesthesia. Median body temperature of the animals
increased from 27.3 °C to 27.9 °C during anaesthesia, as room temperature increased from
24.5 °C to 29.0 °C during surgery. Anaesthesia was successfully induced with intramuscular
medetomidine and intravenous propofol and was maintained with isoflurane for the placement
of telemetric implants. Intraoperative analgesia was supplemented with lidocaine infiltration.
Perioperative physiological parameters remained stable and within acceptable clinical limits.
Multiple factors appear to influence these variables during the recovery period, including
residual anaesthetic effects, environmental temperature and physical activity.http://www.jsava.co.za/am2017Companion Animal Clinical Studie
Medium Effects in the Normal Component Polarization Observables for the 13-C(p,p')13-C, (1/2)- â (9/2)+ Reaction at 200 MeV
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Can forest management based on natural disturbances maintain ecological resilience?
Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance
Soil biochemistry and microbial activity in vineyards under conventional and organic management at Northeast Brazil.
The SĂŁo Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that orgThe SĂŁo Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that organic fertilization can improve soil quality, we compared the effects of conventional and organic soil management on microbial activity and mycorrhization of seedless grape crops. We measured glomerospores number, most probable number (MPN) of propagules, richness of arbuscular mycorrhizal fungi (AMF) species, AMF root colonization, EE-BRSP production, carbon microbial biomass (C-MB), microbial respiration, fluorescein diacetate hydrolytic activity (FDA) and metabolic coefficient (qCO2). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO2. Mycorrhizal colonization increased from 4.7% in conventional crops to 15.9% in organic crops. Spore number ranged from 4.1 to 12.4 per 50 g-1 soil in both management systems. The most probable number of AMF propagules increased from 79 cm-3 soil in the conventional system to 110 cm-3 soil in the organic system. Microbial carbon, CO2 emission, and FDA activity were increased by 100 to 200% in the organic crop. Thirteen species of AMF were identified, the majority in the organic cultivation system. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 and Scutellospora sp. were found only in the organically managed crop. S. gregaria was found only in the conventional crop. Organically managed vineyards increased mycorrhization and general soil microbial activity
The flyby anomaly: a multivariate analysis approach
[EN] The flyby anomaly is the unexpected variation of the asymptotic post-encounter velocity of a spacecraft with respect to the pre-encounter velocity as it performs a slingshot manoeuvre. This effect has been detected in, at least, six flybys of the Earth but it has not appeared in other recent flybys. In order to find a pattern in these, apparently contradictory, data several phenomenological formulas have been proposed but all have failed to predict a new result in agreement with the observations. In this paper we use a multivariate dimensional analysis approach to propose a fitting of the data in terms of the local parameters at perigee, as it would occur if this anomaly comes from an unknown fifth force with latitude dependence. Under this assumption, we estimate the range of this force around 300 km .Acedo RodrĂguez, L. (2017). The flyby anomaly: a multivariate analysis approach. Astrophysics and Space Science. 362(2):1-7. doi:10.1007/s10509-017-3025-zS173622Acedo, L.: Adv. 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Pheromone biosynthesis in the bark beetle, Ips paraconfusus, during feeding or exposure to vapours of host plant precursors
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