2,051 research outputs found
The rare case of positive FDG-positron emission tomography for giant cavernous hemangioma of the liver
Hemangioma is the most common benign liver tumor and the second most common liver tumor after metastases. Large hemangiomas are often heterogeneous. When they exceed 4 cm in diameter, they are termed giant hemangiomas. These giant hemangiomas often present heterogeneous patterns. These heterogeneous appearances are shown because of intratumoral changes due to several
degenerative phenomena. PET/CT is reported to be useful for the differentiation of benign from malignant liver lesions. We report the case of a large hepatic hemangioma characterized by high FDG uptake
On the Complexity of Case-Based Planning
We analyze the computational complexity of problems related to case-based
planning: planning when a plan for a similar instance is known, and planning
from a library of plans. We prove that planning from a single case has the same
complexity than generative planning (i.e., planning "from scratch"); using an
extended definition of cases, complexity is reduced if the domain stored in the
case is similar to the one to search plans for. Planning from a library of
cases is shown to have the same complexity. In both cases, the complexity of
planning remains, in the worst case, PSPACE-complete
A discussion of possible approaches to the integration of thermochemical storage systems in concentrating solar power plants
One of the most interesting perspectives for the development of concentrated solar power (CSP) is the storage of solar energy on a seasonal basis, intending to exploit the summer solar radiation in excess and use it in the winter months, thus stabilizing the yearly production and increasing the capacity factor of the plant. By using materials subject to reversible chemical reactions, and thus storing the thermal energy in the form of chemical energy, thermochemical storage systems can potentially serve to this purpose. The present work focuses on the identification of possible integration solutions between CSP plants and thermochemical systems for long-term energy storage, particularly for high-temperature systems such as central receiver plants. The analysis is restricted to storage systems potentially compatible with temperatures ranging from 700 to 1000 â—¦C and using gases as heat transfer fluids. On the basis of the solar plant specifications, suitable reactive systems are identified and the process interfaces for the integration of solar plant/storage system/power block are discussed. The main operating conditions of the storage unit are defined for each considered case through process simulation
Tomato yield heterosis is triggered by a dosage sensitivity of the florigen pathway that fine-tunes shoot architecture
The superiority of hybrids has long been exploited in agriculture, and although many models explaining "heterosis" have been put forth, direct empirical support is limited. Particularly elusive have been cases of heterozygosity for single gene mutations causing heterosis under a genetic model known as overdominance. In tomato (Solanum lycopersicum), plants carrying mutations in SINGLE FLOWER TRUSS (SFT) encoding the flowering hormone florigen are severely delayed in flowering, become extremely large, and produce few flowers and fruits, but when heterozygous, yields are dramatically increased. Curiously, this overdominance is evident only in the background of "determinate" plants, in which the continuous production of side shoots and inflorescences gradually halts due to a defect in the flowering repressor SELF PRUNING (SP). How sp facilitates sft overdominance is unclear, but is thought to relate to the opposing functions these genes have on flowering time and shoot architecture. We show that sft mutant heterozygosity (sft/+) causes weak semi-dominant delays in flowering of both primary and side shoots. Using transcriptome sequencing of shoot meristems, we demonstrate that this delay begins before seedling meristems become reproductive, followed by delays in subsequent side shoot meristems that, in turn, postpone the arrest of shoot and inflorescence production. Reducing SFT levels in sp plants by artificial microRNAs recapitulates the dose-dependent modification of shoot and inflorescence production of sft/+ heterozygotes, confirming that fine-tuning levels of functional SFT transcripts provides a foundation for higher yields. Finally, we show that although flowering delays by florigen mutant heterozygosity are conserved in Arabidopsis, increased yield is not, likely because cyclical flowering is absent. We suggest sft heterozygosity triggers a yield improvement by optimizing plant architecture via its dosage response in the florigen pathway. Exploiting dosage sensitivity of florigen and its family members therefore provides a path to enhance productivity in other crops, but species-specific tuning will be required
Pseudozyma aphidis bloodstream infection in a patient with aggressive lymphoma and a history of intravenous drug use: Case report and review of the literature
Pseudozyma aphidis is an environmental fungus which causes opportunistic infections in immunocompromised patients. Here we report the case of a 54-year-old, intravenous drug user woman, newly diagnosed to have an aggressive lymphoma, who developed a bloodstream infection caused by P. aphidis treated successfully with amphotericin-B therapy. The precise identification was assessed by sequencing. We propose to consider intravenous drug use as a risk factor for invasive infections due to this environmental yeast
Compilability of Abduction
Abduction is one of the most important forms of reasoning; it has been
successfully applied to several practical problems such as diagnosis. In this
paper we investigate whether the computational complexity of abduction can be
reduced by an appropriate use of preprocessing. This is motivated by the fact
that part of the data of the problem (namely, the set of all possible
assumptions and the theory relating assumptions and manifestations) are often
known before the rest of the problem. In this paper, we show some complexity
results about abduction when compilation is allowed
Three-component modeling of C-rich AGB star winds I. Method and first results
Radiative acceleration of newly-formed dust grains and transfer of momentum
from the dust to the gas plays an important role for driving winds of AGB
stars. Therefore a detailed description of the interaction of gas and dust is a
prerequisite for realistic models of such winds. In this paper we present the
method and first results of a three-component time-dependent model of
dust-driven AGB star winds. With the model we plan to study the role and
effects of the gas-dust interaction on the mass loss and wind formation. The
wind model includes separate conservation laws for each of the three components
of gas, dust and the radiation field and is developed from an existing model
which assumes position coupling between the gas and the dust. As a new feature
we introduce a separate equation of motion for the dust component in order to
fully separate the dust phase from the gas phase. The transfer of mass, energy
and momentum between the phases is treated by interaction terms. We also carry
out a detailed study of the physical form and influence of the momentum
transfer term (the drag force) and three approximations to it. In the present
study we are interested mainly in the effect of the new treatment of the dust
velocity on dust-induced instabilities in the wind. As we want to study the
consequences of the additional freedom of the dust velocity on the model we
calculate winds both with and without the separate dust equation of motion. The
wind models are calculated for several sets of stellar parameters. We find that
there is a higher threshold in the carbon/oxygen abundance ratio at which winds
form in the new model. The winds of the new models, which include drift, differ
from the previously stationary winds, and the winds with the lowest mass loss
rates no longer form.Comment: 15 pages, 5 figures, accepted by A&
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