759 research outputs found

    Bayesian Inference Semantics: A Modelling System and A Test Suite

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    We present BIS, a Bayesian Inference Seman- tics, for probabilistic reasoning in natural lan- guage. The current system is based on the framework of Bernardy et al. (2018), but de- parts from it in important respects. BIS makes use of Bayesian learning for inferring a hy- pothesis from premises. This involves estimat- ing the probability of the hypothesis, given the data supplied by the premises of an argument. It uses a syntactic parser to generate typed syn- tactic structures that serve as input to a model generation system. Sentences are interpreted compositionally to probabilistic programs, and the corresponding truth values are estimated using sampling methods. BIS successfully deals with various probabilistic semantic phe- nomena, including frequency adverbs, gener- alised quantifiers, generics, and vague predi- cates. It performs well on a number of interest- ing probabilistic reasoning tasks. It also sus- tains most classically valid inferences (instan- tiation, de Morgan’s laws, etc.). To test BIS we have built an experimental test suite with examples of a range of probabilistic and clas- sical inference patterns

    Lev Vigotski y George Mead. Una psicologia social de los procesos cognitivos

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    Wetensch. publicatieFaculteit der Sociale Wetenschappe

    (R,R)-Disynephrine ether bis­(hydrogen sulfate)

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    The asymmetric unit of the title compound [systematic name: (R,R)-2,4-bis­(4-hydroxy­phen­yl)-N,N′-dimethyl-3-oxapentane-1,5-diammonium bis­(hydrogen sulfate)], C18H26N2O3 2+·2HSO4 −, contains one half-cation and one hydrogen sulfate anion. The cation has crystallographically imposed twofold symmetry with the rotation axis passing through the central ether O atom. Hydrogen bonds between the hydr­oxy group and amine H atoms of the cation to two hydrogen sulfate anions link the three ions in a ring motif. A three-dimensional network is accomplished by additional O—H⋯O hydrogen bonds between the anions and by N—H⋯O hydrogen bonds between the cations. Disorder with equally occupied sites affects the H-atom position in the anion

    Nanohybrid biosensor based on mussel-inspired electro-cross-linking of tannic acid capped gold nanoparticles and enzymes

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    Complementary tools to classical analytical methods, enzymatic biosensors are widely applied in medical diagnosis due to their high sensitivity, potential selectivity, and their possibility of miniaturization/automation. Among the different protocols of enzyme immobilization, the covalent binding and cross-linking of enzymes ensure the great stability of the developed biosensor. Obtained manually by drop-casting using a specific cross-linker, this immobilization process is not suitable for the specific functionalization of a single electrode out of a microelectrode array. In the present work, we developed a nanohybrid enzymatic biosensor with high sensitivity by a mussel-inspired electro-cross-linking process using a cheap and abundant natural molecule (tannic acid, TA), gold salt, and native enzymes. Based on the use of a cheap natural compound and gold salt, this electro-cross-linking process based on catechol/amine reaction (i) is versatile, likely to be applied on any kind of enzymes, (ii) does not require the synthesis of a specific cross-linker, (ii) gives enzymatic biosensors with high and very stable sensitivity over two weeks upon storage at room temperature and (iv) is temporally and spatially controlled, allowing the specific functionalization of a single electrode out of a microelectrode array. Besides the development of microbiosensors, this process can also be used for the design of enzymatic biofuel cells

    Towards real-time MRI-guided 3D localization of deforming targets for non-invasive cardiac radiosurgery.

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    Radiosurgery to the pulmonary vein antrum in the left atrium (LA) has recently been proposed for non-invasive treatment of atrial fibrillation (AF). Precise real-time target localization during treatment is necessary due to complex respiratory and cardiac motion and high radiation doses. To determine the 3D position of the LA for motion compensation during radiosurgery, a tracking method based on orthogonal real-time MRI planes was developed for AF treatments with an MRI-guided radiotherapy system. Four healthy volunteers underwent cardiac MRI of the LA. Contractile motion was quantified on 3D LA models derived from 4D scans with 10 phases acquired in end-exhalation. Three localization strategies were developed and tested retrospectively on 2D real-time scans (sagittal, temporal resolution 100 ms, free breathing). The best-performing method was then used to measure 3D target positions in 2D-2D orthogonal planes (sagittal-coronal, temporal resolution 200-252 ms, free breathing) in 20 configurations of a digital phantom and in the volunteer data. The 3D target localization accuracy was quantified in the phantom and qualitatively assessed in the real data. Mean cardiac contraction was  ⩽  3.9 mm between maximum dilation and contraction but anisotropic. A template matching approach with two distinct template phases and ECG-based selection yielded the highest 2D accuracy of 1.2 mm. 3D target localization showed a mean error of 3.2 mm in the customized digital phantoms. Our algorithms were successfully applied to the 2D-2D volunteer data in which we measured a mean 3D LA motion extent of 16.5 mm (SI), 5.8 mm (AP) and 3.1 mm (LR). Real-time target localization on orthogonal MRI planes was successfully implemented for highly deformable targets treated in cardiac radiosurgery. The developed method measures target shifts caused by respiration and cardiac contraction. If the detected motion can be compensated accordingly, an MRI-guided radiotherapy system could potentially enable completely non-invasive treatment of AF

    Substrate Binding Kinetics and its Role in the Cytochrome P450 Hydroxylation Sequence

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    The kinetics of the binding of type I and type II substrates to cytochrome P450LM has been investigated. Type I substrates are preferentially bound compared to type II compounds. The rate constants range between 103 and 105 [M-1 s-1], indicating possible interference with rate limiting steps. Substrates bind to the reduced cytochrome with considerably lower rate constants. The results are in favour of the sequential reaction mechanism. The solubilized enzyme preparation shows properties similar to the microsomal enzyme system
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