Robust Framework for PET Image Reconstruction Incorporating System and Measurement Uncertainties

In Positron Emission Tomography (PET), an optimal estimate of the radioactivity concentration is obtained from the measured emission data under certain criteria. So far, all the well-known statistical reconstruction algorithms require exactly known system probability matrix a priori, and the quality of such system model largely determines the quality of the reconstructed images. In this paper, we propose an algorithm for PET image reconstruction for the real world case where the PET system model is subject to uncertainties. The method counts PET reconstruction as a regularization problem and the image estimation is achieved by means of an uncertainty weighted least squares framework. The performance of our work is evaluated with the Shepp-Logan simulated and real phantom data, which demonstrates significant improvements in image quality over the least squares reconstruction efforts

Sparse Matrix-Based HPC Tomography

Tomographic imaging has benefited from advances in X-ray sources, detectors and optics to enable novel observations in science, engineering and medicine. These advances have come with a dramatic increase of input data in the form of faster frame rates, larger fields of view or higher resolution, so high performance solutions are currently widely used for analysis. Tomographic instruments can vary significantly from one to another, including the hardware employed for reconstruction: from single CPU workstations to large scale hybrid CPU/GPU supercomputers. Flexibility on the software interfaces and reconstruction engines are also highly valued to allow for easy development and prototyping. This paper presents a novel software framework for tomographic analysis that tackles all aforementioned requirements. The proposed solution capitalizes on the increased performance of sparse matrix-vector multiplication and exploits multi-CPU and GPU reconstruction over MPI. The solution is implemented in Python and relies on CuPy for fast GPU operators and CUDA kernel integration, and on SciPy for CPU sparse matrix computation. As opposed to previous tomography solutions that are tailor-made for specific use cases or hardware, the proposed software is designed to provide flexible, portable and high-performance operators that can be used for continuous integration at different production environments, but also for prototyping new experimental settings or for algorithmic development. The experimental results demonstrate how our implementation can even outperform state-of-the-art software packages used at advanced X-ray sources worldwide

Metabolic state alters economic decision making under risk in humans

Background: Animals' attitudes to risk are profoundly influenced by metabolic state (hunger and baseline energy stores). Specifically, animals often express a preference for risky (more variable) food sources when below a metabolic reference point (hungry), and safe (less variable) food sources when sated. Circulating hormones report the status of energy reserves and acute nutrient intake to widespread targets in the central nervous system that regulate feeding behaviour, including brain regions strongly implicated in risk and reward based decision-making in humans. Despite this, physiological influences per se have not been considered previously to influence economic decisions in humans. We hypothesised that baseline metabolic reserves and alterations in metabolic state would systematically modulate decision-making and financial risk-taking in humans. Methodology/Principal Findings: We used a controlled feeding manipulation and assayed decision-making preferences across different metabolic states following a meal. To elicit risk-preference, we presented a sequence of 200 paired lotteries, subjects' task being to select their preferred option from each pair. We also measured prandial suppression of circulating acyl-ghrelin (a centrally-acting orexigenic hormone signalling acute nutrient intake), and circulating leptin levels (providing an assay of energy reserves). We show both immediate and delayed effects on risky decision-making following a meal, and that these changes correlate with an individual's baseline leptin and changes in acyl-ghrelin levels respectively. Conclusions/Significance: We show that human risk preferences are exquisitely sensitive to current metabolic state, in a direction consistent with ecological models of feeding behaviour but not predicted by normative economic theory. These substantive effects of state changes on economic decisions perhaps reflect shared evolutionarily conserved neurobiological mechanisms. We suggest that this sensitivity in human risk-preference to current metabolic state has significant implications for both real-world economic transactions and for aberrant decision-making in eating disorders and obesity

Weapons Make the Man (Larger): Formidability Is Represented as Size and Strength in Humans

In order to determine how to act in situations of potential agonistic conflict, individuals must assess multiple features of a prospective foe that contribute to the foe's resource-holding potential, or formidability. Across diverse species, physical size and strength are key determinants of formidability, and the same is often true for humans. However, in many species, formidability is also influenced by other factors, such as sex, coalitional size, and, in humans, access to weaponry. Decision-making involving assessments of multiple features is enhanced by the use of a single summary variable that encapsulates the contributions of these features. Given both a) the phylogenetic antiquity of the importance of size and strength as determinants of formidability, and b) redundant experiences during development that underscore the contributions of size and strength to formidability, we hypothesize that size and strength constitute the conceptual dimensions of a representation used to summarize multiple diverse determinants of a prospective foe's formidability. Here, we test this hypothesis in humans by examining the effects of a potential foe's access to weaponry on estimations of that individual's size and strength. We demonstrate that knowing that an individual possesses a gun or a large kitchen knife leads observers to conceptualize him as taller, and generally larger and more muscular, than individuals who possess only tools or similarly mundane objects. We also document that such patterns are not explicable in terms of any actual correlation between gun ownership and physical size, nor can they be explained in terms of cultural schemas or other background knowledge linking particular objects to individuals of particular size and strength. These findings pave the way for a fuller understanding of the evolution of the cognitive systems whereby humans – and likely many other social vertebrates – navigate social hierarchies

The Taylor expansion of the exponential map and geometric applications

The final publication is available at Springer via http://dx.doi.org/10.1007/s13398-013-0149-zIn this work we consider the Taylor expansion of the exponential map of a submanifold immersed in Rn up to order three, in order to introduce the concepts of lateral and frontal deviation. We compute the directions of extreme lateral and frontal deviation for surfaces in R3. Also we compute, by using the Taylor expansion, the directions of high contact with hyperspheres of a surface immersed in R4 and the asymptotic directions of a surface immersed in RnThis work was partially supported by DGCYT grant no. MTM2009-08933.Monera, M.; Montesinos Amilibia, Á.; Sanabria Codesal, E. (2014). The Taylor expansion of the exponential map and geometric applications. Revista de la Real Academia de Ciencias Exactas, Físicas y Naturales. Serie A: Matemáticas (RACSAM). 108(2):881-906. https://doi.org/10.1007/s13398-013-0149-zS8819061082Arnol’d, V.I., Gusein-zade, V.I., Varchenko, A.N.: Singularities of Differentiable Maps. Monographs in Mathematics, vol. 82. Birkhäuser, Boston (1985)Chen, B.-Y., Li, S.-J.: The contact number of a Euclidean submanifold. Proc. Edinburgh Math. Soc. 47, 69–100 (2004)Fessler, W.: $$\ddot{U}$$ U ¨ ber die normaltorsion von Fl $$\ddot{a}$$ a ¨ chen im vierdimensionalen euklidischen. Raum. Comm. Math. Helv. 33(2), 89–108 (1959)García, R., Sotomayor, J.: Geometric mean curvature lines on surfaces immersed in $$\mathbb{R}^3$$ R 3 . Annales de la faculté des sciences de Toulouse, $$6^e$$ 6 e ser, vol. 11, No. 3, pp. 377–401 (2002)García, R., Sotomayor, J.: Lines of axial curvature on surfaces immersed in $$R^4$$ R 4 . Differ. Geom. Appl. 12, 253–269 (2000)Golubitsky, M., Gillemin, V.: Stable Mappings and their Singularities. Springer, Berlin (1973)Hartmann, F., Hanzen, R.: Apollonius’s Ellipse and Evolute Revisited–The Discriminant of the Related Quartic. http://www3.villanova.edu/maple/misc/ellipse/Apollonius2004.pdfLlibre, J., Yanquian, Y.: On the dynamics of surface vector fields and homeomofphisms (preprint)Looijenga, E.J.N.: Structural stability of smooth families of $$C^{\infty }$$ C ∞ -functions. University of Amsterdam, Doctoral Thesis (1974)Mochida, D.K.H., Romero-Fuster, M.C., Ruas, M.A.S.: Inflection points and nonsingular embeddings of surfaces in $$\mathbb{R}^5$$ R 5 . Rocky Mt. J. Math. 33, 3 (2003)Mochida, D.K.H., Romero-Fuster, M.C., Ruas, M.A.S.: Osculating hyperplanes and asymptotic directions of codimension two submanifolds of Euclidean spaces. Geom. Dedicata 77(3), 305–315 (1999)Mochida, D.K.H., Romero Fuster, M.C., Ruas, M.A.S.: The geometry of surfaces in 4-space from a contact viewpoint. Geom. Dedicata 54, 323–332 (1995)Monera, G.M., Montesinos-Amilibia, A., Moraes, S.M., Sanabria-Codesal, E.: Critical points of higher order for the normal map of immersions in $$\mathbb{R}^d$$ R d . Topol. Appl. 159, 537–544 (2012)Montaldi, J.A.: Contact with application to submanifolds, PhD Thesis, University of Liverpool (1983)Montaldi, J.A.: On contact between submanifolds. Michigan Math. J. 33, 195–199 (1986)Montesinos-Amilibia, A.: Parametricas4, computer program freely available from http://www.uv.es/montesinMontesinos-Amilibia, A.: Parametricas5, computer program freely available from http://www.uv.es/montesinMoraes, S., Romero-Fuster, M.C., Sánchez-Bringas, F.: Principal configurations and umbilicity of submanifolds in $$I\!\! R^n$$ I R n . Bull. Bel. Math. Soc. 10, 227–245 (2003)Porteous, I.R.: The normal singularities of a submanifold. J. Differ. Geom. 5, 543–564 (1971)Romero-Fuster, M.C., Ruas, M.A.S., Tari, F.: Asymptotic curves on surfaces in $$R^5$$ R 5 . Commun. Contemp. Math. 10, 309–335 (2008)Romero-Fuster, M.C., Sánchez-Bringas, F.: Umbilicity of surfaces with orthogonal asymptotiv lines in $$R^4$$ R 4 . Differ. Geom. Appl. 16, 213–224 (2002)Tari, F.: On pairs of geometric foliations on a cross-cap. Tohoku Math. J. 59(2), 233–258 (2007

A Minimal Fragment of MUC1 Mediates Growth of Cancer Cells

The MUC1 protein is aberrantly expressed on many solid tumor cancers. In contrast to its apical clustering on healthy epithelial cells, it is uniformly distributed over cancer cells. However, a mechanistic link between aberrant expression and cancer has remained elusive. Herein, we report that a membrane-bound MUC1 cleavage product, that we call MUC1*, is the predominant form of the protein on cultured cancer cells and on cancerous tissues. Further, we demonstrate that transfection of a minimal fragment of MUC1, MUC1*1110, containing a mere forty-five (45) amino acids of the extracellular domain, is sufficient to confer the oncogenic activities that were previously attributed to the full-length protein. By comparison of molecular weight and function, it appears that MUC1* and MUC1*1110 are approximately equivalent. Evidence is presented that strongly supports a mechanism whereby dimerization of the extracellular domain of MUC1* activates the MAP kinase signaling cascade and stimulates cell growth. These findings suggest methods to manipulate this growth mechanism for therapeutic interventions in cancer treatments

History of Spinal Neurosurgery and Spine Societies

info:eu-repo/semantics/publishedVersio

Joint multi-field T1 quantification for fast field-cycling MRI

Acknowledgment This article is based upon work from COST Action CA15209, supported by COST (European Cooperation in Science and Technology). Oliver Maier is a Recipient of a DOC Fellowship (24966) of the Austrian Academy of Sciences at the Institute of Medical Engineering at TU Graz. The authors would like to acknowledge the NVIDIA Corporation Hardware grant support.Peer reviewedPublisher PD