The role of the human hippocampus in decision-making under uncertainty

The role of the hippocampus in decision-making is beginning to be more understood. Because of its prospective and inferential functions, we hypothesized that it might be required specifically when decisions involve the evaluation of uncertain values. A group of individuals with autoimmune limbic encephalitis—a condition known to focally affect the hippocampus—were tested on how they evaluate reward against uncertainty compared to reward against another key attribute: physical effort. Across four experiments requiring participants to make trade-offs between reward, uncertainty and effort, patients with acute limbic encephalitis demonstrated blunted sensitivity to reward and effort whenever uncertainty was considered, despite demonstrating intact uncertainty sensitivity. By contrast, the valuation of these two attributes (reward and effort) was intact on uncertainty-free tasks. Reduced sensitivity to changes in reward under uncertainty correlated with the severity of hippocampal damage. Together, these findings provide evidence for a context-sensitive role of the hippocampus in value-based decision-making, apparent specifically under conditions of uncertainty

Empirical Installation of Linear Algebra Shared-Memory Subroutines for Auto-Tuning

The final publication is available at Springer via http://dx.doi.org/10.1007/s10766-013-0249-6The introduction of auto-tuning techniques in linear algebra shared-memory routines is analyzed. Information obtained in the installation of the routines is used at running time to take some decisions to reduce the total execution time. The study is carried out with routines at different levels (matrix multiplication, LU and Cholesky factorizations and linear systems symmetric or general routines) and with calls to routines in the LAPACK and PLASMA libraries with multithread implementations. Medium NUMA and large cc-NUMA systems are used in the experiments. This variety of routines, libraries and systems allows us to obtain general conclusions about the methodology to use for linear algebra shared-memory routines auto-tuning. Satisfactory execution times are obtained with the proposed methodology.Partially supported by Fundacion Seneca, Consejeria de Educacion de la Region de Murcia, 08763/PI/08, PROMETEO/2009/013 from Generalitat Valenciana, the Spanish Ministry of Education and Science through TIN2012-38341-C04-03, and the High-Performance Computing Network on Parallel Heterogeneus Architectures (CAPAP-H). The authors gratefully acknowledge the computer resources and assistance provided by the Supercomputing Centre of the Scientific Park Foundation of Murcia and by the Centre de Supercomputacio de Catalunya.Cámara, J.; Cuenca, J.; Giménez, D.; García, LP.; Vidal Maciá, AM. (2014). Empirical Installation of Linear Algebra Shared-Memory Subroutines for Auto-Tuning. International Journal of Parallel Programming. 42(3):408-434. https://doi.org/10.1007/s10766-013-0249-6S408434423Agullo, E., Demmel, J., Dongarra, J., Hadri, B., Kurzak, J., Langou, J., Ltaief, H., Luszczek, P., Tomov, S.: Numerical linear algebra on emerging architectures: the PLASMA and MAGMA projects. J. Phys. Conf. Ser. 180(1), 1–5 (2009)Alberti, P., Alonso, P., Vidal, A.M., Cuenca, J., Giménez, D.: Designing polylibraries to speed up linear algebra computations. Int. J. High Perform. Comput. Netw. 1/2/3(1), 75–84 (2004)Anderson, E., Bai, Z., Bischof, C., Demmel, J., Dongarra, J.J., Du Croz, J., Grenbaum, A., Hammarling, S., McKenney, A., Ostrouchov, S., D. Sorensen, S.: LAPACK User’s Guide. Society for Industrial and Applied Mathematics, Philadelphia (1995)Bernabé, G., Cuenca, J., Giménez, D.: Optimization techniques for 3D-FWT on systems with manycore GPUs and multicore CPUs. In: ICCS (2013)Buttari, A., Langou, J., Kurzak, J., Dongarra, J.: A class of parallel tiled linear algebra algorithms for multicore architectures. Parallel Comput. 35(1), 38–53 (2009)Cámara, J., Cuenca, J., Giménez, D., Vidal. A.M.: Empirical autotuning of two-level parallel linear algebra routines on large cc-NUMA systems. In: ISPA (2012)Caron, E., Desprez, F., Suter, F.: Parallel extension of a dynamic performance forecasting tool. Scalable Comput. Pract. Exp. 6(1), 57–69 (2005)Chen, Z., Dongarra, J., Luszczek, P., Roche, K.: Self adapting software for numerical linear algebra and LAPACK for clusters. Parallel Comput. 29, 1723–1743 (2003)Cuenca, J., Giménez, D., González, J.: Achitecture of an automatic tuned linear algebra library. Parallel Comput. 30(2), 187–220 (2004)Cuenca, J., García, L.P., Giménez, D.: Improving linear algebra computation on NUMA platforms through auto-tuned nested parallelism. In: Proceedings of the 2012 EUROMICRO Conference on Parallel, Distributed and Network Processing (2012)Frigo, M.: FFTW: An adaptive software architecture for the FFT. In: Proceedings of the ICASSP Conference, vol. 3, p. 1381 (1998)Golub, G., Van Loan, C.F.: Matrix Computations, 3rd edn. The John Hopkins University Press, Baltimore (1996)Im, E.-J., Yelick, K., Vuduc, R.: Sparsity: optimization framework for sparse matrix kernels. Int. J. High Perform. Comput. Appl. (IJHPCA) 18(1), 135–158 (2004)Intel MKL web page.: http://software.intel.com/en-us/intel-mkl/Jerez, S., Montávez, J.-P., Giménez, D.: Optimizing the execution of a parallel meteorology simulation code. In: Proceedings of the 23rd IEEE International Parallel and Distributed Processing Symposium. IEEE (2009)Katagiri, T., Kise, K., Honda, H., Yuba, T.: Fiber: a generalized framework for auto-tuning software. Springer LNCS 2858, 146–159 (2003)Katagiri, T., Kise, K., Honda, H., Yuba, T.: ABCLib-DRSSED: a parallel eigensolver with an auto-tuning facility. Parallel Comput. 32(3), 231–250 (2006)Kurzak, J., Tomov, S., Dongarra, J.: Autotuning gemm kernels for the FERMI GPU. IEEE Trans. Parallel Distrib. Syst. 23(11), 2045–2057 (2012)Lastovetsky, A.L., Reddy, R., Higgins, R.: Building the functional performance model of a processor. In: SAC, pp. 746–753 (2006)Li, J., Skjellum, A., Falgout, R.D.: A poly-algorithm for parallel dense matrix multiplication on two-dimensional process grid topologies. Concurrency Pract. Exp. 9(5), 345–389 (1997)Naono, K., Teranishi, K., Cavazos, J., Suda, R., (eds.): Software Automatic Tuning. From Concepts to State-of-the-Art Results. Springer, Berlin (2010)Nath, R., Tomov, S., Dongarra, J.: An improved MAGMA gemm for FERMI graphics processing units. IJHPCA 24(4), 511–515 (2010)Petitet, A., Blackford, L.S., Dongarra, J., Ellis, B., Fagg, G.E., Roche, K., Vadhiyar, S.S.: Numerical libraries and the grid. IJHPCA 15(4), 359–374 (2001)PLASMA.: http://icl.cs.utk.edu/plasma/Püschel, M., Moura, J.M.F., Singer, B., Xiong, J., Johnson, J.R., Padua, D.A., Veloso, M.M., Johnson, R.W.: Spiral: a generator for platform-adapted libraries of signal processing algorithms. IJHPCA 18(1), 21–45 (2004)Seshagiri, L., Wu, M.-S., Sosonkina, M., Zhang, Z., Gordon, M.S., Schmidt, M.W.: Enhancing adaptive middleware for quantum chemistry applications with a database framework. In: IPDPS Workshops, pp. 1–8 (2010)Tanaka, T., Katagiri, T., Yuba, T.: d-Spline based incremental parameter estimation in automatic performance tuning. In: PARA, pp. 986–995 (2006)Vuduc, R., Demmel, J., Bilmes, J.: Statistical models for automatic performance tuning. In: International Conference on Computational Science (1), pp. 117–126 (2001)Whaley, R.C., Petitet, A., Dongarra, J.: Automated empirical optimizations of software and the ATLAS project. Parallel Comput. 27(1–2), 3–35 (2001

“If it’s a broad spectrum, it can shoot better”: inappropriate antibiotic prescribing in Cambodia

Abstract Background Cambodia is affected by antibiotic resistance but interventions to reduce the level of resistance require knowledge of the phenomena that lead to inappropriate prescribing. We interviewed physicians working in public hospitals to explore the drivers of inappropriate antibiotic prescribing. Methods Hospitals participating in a knowledge, attitudes and practices survey prior to this study were purposively selected and physicians were randomly recruited to participate in focus group discussions. Nvivo version 10 was used to inductively code the qualitative transcripts and manage thematic data analysis. Results Inappropriate antibiotic prescribing was a common practice and driven by seven factors: prescribing habit, limited diagnostic capacity, lack of microbiology evidence, non-evidence-based clinical guidelines, perceived patient demand, poor hygiene and infection control, and perceived bacterial resistance to narrow spectrum antibiotics. “Every day, doctors are not performing appropriately. We have made lots of mistakes with our antibiotic prescribing.” When a patient’s clinical condition was not responsive to empiric treatment, physicians changed to a broader spectrum antibiotic and microbiology services were sought only after failure of a treatment with a broad-spectrum antibiotic. This habitual empirical prescribing was a common practice regardless of microbiology service accessibility. Poor hygiene and infection control practices were commonly described as reasons for ‘preventive’ prescribing with full course of antibiotics while perception of bacterial resistance to narrow-spectrum antibiotics due to unrestricted access in the community resulted in unnecessary prescribing of broad spectrum antibiotics in private practices. Conclusions The practice of prescribing antibiotics by Cambodian physicians is inappropriate and based on prescribing habit rather than microbiology evidence. Improvement in prescribing practice is unlikely to occur unless an education program for physicians focuses on the diagnostic capacity and usefulness of microbiology services. In parallel, hygiene and infection control in hospital must be improved, evidence-based antibiotic prescribing guidelines must be developed, and access to antibiotics in community must be restricted

Distinct Neurobehavioural Effects of Cannabidiol in Transmembrane Domain Neuregulin 1 Mutant Mice

The cannabis constituent cannabidiol (CBD) possesses anxiolytic and antipsychotic properties. We have previously shown that transmembrane domain neuregulin 1 mutant (Nrg1 TM HET) mice display altered neurobehavioural responses to the main psychoactive constituent of cannabis, Δ9-tetrahydrocannabinol. Here we investigated whether Nrg1 TM HET mice respond differently to CBD and whether CBD reverses schizophrenia-related phenotypes expressed by these mice. Adult male Nrg1 TM HET and wild type-like littermates (WT) received vehicle or CBD (1, 50 or 100 mg/kg i.p.) for 21 days. During treatment and 48 h after withdrawal we measured behaviour, whole blood CBD concentrations and autoradiographic receptor binding. Nrg1 HET mice displayed locomotor hyperactivity, PPI deficits and reduced 5-HT2A receptor binding density in the substantia nigra, but these phenotypes were not reversed by CBD. However, long-term CBD (50 and 100 mg/kg) selectively enhanced social interaction in Nrg1 TM HET mice. Furthermore, acute CBD (100 mg/kg) selectively increased PPI in Nrg1 TM HET mice, although tolerance to this effect was manifest upon repeated CBD administration. Long-term CBD (50 mg/kg) also selectively increased GABAA receptor binding in the granular retrosplenial cortex in Nrg1 TM HET mice and reduced 5-HT2A binding in the substantia nigra in WT mice. Nrg1 appears necessary for CBD-induced anxiolysis since only WT mice developed decreased anxiety-related behaviour with repeated CBD treatment. Altered pharmacokinetics in mutant mice could not explain our findings since no genotype differences existed in CBD blood concentrations. Here we demonstrate that Nrg1 modulates acute and long-term neurobehavioural effects of CBD, which does not reverse the schizophrenia-relevant phenotypes

Automated empirical optimizations of software and the ATLAS project

This paper describes the automatically tuned linear algebra software (ATLAS) project, as well as the fundamental principles that underly it. ATLAS is an instantiation of a new paradigm in high performance library production and maintenance, which we term automated empirical optimization of software (AEOS); this style of library management has been created in order to allow software to keep pace with the incredible rate of hardware advancement inherent in Moore's Law. ATLAS is the application of this new paradigm to linear algebra software, with the present emphasis on the basic linear algebra subprograms (BLAS), a widely used, performance-critical

More on Scheduling Block-Cyclic Array Redistribution

This article is devoted to the run-time redistribution of one-dimensional arrays that are distributed in a block-cyclic fashion over a processor grid. In a previous paper, we have reported how to derive optimal schedules made up of successive communication-steps. In this paper we assume that successive steps may overlap. We show how to obtain an optimal scheduling for the most general case, namely, moving from a CYCLIC(r) distribution on a P-processor grid to a CYCLIC(s) distribution on a Q-processor grid, for arbitrary values of the redistribution parameters P , Q, r, and s. We use graph-theoretic algorithms, and modular algebra techniques to derive these optimal schedulings

Scheduling Block-Cyclic Array Redistribution

This article is devoted to the run-time redistribution of arrays that are distributed in a blockcyclic fashion over a multidimensional processor grid. While previous studies have concentrated on efficiently generating the communication messages to be exchanged by the processors involved in the redistribution, we focus on the scheduling of those messages: how to organize the message exchanges into "structured" communication steps that minimize contention. We build upon results of Walker and Otto, who solved a particular instance of the problem, and we derive an optimal scheduling for the most general case, namely, moving from a CYCLIC(r) distribution on a P -processor grid to a CYCLIC(s) distribution on a Q-processor grid, for arbitrary values of the redistribution parameters P , Q, r, and s. Key-words: distributed arrays, redistribution, block-cyclic distribution, scheduling, MPI, HPF. This work was supported in part by the National Science Foundation Grant No. ASC-9005933; by the De..

Scheduling block-cyclic array redistribution

This article is devoted to the run-time redistribution of arrays that are distributed in a blockcyclic fashion over a multidimensional processor grid. While previous studies have concentrated on e ciently generating the communication messages to be exchanged by the processors involved in the redistribution, we focus on the scheduling of those messages: how to organize the message exchanges into \structured " communication steps that minimize contention. We build upon results of Walker and Otto, who solved a particular instance of the problem, and we derive an optimal scheduling for the most general case, namely, moving from a CYCLIC(r) distribution on a P-processor grid to a CYCLIC(s) distribution on a Q-processor grid, for arbitrary values of the redistribution parameters P, Q, r, and s