Alireza S. Mahani

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Visual context shapes human perception, yet our understanding of this phenomenon in terms of synaptic circuitry is still rudimentary. Our in vitro experiments with avian tectum reveal two distinct GABAergic pathways that mediate the spatiotemporal tectal interaction of retinal inputs. One pathway mediates postsynaptic lateral inhibition. The other pathway(More)
Motion repulsion is the perceived enlargement of the angle between the directions of motion of two transparently moving patterns. An explanation of this illusion has long been sought for in the neural circuitry of the brain. We show that motion repulsion already arises from the statistical properties of the motion transparency problem when analyzed with a(More)
The avian retino-tecto-rotundal pathway plays a central role in motion analysis and features complex connectivity. Yet, the relation between the pathway’s structural arrangement and motion computation has remained elusive. For an important type of tectal wide-field neuron, the stratum griseum centrale type I (SGC-I) neuron, we quantified its structure and(More)
If noise is uncorrelated during repeated measurements of the same physical variable, averaging these measurements improves the accuracy of estimating the variable. When two values of a variable are measured separately, the smallest separation of these two values that can be discriminated with a certain reliability (resolution) is inversely proportional to(More)
BACKGROUND There are several options available for aortic valve replacement (AVR), with few comparative reports in the literature. The optimal choice for AVR in each age group is not clear. OBJECTIVES The study sought to report and compare outcomes after AVR in the young using data from a national database. METHODS AVR procedures were compared after(More)
In a typical visual scene, one or more objects move relative to a larger background, which can itself be in motion as a result of the observer’s eyes moving with respect to the outside world. Here we show that accurate estimation of the background motion from an image velocity field can be accomplished through an iterative cooperation between two modules:(More)
OBJECTIVES The systemic-to-pulmonary shunt (SPS) remains an important palliative therapy in many congenital heart defects. Unlike other surgical treatments, the mortality after shunt operations has risen. We used an audit dataset to investigate potential reasons for this change and to report national results. METHODS A total of 1993 patients classified in(More)
We present a single-chain parallelization strategy for Gibbs sampling of probabilistic Directed Acyclic Graphs, where contributions from child nodes to the conditional posterior distribution of a given node are calculated concurrently. For statistical models with many independent observations, such parallelism takes a Single-Instruction-Multiple-Data form,(More)
We present the R package mnlogit for estimating multinomial logistic regression models, particularly those involving a large number of categories and variables. Compared to existing software, mnlogit offers speedups of 10–50 times for modestly sized problems and more than 100 times for larger problems. Running in parallel mode on a multicore machine gives(More)
Despite the fact that ensemble meta-learning of a heterogeneous collection of base learners is an effective means to reduce the generalization error in predictive models, several factors have impeded a broad adoption of such techniques among practitioners. These factors include an intractable number of choices of base learners and their tuning parameters,(More)