2,107 research outputs found

    Three-dimensional scanless holographic optogenetics with temporal focusing (3D-SHOT).

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    Optical methods capable of manipulating neural activity with cellular resolution and millisecond precision in three dimensions will accelerate the pace of neuroscience research. Existing approaches for targeting individual neurons, however, fall short of these requirements. Here we present a new multiphoton photo-excitation method, termed three-dimensional scanless holographic optogenetics with temporal focusing (3D-SHOT), which allows precise, simultaneous photo-activation of arbitrary sets of neurons anywhere within the addressable volume of a microscope. This technique uses point-cloud holography to place multiple copies of a temporally focused disc matching the dimensions of a neurons cell body. Experiments in cultured cells, brain slices, and in living mice demonstrate single-neuron spatial resolution even when optically targeting randomly distributed groups of neurons in 3D. This approach opens new avenues for mapping and manipulating neural circuits, allowing a real-time, cellular resolution interface to the brain

    Change-point model on nonhomogeneous Poisson processes with application in copy number profiling by next-generation DNA sequencing

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    We propose a flexible change-point model for inhomogeneous Poisson Processes, which arise naturally from next-generation DNA sequencing, and derive score and generalized likelihood statistics for shifts in intensity functions. We construct a modified Bayesian information criterion (mBIC) to guide model selection, and point-wise approximate Bayesian confidence intervals for assessing the confidence in the segmentation. The model is applied to DNA Copy Number profiling with sequencing data and evaluated on simulated spike-in and real data sets.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS517 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

    A backward procedure for change-point detection with applications to copy number variation detection

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    Change-point detection regains much attention recently for analyzing array or sequencing data for copy number variation (CNV) detection. In such applications, the true signals are typically very short and buried in the long data sequence, which makes it challenging to identify the variations efficiently and accurately. In this article, we propose a new change-point detection method, a backward procedure, which is not only fast and simple enough to exploit high-dimensional data but also performs very well for detecting short signals. Although motivated by CNV detection, the backward procedure is generally applicable to assorted change-point problems that arise in a variety of scientific applications. It is illustrated by both simulated and real CNV data that the backward detection has clear advantages over other competing methods especially when the true signal is short

    INTERPLANETARY DUST PARTICLES AS SAMPLES OF ICY ASTEROIDS

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    Meteorites have long been considered as reflections of the compositional diversity of main belt asteroids and consequently they have been used to decipher their origin, formation, and evolution. However, while some meteorites are known to sample the surfaces of metallic, rocky and hydrated asteroids (about one-third of the mass of the belt), the low-density icy asteroids (C-, P-, and D-types), representing the rest of the main belt, appear to be unsampled in our meteorite collections. Here we provide conclusive evidence that the surface compositions of these icy bodies are compatible with those of the most common extraterrestrial materials (by mass), namely anhydrous interplanetary dust particles (IDPs). Given that these particles are quite different from known meteorites, it follows that the composition of the asteroid belt consists largely of more friable material not well represented by the cohesive meteorites in our collections. In the light of our current understanding of the early dynamical evolution of the solar system, meteorites likely sample bodies formed in the inner region of the solar system (0.5–4 AU) whereas chondritic porous IDPs sample bodies that formed in the outer region (>5 AU)

    The relationship between budgetary expenditure and economic growth in Poland

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    Abstract This paper investigates the association between different kinds of budgetary expenditure and economic growth of Poland. The empirical analysis makes use of linear and nonlinear Granger causality tests to evaluate the applicability of Wagner’s Law and that of the contrasting Keynesian theory.We employ aggregate and disaggregate data with the sub-categories of most important budgetary expenditure, including health care and social security, education and science, national defence and public security expenditure and government administration expenditure for the period Q1 2000 to Q3 2008. This causality analysis indicates that total relation between budgetary expenditure and economic growth is consistent with Keynesian theory. The results of our computations have important policy implications. In case of Poland the health care expenditure was found to be as important for economic growth as expenditures on education and science. Furthermore, in order to stimulate economic growth, Polish government should consider reallocating some of national defence, public security and government administration expenditure to health care, social security, education and science expenditure.Government expenditure · Linear and nonlinear causality · Bootstrap techniques
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