Space-time estimation of a particle system model

13 pagesLet X be a discrete time contact process (CP) on the discrete bidimensional lattice as define by Durett - Levin (1994) . We study estimation of the model based on space-time evolution on a finite subset of sites. For this, we make use of a marginal pseudo-likelihood. The estimator obtained is consistent and asymptoticaly normal for non-vanishing supercritical CP. Numerical studies confirm these results

Adaptive optics in high-contrast imaging

The development of adaptive optics (AO) played a major role in modern astronomy over the last three decades. By compensating for the atmospheric turbulence, these systems enable to reach the diffraction limit on large telescopes. In this review, we will focus on high contrast applications of adaptive optics, namely, imaging the close vicinity of bright stellar objects and revealing regions otherwise hidden within the turbulent halo of the atmosphere to look for objects with a contrast ratio lower than 10^-4 with respect to the central star. Such high-contrast AO-corrected observations have led to fundamental results in our current understanding of planetary formation and evolution as well as stellar evolution. AO systems equipped three generations of instruments, from the first pioneering experiments in the nineties, to the first wave of instruments on 8m-class telescopes in the years 2000, and finally to the extreme AO systems that have recently started operations. Along with high-contrast techniques, AO enables to reveal the circumstellar environment: massive protoplanetary disks featuring spiral arms, gaps or other asymmetries hinting at on-going planet formation, young giant planets shining in thermal emission, or tenuous debris disks and micron-sized dust leftover from collisions in massive asteroid-belt analogs. After introducing the science case and technical requirements, we will review the architecture of standard and extreme AO systems, before presenting a few selected science highlights obtained with recent AO instruments.Comment: 24 pages, 14 figure

Is This a Joke? Detecting Humor in Spanish Tweets

While humor has been historically studied from a psychological, cognitive and linguistic standpoint, its study from a computational perspective is an area yet to be explored in Computational Linguistics. There exist some previous works, but a characterization of humor that allows its automatic recognition and generation is far from being specified. In this work we build a crowdsourced corpus of labeled tweets, annotated according to its humor value, letting the annotators subjectively decide which are humorous. A humor classifier for Spanish tweets is assembled based on supervised learning, reaching a precision of 84% and a recall of 69%.Comment: Preprint version, without referra

The Vector Vortex Coronagraph: Laboratory Results and First Light at Palomar Observatory

High-contrast coronagraphy will be needed to image and characterize faint extra-solar planetary systems. Coronagraphy is a rapidly evolving field, and many enhanced alternatives to the classical Lyot coronagraph have been proposed in the past ten years. Here, we discuss the operation of the vector vortex coronagraph, which is one of the most efficient possible coronagraphs. We first present recent laboratory results, and then first light observations at the Palomar observatory. Our near-infrared H-band (centered at ~ 1.65 microns) and K-band (centered at ~ 2.2 microns) vector vortex devices demonstrated excellent contrast results in the lab, down to ~ 1e-6 at an angular separation of 3 lb/d. On sky, we detected a brown dwarf companion 3000 times fainter than its host star (HR 7672) in the Ks band (centered at ~2.15 microns), at an angular separation of ~ 2.5 lb/d. Current and next-generation high-contrast instruments can directly benefit from the demonstrated capabilities of such a vector vortex: simplicity, small inner working angle, high optical throughput (>90%), and maximal off-axis discovery space

Digging into acceptor splice site prediction : an iterative feature selection approach

Feature selection techniques are often used to reduce data dimensionality, increase classification performance, and gain insight into the processes that generated the data. In this paper, we describe an iterative procedure of feature selection and feature construction steps, improving the classification of acceptor splice sites, an important subtask of gene prediction. We show that acceptor prediction can benefit from feature selection, and describe how feature selection techniques can be used to gain new insights in the classification of acceptor sites. This is illustrated by the identification of a new, biologically motivated feature: the AG-scanning feature. The results described in this paper contribute both to the domain of gene prediction, and to research in feature selection techniques, describing a new wrapper based feature weighting method that aids in knowledge discovery when dealing with complex datasets

A Comparison of U. S. and European University-Industry Relations in the Life Sciences

We draw on diverse data sets to compare the institutional organization of upstream life science research across the United States and Europe. Understanding cross-national differences in the organization of innovative labor in the life sciences requires attention to the structure and evolution of biomedical networks involving public research organizations (universities, government laboratories, nonprofit research institutes, and research hospitals), science-based biotechnology firms, and multinational pharmaceutical corporations. We use network visualization methods and correspondence analyses to demonstrate that innovative research in biomedicine has its origins in regional clusters in the United States and in European nations. But the scientific and organizational composition of these regions varies in consequential ways. In the United States, public research organizations and small firms conduct R&D across multiple therapeutic areas and stages of the development process. Ties within and across these regions link small firms and diverse public institutions, contributing to the development of a robust national network. In contrast, the European story is one of regional specialization with a less diverse group of public research organizations working in a smaller number of therapeutic areas. European institutes develop local connections to small firms working on similar scientific problems, while cross-national linkages of European regional clusters typically involve large pharmaceutical corporations. We show that the roles of large and small firms differ in the United States and Europe, arguing that the greater heterogeneity of the U. S. system is based on much closer integration of basic science and clinical development

Fast Fourier Optimization: Sparsity Matters

Many interesting and fundamentally practical optimization problems, ranging from optics, to signal processing, to radar and acoustics, involve constraints on the Fourier transform of a function. It is well-known that the {\em fast Fourier transform} (fft) is a recursive algorithm that can dramatically improve the efficiency for computing the discrete Fourier transform. However, because it is recursive, it is difficult to embed into a linear optimization problem. In this paper, we explain the main idea behind the fast Fourier transform and show how to adapt it in such a manner as to make it encodable as constraints in an optimization problem. We demonstrate a real-world problem from the field of high-contrast imaging. On this problem, dramatic improvements are translated to an ability to solve problems with a much finer grid of discretized points. As we shall show, in general, the "fast Fourier" version of the optimization constraints produces a larger but sparser constraint matrix and therefore one can think of the fast Fourier transform as a method of sparsifying the constraints in an optimization problem, which is usually a good thing.Comment: 16 pages, 8 figure

Speckle Control with a remapped-pupil PIAA-coronagraph

The PIAA is a now well demonstrated high contrast technique that uses an intermediate remapping of the pupil for high contrast coronagraphy (apodization), before restoring it to recover classical imaging capabilities. This paper presents the first demonstration of complete speckle control loop with one such PIAA coronagraph. We show the presence of a complete set of remapping optics (the so-called PIAA and matching inverse PIAA) is transparent to the wavefront control algorithm. Simple focal plane based wavefront control algorithms can thus be employed, without the need to model remapping effects. Using the Subaru Coronagraphic Extreme AO (SCExAO) instrument built for the Subaru Telescope, we show that a complete PIAA-coronagraph is compatible with a simple implementation of a speckle nulling technique, and demonstrate the benefit of the PIAA for high contrast imaging at small angular separation.Comment: 6 figures, submitted to PAS

Near Infrared Adaptive Optics Imaging of QSO Host Galaxies

We report near-infrared (primarily H-band) adaptive optics (AO) imaging with the Gemini-N and Subaru Telescopes, of a representative sample of 32 nearby (z<0.3) QSOs selected from the Palomar-Green (PG) Bright Quasar Survey (BQS), in order to investigate the properties of the host galaxies. 2D modeling and visual inspection of the images shows that ~36% of the hosts are ellipticals, \~39% contain a prominent disk component, and ~25% are of undetermined type. 30% show obvious signs of disturbance. The mean M_H(host) = -24.82 (2.1L_H*), with a range -23.5 to -26.5 (~0.63 to 10 L_H*). At <L_H*, all hosts have a dominant disk component, while at >2 L_H* most are ellipticals. "Disturbed" hosts are found at all M_H(host), while "strongly disturbed" hosts appear to favor the more luminous hosts. Hosts with prominent disks have less luminous QSOs, while the most luminous QSOs are almost exclusively in ellipticals or in mergers (which presumably shortly will be ellipticals). At z<0.13, where our sample is complete at B-band, we find no clear correlation between M_B(QSO) and M_H(host). However, at z>0.15, the more luminous QSOs (M_B<-24.7), and 4/5 of the radio-loud QSOs, have the most luminous H-band hosts (>7L_H*), most of which are ellipticals. Finally, we find a strong correlation between the "infrared-excess", L_IR/L_BB, of QSOs with host type and degree of disturbance. Disturbed and strongly disturbed hosts and hosts with dominant disks have L_IR/L_BB twice that of non-disturbed and elliptical hosts, respectively. QSOs with "disturbed" and "strongly-disturbed" hosts are also found to have morphologies and mid/far-infrared colors that are similar to what is found for "warm" ultraluminous infrared galaxies, providing further evidence for a possible evolutionary connection between both classes of objects.Comment: 80 pages, accepted for publication in ApJ Supp