Using gamma regression for photometric redshifts of survey galaxies

Machine learning techniques offer a plethora of opportunities in tackling big data within the astronomical community. We present the set of Generalized Linear Models as a fast alternative for determining photometric redshifts of galaxies, a set of tools not commonly applied within astronomy, despite being widely used in other professions. With this technique, we achieve catastrophic outlier rates of the order of ~1%, that can be achieved in a matter of seconds on large datasets of size ~1,000,000. To make these techniques easily accessible to the astronomical community, we developed a set of libraries and tools that are publicly available.Comment: Refereed Proceeding of "The Universe of Digital Sky Surveys" conference held at the INAF - Observatory of Capodimonte, Naples, on 25th-28th November 2014, to be published in the Astrophysics and Space Science Proceedings, edited by Longo, Napolitano, Marconi, Paolillo, Iodice, 6 pages, and 1 figur

Detectability of the First Cosmic Explosions

We present a fully self-consistent simulation of a synthetic survey of the furthermost cosmic explosions. The appearance of the first generation of stars (Population III) in the Universe represents a critical point during cosmic evolution, signaling the end of the dark ages, a period of absence of light sources. Despite their importance, there is no confirmed detection of Population III stars so far. A fraction of these primordial stars are expected to die as pair-instability supernovae (PISNe), and should be bright enough to be observed up to a few hundred million years after the big bang. While the quest for Population III stars continues, detailed theoretical models and computer simulations serve as a testbed for their observability. With the upcoming near-infrared missions, estimates of the feasibility of detecting PISNe are not only timely but imperative. To address this problem, we combine state-of-the-art cosmological and radiative simulations into a complete and self-consistent framework, which includes detailed features of the observational process. We show that a dedicated observational strategy using $\lesssim 8$ per cent of total allocation time of the James Webb Space Telescope mission can provide us up to $\sim 9-15$ detectable PISNe per year.Comment: 9 pages, 8 figures. Minor corrections added to match published versio

Gender, the body and organization studies: que(e)rying empirical research

Even in organization studies scholarship that treats gender as performative and fluid, a certain ‘crystallization’ of gender identities as somehow unproblematic and stable may occur because of our methodological decision-making, and especially our categorization of participants. Mobilizing queer theory — and Judith Butler's work on the heterosexual matrix and performativity in particular — as a conceptual lens, we examine this crystallization, suggesting it is based on two implicit assumptions: that gender is a cultural mark over a passive biological body, or is a base identity ‘layered over’ by other identities (class, race, age etc.). Following Butler, we argue that in order to foreground the fluidity and uncertainty of gender categories in our scholarship, it is necessary to understand gender identity as a process of doing and undoing gender that is located very precisely in time and space. Given this perspective on gender identities as complex processes of identification, non-identification and performativity, we offer some pointers on how the methodological decision-making underpinning empirical research on gender, work and organization could and should begin from this premise

Evidence for a Very Large-Scale Fractal Structure in the Universe from Cobe Measurements

In this work, we analyse the temperature fluctuations of the cosmic microwave background radiation observed by COBE and show that the distribution can be fitted by a fractal distribution with a fractal dimension $D= 1.43 \pm 0.07$. This value is in close agreement with the fractal dimension obtained by Coleman and Pietronero (1992) and Luo and Schramm (1992) from galaxy-galaxy and cluster-cluster correlations up to $\sim 100 h^{-1} Mpc$. The fact that the observed temperature fluctuations correspond to scales much larger than $100 h^{-1} Mpc$ and are signatures of the primordial density fluctuations at the recombination layer suggests that the structure of the matter at the early universe was already fractal and thus non-homogeneous on those scales. This result may have important consequences for the theoretical framework that describes the universe.Comment: 11 pages, postscript file, 2 figures available upon request. To appear in ApJ Letter

Queering queer theory in management and organization studies: notes toward queering heterosexuality

This article suggests new possibilities for queer theory in management and organization studies (MOS). MOS has tended to use queer theory as a conceptual resource for studying the workplace experience of ‘minorities’ such as gay men, lesbians and those identifying as bisexual or transgender (LGBT), often focusing on how heteronormativity shapes the discursive constitution of sexualities and genders coded as LGBT. But this deployment is crucial and apposite but it can limit the analytical reach of queer theory, ignoring other objects of analysis such as heterosexuality. Potentially, MOS queer theory scholarship could be vulnerable to criticism about ignoring queer theory as a productive site for acknowledging heterosexuality’s coercive aspects but also its non-normative forms. As such, the principal contribution of this article is twofold. First, it proposes a queering of queer theory in MOS, whereby scholars are alert to and question the potential normativities that MOS queer theory research can produce, opening up a space for exploring how heterosexuality can be queered. Second, we show how queering heterosexuality can be another site where queer theory and politics can come together in the MOS field through a shared attempt to rupture sexual and gender binaries, and challenge normative social relations. This article concludes by outlining the political implications of queering heterosexuality for generating modes of organizing in which heterosexuality can be experienced as non-normative and how it might rupture and dismantle heteronormativity

A Flexible Implementation of a Matrix Laurent Series-Based 16-Point Fast Fourier and Hartley Transforms

This paper describes a flexible architecture for implementing a new fast computation of the discrete Fourier and Hartley transforms, which is based on a matrix Laurent series. The device calculates the transforms based on a single bit selection operator. The hardware structure and synthesis are presented, which handled a 16-point fast transform in 65 nsec, with a Xilinx SPARTAN 3E device.Comment: 4 pages, 4 figures. IEEE VI Southern Programmable Logic Conference 201