763 research outputs found

    Two-divisibility of the coefficients of certain weakly holomorphic modular forms

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    We study a canonical basis for spaces of weakly holomorphic modular forms of weights 12, 16, 18, 20, 22, and 26 on the full modular group. We prove a relation between the Fourier coefficients of modular forms in this canonical basis and a generalized Ramanujan tau-function, and use this to prove that these Fourier coefficients are often highly divisible by 2.Comment: Corrected typos. To appear in the Ramanujan Journa

    Factor copula models for item response data

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    Factor or conditional independence models based on copulas are proposed for multivariate discrete data such as item responses. The factor copula models have interpretations of latent maxima/minima (in comparison with latent means) and can lead to more probability in the joint upper or lower tail compared with factor models based on the discretized multivariate normal distribution (or multidimensional normal ogive model). Details on maximum likelihood estimation of parameters for the factor copula model are given, as well as analysis of the behavior of the log-likelihood. Our general methodology is illustrated with several item response data sets, and it is shown that there is a substantial improvement on existing models both conceptually and in fit to data

    An investigation into the age and origin of Suranga in the foothills of the Western Ghats of India

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    This document is the Accepted Manuscript version. The final publication is available at Springer via: https://doi.org/10.1007/s12685-015-0125-yThis paper presents the evidence for determining the age and origin of suranga irrigation found mainly in southern Karnataka and northern Kerala in the foothills of the Western Ghats of south India. It draws on on-going research that has attempted to use an interdisciplinary approach to date the system using Indian Archives, British and Portuguese colonial archives, etymology, oral testimony archaeology, phenology and palaeo dating techniques. The results from this study put the origins of the system at around 1900–1940 CE. These results are compared with the current academic discourse that supports the view that the system originates from ancient Persia and qanat technology, because of the long established trade links with Persia and the Arabian Peninsula in the Malabar region. We argue that a new ‘origin discourse’ should be framed around these much more recent dates. The methodological constraints behind both theories are discussed throughout to enable the reader to appreciate the limitations of both arguments.Peer reviewedFinal Accepted Versio

    A European aerosol phenomenology-4 : Harmonized concentrations of carbonaceous aerosol at 10 regional background sites across Europe

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    Although particulate organic and elemental carbon (OC and EC) are important constituents of the suspended atmospheric particulate matter (PM), measurements of OC and EC are much less common and More uncertain than measurements of e.g. the ionic components of PM. In the framework of atmospheric research infrastructures supported by the European Union, actions have been undertaken to determine and mitigate sampling artefacts, and assess the comparability of OC and EC data obtained in a network of 10 atmospheric observatories across Europe. Positive sampling artefacts (from 0:4 to 2.8 mu g C/m(3)) and analytical discrepancies (between -50% and +40% for the EC/TC ratio) have been taken into account to generate a robust data set, from which we established the phenomenology of carbonaceous aerosols at regional background sites in Europe. Across the network, TC and EC annual average concentrations range from 0.4 to 9 mu g C/m(3), and from 0.1 to 2 mu g C/m(3), respectively. TC/PM10 annual mean ratios range from 0.11 at a Mediterranean site to 0.34 at the most polluted continental site, and TC/PM2.5 ratios are slightly greater at all sites (0.15-0.42). EC/TC annual mean ratios range from 0.10 to 0.22, and do not depend much on PM concentration levels, especially in winter. Seasonal variations in PM and TC concentrations, and in TC/PM and EC/TC ratios, differ across the network, which can be explained by seasonal changes in PM source contributions at some sites. (C) 2016 The Authors. Published by Elsevier Ltd.Peer reviewe

    Spy, track and archive: The temporality of visibility in Eurosur and Jora

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    This article focuses on the temporalities of visibility that are at stake in the functioning of two mapping monitoring softwares devised by Frontex: Eurosur and Jora. Through a study of border practices and security devices that builds on interviews and direct observation, the article shows that while these two systems elaborate on data and information collected in real time, they work as archives for generating future migration risk scenarios and not for border surveillance purposes. After illustrating in detail the functioning and modes of visualization of Jora and Eurosur, the article takes into account how police officers, Frontex and navies use these devices, and how risk analyses are produced. The article demonstrates that these monitoring mapping devices are sustained by coeval temporalities: the detection of migrants ‘on the spot’ coexists with both a future-oriented temporality and an archival one. The second part of the article analyses the impact that mapping monitoring softwares have on migrant journeys and migrant lives. The article concludes by bringing attention to the ways in which migrants in part strategically appropriate and twist the temporality of security and the field of visibility enacted by these devices

    The Heartbleed bug : insecurity repackaged, rebranded and resold

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    The emergence of a post-industrial information economy shaped by and around networked communication technology has presented new opportunities for identity theft. In particular, the accidental leakage or deliberate harvesting of information, via either hacking or social engineering, is an omnipresent threat to a large number of commercial organisations and state agencies who manage digital databases and sociotechnical forms of data. Throughout the twenty-first century the global media have reported on a series of data breaches fuelling amongst the public an anxiety concerning the safety and security of their personal and financial data. With concern outpacing reliable information a reassurance gap has emerged between the public's expectations and the state's ability to provide safety and security online. This disparity presents a significant opportunity for a commercial computer crime control industry who has sought to position itself as being able to offer consumer citizens the antidotes for such ills. This paper considers how neoliberal discourses of cybercrime control are packaged, branded and sold, through an examination of the social construction of the Heartbleed bug. It demonstrates how security company Codenomicon masterfully communicated the vulnerability, the product of a simple coding error, through its name, a logo and an accompanying website, in turn, shaping news coverage across the mainstream media and beyond

    Quadrupole-deformed and octupole collective bands in 228^{228}Ra

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    Spins and parities for collective states in 228^{228}Ra have been determined from conversion electron measurements with a mini-orange β\beta-spectrometer. The fast-timing βγγ(t)\beta\gamma\gamma(t) method has been used to measure lifetimes of T1/2_{1/2}=550(20) ps and 181(3) ps for the 21+2^{+}_{1} and 41+4^{+}_{1} members of the K=0+^{+} band, and T1/2⩽_{1/2} \leqslant 7 ps and ⩽\leqslant 6 ps for the 11−1^{-}_{1} and 31−3^{-}_1 members of the K = 0−0^{-} band, respectively The quadrupole moments, Q0Q_{0} deduced from the B (E2; 21+→01+_{1}^{+} \rightarrow 0_{1}^{+}) and B (E2; 41+→21+_{1}^{+} \rightarrow 2_1^{+}) rates are in good agreement with the previously measured value and the systematics of the region. However, the B(E1) rates of ⩾\geqslant 4 × 10−4^{−4} e2^{2}fm2^{2}, which represent the first B(E1) measurements for this nucleus, are at least 25 times larger than the value previously suggested for 228^{228}Ra. The new results are consistent with the B(E1) rates recently measured for the neighbouring 227^{227}Ra and reveal octupole correlations in 228^{228}Ra
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