36,422 research outputs found

    Passion and Conflict: Medieval Islamic Views of the West

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    This article analyzes the representation of al-Andalus and North Africa in medieval Islamic maps from the eleventh to the fifteenth centuries. In contrast to other maps of the Mediterranean, which display a veneer of harmony and balance, the image of the Maghrib is by deliberate design one of conflict and confusion; of love and hate; of male vs. female; of desire vs rejection. This paper interprets and explains the reasons behind the unusual depiction of Andalus and the Maghrib by medieval Islamic cartographers. In addition, this article develops a new methodology of interpreting medieval Islamic maps employing a deconstruction of the forms through an analysis of different levels of gaze. The analysis unfolds into the use of erotic and nostalgic Hispano-Arabic poetry as a lens of interpretation for Islamic maps

    Searchin’ His Eyes, Lookin’ for Traces: Piri Reis’ World Map of 1513 & its Islamic Iconographic Connections (A Reading Through Bagdat 334 and Proust)

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    The remnant of the 1513 world map of the Ottoman corsair (and later admiral) Muhiddin Piri, a.k.a. Piri Reis, with its focus on the Atlantic and the New World can be ranked as one of the most famous and controversial maps in the annals of the history of cartography. Following its discovery at Topkapi Palace in 1929, this early modern Ottoman map has raised baffling questions regarding its fons et origo. Some scholars posited ancient sea kings or aliens from outer space as the original creators; while the influence of Columbus’ own map and early Renaissance cartographers tantalized others. One question that remains unanswered is how Islamic cartography influenced Piri Reis’ work. This paper presents hitherto unnoticed iconographical connections between the classical Islamic mapping tradition and the Piri Reis map

    The Phase Structure of the Weakly Coupled Lattice Schwinger Model

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    The weak coupling expansion is applied to the single flavour Schwinger model with Wilson fermions on a symmetric toroidal lattice of finite extent. We develop a new analytic method which permits the expression of the partition function as a product of pure gauge expectation values whose zeroes are the Lee-Yang zeroes of the model. Application of standard finite-size scaling techniques to these zeroes recovers previous numerical results for the small and moderate lattice sizes to which those studies were restricted. Our techniques, employable for arbitrarily large lattices, reveal the absence of accumulation of these zeroes on the real hopping parameter axis at constant weak gauge coupling. The consequence of this previously unobserved behaviour is the absence of a zero fermion mass phase transition in the Schwinger model with single flavour Wilson fermions at constant weak gauge coupling.Comment: 8 pages, 2 figures, insert to figure 2 include

    The Structure of the Aoki Phase at Weak Coupling

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    A new method to determine the phase diagram of certain lattice fermionic field theories in the weakly coupled regime is presented. This method involves a new type of weak coupling expansion which is multiplicative rather than additive in nature and allows perturbative calculation of partition function zeroes. Application of the method to the single flavour Gross-Neveu model gives a phase diagram consistent with the parity symmetry breaking scenario of Aoki and provides new quantitative information on the width of the Aoki phase in the weakly coupled sector.Comment: 9 pages, 1 figure (minor changes) To be published in Phys. Lett.

    Percolation and Connectivity in the Intrinsically Secure Communications Graph

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    The ability to exchange secret information is critical to many commercial, governmental, and military networks. The intrinsically secure communications graph (iS-graph) is a random graph which describes the connections that can be securely established over a large-scale network, by exploiting the physical properties of the wireless medium. This paper aims to characterize the global properties of the iS-graph in terms of: (i) percolation on the infinite plane, and (ii) full connectivity on a finite region. First, for the Poisson iS-graph defined on the infinite plane, the existence of a phase transition is proven, whereby an unbounded component of connected nodes suddenly arises as the density of legitimate nodes is increased. This shows that long-range secure communication is still possible in the presence of eavesdroppers. Second, full connectivity on a finite region of the Poisson iS-graph is considered. The exact asymptotic behavior of full connectivity in the limit of a large density of legitimate nodes is characterized. Then, simple, explicit expressions are derived in order to closely approximate the probability of full connectivity for a finite density of legitimate nodes. The results help clarify how the presence of eavesdroppers can compromise long-range secure communication.Comment: Submitted for journal publicatio

    Continuum Percolation in the Intrinsically Secure Communications Graph

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    The intrinsically secure communications graph (iS-graph) is a random graph which captures the connections that can be securely established over a large-scale network, in the presence of eavesdroppers. It is based on principles of information-theoretic security, widely accepted as the strictest notion of security. In this paper, we are interested in characterizing the global properties of the iS-graph in terms of percolation on the infinite plane. We prove the existence of a phase transition in the Poisson iS-graph, whereby an unbounded component of securely connected nodes suddenly arises as we increase the density of legitimate nodes. Our work shows that long-range communication in a wireless network is still possible when a secrecy constraint is present.Comment: Accepted in the IEEE International Symposium on Information Theory and its Applications (ISITA'10), Taichung, Taiwan, Oct. 201

    ISM composition through X-ray spectroscopy of LMXBs

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    The diffuse interstellar medium (ISM) is an integral part of the evolution of the entire Galaxy. Metals are produced by stars and their abundances are the direct testimony of the history of stellar evolution. However, the interstellar dust composition is not well known and the total abundances are yet to be accurately determined. We probe ISM dust composition, total abundances, and abundance gradients through the study of interstellar absorption features in the high-resolution X-ray spectra of Galactic low-mass X-ray binaries (LMXBs). We use high-quality grating spectra of nine LMXBs taken with XMM-Newton. We measure the column densities of O, Ne, Mg, and Fe with an empirical model and estimate the Galactic abundance gradients. The column densities of the neutral gas species are in agreement with those found in the literature. Solids are a significant reservoir of metals like oxygen and iron. Respectively, 15-25 % and 65-90 % of the total amount of O I and Fe I is found in dust. The dust amount and mixture seem to be consistent along all the lines-of-sight (LOS). Our estimates of abundance gradients and predictions of local interstellar abundances are in agreement with those measured at longer wavelengths. Our work shows that X-ray spectroscopy is a very powerful method to probe the ISM. For instance, on a large scale the ISM appears to be chemically homogeneous showing similar gas ionization ratios and dust mixtures. The agreement between the abundances of the ISM and the stellar objects suggests that the local Galaxy is also chemically homogeneous.Comment: 13 pages, 10 figures, 5 tables, accepted to A&

    Stopping Sexual Harassment in the Empire State: Past, Present, and a Possible Future

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    This report maps current patterns of workplace sexual harassment and their impact in New York State. It also provides a broader frame for understanding how efforts to confront sexual and gender-based harassment and assault have evolved over time, and charts possible directions for future organizing, policy, and research in New York and beyond. The findings presented here are drawn from the 2018 Empire State Poll, an annual statewide survey of 800 New Yorkers conducted by the Cornell Survey Research Institute. Questions added to the survey reflecting existing legal definitions of workplace sexual harassment reveal the following: 10.9 percent of New York residents have experienced quid pro quo workplace sexual harassment, and 21.9 percent have experienced workplace sexual harassment that created a hostile work environment; 31.1 percent of women and 18.9 percent of men have experienced at least one of these forms of harassment. 13.9 percent of people of color and people of Hispanic origin have experienced quid pro quo workplace sexual harassment, as opposed to 8.5 percent of non-Hispanic whites. 38.9 percent of those experiencing at least one form of workplace sexual harassment say it impacted their work or careers; 48.9 percent who experienced quid pro quo harassment reported such an impact. 83.4 percent of New York residents think their leaders should do more to address workplace sexual harassment. There is notable variation by politics and ideology, but regardless of worldview, strong majorities think leaders should do more. In addition to sharing the survey findings, the report discusses experiences and responses of survivors and how they are shaped by different identities and relations of power. It highlights black women’s leadership in propelling wide-reaching shifts in law and culture; efforts initiated by diverse survivors to effect change in specific industries; and culture change work engaging men and women as allies
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