582 research outputs found

    Notes on Conformal Invisibility Devices

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    As a consequence of the wave nature of light, invisibility devices based on isotropic media cannot be perfect. The principal distortions of invisibility are due to reflections and time delays. Reflections can be made exponentially small for devices that are large in comparison with the wavelength of light. Time delays are unavoidable and will result in wave-front dislocations. This paper considers invisibility devices based on optical conformal mapping. The paper shows that the time delays do not depend on the directions and impact parameters of incident light rays, although the refractive-index profile of any conformal invisibility device is necessarily asymmetric. The distortions of images are thus uniform, which reduces the risk of detection. The paper also shows how the ideas of invisibility devices are connected to the transmutation of force, the stereographic projection and Escheresque tilings of the plane

    \u3cem\u3eDENND5B\u3c/em\u3e Regulates Intestinal Triglyceride Absorption and Body Mass

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    Regulation of lipid absorption by enterocytes can influence metabolic status in humans and contribute to obesity and related complications. The intracellular steps of chylomicron biogenesis and transport from the Endoplasmic Reticulum (ER) to the Golgi complex have been described, but the mechanisms for post-Golgi transport and secretion of chylomicrons have not been identified. Using a newly generated Dennd5b−/− mouse, we demonstrate an essential role for this gene in Golgi to plasma membrane transport of chylomicron secretory vesicles. In mice, loss of Dennd5b results in resistance to western diet induced obesity, changes in plasma lipids, and reduced aortic atherosclerosis. In humans, two independent exome sequencing studies reveal that a common DENND5B variant, p.(R52K), is correlated with body mass index. These studies establish an important role for DENND5B in post-Golgi chylomicron secretion and a subsequent influence on body composition and peripheral lipoprotein metabolism

    Evidence and Ideology in Macroeconomics: The Case of Investment Cycles

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    The paper reports the principal findings of a long term research project on the description and explanation of business cycles. The research strongly confirmed the older view that business cycles have large systematic components that take the form of investment cycles. These quasi-periodic movements can be represented as low order, stochastic, dynamic processes with complex eigenvalues. Specifically, there is a fixed investment cycle of about 8 years and an inventory cycle of about 4 years. Maximum entropy spectral analysis was employed for the description of the cycles and continuous time econometrics for the explanatory models. The central explanatory mechanism is the second order accelerator, which incorporates adjustment costs both in relation to the capital stock and the rate of investment. By means of parametric resonance it was possible to show, both theoretically and empirically how cycles aggregate from the micro to the macro level. The same mathematical tool was also used to explain the international convergence of cycles. I argue that the theory of investment cycles was abandoned for ideological, not for evidential reasons. Methodological issues are also discussed

    General Relativity in Electrical Engineering

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    In electrical engineering metamaterials have been developed that offer unprecedented control over electromagnetic fields. Here we show that general relativity lends the theoretical tools for designing devices made of such versatile materials. Given a desired device function, the theory describes the electromagnetic properties that turn this function into fact. We consider media that facilitate space-time transformations and include negative refraction. Our theory unifies the concepts operating behind the scenes of perfect invisibility devices, perfect lenses, the optical Aharonov-Bohm effect and electromagnetic analogs of the event horizon, and may lead to further applications

    Shifting markers of identity in East London's diasporic religious spaces

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    This article discusses the historical and geographical contexts of diasporic religious buildings in East London, revealing – contrary both to conventional narratives of immigrant integration, mobility, and succession and to identitarian understandings of belonging – that in such spaces and in the concrete devotional practices enacted in them, markers and boundaries of identity (ritual, spatial, and political) are contested, renegotiated, erased, and rewritten. It draws on a series of case-studies: Fieldgate Street Synagogue in its interrelationship with the East London Mosque; St Antony's Catholic Church in Forest Gate where Hindus and Christians worship together; and the intertwined histories of Methodism and Anglicanism in Bow Road. Exploration of the intersections between ethnicity, religiosity, and class illuminates the ambiguity and instability of identity-formation and expression within East London's diasporic faith spaces

    "'Asianness Under Construction:' The Contours and Negotiation of Panethnic Identity/Culture among Interethnically Married Asian Americans."

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    Based on life-history interviews of interethnically married U.S.-raised Asians, this article examines the meaning and dynamics of Asian American interethnic marriages, and what they reveal about the complex incorporative process of this “in-between” racial minority group into the U.S.. In particular, this article explores the connection between Asian American interethnic marriage and pan-Asian consciousness/identity, both in terms of how panethnicity shapes romantic/ marital desires of individuals and how pan-Asian culture and identity is invented and negotiated in the process of family-making. My findings indicate that while strong pan-Asian consciousness/ identity underlies the connection among intermarried couples, these unions are not simply a defensive effort to “preserve” Asian-ethnic identity and cultur against a society that still racializes Asian Americans, but a tentative and often unpremeditated effort to navigate a path toward integration into the society through an ethnically based, albeit hybrid and reconstructed identity and culture, that helps the respondents retain the integrity of “Asianness.
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