3,113 research outputs found

    Shut It Down, Open It Up : A History of the New Left at the University Of Virginia, Charlottesville

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    This thesis is a history of social and political activism in Charlottesville during the 1960s focusing on new left student organizing at the University of Virginia. It is a work of social history that establishes a community that has been generally ignored in traditional histories of the new left as one of the most influential centers of new left activism in the South and asserts that this prominence was due to years of activism by local liberals, civil rights advocates, and students during the city\u27s unique experiences on the front lines of the southern desegregation, civil rights, and anti-war struggles. It traces the evolution of social activism in the city and the university from the late 1950s through the early 1970s and demonstrates how local activists and issues interacted with regional, national, and global events during one of the most socially tumultuous decades in American history

    The King of Rockingham County and the Original Bridge to Nowhere

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    This chapter, reveals the story -- the clash of personalities, the economic tensions, and the political significance -- behind Rockingham County v. Luten Bridge Co. Since its publication in 1929, the opinion has proceeded to leave an impression on generations of law students. Luten Bridge, a staple in most contracts casebooks, is known today as the paradigmatic case that demonstrates the duty to mitigate damages in contract law, whereby a nonbreaching party is not compensated for performance that occurs after the other party announces an intention to breach. This chapter takes on three objectives: it identifies the case\u27s original importance, uncovers the opinion\u27s political and jurisprudential significance, and tells a remarkable story, one that arose within a heated tax revolt pitting the county\u27s farmers against its most celebrated industrialist. Much more than a crisp illustration of the duty to mitigate, Rockingham County v. The Luten Bridge Co. offers a window into a southern community\u27s struggles with a divided social order, the introduction of wealth into local politics, and a changing economy

    Association of molecules using a resonantly modulated magnetic field

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    We study the process of associating molecules from atomic gases using a magnetic field modulation that is resonant with the molecular binding energy. We show that maximal conversion is obtained by optimising the amplitude and frequency of the modulation for the particular temperature and density of the gas. For small modulation amplitudes, resonant coupling of an unbound atom pair to a molecule occurs at a modulation frequency corresponding to the sum of the molecular binding energy and the relative kinetic energy of the atom pair. An atom pair with an off-resonant energy has a probability of association which oscillates with a frequency and time-varying amplitude which are primarily dependent on its detuning. Increasing the amplitude of the modulation tends to result in less energetic atom pairs being resonantly coupled to the molecular state, and also alters the dynamics of the transfer from continuum states with off-resonant energies. This leads to maxima and minima in the total conversion from the gas as a function of the modulation amplitude. Increasing the temperature of the gas leads to an increase in the modulation frequency providing the best fit to the thermal distribution, and weakens the resonant frequency dependence of the conversion. Mean-field effects can alter the optimal modulation frequency and lead to the excitation of higher modes. Our simulations predict that resonant association can be effective for binding energies of order h×1h \times 1 MHz.Comment: 8 pages latex, figures revised, references updated and typos correcte

    Classification of zero-energy resonances by dissociation of Feshbach molecules

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    We study the dissociation of Feshbach molecules by a magnetic field sweep across a zero-energy resonance. In the limit of an instantaneous magnetic field change, the distribution of atomic kinetic energy can have a peak indicating dominance of the molecular closed-channel spin configuration over the entrance channel. The extent of this dominance influences physical properties such as stability with respect to collisions, and so the readily measurable presence or absence of the corresponding peak provides a practical method of classifying zero-energy resonances. Currently achievable ramp speeds, e.g. those demonstrated by Duerr et al. [Phys. Rev. A 70, 031601 (2005)], are fast enough to provide magnetic field changes that may be interpreted as instantaneous. We study the transition from sudden magnetic field changes to asymptotically wide, linear ramps. In the latter limit, the predicted form of the atomic kinetic energy distribution is independent of the specific implementation of the two-body physics, provided that the near-resonant scattering properties are properly accounted for.Comment: 10 pages, 5 eps figure

    Radio-frequency dressing of multiple Feshbach resonances

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    We demonstrate and theoretically analyze the dressing of several proximate Feshbach resonances in Rb-87 using radio-frequency (rf) radiation. We present accurate measurements and characterizations of the resonances, and the dramatic changes in scattering properties that can arise through the rf dressing. Our scattering theory analysis yields quantitative agreement with the experimental data. We also present a simple interpretation of our results in terms of rf-coupled bound states interacting with the collision threshold.Comment: 4+ pages, 3 figures, 1 table; revised introduction & references to reflect published versio

    Mutations in human dynamin block an intermediate stage in coated vesicle formation

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    The role of human dynamin in receptor-mediated endocytosis was investigated by transient expression of GTP-binding domain mutants in mammalian cells. Using assays which detect intermediates in coated vesicle formation, the dynamin mutants were found to block endocytosis at a stage after the initiation of coat assembly and preceding the sequestration of ligands into deeply invaginated coated pits. Membrane transport from the ER to the Golgi complex was unaffected indicating that dynamin mutants specifically block early events in endocytosis. These results demonstrate that mutations in the GTP-binding domain of dynamin block Tfn-endocytosis in mammalian cells and suggest that a functional dynamin GTPase is required for receptor-mediated endocytosis via clathrin-coated pits

    Creation and manipulation of Feshbach resonances with radio-frequency radiation

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    We present a simple technique for studying collisions of ultracold atoms in the presence of a magnetic field and radio-frequency radiation (rf). Resonant control of scattering properties can be achieved by using rf to couple a colliding pair of atoms to a bound state. We show, using the example of 6Li, that in some ranges of rf frequency and magnetic field this can be done without giving rise to losses. We also show that halo molecules of large spatial extent require much less rf power than deeply bound states. Another way to exert resonant control is with a set of rf-coupled bound states, linked to the colliding pair through the molecular interactions that give rise to magnetically tunable Feshbach resonances. This was recently demonstrated for 87Rb [Kaufman et al., Phys. Rev. A 80:050701(R), 2009]. We examine the underlying atomic and molecular physics which made this possible. Lastly, we consider the control that may be exerted over atomic collisions by placing atoms in superpositions of Zeeman states, and suggest that it could be useful where small changes in scattering length are required. We suggest other species for which rf and magnetic field control could together provide a useful tuning mechanism.Comment: 21 pages, 8 figures, submitted to New Journal of Physic

    Reclaiming Democratic Control: The Role of Public Ownership in Resisting Corporate Domination

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    In response to increasing inequality, the rising power of large corporations, climate change, and other challenges, public ownership is back on the agenda in the United States and around the world. In this "new gilded age" there is much to learn from past experiments as we construct a new vision of public ownership for the Twenty-First Century

    Archaeal host cell recognition and viral binding of HFTV1 to its Haloferax host

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    Viruses are highly abundant and the main predator of microorganisms. Microorganisms of each domain of life are infected by dedicated viruses. Viruses infecting archaea are genomically and structurally highly diverse. Archaea are undersampled for viruses in comparison with bacteria and eukaryotes. Consequently, the infection mechanisms of archaeal viruses are largely unknown, and most available knowledge stems from viruses infecting a select group of archaea, such as crenarchaea. We employed Haloferax tailed virus 1 (HFTV1) and its host, Haloferax gibbonsii LR2-5, to study viral infection in euryarchaea. We found that HFTV1, which has a siphovirus morphology, is virulent, and interestingly, viral particles adsorb to their host several orders of magnitude faster than most studied haloarchaeal viruses. As the binding site for infection, HFTV1 uses the cell wall component surface (S)-layer protein. Electron microscopy of infected cells revealed that viral particles often made direct contact with their heads to the cell surface, whereby the virion tails were perpendicular to the surface. This seemingly unfavorable orientation for genome delivery might represent a first reversible contact between virus and cell and could enhance viral adsorption rates. In a next irreversible step, the virion tail is orientated toward the cell surface for genome delivery. With these findings, we uncover parallels between entry mechanisms of archaeal viruses and those of bacterial jumbo phages and bacterial gene transfer agents.IMPORTANCE Archaeal viruses are the most enigmatic members of the virosphere. These viruses infect ubiquitous archaea and display an unusually high structural and genetic diversity. Unraveling their mechanisms of infection will shed light on the question if entry and egress mechanisms are highly conserved between viruses infecting a single domain of life or if these mechanisms are dependent on the morphology of the virus and the growth conditions of the host. We studied the entry mechanism of the tailed archaeal virus HFTV1. This showed that despite "typical" siphovirus morphology, the infection mechanism is different from standard laboratory models of tailed phages. We observed that particles bound first with their head to the host cell envelope, and, as such, we discovered parallels between archaeal viruses and nonmodel bacteriophages. This work contributes to a better understanding of entry mechanisms of archaeal viruses and a more complete view of microbial viruses in general.Archaeal viruses are the most enigmatic members of the virosphere. These viruses infect ubiquitous archaea and display an unusually high structural and genetic diversity.Peer reviewe
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