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Myasthenia gravis is an autoimmune disease of the neuromuscular junction (NMJ) caused by antibodies that attack components of the postsynaptic membrane, impair neuromuscular transmission, and lead to weakness and fatigue of skeletal muscle. This can be generalised or localised to certain muscle groups, and involvement of the bulbar and respiratory muscles can be life threatening. The pathogenesis of myasthenia gravis depends upon the target and isotype of the autoantibodies. Most cases are caused by immunoglobulin (Ig)G1 and IgG3 antibodies to the acetylcholine receptor (AChR). They produce complement-mediated damage and increase the rate of AChR turnover, both mechanisms causing loss of AChR from the postsynaptic membrane. The thymus gland is involved in many patients, and there are experimental and genetic approaches to understand the failure of immune tolerance to the AChR. In a proportion of those patients without AChR antibodies, antibodies to muscle-specific kinase (MuSK), or related proteins such as agrin and low-density lipoprotein receptor-related protein 4 (LRP4), are present. MuSK antibodies are predominantly IgG4 and cause disassembly of the neuromuscular junction by disrupting the physiological function of MuSK in synapse maintenance and adaptation. Here we discuss how knowledge of neuromuscular junction structure and function has fed into understanding the mechanisms of AChR and MuSK antibodies. Myasthenia gravis remains a paradigm for autoantibody-mediated conditions and these observations show how much there is still to learn about synaptic function and pathological mechanisms.

\"The rich cultural and political life of Spain has emerged from its complex history, from the diversity of its peoples, and from continual contact with outside influences. This updated edition traces that history from prehistoric times to the present, focusing particularly on culture, society, politics, and personalities. Written in an engaging style, it introduces readers to key themes that have shaped Spain's history and culture. These include its varied landscapes and climates; the impact of waves of diverse human migrations; the importance of its location as a bridge between the Atlantic and the Mediterranean and Europe and Africa; and religion, particularly militant Catholic Christianity and its centuries of conflict with Islam and Protestantism, as well as debates over the place of the Church in modern Spain. Illustrations, maps, and a guide to further reading, major cultural figures, and places to see, make the history of this fascinating country come alive\"-- Provided by publisher.

On October 04, 2022, the Royal Swedish Academy of Sciences announced that the Nobel Prize for Physics of 2022 was awarded jointly to Alain Aspect, John Clauser, and Anton Zeilinger “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science.” What follows is an interview of Alain Aspect, conducted by Bill Phillips and Jean Dalibard, during the summer of 2022, and completed not long before the announcement of the Nobel Prize. The subject matter is essentially that for which the Nobel Prize was awarded.

Black soldiers first entered the regular army of the United States in 1866. While their segregated regiments served in the American West for the following three decades, the promise of Reconstruction gave way to the repressiveness of Jim Crow. But black men found a degree of equality in the service: the army treated them no worse than it did their white counterparts. This book uses army correspondence, court-martial transcripts, and pension applications to tell who these men were, often in their own words: how they were recruited and how their officers were selected; how the black regiments survived hostile congressional hearings and stringent budget cuts; how enlisted men spent their time, both on and off duty; and how regimental chaplains tried to promote literacy through the army's schools. The authors shed light on the military justice system, relations between black troops and their mostly white civilian neighbors, their professional reputations, and what veterans faced when they left the army for civilian life. --Publisher description.

Loss of connections between motor neurons and skeletal muscle fibers contribute to motor impairment in old age, but the sequence of age-associated changes that precede loss of the neuromuscular synapse remains uncertain. Here we determine changes in the size of neuromuscular synapses within the tibialis anterior muscle across the life span of C57BL/6J mice. Immunofluorescence, confocal microscopy and morphometry were used to measure the area occupied by nerve terminal synaptophysin staining and postsynaptic acetylcholine receptors at motor endplates of 2, 14, 19, 22, 25 and 28 month old mice. The key findings were: 1) At middle age (14-months) endplate acetylcholine receptors occupied 238 ± 11 µm(2) and nerve terminal synaptophysin 168 ± 14 µm(2) (mean ± SEM). 2) Between 14-months and 19-months (onset of old age) the area occupied by postsynaptic acetylcholine receptors declined 30%. At many endplates the large acetylcholine receptor plaque became fragmented into multiple smaller acetylcholine receptor clusters. 3) Between 19- and 25-months, the fraction of endplate acetylcholine receptors covered by synaptophysin fell 21%. By 28-months, half of the endplates imaged retained ≤ 50 µm(2) area of synaptophysin staining. 4) Within aged muscles, the degree to which an endplate remained covered by synaptophysin did not depend upon the total area of acetylcholine receptors, nor upon the number of discrete receptor clusters. 5) Voluntary wheel-running exercise, beginning late in middle-age, prevented much of the age-associated loss of nerve terminal synaptophysin. In summary, a decline in the area of endplate acetylcholine receptor clusters at the onset of old age was followed by loss of nerve terminal synaptophysin from the endplate. Voluntary running exercise, begun late in middle age, substantially inhibited the loss of nerve terminal from aging motor endplates.

The history of modern art owes a great debt to William Merritt Chase (1849-1916), one of America's influential artists and educators. Chase was a leading member of the international artistic avant-garde and was best known for his mastery of a wide range of subjects in oil and pastel, including figures, landscapes, urban park scenes, interiors, and portraits. As a teacher and founder of the Shinnecock Summer School of Art and the New York School of Art, Chase mentored a new generation of modernists, including Edward Hopper, Georgia O'Keeffe, and Joseph Stella. A century after his death, the breadth and richness of Chase's career are celebrated in this beautifully illustrated publication. Five essays by prominent scholars of American art offer new insights into Chase's multi-faceted artistic practice and his position in the international cultural climate at the turn of the 20th century.

The enslaved population of medieval Iberia composed only a small percentage of the general populace at any given point, and slave labor was not essential to the regional economy during the period. Yet slaves were present in Iberia from the beginning of recorded history until the early modern era, and the regulations and norms for slavery and servitude shifted as time passed and kingdoms rose and fell. The Romans brought their imperially sanctioned forms of slavery to the Iberian peninsula, and these were adapted by successive Christian kingdoms during the Middle Ages. The Muslim conquest of Iberia introduced new ideas about slavery and effected an increase in slave trade. During the later Middle Ages and the early modern period, slave owners in Christian Spain and Portugal maintained slaves at home, frequently captives taken in wars and sea raids, and exported their slave systems to colonies across the Atlantic.Slavery in Medieval and Early Modern Iberiaprovides a magisterial survey of the many forms of bound labor in Iberia from ancient times to the decline of slavery in the eighteenth century. William D. Phillips, Jr., examines the pecuniary and legal terms of slavery from purchase to manumission. He pays particular attention to the conditions of life for the enslaved, which, in a religiously diverse society, differed greatly for Muslims and Christians as well as for men and women. This sweeping narrative will become the definitive account of slavery in a place and period that deeply influenced the forms of forced servitude that shaped the New World.

Entangling atom pairs Controlled two-particle interaction is a fundamental requirement for quantum computing, and achieving it has long been a goal for research on neutral atom systems. Anderlini et al . have used a system, consisting of arrays of paired ultracold rubidium-87 atoms in an optical lattice of double-well potentials, to induce controlled entangling interactions within each atom pair. Repeated interchange of spin between atoms occupying different vibrational levels occurs with a coherence time of more than ten milliseconds. This demonstrates an essential component of a quantum gate. An optical lattice of double-well potentials is used to isolate and manipulate arrays of paired 87 Rb atoms, inducing controlled entangling interactions within each pair. Repeated interchange of spin between atoms occupying different vibrational levels occurs with a coherence time of more than ten milliseconds. This observation demonstrates the essential component of a quantum gate important for quantum computation. Ultracold atoms trapped by light offer robust quantum coherence and controllability, providing an attractive system for quantum information processing and for the simulation of complex problems in condensed matter physics. Many quantum information processing schemes require the manipulation and deterministic entanglement of individual qubits; this would typically be accomplished using controlled, state-dependent, coherent interactions among qubits. Recent experiments have made progress towards this goal by demonstrating entanglement among an ensemble of atoms 1 confined in an optical lattice. Until now, however, there has been no demonstration of a key operation: controlled entanglement between atoms in isolated pairs. Here we use an optical lattice of double-well potentials 2 , 3 to isolate and manipulate arrays of paired 87 Rb atoms, inducing controlled entangling interactions within each pair. Our experiment realizes proposals to use controlled exchange coupling 4 in a system of neutral atoms 5 . Although 87 Rb atoms have nearly state-independent interactions, when we force two atoms into the same physical location, the wavefunction exchange symmetry of these identical bosons leads to state-dependent dynamics. We observe repeated interchange of spin between atoms occupying different vibrational levels, with a coherence time of more than ten milliseconds. This observation demonstrates the essential component of a neutral atom quantum SWAP gate (which interchanges the state of two qubits). Its ‘half-implementation’, the gate, is entangling, and together with single-qubit rotations it forms a set of universal gates for quantum computation 4 .

Measurement techniques based upon the Hall effect are invaluable tools in condensed-matter physics. When an electric current flows perpendicular to a magnetic field, a Hall voltage develops in the direction transverse to both the current and the field. In semiconductors, this behavior is routinely used to measure the density and charge of the current carriers (electrons in conduction bands or holes in valence bands)—internal properties of the system that are not accessible from measurements of the conventional resistance. For strongly interacting electron systems, whose behavior can be very different from the free electron gas, the Hall effect’s sensitivity to internal properties makes it a powerful tool; indeed, the quantum Hall effects are named after the tool by which they are most distinctly measured instead of the physics from which the phenomena originate. Here we report the first observation of a Hall effect in an ultracold gas of neutral atoms, revealed by measuring a Bose–Einstein condensate’s transport properties perpendicular to a synthetic magnetic field. Our observations in this vortex-free superfluid are in good agreement with hydrodynamic predictions, demonstrating that the system’s global irrotationality influences this superfluid Hall signal.