Exploring More-Coherent Quantum Annealing

In the quest to reboot computing, quantum annealing (QA) is an interesting candidate for a new capability. While it has not demonstrated an advantage over classical computing on a real-world application, many important regions of the QA design space have yet to be explored. In IARPA's Quantum Enhanced Optimization (QEO) program, we have opened some new lines of inquiry to get to the heart of QA, and are designing testbed superconducting circuits and conducting key experiments. In this paper, we discuss recent experimental progress related to one of the key design dimensions: qubit coherence. Using MIT Lincoln Laboratory's qubit fabrication process and extending recent progress in flux qubits, we are implementing and measuring QA-capable flux qubits. Achieving high coherence in a QA context presents significant new engineering challenges. We report on techniques and preliminary measurement results addressing two of the challenges: crosstalk calibration and qubit readout. This groundwork enables exploration of other promising features and provides a path to understanding the physics and the viability of quantum annealing as a computing resource.Comment: 7 pages, 3 figures. Accepted by the 2018 IEEE International Conference on Rebooting Computing (ICRC

OPA1 disease alleles causing dominant optic atrophy have defects in cardiolipin-stimulated GTP hydrolysis and membrane tubulation

The dynamin-related GTPase OPA1 is mutated in autosomal dominant optic atrophy (DOA) (Kjer type), an inherited neuropathy of the retinal ganglion cells. OPA1 is essential for the fusion of the inner mitochondrial membranes, but its mechanism of action remains poorly understood. Here we show that OPA1 has a low basal rate of GTP hydrolysis that is dramatically enhanced by association with liposomes containing negative phospholipids such as cardiolipin. Lipid association triggers assembly of OPA1 into higher order oligomers. In addition, we find that OPA1 can promote the protrusion of lipid tubules from the surface of cardiolipin-containing liposomes. In such lipid protrusions, OPA1 assemblies are observed on the outside of the lipid tubule surface, a protein-membrane topology similar to that of classical dynamins. The membrane tubulation activity of OPA1 is suppressed by GTPγS. OPA1 disease alleles associated with DOA display selective defects in several activities, including cardiolipin association, GTP hydrolysis and membrane tubulation. These findings indicate that interaction of OPA1 with membranes can stimulate higher order assembly, enhance GTP hydrolysis and lead to membrane deformation into tubules

Blocking NMDAR Disrupts Spike Timing and Decouples Monkey Prefrontal Circuits: Implications for Activity-Dependent Disconnection in Schizophrenia

We employed multi-electrode array recording to evaluate the influence of NMDA receptors (NMDAR) on spike-timing dynamics in prefrontal networks of monkeys as they performed a cognitive control task measuring specific deficits in schizophrenia. Systemic, periodic administration of an NMDAR antagonist (phencyclidine) reduced the prevalence and strength of synchronous (0-lag) spike correlation in simultaneously recorded neuron pairs. We employed transfer entropy analysis to measure effective connectivity between prefrontal neurons at lags consistent with monosynaptic interactions and found that effective connectivity was persistently reduced following exposure to the NMDAR antagonist. These results suggest that a disruption of spike timing and effective connectivity might be interrelated factors in pathogenesis, supporting an activity-dependent disconnection theory of schizophrenia. In this theory, disruption of NMDAR synaptic function leads to dys-regulated timing of action potentials in prefrontal networks, accelerating synaptic disconnection through a spike-timing-dependent mechanism

The Making of Modern America: Quantifying Chaos

As we begin to explore the Gilded Age (1870-1900), that era in American History sandwiched between the Civil War/Reconstruction and the Progressive Era to the Great War, we want students to grasp the enormity of the changes impacting the lives of Americans who have largely been engaged in farming in many cases not so different than their ancestors had for several hundreds of years. Technological changes in the first half of the 19th century contributed to some mechanization and manufacturing, but the enormity of the Civil War and the acquisition of the entire continental territory in the 1850s, accelerated changes in the production of goods, in the development of communication and transportation, in the growth of cities, in the opportunities for immigrants, for participation in politics, and in the reach of the government. In this lesson, students will dip into the many changes over the decades from 1860 to 1900 by searching for information on a variety of topics, including: Banking or Finance, Demographics, Government, Industrialization, Immigration, Middle Class Angst, Military, Natural Resources, Politics, Racism, Robber Barons/Captains of Industry, Technological Innovations, Transportation, Urbanization, Voter Turnout, and Xenophobia.https://repository.stcloudstate.edu/gilded_age/1001/thumbnail.jp

Ureter tracking and segmentation in CT urography (CTU) using COMPASS

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134875/1/mp1412_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134875/2/mp1412.pd

OPA1 and cardiolipin team up for mitochondrial fusion

Fusion between the inner membranes of two mitochondria requires the GTPase optic atrophy 1 (OPA1), but the molecular mechanism is poorly understood. A study now shows that fusion of two liposomes can be performed by OPA1 tethered to just one liposome, through an interaction with the phospholipid cardiolipin on the opposing liposome

Waste, Industry and Romantic Leisure: Veblen's Theory of Recognition

types: ArticleVeblen’s work contains a neglected, since for the most part implicit, theory of recognition centred on his concepts of waste and workmanship. This article tries to develop this theory in order to shed new light on the theorem of conspicuous leisure and consumption. The legitimacy of violence at the ‘predatory stage’ of culture has been partly superseded by a legitimacy of industrial efficiency, so that the leisure classes need to disguise their conspicuous waste as socially useful productive endeavours. At the same time waste remains a powerful symbol of legitimate status, so that even the industrial classes turn to it in order to assert their social worth and demand social recognition. Waste - which is far more central in Veblen’s theory than is emulation - becomes an ambiguous symbol which can stand for both unproductive privilege and industrial efficiency. The utilitarian urge for efficiency and the meaninglessness of a struggle for recognition through conspicuous waste produce a desire for a romantic escape, also acknowledged by Veblen, but often overlooked in his sharp criticism of consumerism