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Search Results: 1 - 10 of 139521 matches for " Samantha K Segall "
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Serotonin-Induced Hypersensitivity via Inhibition of Catechol O-Methyltransferase Activity
Douglas Tsao, Jeffrey S Wieskopf, Naim Rashid, Robert E Sorge, Rachel L Redler, Samantha K Segall, Jeffrey S Mogil, William Maixner, Nikolay V Dokholyan, Luda Diatchenko
Molecular Pain , 2012, DOI: 10.1186/1744-8069-8-25
Thermal depinning of fluxons in discrete Josephson rings
J. J. Mazo,F. Naranjo,K. Segall
Physics , 2008, DOI: 10.1103/PhysRevB.78.174510
Abstract: We study the thermal depinning of single fluxons in rings made of Josephson junctions. Due to thermal fluctuations a fluxon can be excited from its energy minima and move through the array, causing a voltage across each junction. We find that for the initial depinning, the fluxon behaves as a single particle and follows a Kramers-type escape law. However, under some conditions this single particle description breaks down. At low values of the discreteness parameter and low values of the damping, the depinning rate is larger than the single particle result would suggest. In addition, for some values of the parameters the fluxon can undergo low-voltage diffusion before switching to the high-voltage whirling mode. This type of diffusion is similar to phase diffusion in a single junction, but occurs without frequency-dependent damping. We study the switching to the whirling state as well.
Search for Anomalous Production of Photon+Jets
Samantha K. Hewamanage
Physics , 2008,
Abstract: Many new physics models predict mechanisms that could produce a photon and jets signature. We search in the photon + jets channel, independent of any model, for new physics using CDF Run II data collected at the Fermilab Tevatron from p-pbar collisions at a center of mass energy of 1.96 TeV. A variety of techniques are applied to estimate the standard model expectation and non-collision backgrounds. We examine several kinematic distributions including transverse energy of the photon and invariant masses for discrepancies with the standard model.
Switching Current Measurements in Josephson Rings
K. Segall,A. Dioguardi,N. Fernandes,J. J. Mazo
Physics , 2008,
Abstract: We present switching current measurements in niobium-aluminum oxide-niobium underdamped Josephson rings. Underdamped Josephson rings display hysteretic current-voltage curves which can be characterized by their switching current, the value of applied current at which the junctions switch to the energy-gap voltage. The value of the switching current is strongly affected by temperature and by the presence of fluxons in the system. We observe a very small voltage (0.2 nV) across the ring prior to switching, indicating a low-velocity fluxon diffusion state before the jump to a full running state. In analogy with previous work on single junctions, we analyze the switching current data with the process of thermal activation over a dissipation barrier, where the system switches from a low velocity state to a high velocity state. We find that our data agrees qualitatively with this description, further supporting the observation of fluxon diffusion.
Multiple junction biasing of superconducting tunnel junction detectors
K. Segall,J. J. Mazo,T. P. Orlando
Physics , 2004, DOI: 10.1063/1.1890467
Abstract: We describe a new biasing scheme for single photon detectors based on superconducting tunnel junctions. It replaces a single detector junction with a circuit of three junctions and achieves biasing of a detector junction at subgap currents without the use of an external magnetic field. The biasing occurs through the nonlinear interaction of the three junctions, which we demonstrate through numerical simulation. This nonlinear state is numerically stable against external fluctuations and is compatible with high fidelity electrical readout of the photon-induced current. The elimination of the external magnetic field potentially increases the capability of these types of photon detectors and eases constraints involved in the fabrication of large detector arrays.
HDR - A Hysteresis-Driven Routing Algorithm for Energy Harvesting Tag Networks
Adrian Segall
Computer Science , 2015,
Abstract: The work contains a first attempt to treat the problem of routing in networks with energy harvesting units. We propose HDR - a Hysteresis Based Routing Algorithm and analyse it in a simple diamond network. We also consider a network with three forwarding nodes. The results are used to give insight into its application in general topology networks and to general harvesting patterns.
Exploring Possible Encounters between New Governance, Law and Constitutionalism in the European Union  [PDF]
Samantha Velluti
Beijing Law Review (BLR) , 2013, DOI: 10.4236/blr.2013.41002

The current European Union (EU) is a highly institutionalized template for integration, equipped with a whole spectrum of different modes of regulation ranging from “hard” to “soft” which, particularly in recent years, have been pragmatically combined together to develop a hybrid and multi-tiered EU system. The dramatic expansion of the EU’s governance tool-kit and the variety of objectives and internal structures of these EU governance tools have relied on a non-clearly identifiable mix of legal and policy instruments. These changes in EU governance pose a challenge to the rule of law and its main tenets and do not sit well with the jurisprudence of the Court of Justice of the European Union (CJEU) because they occupy an unsettled constitutional space. This space is characterized by a range of possible encounters between constitutionalism and governance. In this context, New Governance forces European scholars to rethink the way the EU system operates and the way Europeanization is being pursued. The paper explores the relationship between New Governance, law and constitutionalism and the problems concerning their conceptualization and further understanding. Its main argument is that a stronger dialogue between what are known as “soft” and “hard” regulatory mechanisms may lead to a hybridized EU governance regime in which all governance tools are designed to achieve the same set of goals.

Dynamics and Energy Distribution of Non-Equilibrium Quasiparticles in Superconducting Tunnel Junctions
K. Segall,C. Wilson,L. Li,L. Frunzio,S. Friedrich,M. C. Gaidis,D. E. Prober
Physics , 2004, DOI: 10.1103/PhysRevB.70.214520
Abstract: We present a full theoretical and experimental study of the dynamics and energy distribution of non-equilibrium quasiparticles in superconducting tunnel junctions (STJs). STJs are often used for single-photon spectrometers, where the numbers of quasiparticles excited by a photon provide a measure of the photon energy. The magnitude and fluctuations of the signal current in STJ detectors are in large part determined by the quasiparticle dynamics and energy distribution during the detection process. We use this as motivation to study the transport and energy distribution of non-equilibrium quasiparticles excited by x-ray photons in a lateral, imaging junction configuration. We present a full numerical model for the tunneling current of the major physical processes which determine the signal. We find that a diffusion framework models the quasiparticle dynamics well and that excited quasiparticles do not equilibrate to the lattice temperature during the timescales for tunneling. We extract physical timescales from the measured data, make comparisons with existing theories, and comment on implications for superconducting mesoscopic systems and single-photon detectors.
Breather decay into a vortex/anti-vortex pair in a Josephson Ladder
K. Segall,P. Williams,O. Svitelskiy,D. Edwards,N. Zhelev,G. Brummer,J. J. Mazo
Physics , 2014, DOI: 10.1103/PhysRevB.90.064502
Abstract: We present experimental evidence for a new behavior which involves discrete breathers and vortices in a Josephson Ladder. Breathers can be visualized as the creation and subsequent annihilation of vortex/anti-vortex pairs. An externally applied magnetic field breaks the vortex/anti-vortex symmetry and causes the breather to split apart. The motion of the vortex or anti-vortex creates multi-site breathers, which are always to one side or the other of the original breather depending on the sign of the applied field. This asymmetry in applied field is experimentally observed.
Expanding the Temporal Analysis in Single-Molecule Switching Experiments Through the Auto-Correlation Function: Mathematical Framework
Darren E. Segall
Quantitative Biology , 2005,
Abstract: A method is presented that, when used in conjunction with single molecule experimental techniques, allows for the extraction of rates and mechanical properties of a biomolecule undergoing transitions between mechanically distinct states. This analysis enables the exploration of systems where the lifetimes of survival are of order of the intrinsic time constant of the experimental apparatus; permitting the study of kinetic events whose transition rates are an order of magnitude (or two) larger than those that can be studied with traditional averaging methods. Using current experimental techniques, this allows for the study of biomolecules whose lifetime of survival in a given state are as low as milliseconds down to microseconds. The relevant observable is the auto-correlation function of the experimental probe that is attached to the biomolecule of interest. General solutions are expressed in terms of a series. Closed form solutions are found for two physically opposing limits: where transitions between the mechanically distinct states of the biomolecule occur on either much faster or much slower time scales than those governing the motion of the experimental probe. Motivated by the derivation of these opposing bounds, two series solutions for the general case are then presented. We present an error analysis for truncating each series at arbitrary order and obtain a range of parameters for which this method could be applicable to the study of the two state biomolecular problem. Finally, both series (up to third order) are expressed for the two state problem when the system obeys Markov statistics. These solutions should be amiable to the analysis of experimental data, expanding temporal analysis of data from single molecule experiments.
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