789 research outputs found
Rapid Onset Pressor Response During Isometric Exercise in Postmenopausal Hypertensive Women
Please view abstract in the attached PDF file
Compressed sensing quantum process tomography for superconducting quantum gates
We apply the method of compressed sensing (CS) quantum process tomography
(QPT) to characterize quantum gates based on superconducting Xmon and phase
qubits. Using experimental data for a two-qubit controlled-Z gate, we obtain an
estimate for the process matrix with reasonably high fidelity compared
to full QPT, but using a significantly reduced set of initial states and
measurement configurations. We show that the CS method still works when the
amount of used data is so small that the standard QPT would have an
underdetermined system of equations. We also apply the CS method to the
analysis of the three-qubit Toffoli gate with numerically added noise, and
similarly show that the method works well for a substantially reduced set of
data. For the CS calculations we use two different bases in which the process
matrix is approximately sparse, and show that the resulting estimates of
the process matrices match each ther with reasonably high fidelity. For both
two-qubit and three-qubit gates, we characterize the quantum process by not
only its process matrix and fidelity, but also by the corresponding standard
deviation, defined via variation of the state fidelity for different initial
states.Comment: 16 pages, 11 figure
A temporal and spatial study of invertebrate communities associated with hard-bottom habitats in the South Atlantic Bight
Species composition, biomass, density, and diversity of benthic invertebrates from six bard-bottom areas were evaluated. Seasonal collections using a dredge, trawl, and suction and grab samplers yielded 432, 525, and 845 taxa, respectively. Based on collections wltb the different gear types, species composition of invertebrates was found to change bathymetrically. Inner- and mlddle-shelf sites were more similar to each other in terms of invertebrate species composition than they were to outer-shelf sites, regardless of season. Sites on the inner and outer shelf were grouped according to latitude; however, results suggest that depth is apparently a more important determinant of invertebrate species composition than either season or latitude. Sponges generally dominated dredge and trawl collections in terms of biomass. Generally, cnidarians, bryozoans, and sponges
dominated at sites In terms of number of taxa collected.
The most abundant smaller macrofauna collected in suction and grab samples were polychaetes, amphipods, and mollusks. Densities of the numerically dominant species changed botb seasonally and bathymetrically, with very few of these species restricted to a specific bathymetrlc zone.
The high diversity of invertebrates from hard-bottom sites is attributed to the large number of rare species. No consistent seasonal changes in diversity or number of species were noted for individual stations or depth zones. In addition, H and its components showed no definite patterns related to depth or latitude. However, more species were collected at middle-shelf sites than at inner- or outer-shelf sites, which may be related to more
stable bottom temperature or greater habitat complexity in that area. (PDF file contains 110 pages.
Inferring the effective thickness of polyelectrolytes from stretching measurements at various ionic strengths: applications to DNA and RNA
By resorting to the thick-chain model we discuss how the stretching response
of a polymer is influenced by the self-avoidance entailed by its finite
thickness. The characterization of the force versus extension curve for a thick
chain is carried out through extensive stochastic simulations. The
computational results are captured by an analytic expression that is used to
fit experimental stretching measurements carried out on DNA and single-stranded
RNA (poly-U) in various solutions. This strategy allows us to infer the
apparent diameter of two biologically-relevant polyelectrolytes, namely DNA and
poly-U, for different ionic strengths. Due to the very different degree of
flexibility of the two molecules, the results provide insight into how the
apparent diameter is influenced by the interplay between the
(solution-dependent) Debye screening length and the polymers' ``bare''
thickness. For DNA, the electrostatic contribution to the effective radius,
, is found to be about 5 times larger than the Debye screening length,
consistently with previous theoretical predictions for highly-charged stiff
rods. For the more flexible poly-U chains the electrostatic contribution to
is found to be significantly smaller than the Debye screening length.Comment: iopart, 14 pages, 13 figures, to appear in J. Phys.: Condens. Matte
Planar Superconducting Resonators with Internal Quality Factors above One Million
We describe the fabrication and measurement of microwave coplanar waveguide
resonators with internal quality factors above 10 million at high microwave
powers and over 1 million at low powers, with the best low power results
approaching 2 million, corresponding to ~1 photon in the resonator. These
quality factors are achieved by controllably producing very smooth and clean
interfaces between the resonators' aluminum metallization and the underlying
single crystal sapphire substrate. Additionally, we describe a method for
analyzing the resonator microwave response, with which we can directly
determine the internal quality factor and frequency of a resonator embedded in
an imperfect measurement circuit.Comment: 4 pages, 3 figures, 1 tabl
Computing prime factors with a Josephson phase qubit quantum processor
A quantum processor (QuP) can be used to exploit quantum mechanics to find
the prime factors of composite numbers[1]. Compiled versions of Shor's
algorithm have been demonstrated on ensemble quantum systems[2] and photonic
systems[3-5], however this has yet to be shown using solid state quantum bits
(qubits). Two advantages of superconducting qubit architectures are the use of
conventional microfabrication techniques, which allow straightforward scaling
to large numbers of qubits, and a toolkit of circuit elements that can be used
to engineer a variety of qubit types and interactions[6, 7]. Using a number of
recent qubit control and hardware advances [7-13], here we demonstrate a
nine-quantum-element solid-state QuP and show three experiments to highlight
its capabilities. We begin by characterizing the device with spectroscopy.
Next, we produces coherent interactions between five qubits and verify bi- and
tripartite entanglement via quantum state tomography (QST) [8, 12, 14, 15]. In
the final experiment, we run a three-qubit compiled version of Shor's algorithm
to factor the number 15, and successfully find the prime factors 48% of the
time. Improvements in the superconducting qubit coherence times and more
complex circuits should provide the resources necessary to factor larger
composite numbers and run more intricate quantum algorithms.Comment: 5 pages, 3 figure
Generation of Three-Qubit Entangled States using Superconducting Phase Qubits
Entanglement is one of the key resources required for quantum computation, so
experimentally creating and measuring entangled states is of crucial importance
in the various physical implementations of a quantum computer. In
superconducting qubits, two-qubit entangled states have been demonstrated and
used to show violations of Bell's Inequality and to implement simple quantum
algorithms. Unlike the two-qubit case, however, where all maximally-entangled
two-qubit states are equivalent up to local changes of basis, three qubits can
be entangled in two fundamentally different ways, typified by the states
and . Here we demonstrate the operation of three coupled
superconducting phase qubits and use them to create and measure
and states. The states are fully characterized
using quantum state tomography and are shown to satisfy entanglement witnesses,
confirming that they are indeed examples of three-qubit entanglement and are
not separable into mixtures of two-qubit entanglement.Comment: 9 pages, 5 figures. Version 2: added supplementary information and
fixed image distortion in Figure 2
Beers and blurred boundaries: The spatial and gendered organisation of pre-match venues for English football fans
Academic research into sports fans has grown in recent years with studies examining a variety of aspects associated with fandom. However, recent changes in the professionalisation and commercialisation of sport have resulted in the creation of new spaces for fan experiences. In this article, we examine one of these created spaces, the fan zone. Through a case study on matchgoing fans from Everton Football Club we explore how this new space sits alongside traditional pre-match gathering places such as the ?pub? and examine the gendered organisation of these spaces. Drawing on Bale?s concept of boundaries within sports fan communities we show that traditional venues for pre-match activities enhance, maintain and legitimise masculine boundaries within sports fandom. We argue that fan zones provide an alternative match day atmosphere and experience that is centred on a family-friendly or at least family-inclusive culture
Exercise-Induced Changes in Metabolic Intermediates, Hormones, and Inflammatory Markers Associated With Improvements in Insulin Sensitivity
OBJECTIVE: To understand relationships between exercise training-mediated improvements in insulin sensitivity (S(I)) and changes in circulating concentrations of metabolic intermediates, hormones, and inflammatory mediators. RESEARCH DESIGN AND METHODS: Targeted mass spectrometry and enzyme-linked immunosorbent assays were used to quantify metabolic intermediates, hormones, and inflammatory markers at baseline, after 6 months of exercise training, and 2 weeks after exercise training cessation (n = 53). A principal components analysis (PCA) strategy was used to relate changes in these intermediates to changes in S(I). RESULTS: PCA reduced the number of intermediates from 90 to 24 factors composed of biologically related components. With exercise training, improvements in S(I) were associated with reductions in by-products of fatty acid oxidation and increases in glycine and proline (P < 0.05, RĀ² = 0.59); these relationships were retained 15 days after cessation of exercise training (P < 0.05, RĀ² = 0.34). CONCLUSIONS: These observations support prior observations in animal models that exercise training promotes more efficient mitochondrial Ī²-oxidation and challenges current hypotheses regarding exercise training and glycine metabolism
- ā¦