9,087 research outputs found
On the theory of polarization transfer in inhomogeneous magnetized plasmas
Polarization transfer theory in inhomogeneous magnetized plasmas with mode couplin
Ultracold molecules: vehicles to scalable quantum information processing
We describe a novel scheme to implement scalable quantum information
processing using Li-Cs molecular state to entangle Li and Cs
ultracold atoms held in independent optical lattices. The Li atoms will
act as quantum bits to store information, and Cs atoms will serve as
messenger bits that aid in quantum gate operations and mediate entanglement
between distant qubit atoms. Each atomic species is held in a separate optical
lattice and the atoms can be overlapped by translating the lattices with
respect to each other. When the messenger and qubit atoms are overlapped,
targeted single spin operations and entangling operations can be performed by
coupling the atomic states to a molecular state with radio-frequency pulses. By
controlling the frequency and duration of the radio-frequency pulses,
entanglement can either be created or swapped between a qubit messenger pair.
We estimate operation fidelities for entangling two distant qubits and discuss
scalability of this scheme and constraints on the optical lattice lasers
An information adaptive system study report and development plan
The purpose of the information adaptive system (IAS) study was to determine how some selected Earth resource applications may be processed onboard a spacecraft and to provide a detailed preliminary IAS design for these applications. Detailed investigations of a number of applications were conducted with regard to IAS and three were selected for further analysis. Areas of future research and development include algorithmic specifications, system design specifications, and IAS recommended time lines
Intercontinental transport of pollution and dust aerosols: implications for regional air quality
International audienceWe use the global model GOCART to examine the impact of pollution and dust aerosols emitted from their major sources on surface fine particulate matter concentrations at regional and hemispheric scales. Focusing on the North America region in 2001, we use measurements from the IMPROVE network in the United States to evaluate the model-simulated surface concentrations of the "reconstructed fine mass" (RCFM) and its components of ammonium sulfate, black carbon (BC), organic matter (OM), and fine mode dust. We then quantify the RCFM budget in terms of the RCFM composition, type, and origin to find that in the eastern U.S., ammonium sulfate is the dominant RCFM component (~60%) whereas in the western U.S., dust and OM are just as important as sulfate but have considerable seasonal variations, especially in the NW. On an annual average, North America regional pollution accounts for nearly 30?40% of the surface RCFM in the western U.S., and for a much higher proportion of 65?70% in the eastern U.S. By contrast, pollution from outside of North America contributes to just 2?6% (~0.2 ?g m?3) of the total RCFM over the U.S. on an annual average. In comparison, long-range transport of dust is more efficient than that of pollution, which brings 3 to 4 times more fine particles to the U.S. (0.5?0.8 ?g m?3 on an annual average) with a maximum influence in spring and over the NW. Of the major pollution regions, Europe has the largest potential to affect the surface aerosol concentrations in other continents due to its shorter distance from receptor continents and its larger fraction of sulfate-producing precursor gas in the outflow. With the IPCC emission scenario for the year 2000, we find that European emissions increase levels of ammonium sulfate by 1?5 ?g m?3 over the surface of northern Africa and western Asia, and its contribution to eastern Asia (?0.2 ?g m?3) is twice as much as the Asian contribution to North America. Asia and North America pollution emissions exert strong impacts on their neighboring oceans, but their influences on other continents are relatively small (?10%) due to the long traveling distance across the oceans and efficient removal during transport. Among the major dust source regions, Asia displays a significant influence over large areas in the Northern Hemisphere except over the North Atlantic and the tropics, where African dust dominates. The trans-Pacific transport of Asian dust is much more efficient than that of Asian pollution because of the higher elevation and lower removal rate of dust. We notice that the African dust can travel eastward through a pathway spanning across Asia and North Pacific to settle down over the surface of western North America. African dust transported through such a pathway is difficult to detect because it usually merges and travels together with the Asian dust
Antioxidant properties: effects of solid-to-solvent ratio on antioxidant compounds and capacities of pegaga (Centella asiatica)
The objective of this study was to evaluate the effects of solid-to-solvent ratio (1:5, 1:10, 1:15 and 1:20) on the extraction of phenolic compounds (TPC and TFC) and antioxidant capacity (ABTS and DPPH radical scavenging capacity) of C. asiatica. Solid-to-solvent ratio 1:15 was the optimum condition for extraction of phenolic compounds (TPC and TFC) with a value of 967.2 mg GAE/100 g DW and 908.3 mg CE/100 g DW, respectively and exhibited high antioxidant capacities (ABTS and DPPH radical scavenging capacities) with a value of 0.8133 mM and 2.0945 mM, respectively. TPC was positively and strongly correlated with ABTS and DPPH (r=0.808 and r=0.859, respectively) under the effects of solid-to-solvent ratio as compared to TFC, positively and moderately correlated (r=0.590, r=0.663) with ABTS and DPPH
Isolation and characterization of cDNA clones for α- and β-subunits of ovine luteinizing hormone
A cDNA library of ovine pituitary DNA in plasmid pBR322 has been constructed by conventional methods with certain modifications. The library was screened using partial cDNAs for rat α-subunit and LHβ. We have isolated cDNA clones for ovineα -subunit and LHβ. The identification of these clones was confirmed by partial sequencing. The clones bear about 80% sequence homology with the respective rat cDNAs in the sequenced regions and hybridize with the rat clones in 5 X SSC at 55°C. The ovine LHβ clone has an insert of about 650 bp and selects an RNA of about 750 bases in a northern blot. The α-subunit cDNA clone has an insert of about 550 bp; it has two internal Pst I sites and thus shows restriction-based differences from rat α-subunit cDNA, which does not have anyPst I site
A new broken U(1)-symmetry in extreme type-II superconductors
A phase transition within the molten phase of the Abrikosov vortex system
without disorder in extreme type-II superconductors is found via large-scale
Monte-Carlo simulations. It involves breaking a U(1)-symmetry, and has a
zero-field counterpart, unlike vortex lattice melting. Its hallmark is the loss
of number-conservation of connected vortex paths threading the entire system
{\it in any direction}, driving the vortex line tension to zero. This tension
plays the role of a generalized ``stiffness'' of the vortex liquid, and serves
as a probe of the loss of order at the transition, where a weak specific heat
anomaly is found.Comment: 5 pages, 3 figure
Fractional-Period Excitations in Continuum Periodic Systems
We investigate the generation of fractional-period states in continuum
periodic systems. As an example, we consider a Bose-Einstein condensate
confined in an optical-lattice potential. We show that when the potential is
turned on non-adiabatically, the system explores a number of transient states
whose periodicity is a fraction of that of the lattice. We illustrate the
origin of fractional-period states analytically by treating them as resonant
states of a parametrically forced Duffing oscillator and discuss their
transient nature and potential observability.Comment: 10 pages, 6 figures (some with multiple parts); revised version:
minor clarifications of a couple points, to appear in Physical Review
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