130 research outputs found
Are viable democratic government and effective foreign policy irreconcilable aims?.
http://www.archive.org/details/areviabledemocra00bus
Quantum optical signal processing in diamond
Controlling the properties of single photons is essential for a wide array of
emerging optical quantum technologies spanning quantum sensing, quantum
computing, and quantum communications. Essential components for these
technologies include single photon sources, quantum memories, waveguides, and
detectors. The ideal spectral operating parameters (wavelength and bandwidth)
of these components are rarely similar; thus, frequency conversion and spectral
control are key enabling steps for component hybridization. Here we perform
signal processing of single photons by coherently manipulating their spectra
via a modified quantum memory. We store 723.5 nm photons, with 4.1 nm
bandwidth, in a room-temperature diamond crystal; upon retrieval we demonstrate
centre frequency tunability over 4.2 times the input bandwidth, and bandwidth
modulation between 0.5 to 1.9 times the input bandwidth. Our results
demonstrate the potential for diamond, and Raman memories in general, to be an
integrated platform for photon storage and spectral conversion.Comment: 6 pages, 4 figure
Storage of polarization-entangled THz-bandwidth photons in a diamond quantum memory
Bulk diamond phonons have been shown to be a versatile platform for the
generation, storage, and manipulation of high-bandwidth quantum states of
light. Here we demonstrate a diamond quantum memory that stores, and releases
on demand, an arbitrarily polarized 250 fs duration photonic qubit. The
single-mode nature of the memory is overcome by mapping the two degrees of
polarization of the qubit, via Raman transitions, onto two spatially distinct
optical phonon modes located in the same diamond crystal. The two modes are
coherently recombined upon retrieval and quantum process tomography confirms
that the memory faithfully reproduces the input state with average fidelity
with a total memory efficiency of . In an
additional demonstration, one photon of a polarization-entangled pair is stored
in the memory. We report that entanglement persists in the retrieved state for
up to 1.3 ps of storage time. These results demonstrate that the diamond phonon
platform can be used in concert with polarization qubits, a key requirement for
polarization-encoded photonic processing
Storage and retrieval of ultrafast single photons using a room-temperature diamond quantum memory
We report the storage and retrieval of single photons, via a quantum memory,
in the optical phonons of room-temperature bulk diamond. The THz-bandwidth
heralded photons are generated by spontaneous parametric downconversion and
mapped to phonons via a Raman transition, stored for a variable delay, and
released on demand. The second-order correlation of the memory output is
, demonstrating preservation of non-classical
photon statistics throughout storage and retrieval. The memory is low-noise,
high-speed and broadly tunable; it therefore promises to be a versatile
light-matter interface for local quantum processing applications.Comment: 6 pages, 4 figure
Deriving a Generic Energy Consumption Model for Network Enabled Devices
Abstract-Energy saving has become a global issue when people use network enabled equipment in the office or at home. However few methods exist to measure and monitor energy use per user or per application, or to control equipment power states. We propose a generic energy consumption model that is based on the power state of network attached equipment, and that supports power management capabilities. This includes measures for each power state (on/off/sleep) and for per bit energy consumption, per interface, per application and at the network QoS (Quality of Services) level. Given the power state of a network device, a network manger could remotely inspect the energy consumption and make changes to the power management setting; for this to happen we introduce a new MIB (Management Information Base) schema to capture the attributes of relevance. Using an agent based modeling framework, we introduce the overall autonomic architecture that makes it possible to minimize energy consumption of network enabled equipment
Metabolism-dependent bioaccumulation of uranium by Rhodosporidium toruloides isolated from the flooding water of a former uranium mine
Remediation of former uranium mining sites represents one of the biggest challenges worldwide
that have to be solved in this century. During the last years, the search of alternative
strategies involving environmentally sustainable treatments has started. Bioremediation,
the use of microorganisms to clean up polluted sites in the environment, is considered one
the best alternative. By means of culture-dependent methods, we isolated an indigenous
yeast strain, KS5 (Rhodosporidium toruloides), directly from the flooding water of a former
uranium mining site and investigated its interactions with uranium. Our results highlight
distinct adaptive mechanisms towards high uranium concentrations on the one hand, and
complex interaction mechanisms on the other. The cells of the strain KS5 exhibit high a
uranium tolerance, being able to grow at 6 mM, and also a high ability to accumulate this
radionuclide (350 mg uranium/g dry biomass, 48 h). The removal of uranium by KS5 displays
a temperature- and cell viability-dependent process, indicating that metabolic activity
could be involved. By STEM (scanning transmission electron microscopy) investigations,
we observed that uranium was removed by two mechanisms, active bioaccumulation and
inactive biosorption. This study highlights the potential of KS5 as a representative of indigenous
species within the flooding water of a former uranium mine, which may play a key role
in bioremediation of uranium contaminated sites.This work was supported by the
Bundesministerium fĂŒr Bildung und Forschung
grand nÂș 02NUK030F (TransAqua). Further support
took place by the ERDF-co-financed Grants
CGL2012-36505 and 315 CGL2014-59616R,
Ministerio de Ciencia e InnovaciĂłn, Spain
The multi-peak adaptive landscape of crocodylomorph body size evolution
Background: Little is known about the long-term patterns of body size evolution in Crocodylomorpha, the > 200-million-year-old group that includes living crocodylians and their extinct relatives. Extant crocodylians are mostly large-bodied (3â7 m) predators. However, extinct crocodylomorphs exhibit a wider range of phenotypes, and many of the earliest taxa were much smaller (
Results: Crocodylomorphs reached an early peak in body size disparity during the Late Jurassic, and underwent an essentially continual decline since then. A multi-peak Ornstein-Uhlenbeck model outperforms all other evolutionary models fitted to our data (including both uniform and non-uniform), indicating that the macroevolutionary dynamics of crocodylomorph body size are better described within the concept of an adaptive landscape, with most body size variation emerging after shifts to new macroevolutionary regimes (analogous to adaptive zones). We did not find support for a consistent evolutionary trend towards larger sizes among lineages (i.e., Copeâs rule), or strong correlations of body size with climate. Instead, the intermediate to large body sizes of some crocodylomorphs are better explained by group-specific adaptations. In particular, the evolution of a more aquatic lifestyle (especially marine) correlates with increases in average body size, though not without exceptions.
Conclusions: Shifts between macroevolutionary regimes provide a better explanation of crocodylomorph body size evolution on large phylogenetic and temporal scales, suggesting a central role for lineage-specific adaptations rather than climatic forcing. Shifts leading to larger body sizes occurred in most aquatic and semi-aquatic groups. This, combined with extinctions of groups occupying smaller body size regimes (particularly during the Late Cretaceous and Cenozoic), gave rise to the upward-shifted body size distribution of extant crocodylomorphs compared to their smaller-bodied terrestrial ancestors.</p
Metabolic analysis of the response of Pseudomonas putida DOT-T1E strains to toluene using Fourier transform infrared spectroscopy and gas chromatography mass spectrometry
Distribution patterns and trophic characteristics of salmonids and native species inhabiting high altitude rivers of Pampa de Achala region, Argentina
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