218 research outputs found
Autonomic Computing Correlation for Fault Management System Evolution
This paper discusses the emerging area of autonomic computing and its implications for the evolution of faultmanagement systems. Particular emphasis is placed on the concept of event correlation and its role in system self-management. A new correlation analysis tool to assist with the development, management and maintenance of correlation rules and beliefs is described
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
Biodegradation of high-concentration isopropanol by a solvent-tolerant thermophile, Bacillus pallidus
The aerobic biodegradation of high-concentration,
to 24 g l
–1
, 2-propanol (IPA) by a thermophilic isolate
ST3, identified as
Bacillus pallidus
, was successfully carried
out for the first time. This solvent-tolerant
B. pallidus
utilized
IPA as the sole carbon source within a minimal salts
medium. Cultivation was carried out in 100-ml shake flasks
at 60°C and compared with cultivation within a 1-l stirred
tank reactor (STR). Specific growth rate () was about
0.2 h–1
for both systems, with a maximum cell density of 2.4 x 10
8 cells ml–1
obtained with STR cultivation. During exponential
growth and stationary phase, IPA biodegradation
rates were found to be 0.14 and 0.02 g l
–1h–1, respectively, in
shake-flask experiments, whereas corresponding values of
0.09 and 0.018 g l
–1h–1
were achievable in the STR. Generation
of acetone, the major intermediate in aerobic IPA biodegradation,
was also monitored as an indicator of
microbial IPA utilization. Acetone levels reached a maximum
of 2.2–2.3 g l–1
after 72 and 58 h for 100-ml and 1-l systems,
respectively. Both IPA and acetone were completely
removed from the medium following 160 and 175 h, respectively,
during STR growth, although this was not demonstrated
within shake-flask reactions. Growth of
B. pallidus
on acetone or IPA alone demonstrated that the maximum
growth rate () obtainable was 0.247 h–1
at 4 g l–1
acetone
and 0.202 h–1
at 8 g l–1
IPA within shake-flask cultivation.
These results indicate the potential of the solvent-tolerant
thermophile
B. pallidus
ST3 in the bioremediation of hot
solvent-containing industrial waste streams
Nest site selection by sea turtles
The distribution of 38 nests of loggerhead turtles (Caretta caretta) on beaches on Sanibel and Captiva islands, south-western Florida (26°26\u27N 82°16\u27W), and of 70 first digging attempts by green turtles (Chelonia mydas) on Ascension Island (7°57\u27S 14°22\u27W), was quantified. For loggerhead turtles on Sanibel and Captiva, nests were clumped close to the border between the open sand and the supra-littoral vegetation that backed the beaches. This spatial pattern of nests was closely reproduced by assuming simply that turtles crawled a random distance above the most recent high water line prior to digging. In contrast, green turtles on Ascension Island clumped their first digging attempts on the uneven beach above the springs high water line, crawling up to 80 m to reach this beach zone
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