5,472 research outputs found
Free initial wave packets and the long-time behavior of the survival and nonescape probabilities
The behavior of both the survival S(t) and nonescape P(t) probabilities at
long times for the one-dimensional free particle system is shown to be closely
connected to that of the initial wave packet at small momentum. We prove that
both S(t) and P(t) asymptotically exhibit the same power-law decrease at long
times, when the initial wave packet in momentum representation behaves as O(1)
or O(k) at small momentum. On the other hand, if the integer m becomes greater
than 1, S(t) and P(t) decrease in different power-laws at long times.Comment: 4 pages, 3 figures, Title and organization changed, however the
results not changed, To appear in Phys. Rev.
COMPTEL observations of the inner galaxy
This paper presents a first global study of COMPTEL observations of the inner Galaxy in the energy range 0.75–10 MeV. Preliminary findings demonstrate COMPTEL’s capabilities for mapping the observed gamma radiation and disentangling the contributions from point sources and diffuse emission
Target and (Astro-)WISE technologies - Data federations and its applications
After its first implementation in 2003 the Astro-WISE technology has been
rolled out in several European countries and is used for the production of the
KiDS survey data. In the multi-disciplinary Target initiative this technology,
nicknamed WISE technology, has been further applied to a large number of
projects. Here, we highlight the data handling of other astronomical
applications, such as VLT-MUSE and LOFAR, together with some non-astronomical
applications such as the medical projects Lifelines and GLIMPS, the MONK
handwritten text recognition system, and business applications, by amongst
others, the Target Holding. We describe some of the most important lessons
learned and describe the application of the data-centric WISE type of approach
to the Science Ground Segment of the Euclid satellite.Comment: 9 pages, 5 figures, Proceedngs IAU Symposium No 325 Astroinformatics
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Operation of EMEP ‘supersites’ in the United Kingdom. Annual report for 2008.
As part of its commitment to the UN-ECE Convention on Long-range Transboundary Air Pollution the United Kingdom operates two ‘supersites’ reporting data to the Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP).
This report provides the annual summary for 2008, the second full calendar year of operation of the first EMEP ‘supersite’ to be established in the United Kingdom. Detailed operational reports have been submitted to Defra every 3 months, with unratified data. This annual report contains a summary of the ratified data for 2008.
The EMEP ‘supersite’ is located in central southern Scotland at Auchencorth (3.2oW, 55.8oN), a remote rural moorland site ~20 km south-west of Edinburgh. Monitoring operations started formally on 1 June 2006.
In addition to measurements made specifically under this contract, the Centre for Ecology & Hydrology also acts as local site operator for measurements made under other UK monitoring networks: the Automated Urban and Rural Network (AURN), the UK Eutrophication and Acidification Network (UKEAP), the UK Hydrocarbons Network, and the UK Heavy Metals Rural Network. Some measurements were also made under the auspices of the ‘Air Pollution Deposition Processes’ contract. All these associated networks are funded by Defra.
This report summarises the measurements made between January and December 2008, and presents summary statistics on average concentrations.
The site is dominated by winds from the south-west, but wind direction data highlight potential sources of airborne pollutants (power stations, conurbations).
The average diurnal patterns of gases and particles are consistent with those expected for a remote rural site.
The frequency distributions are presented for data where there was good data capture throughout the whole period. Some components (e.g. black carbon) show log-normal frequency distributions, while other components (e.g. ozone) have more nearly normal frequency distributions.
A case study is presented for a period in June 2008, showing the influence of regional air pollutants at this remote rural site.
All the data reported under the contract are shown graphically in the Appendix
A compact and reconfigurable silicon nitride time-bin entanglement circuit
Photonic chip based time-bin entanglement has attracted significant attention
because of its potential for quantum communication and computation. Useful
time-bin entanglement systems must be able to generate, manipulate and analyze
entangled photons on a photonic chip for stable, scalable and reconfigurable
operation. Here we report the first time-bin entanglement photonic chip that
integrates time-bin generation, wavelength demultiplexing and entanglement
analysis. A two-photon interference fringe with an 88.4% visibility is measured
(without subtracting any noise), indicating the high performance of the chip.
Our approach, based on a silicon nitride photonic circuit, which combines the
low-loss characteristic of silica and tight integration features of silicon,
paves the way for scalable real-world quantum information processors.Comment: 4 pages, 5 figure
Anisotropic and strong negative magneto-resistance in the three-dimensional topological insulator Bi2Se3
We report on high-field angle-dependent magneto-transport measurements on
epitaxial thin films of Bi2Se3, a three-dimensional topological insulator. At
low temperature, we observe quantum oscillations that demonstrate the
simultaneous presence of bulk and surface carriers. The magneto- resistance of
Bi2Se3 is found to be highly anisotropic. In the presence of a parallel
electric and magnetic field, we observe a strong negative longitudinal
magneto-resistance that has been consid- ered as a smoking-gun for the presence
of chiral fermions in a certain class of semi-metals due to the so-called axial
anomaly. Its observation in a three-dimensional topological insulator implies
that the axial anomaly may be in fact a far more generic phenomenon than
originally thought.Comment: 6 pages, 4 figure
Skin, Thermal and Umbilical Cord Care Practices for Neonates in Southern, Rural Zambia: A Qualitative Study
Background: In Choma District, southern Zambia, the neonatal mortality rate is approximately 40 per 1000 live births and, although the rate is decreasing, many deliveries take place outside of formal facilities. Understanding local practices during the postnatal period is essential for optimizing newborn care programs. Methods: We conducted 36 in-depth interviews, five focus groups and eight observational sessions with recently-delivered women, traditional birth attendants, and clinic and hospital staff from three sites, focusing on skin, thermal and cord care practices for newborns in the home. Results: Newborns were generally kept warm by application of hats and layers of clothing. While thermal protection is provided for preterm and small newborns, the practice of nighttime bathing with cold water was common. The vernix was considered important for the preterm newborn but dangerous for HIV-exposed infants. Mothers applied various substances to the skin and umbilical cord, with special practices for preterm infants. Applied substances included petroleum jelly, commercial baby lotion, cooking oil and breastmilk. The most common substances applied to the umbilical cord were powders made of roots, burnt gourds or ash. To ward off malevolent spirits, similar powders were reportedly placed directly into dermal incisions, especially in ill children. Conclusions: Thermal care for newborns is commonly practiced but co-exists with harmful practices. Locally appropriate behavior change interventions should aim to promote chlorhexidine in place of commonly-reported application of harmful substances to the skin and umbilical cord, reduce bathing of newborns at night, and address the immediate bathing of HIV-infected newborns
Memory effects induced by initial switching conditions
Initial-switching refers to the way in which the decay of an initially
confined state begins, as the barrier isolating it from the exterior is
relaxed. We study these effects in the context of Longhi's version of the
Fano-Anderson model. Most authors assume the sudden approximation where the
coupling is turned on instantaneously. We consider a finite rise time T, both
numerically and analytically. When the coupling is ramped up linearly over a
switching time T, we show that the asymptotic survival amplitude acquires a
phase T and is modulated by a factor (sin T)/T. Several other results relating
to the solution of the model are obtained. All site amplitudes have the same
decay constant during the exponential decay regime. In the asymptotic regime,
the amplitude and phase of decay oscillations depend on the initial-switching
profile, but the period does not.Comment: 12 pages, 10 figures, accepted by Phys. Rev.
Personal Contact with Refugees is Key to Welcoming Them: An Analysis of Politicians' and Citizens' Attitudes Towards Refugee Integration
Redox properties of the iron-sulfur clusters in activated Fe-hydrogenase from Desulfovibrio vulgaris (Hildenborough)
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65750/1/j.1432-1033.1992.tb17261.x.pd
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