4,094 research outputs found
How labour organization may affect technology adoption: an analytical framework analysing the case of integrated pest management
Integrated Pest Management (IPM) is an important component of sustainable agriculture. Farmers who switch from a more capital-intensive pesticide-based pest management strategy to IPM have to substitute capital with labour. The adoption of IPM will therefore depend, among other things, on the opportunity costs of labour. A simple model analyses the trade-off between IPM and current farmers' best practice in developing countries. Modifications of the model include different forms of labour organization in pest management, such as owner operated and short- and long-term labour contracts. The implications are that agricultural policies, environmental policies, and labour market policies can go hand in hand. Unfortunately, this will be more likely at a higher level of original pesticide use and hence a higher level of environmental costs
Experimental Evidence for Crossed Andreev Reflection
We report on electronic transport properties of mesoscopic
superconductor-ferromagnet spin-valve structures. Two ferromagnetic iron leads
form planar tunnel contacts to a superconducting aluminum wire, where the
distance of the two contacts is of the order of the coherence length of the
aluminum. We observe a negative non-local resistance which can be explained by
crossed Andreev reflection, a process where an electron incident from one of
the leads gets reflected as a hole into the other, thereby creating a pair of
spatially separated, entangled particles.Comment: LT24 conference proceeding, 2 pages, 2 figure
Fermi detected blazars seen by INTEGRAL
Multiwavelength observations are essential to constrain physical parameters
of the blazars observed by Fermi/LAT. Among the 187 AGN significantly detected
in public INTEGRAL data above 20 keV by the imager IBIS/ISGRI, 20 blazars were
detected. 15 of these sources allowed significant spectral extraction. They
show hard X-ray spectra with an average photon index of 2.1+-0.1 and a hard
X-ray luminosity of L(20-100 keV) = 1.3e46 erg/s. 15 of the INTEGRAL blazars
are also visible in the first 16 months of the Fermi/LAT data, thus allowing to
constrain the inverse Compton branch in these cases. Among others, we analyse
the LAT data of four blazars which were not included in the Fermi LAT Bright
AGN Sample based on the first 3 months of the mission: QSO B0836+710, H
1426+428, RX J1924.8-2914, and PKS 2149-306. Especially for blazars during
bright outbursts, as already observed simultaneously by INTEGRAL and Fermi
(e.g. 3C 454.3 and Mrk 421), INTEGRAL provides unique spectral coverage up to
several hundred keV. We present the spectral analysis of INTEGRAL and Fermi
data and demonstrate the potential of INTEGRAL observations of Fermi detected
blazars in outburst by analysing the combined data set of the persistent radio
galaxy Cen A.Comment: 5 pages, 5 figures, 2009 Fermi Symposium, eConf Proceedings C09112
Gamma-Ray Bursts Observed with the Spectrometer SPI Onboard INTEGRAL
The spectrometer SPI is one of the main detectors of ESA's INTEGRAL mission.
The instrument offers two interesting and valuable capabilities for the
detection of the prompt emission of Gamma-ray bursts. Within a field of view of
16 degrees, SPI is able to localize Gamma-ray bursts with an accuracy of 10
arcmin. The large anticoincidence shield, ACS, consisting of 512 kg of BGO
crystals, detects Gamma-ray bursts quasi omnidirectionally above ~70 keV. Burst
alerts from SPI/ACS are distributed to the interested community via the
INTEGRAL Burst Alert System. The ACS data have been implemented into the 3rd
Interplanetary Network and have proven valuable for the localization of bursts
using the triangulation method. During the first 8 months of the mission
approximately one Gamma-ray burst per month was localized within the field of
fiew of SPI and 145 Gamma-ray burst candidates were detected by the ACS from
which 40 % have been confirmed by other instruments.Comment: 4 pages, 2 figures, to appear in the Proceedings of the Conference
"30 Years of GRB Discovery", Santa Fe, New Mexico, USA, September 8-12, 200
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