723 research outputs found
Introducing Public Procurement
This chapter introduces the concept of public procurement and explains what itis and is not and how it is distinct from private purchasing. To do so it describesthe public-private continuum and explains what publicness is. Subsequently, thepublic procurement process is described using the circular 3P (Prepare, Purchase, and Perform) model. This is followed by a discussion of the seven developmental stages of public procurement. It explains how public procurement has developed over time from an executive management function aimed at fulfilling an internal demand to a policy instrument that can collaboratively create public value. The chapter ends with an explanation of the multifaceted nature of public procurement and why understanding and applying multiple perspectives (e.g., economic, legal, societal, and political) is necessary to bring public procurement into a new era and fully understand and utilize the impact of public procurement
Promoting self-facilitating feedback processes in coastal ecosystem engineers to increase restoration success:Testing engineering measures
Coastal ecosystem engineers often depend on self‐facilitating feedbacks to ameliorate environmental stress. This makes the restoration of such coastal ecosystem engineers difficult. We question if we can increase transplantation success in highly dynamic coastal areas by engineering measures that promote the development of self‐facilitating feedback processes.Intertidal blue mussels Mytilus edulis are a typical example of ecosystem engineers that are difficult to restore. A lack of self‐facilitating feedbacks at low densities limits establishment success when young mussels are transplanted on dynamic mudflats.In a large field experiment, we investigated the possibility of increasing transplantation success by stimulating the formation of an aggregated spatial configuration in mussels, thereby reducing hydrologically induced dislodgment and the risks of predation. For this, we applied engineering measures in the form of fences that trapped wave dislodged mussels.Mussel loss rates were significantly lower when mussels were placed between both artificial fences, and in high densities (4.2 kg/m2) compared with mussels placed in areas without fences and in low densities (2.1 kg/m2). The fences induced the formation of a banded pattern with high local mussel densities, which locally reduced predation.Synthesis and applications. Our results underline the importance of actively promoting the development of self‐facilitating processes, such as aggregation into patterns, in restoration projects of ecosystem engineers. In particular, the current study shows that engineering measures can help to initiate these kinds of self‐facilitating interactions, especially in highly dynamic areas
Search for Scalar Leptons in e+e- collisions at \sqrt{s}=189 GeV
We report the result of a search for scalar leptons in e+e- collisions at 189
GeV centre-of-mass energy at LEP. No evidence for such particles is found in a
data sample of 176 pb^{-1}. Improved upper limits are set on the production
cross sections for these new particles. New exclusion contours in the parameter
space of the Minimal Supersymmetric Standard Model are derived, as well as new
lower limits on the masses of these supersymmetric particles. Under the
assumptions of common gaugino and scalar masses at the GUT scale, we set an
absolute lower limit on the mass of the lightest scalar electron of 65.5 Ge
Search for Low Scale Gravity Effects in e+e- Collisions at LEP
Recent theories propose that quantum gravity effects may be observable at LEP
energies via gravitons that couple to Standard Model particles and propagate
into extra spatial dimensions. The associated production of a graviton and a
photon is searched for as well as the effects of virtual graviton exchange in
the processes: e+e- -> gamma gamma, ZZ, WW, mu mu, tau tau, qq and ee No
evidence for this new interaction is found in the data sample collected by the
L3 detector at LEP at centre-of-mass energies up to 183 GeV. Limits close to 1
TeV on the scale of this new scenario of quantum gravity are set
Formation of the in Two-Photon Collisions at LEP
The two-photon width of the meson has been
measured with the L3 detector at LEP. The is studied in the decay
modes , KK, KK,
KK, , , and
using an integrated luminosity of 140 pb at GeV and
of 52 pb at GeV. The result is
(BR) keV. The dependence of the cross section is studied for
GeV. It is found to be better described by a Vector Meson
Dominance model form factor with a J-pole than with a -pole. In addition,
a signal of events is observed at the mass. Upper limits
for the two-photon widths of the , , and are also
given
Search for Charginos with a Small Mass Difference with the Lightest Supersymmetric Particle at \sqrt{s} = 189 GeV
A search for charginos nearly mass-degenerate with the lightest
supersymmetric particle is performed using the 176 pb^-1 of data collected at
189 GeV in 1998 with the L3 detector. Mass differences between the chargino and
the lightest supersymmetric particle below 4 GeV are considered. The presence
of a high transverse momentum photon is required to single out the signal from
the photon-photon interaction background. No evidence for charginos is found
and upper limits on the cross section for chargino pair production are set. For
the first time, in the case of heavy scalar leptons, chargino mass limits are
obtained for any \tilde{\chi}^{+-}_1 - \tilde{\chi}^0_1 mass difference
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