Search results for "Effective"
showing 10 items of 1371 documents
Process-independent strong running coupling
2016
We unify two widely different approaches to understanding the infrared behaviour of quantum chromodynamics (QCD), one essentially phenomenological, based on data, and the other computational, realised via quantum field equations in the continuum theory. Using the latter, we explain and calculate a process-independent running-coupling for QCD, a new type of effective charge that is an analogue of the Gell-Mann--Low effective coupling in quantum electrodynamics. The result is almost identical to the process-dependent effective charge defined via the Bjorken sum rule, which provides one of the most basic constraints on our knowledge of nucleon spin structure. This reveals the Bjorken sum to be…
Implementation of local chiral interactions in the hyperspherical harmonics formalism
2021
With the goal of using chiral interactions at various orders to explore properties of the few-body nuclear systems, we write the recently developed local chiral interactions as spherical irreducible tensors and implement them in the hyperspherical harmonics expansion method. We devote particular attention to three-body forces at next-to-next-to leading order, which play an important role in reproducing experimental data. We check our implementation by benchmarking the ground-state properties of $^3$H, $^3$He and $^4$He against the available Monte Carlo calculations. We then confirm their order-by-order truncation error estimates and further investigate uncertainties in the charge radii obta…
Multitemporal Monitoring of Plant Area Index in the Valencia Rice District with PocketLAI
2016
Leaf area index (LAI) is a key biophysical parameter used to determine foliage cover and crop growth in environmental studies in order to assess crop yield. Frequently, plant canopy analyzers (LAI-2000) and digital cameras for hemispherical photography (DHP) are used for indirect effective plant area index (PAI(eff)) estimates. Nevertheless, these instruments are expensive and have the disadvantages of low portability and maintenance. Recently, a smartphone app called PocketLAI was presented and tested for acquiring PAI(eff) measurements. It was used during an entire rice season for indirect PAI(eff) estimations and for deriving reference high-resolution PAI(eff) maps. Ground PAI(eff) value…
Comprehending city and its production in Africa through a systemic approach : example of the city of Diamniadio, Dakar
2022
For a long time, the analysis of the production of the city in Africa was based on an exogenous perception according to urban models theorized and experimented with in the Occidental countries, then diffused and applied through different mechanisms in the South, bearing witness to historical relations - through the making of the colonial city - and present relations - in the context of the making of new towns. After independence, researchers looked at the redefinition of the city in Africa with its complexity and plurality according to geographical and historical trajectories, proposing new urban theories that were more nuanced and linked to local and contextual realities. Therefore, follow…
Finding the right dose of fulvestrant in breast cancer
2012
Fulvestrant is a selective estrogen receptor downregulator, behaving as a complete antagonist. It was initially approved, at a dose of 250 mg, to treat hormone dependant breast cancer in second line setting. However, a series of pharmacological and pre-clinical studies have suggested that a higher dose of 500 mg may be more effective. The present work summarizes and discusses clinical trials that have aimed to test the benefits of administering fulvestrant at a higher dose. The data support the use of a higher, and more possibly, effective dose of the agent.
A numerical model of the cloud-topped planetary boundary-layer: Impact of aerosol particles on the radiative forcing of stratiform clouds
1997
In a numerical sensitivity study, the microphysical model of stratus MISTRA, is used to investigate the impact of aerosol particles on the evolution of stratiform clouds. Four model runs are presented, each for a different type of background aerosol. Two include aerosol particle size-distributions which are typical of marine and rural continental air masses; a third represents a mixture of marine and rural continental aerosol particles, and the fourth rural continental aerosol particles with a reduced solubility in water. The results show that the microphysical structure of layer clouds was strongly affected by the physico-chemical properties of the aerosol particles from which the cloud dr…
A numerical model of the cloud-topped planetary boundary-layer: radiative forcing of aerosols in stratiform clouds
1998
In a numerical sensitivity study with the microphysical stratus model MISTRA the impact of aerosol particles on the time evolution of stratiform clouds is investigated. Four model runs with different aerosol size distributions are presented. Two size distributions are typical for maritime and continental air masses. The third model run consists of a mixture of maritime and rural aerosol particles, while in the fourth case study rural aerosol particles with a reduced water solubility are utilized. The numerical results show that the microphysical structure of the clouds is strongly affected by the physico-chemical properties of the aerosol particles. In the maritime case, with a relatively l…
Linear relationship between effective radius and precipitation water content near the top of convective clouds
2021
Quantifying the precipitation within clouds is a crucial challenge to improve our current understanding of the Earth’s hydrological cycle. We have investigated the relationship between the effective radius of droplets and ice particles (re) and precipitation water content (PWC) measured by cloud probes near the top of growing convective cumuli. The data for this study were collected by aircraft measurements in clean and polluted conditions over the Amazon Basin and over the western tropical Atlantic in September 2014. Our results indicate a threshold of re ∼ 13 μm for warm rain initiation in convective clouds, which is in agreement with previous studies. In…
Hausdorff dimension from the minimal spanning tree
1993
A technique to estimate the Hausdorff dimension of strange attractors, based on the minimal spanning tree of the point distribution is extensively tested in this work. This method takes into account in some sense the infimum requirement appearing in the definition of the Hausdorff dimension. It provides accurate estimates even for a low number of data points and it is especially suited to high-dimensional systems.