366 research outputs found
Local minimal energy landscapes in river networks
The existence and stability of the universality class associated to local
minimal energy landscapes is investigated. Using extensive numerical
simulations, we first study the dependence on a parameter of a partial
differential equation which was proposed to describe the evolution of a rugged
landscape toward a local minimum of the dissipated energy. We then compare the
results with those obtained by an evolution scheme based on a variational
principle (the optimal channel networks). It is found that both models yield
qualitatively similar river patterns and similar dependence on . The
aggregation mechanism is however strongly dependent on the value of . A
careful analysis suggests that scaling behaviors may weakly depend both on
and on initial condition, but in all cases it is within observational
data predictions. Consequences of our resultsComment: 12 pages, 13 figures, revtex+epsfig style, to appear in Phys. Rev. E
(Nov. 2000
Measurement report: In situ observations of deep convection without lightning during the tropical cyclone Florence 2018
Hurricane Florence was the sixth named storm in the Atlantic hurricane season 2018. It caused dozens of deaths and major economic damage. In this study, we present in situ observations of trace gases within tropical storm Florence on 2 September 2018, after it had developed a rotating nature, and of a tropical wave observed close to the African continent on 29 August 2018 as part of the research campaign CAFE Africa (Chemistry of the Atmosphere: Field Experiment in Africa) with HALO (High Altitude and LOng Range Research Aircraft). We show the impact of deep convection on atmospheric composition by measurements of the trace gases nitric oxide (NO), ozone (O), carbon monoxide (CO), hydrogen peroxide (HO), dimethyl sulfide (DMS) and methyl iodide (CHI) and by the help of color-enhanced infrared satellite imagery taken by GOES-16. While both systems, i.e., the tropical wave and the tropical storm, are deeply convective, we only find evidence for lightning in the tropical wave using both in situ NO measurements and data from the World Wide Lightning Location Network (WWLLN)
Oral administration of antineoplastic agents: the challenges for healthcare professionals
Recent progress in cancer treatmen
Effects of tetracycline, sulfonamide, fluoroquinolone, and lincosamide load in pig slurry on lettuce: Agricultural and human health implications
The application of pig slurry as fertilizer in agriculture provides nutrients, but it can also contain veterinary
medicines, including antibiotic residues (ABs), which can have an ecotoxicological impact on agroecosystems.
Furthermore, uptake, translocation, and accumulation of ABs in crops can mobilize them throughout the food
chain. This greenhouse study aims to assess AB uptake from soil fertilized with pig slurry and its phenotypical
effects on Lactuca sativa LThe authors gratefully acknowledge the financial support of the
Spanish Ministry of Science and Innovation through project AGL 2017-
89518-R. IDAEA-CSIC is a Severo Ochoa Centre of Excellence (Spanish
Ministry of Science and Innovation, Project CEX 2018-000794-S).
Monica Escola Casas wishes to thank the Beatriu de Pinos 2018 grant
program (MSCA grant agreement number 801370) for the funding. The
authors likewise thank Miquel Massip, Daniel Fenero, and Nerea Gran-
ados for their technical assistance in the greenhouse facilityPostprint (published version
Occurrence of antibiotics in Lettuce (Lactuca sativa L.) and Radish (Raphanus sativus L.) following organic soil fertilisation under plot-scale conditions: Crop and human health implications
Recent studies have demonstrated the crop uptake of antibiotics (ABs) from soils treated with AB-carrying fertilisers. However, there is a lack of plot-scale studies linking their effects at the agronomic and metabolomic/transcriptomic level to their impact on human health. This paper assesses the plant uptake of 23 ABs following two productive cycles of lettuce and radish cropped with sewage sludge, pig slurry, the organic fraction of municipal solid waste, or chemical fertilisation under plot-scale conditions (32 plots spanning 3-10 m2 each). AB uptake by plants depended on both the vegetable and the AB class and was higher in radish than in lettuce edible parts. Levels ranged from undetectable to up to 76 ng/g (fresh weight). Repetitive organic fertilisation resulted in an increase in the concentration of ABs in lettuce leaves, but not in radish roots. Significant metabolomic and transcriptomic changes were observed following soil fertilisation. Nevertheless, a human health risk assessment indicates that the occurrence of ABs in lettuce or radish edible parts does not pose any risk. To our knowledge, this is the first holistic plot-scale study demonstrating that the use of organic fertilisers containing ABs is safe for crop security and human health.The authors gratefully acknowledge the financial support of the Spanish Ministry of Science and Innovation through projects AGL2017-
89518-R and RTI2018-096175-B-I00. IDAEA-CSIC is a Severo Ochoa Centre of Excellence (Spanish Ministry of Science and Innovation,
Project CEX2018-000794-S). Mònica Escolà Casas wishes to thank the Beatriu de Pinós 2018 grant programme (MSCA grant agreement number 801370) for the funding.Peer ReviewedPostprint (published version
An Exactly Solvable Anisotropic Directed Percolation Model in Three Dimensions
We solve exactly a special case of the anisotropic directed bond percolation
problem in three dimensions, in which the occupation probability is 1 along two
spatial directions, by mapping it to a five-vertex model. We determine the
asymptotic shape of the ininite cluster and hence the direction dependent
critical probability. The exponents characterising the fluctuations of the
boundary of the wetted cluster in d-dimensions are related to those of the
(d-2)-dimensional KPZ equation.Comment: 4 pages, RevTex, 4 figures. 1 reference added, minor change
Modification of a conventional photolytic converter for improving aircraft measurements of NO via chemiluminescence
Nitrogen oxides (NO≡NO+NO) are centrally involved in the photochemical processes taking place in the Earth\u27s atmosphere. Measurements of NO, particularly in remote areas where concentrations are of the order of parts per trillion by volume (pptv), are still a challenge and subject to extensive research. In this study, we present NO measurements via photolysis–chemiluminescence during the research aircraft campaign CAFE Africa (Chemistry of the Atmosphere – Field Experiment in Africa) 2018 around Cabo Verde and the results of laboratory experiments to characterize the photolytic converter used. We find the NO reservoir species MPN (methyl peroxy nitrate) to produce the only relevant thermal interference in the converter under the operating conditions during CAFE Africa. We identify a memory effect within the conventional photolytic converter (type 1) associated with high NO concentrations and rapidly changing water vapor concentrations, accompanying changes in altitude during aircraft measurements, which is due to the porous structure of the converter material. As a result, NO artifacts, which are amplified by low conversion efficiencies, and a varying instrumental background adversely affect the NO measurements. We test and characterize an alternative photolytic converter (type 2) made from quartz glass, which improves the reliability of NO measurements in laboratory and field studies
Parity nonconservation in deuteron photoreactions
We calculate the asymmetries in parity nonconserving deuteron
photodisintegration due to circularly polarized photons gamma+d to n+p with the
photon laboratory energy ranging from the threshold up to 10 MeV and the
radiative capture of thermal polarized neutrons by protons n+p to gamma+d. We
use the leading order electromagnetic Hamiltonian neglecting the smaller
nuclear exchange currents. Comparative calculations are done by using the
Reid93 and Argonne v18 potentials for the strong interaction and the DDH and
FCDH "best" values for the weak couplings in a weak one-meson exchange
potential. A weak NDelta transition potential is used to incorporate also the
Delta(1232)-isobar excitation in the coupled-channels formalism.Comment: 14 pages, 13 figures (18 eps files), LaTeX2
Local mean-field study of capillary condensation in silica aerogels
We apply local mean-field (i.e. density functional) theory to a lattice model
of a fluid in contact with a dilute, disordered gel network. The gel structure
is described by a diffusion-limited cluster aggregation model. We focus on the
influence of porosity on both the hysteretic and the equilibrium behavior of
the fluid as one varies the chemical potential at low temperature. We show that
the shape of the hysteresis loop changes from smooth to rectangular as the
porosity increases and that this change is associated to disorder-induced
out-of-equilibrium phase transitions that differ on adsorption and on
desorption. Our results provide insight in the behavior of He in silica
aerogels.Comment: 19 figure
Parity nonconserving cold neutron-parahydrogen interactions
Three pion dominated observables of the parity nonconserving interactions
between the cold neutrons and parahydrogen are calculated. The transversely
polarized neutron spin rotation, unpolarized neutron longitudinal polarization,
and photon-asymmetry of the radiative polarized neutron capture are considered.
For the numerical evaluation of the observables, the strong interactions are
taken into account by the Reid93 potential and the parity nonconserving
interactions by the DDH model along with the two-pion exchange.Comment: 17 pages, 2 figure
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