1,776 research outputs found
Agro-environmental evaluation of vineyard management using organic farming and integrated plant production systems
Organic farming is often considered to be the most environmentally-friendly crop management system, even if integrated production also aims at decreasing the impact of agriculture on the natural environment. In order to establish references for the agro-environmental evaluation of these two production systems in relation to grape growing, INRA carried out an initial study from 2001 to 2004 at the plot scale. This study focused on two grape varieties (Merlot N and Cabernet Sauvignon) in its Couhins vineyard (Graves cru classé), located on two organically-farmed plots and two plots using integrated production, a system based on the implementation of decision rules aimed at limiting the number of pest control treatments. Production means only differed in terms of pest control management (choice of products and application strategy). Each of the parcels covered approximately 0.30 ha. An agro-environmental evaluation of these two systems was made for 2003, using the INDIGO Vigne method at the plot level. Because of their nature, the choice of parameters for the indicators used determines the interpretation of the results. Nevertheless, it appears that the environmental impact of integrated production is more favourable in this case than that of organic farming, particularly in terms of pest control and energy indicators. One of the reasons for this is the high number of applications of pest control treatments in organic farming and, as a result, higher energy consumption, as well as the use of copper that has a major impact on deep waters, the ground and the air. The two systems can decrease their environmental impact by limiting the number of tractor runs for soil maintenance. Flexibility appears to be greater in the case of integrated production since, contrary to organic farming, it can use herbicides under the row. The calculation of the agro-environmental evaluation on the parcel using integrated protection with chemical weeding under the row leads to a clear improvement of the energy indicator, without significantly decreasing the value of the pest control indicator. Natural sodding of the inter-row, when the vigour of the vineyard allows it, provides an effective solution since the decrease in the number of tractor runs leads to an improvement of erosion and organic matter indicators. This type of evaluation should be carried out at the scale of a group of plots or of an entire wine-farm. Ground maintenance is an important factor in decreasing the impact of grape growing on the environment. In this respect, organic farming offers some promising prospects
A Note on Partitioning Effects Estimates Over Space
In this paper we provide an applied example for calculating the so-called effects estimates of LeSage and Pace (2009) for partitions of the impacts over space. While the partitioning of the impacts by orders of neighbors over space for the spatial autoregressive (SAR) model is a relatively straightforward procedure, care must be taken in the case of the spatial Durbin model (SDM). We provide an illustration of these calculations for both models using a widely available data set on voter turnout for the 1980 United States presidential election
Skyrmions and the Nuclear Force
The derivation of the nucleon-nucleon force from the Skyrme model is
reexamined. Starting from previous results for the potential energy of
quasistatic solutions, we show that a calculation using the Born-Oppenheimer
approximation properly taking into account the mixing of nucleon resonances,
leads to substantial central attraction. We obtain a potential that is in
qualitative agreement with phenomenological potentials. We also study the
non-adiabatic corrections, such as the velocity dependent transition
potentials, and discuss their importance.Comment: 24 pages, UPR-0124M
A probable giant planet imaged in the Beta Pictoris disk
Since the discovery of its dusty disk in 1984, Beta Pictoris has become the
prototype of young early-type planetary systems, and there are now various
indications that a massive Jovian planet is orbiting the star at ~ 10 AU.
However, no planets have been detected around this star so far. Our goal was to
investigate the close environment of Beta Pic, searching for planetary
companion(s). Deep adaptive-optics L'-band images of Beta Pic were recorded
using the NaCo instrument at the Very Large Telescope. A faint point-like
signal is detected at a projected distance of ~ 8 AU from the star, within the
North-East side of the dust disk. Various tests were made to rule out with a
good confidence level possible instrumental or atmospheric artifacts. The
probability of a foreground or background contaminant is extremely low, based
in addition on the analysis of previous deep Hubble Space Telescope images. The
object L'=11.2 apparent magnitude would indicate a typical temperature of ~1500
K and a mass of ~ 8 Jovian masses. If confirmed, it could explain the main
morphological and dynamical peculiarities of the Beta Pic system. The present
detection is unique among A-stars by the proximity of the resolved planet to
its parent star. Its closeness and location inside the Beta Pic disk suggest a
formation process by core accretion or disk instabilities rather than a
binary-like formation process.Comment: 5 pages, 3 figures, 1 table. A&A Letters, in pres
Impact of the European Clinical Trials Directive on prospective academic clinical trials associated with BMT
The European Clinical Trials Directive (EU 2001; 2001/20/EC) was introduced to improve the efficiency of commercial and academic clinical trials. Concerns have been raised by interested organizations and institutions regarding the potential for negative impact of the Directive on non-commercial European clinical research. Interested researchers within the European Group for Blood and Marrow Transplantation (EBMT) were surveyed to determine whether researcher experiences confirmed this view. Following a pilot study, an internet-based questionnaire was distributed to individuals in key research positions in the European haemopoietic SCT community. Seventy-one usable questionnaires were returned from participants in different EU member states. The results indicate that the perceived impact of the European Clinical Trials Directive has been negative, at least in the research areas of interest to the EBMT
Comment on Neutron-Proton Spin-Correlation Parameter A_{ZZ} at 68 Mev
We present two arguments indicating that the large value for the
mixing parameter at 50 MeV, which the Basel group extracted from their recent
measurement, may be incorrect. First, there are nucleon-nucleon (NN)
potentials which predict the at 50 MeV substantially below the
Basel value and reproduce the Basel data accurately. Second, the large
value for at 50 MeV proposed by the Basel group can only be
explained by a model for the NN interaction which is very unrealistic (no
-meson and essentially a point-like vertex) and overpredicts the
in the energy range where it is well determined (150--500 MeV) by
a factor of two.Comment: 6 pages text (LaTex) and 2 figures (paper, will be faxed upon
request), UI-NTH-930
Final state interaction effects in mu-capture induced two-body decay of 3He
The mu-capture process on 3He leading to a neutron, a deuteron and a
mu-neutrino in the final state is studied. Three-nucleon Faddeev wave functions
for the initial 3He bound and the final neutron-deuteron scattering states are
calculated using the BonnB and Paris nucleon-nucleon potentials. The nuclear
weak current operator is restricted to impulse approximation. Large effects on
the decay rates of the final state interaction are found. The comparison to
recent experimental data shows that the inclusion of final state interactions
drastically improves the description of the data.Comment: 14 pages, 6 eps figure
Density fluctuations measured by ISEE 1-2 in the Earth's magnetosheath and the resultant scattering of radio waves
A method for detection of structure
Context. In order to understand the evolution of molecular clouds it is
important to identify the departures from self-similarity associated with the
scales of self-gravity and the driving of turbulence.
Aims. A method is described based on structure functions for determining
whether a region of gas, such as a molecular cloud, is fractal or contains
structure with characteristic scale sizes.
Methods. Using artificial data containing structure it is shown that
derivatives of higher order structure functions provide a powerful way to
detect the presence of characteristic scales should any be present and to
estimate the size of such structures. The method is applied to observations of
hot H2 in the Kleinman-Low nebula, north of the Trapezium stars in the Orion
Molecular Cloud, including both brightness and velocity data. The method is
compared with other techniques such as Fourier transform and histogram
techniques.
Results. It is found that the density structure, represented by H2 emission
brightness in the K-band (2-2.5micron), exhibits mean characteristic sizes of
110, 550, 1700 and 2700AU. The velocity data show the presence of structure at
140, 1500 and 3500AU. Compared with other techniques such as Fourier transform
or histogram, the method appears both more sensitive to characteristic scales
and easier to interpret.Comment: Astronomy and Astrophysics, in pres
Cross section and analyzing power of pol{p}p -> pn pi+ near threshold
The cross section and analyzing power of the pol{p}p -> pn pi+ reaction near
threshold are estimated in terms of data obtained from the pol{p}p -> d pi+ and
pp -> pp pi0 reactions. A simple final state interaction theory is developed
which depends weakly upon the form of the pion-production operator and includes
some Coulomb corrections. Within the uncertainties of the model and the input
data, the approach reproduces well the measured energy dependence of the total
cross section and the proton analyzing power at a fixed pion c.m. angle of
90deg, from threshold to T_p = 330 MeV. The variation of the differential cross
section with pion angle is also very encouraging.Comment: 20 pages, Latex including 4 eps figure
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