1,168 research outputs found
Value creation strategies in credence food productions. The case of organic farming in Italy
In this paper we analyse different strategies used by Italian organic farmers to create value from credence food production. More specifically, we consider the following strategies: participation in policy support programmes (i.e. rural development measures and agro-environmental schemes), direct marketing (i.e. short-chains, on-farm businesses, agro-tourism), on-farm processing and being a member of a marketing and/or processing cooperative. We use data from the 2006 Italian FADN (Farm Accountancy Data Network) related to 981 organic farmers. To estimate the factors affecting farmers’ strategies and to evaluate them simultaneously we implement a multivariate probit model (MVP). The results could be helpful to implement guidelines for public and private intervention in the next CAP programming period. Allowing for differences in farmers’ goals and their impact on the choice of farming method and strategies is important in a modern competitive scenario
Community Supported Agriculture in the urban fringe: empirical evidence for project potentiality in the metropolitan area of Naples (Italy)
Urbanisation of city-side areas effects on farm land use and organisation are analysed in this study with the objective of seeking the most effective way to implement a Community Supported Agriculture (CSA) scheme. Specifically, we used a theoretical framework to describe and assess the relationships between urbanisation and changes in farm-styles in the city belt. Our analysis is based on a case study in the protected area of the Campi Flegrei Regional Park situated in the north-western part of the Neapolitan metropolitan area, which is a peri-urban rural area with severe environmental management problems. Our results from the empirical analysis allowed us to distinguish the farms of the area into three behavioural-social groups on the basis of specific features, in order to identify the best suited type of farm for the strategic implementation of the CSA. A market scenario was predicted for each of them without any intervention
Factors Affecting Participation of Italian Farmers in Rural Development Policy
In this paper a (micro)econometric approach is developed by considering the farmer likelihood to participate in different policy programs as linked to the objective of farmer to maximize their welfare. In this way we model farmers participation in policy support scheme by using a new institutional economics approach and conceptualizing the decision to entry as a contractual choice between two rural development types of policy. Different discrete choice modelling approaches are used to analyze the complementarity/ substitutability of different policy programs such as environmental-related measures and farm investment supports policy schemes and the main driving factors behind them. We use an extensive cross-sectional database related to the Italian FADN 2006. Results indicate that social capital and institutional factors should be taken much more into account in order to understand farmers likelihood to entry in policy support schemes. Location and farm(er) socio-economic features are also relevant factors. Moreover complementarity has been found between different policy schemes
Analysis of multi-sensor data, 12 September - 11 December 1968
Analysis of multi-sensor data obtained by Earth Resources Aircraft Progra
High-resolution Spectroscopy of [Ne II] Emission from TW Hya
We present high-resolution echelle spectra of [Ne II] 12.81 micron emission
from the classical T Tauri star (CTTS) TW Hya obtained with MICHELLE on Gemini
North. The line is centered at the stellar radial velocity and has an intrinsic
FWHM of 21\pm 4 km/s. The line width is broader than other narrow emission
lines typically associated with the disk around TW Hya. If formed in a disk,
the line broadening could result from turbulence in a warm disk atmosphere,
Keplerian rotation at an average distance of 0.1 AU from the star, or a
photoevaporative flow from the optically-thin region of the disk. We place
upper limits on the [Ne II] emission flux from the CTTSs DP Tau and BP Tau.Comment: Accepted by ApJ. 18 pages, including 2 figures and 2 table
The Inner Rim of YSO Disks: Effects of dust grain evolution
Dust-grain growth and settling are the first steps towards planet formation.
An understanding of dust physics is therefore integral to a complete theory of
the planet formation process. In this paper, we explore the possibility of
using the dust evaporation front in YSO disks (`the inner rim') as a probe of
the dust physics operating in circumstellar disks. The geometry of the rim
depends sensitively on the composition and spatial distribution of dust. Using
radiative transfer and hydrostatic equilibrium calculations we demonstrate that
dust growth and settling can curve the evaporation front dramatically (from a
cylindrical radius of about 0.5 AU in the disk mid-plane to 1.2 AU in the disk
upper layers for an A0 star). We compute synthetic images and interferometric
visibilities for our representative rim models and show that the current
generation of near-IR long-baseline interferometers (VLTI, CHARA) can strongly
constrain the dust properties of circumstellar disks, shedding light on the
relatively poorly understood processes of grain growth, settling and turbulent
mixing.Comment: 26 pages, 9 figures. Accepted for publication in Ap
Tracing Slow Winds from T Tauri Stars via Low Velocity Forbidden Line Emission
Using Keck/HIRES spectra {\Delta}v ~ 7 km/s, we analyze forbidden lines of [O
I] 6300 {\AA}, [O I] 5577 {\AA} and [S II] 6731 {\AA} from 33 T Tauri stars
covering a range of disk evolutionary stages. After removing a high velocity
component (HVC) associated with microjets, we study the properties of the low
velocity component (LVC). The LVC can be attributed to slow disk winds that
could be magnetically (MHD) or thermally (photoevaporative) driven. Both of
these winds play an important role in the evolution and dispersal of
protoplanetary material.
LVC emission is seen in all 30 stars with detected [O I] but only in 2 out of
eight with detected [S II] , so our analysis is largely based on the properties
of the [O I] LVC. The LVC itself is resolved into broad (BC) and narrow (NC)
kinematic components. Both components are found over a wide range of accretion
rates and their luminosity is correlated with the accretion luminosity, but the
NC is proportionately stronger than the BC in transition disks.
The FWHM of both the BC and NC correlates with disk inclination, consistent
with Keplerian broadening from radii of 0.05 to 0.5 AU and 0.5 to 5 AU,
respectively. The velocity centroids of the BC suggest formation in an MHD disk
wind, with the largest blueshifts found in sources with closer to face-on
orientations. The velocity centroids of the NC however, show no dependence on
disk inclination. The origin of this component is less clear and the evidence
for photoevaporation is not conclusive
Eggshell Assembly inDrosophila:Processing and Localization of Vitelline Membrane and Chorion Proteins
AbstractTheDrosophilaeggshell consists of three major proteinaceous layers: the vitelline membrane, the inner chorionic layer, and the outer endochorion. During the latter stages of oogenesis, the proteins that comprise these layers are synthesized and secreted by epithelial follicle cells which surround the maturing oocyte. While there is considerable knowledge of the structural units which comprise the eggshell layers, there is little knowledge of how individual proteins function or interact with one another to form the structure. Immunoelectron microscopy was used to follow the distribution of four different eggshell proteins in the assembling and mature eggshell. sV23 and sV17, follicle cell proteins synthesized during the early stages of eggshell formation (stages 8–10), were distributed within the vitelline membrane layer at all stages. Despite marked temporal differences in their accumulation profiles, s36 and s18, putative chorion proteins, were similarly distributed throughout the floor, pillars, and roof of the endochorion. Although the vitelline membrane appears to be morphologically complete by stage 11, developmental Western blots and immunolocalization data indicate that molecular dynamism persists within the layer throughout the subsequent choriogenic stages. During early chorion formation the vitelline membrane appears to act as a reservoir for chorion proteins since s36 was found predominantly in the vitelline membrane layer of stage 12 egg chambers. During the late choriogenic stages (13–14), both sV17 and sV23 are processed to smaller derivatives. Interactions between the eggshell layers were suggested by ultrastructural analysis of a sV23 protein null mutant which showed that the structural integrity of the outer chorion is dependent upon the presence of a vitelline membrane component
Close-in ice lines and the super-stellar C/O ratio in discs around very low-mass stars
The origin of the elevated C/O ratios in discs around late M dwarfs compared
to discs around solar-type stars is not well understood. Here we endeavour to
reproduce the observed differences in the disc C/O ratios as a function of
stellar mass using a viscosity-driven disc evolution model and study the
corresponding atmospheric composition of planets that grow inside the water-ice
line in these discs. We carried out simulations using a coupled disc evolution
and planet formation code that includes pebble drift and evaporation. We used a
chemical partitioning model for the dust composition in the disc midplane.
Inside the water-ice line, the disc's C/O ratio initially decreases to
sub-stellar due to the inward drift and evaporation of water-ice-rich pebbles
before increasing again to super-stellar values due to the inward diffusion of
carbon-rich vapour. We show that this process is more efficient for very
low-mass stars compared to solar-type stars due to the closer-in ice lines and
shorter disc viscous timescales. In high-viscosity discs, the transition from
sub-stellar to super-stellar takes place faster due to the fast inward
advection of carbon-rich gas. Our results suggest that planets accreting their
atmospheres early (when the disc C/O is still sub-stellar) will have low
atmospheric C/O ratios, while planets that accrete their atmospheres late (when
the disc C/O has become super-stellar) can obtain high C/O ratios. Our model
predictions are consistent with observations, under the assumption that all
stars have the same metallicity and chemical composition, and that the vertical
mixing timescales in the inner disc are much shorter than the radial advection
timescales. This further strengthens the case for considering stellar
abundances alongside disc evolution in future studies that aim to link planet
(atmospheric) composition to disc composition.Comment: Accepted for publication in A&
Dynamic PRA: an Overview of New Algorithms to Generate, Analyze and Visualize Data
State of the art PRA methods, i.e. Dynamic PRA
(DPRA) methodologies, largely employ system
simulator codes to accurately model system dynamics.
Typically, these system simulator codes (e.g., RELAP5 )
are coupled with other codes (e.g., ADAPT,
RAVEN that monitor and control the simulation. The
latter codes, in particular, introduce both deterministic
(e.g., system control logic, operating procedures) and
stochastic (e.g., component failures, variable uncertainties)
elements into the simulation. A typical DPRA analysis is
performed by:
1. Sampling values of a set of parameters from the
uncertainty space of interest
2. Simulating the system behavior for that specific set of
parameter values
3. Analyzing the set of simulation runs
4. Visualizing the correlations between parameter values
and simulation outcome
Step 1 is typically performed by randomly sampling
from a given distribution (i.e., Monte-Carlo) or selecting
such parameter values as inputs from the user (i.e.,
Dynamic Event Tre
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