21 research outputs found
Does farm level diversification improve household dietary diversity? Evidence from Rural India
Using data from a nationally representative survey of farm households in India we identify a causal link between dietary-diversity and farm level diversification. Propensity score matching techniques show that households which exclusively grow cereals (our treatment-group) consume significantly less diverse diet compared to those who grow both cereals and other crop-groups (our control-group). Various matching rules have been used to check for robustness of our results
Indian Agricultural Growth- A Spatial Perspective
In this paper, we study the role of relative spatial location of states on agricultural growth in India.
We use different definitions of neighbourhood and through a Spatial Durbin Model in a dynamic
panel framework, we find that district based weighing scheme best explains the spatial dependence.
The channels through which spatial spill-over occur are rural literacy, roads, irrigation and income
of neighbouring states. The other factors driving agricultural income growth in India are inputs,
infrastructural support and agricultural diversification. Identification of these channels of spatial
interdependence will have implications for policies aimed at reducing spatial differences across
Indian states
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Farm households that adopt ICT change production decisions: evidence from India
Neighborhood and agricultural clusters across states of India
In this study we trace how number and members of income clusters have changed in Indian agriculture over the last four and a half decades. Two features which stand out in our results are that not all geographical neighbors belong to the same cluster and clusters include both geographical neighbors and non-neighbors. To identify the factors driving a pair of states to common cluster we then use a logit model and find that smaller is the relative difference between them in terms of mechanization, infrastructural support, deviations from normal rainfall and price differences, higher are the chances
that they will be in the same income cluster. Between contiguous and non-contiguous state pairs we find that apart from the common factors, smaller relative differences in irrigation support, rainfall and price differences additionally brings non-contiguous states together
Shear-Dependent Interactions in Hydrophobically Modified Ethylene Oxide Urethane (HEUR) Based Rheology Modifier–Latex Suspensions: Part 1. Molecular Microstructure
We have studied the microstructure
of latex suspensions formulated
with hydrophobically modified ethylene (oxide) urethane (HEUR) thickener
(or rheology modifier, RM) using small-angle neutron scattering under
shear (rheo-SANS). Within the shear rate range studied (0–1000
s<sup>–1</sup>), the neutron scattering profiles are consistent
with a polydisperse core–shell model, with the latex particles
comprising the core and an adsorbed layer of water-swollen RM on the
latex surface forming the shell. The core–shell structure is
isotropic under quiescent conditions but becomes anisotropic under
shear (with the major axis along the vorticity direction). During
shear, the solvent (D<sub>2</sub>O/H<sub>2</sub>O) is expelled (hydrodynamic
squeezing) from the swollen polymer chains, and the shell structure
becomes denser. The <i>anisotropic</i> shell is a result
of differing degrees of compression along the flow and vorticity directions.
With increasing shear rate, the shell thickness (in both the flow
and vorticity direction) tends toward asymptotic values (with the
shell thickness in the vorticity direction greater than the shell
thickness in the flow direction) independent of the RM hydrophobe
density (defined as the average number of hydrophobes per polymer
chain). The RM concentration (w/w) in the adsorbed layer varies from
∼0.05–0.1 (at low shear) to ∼0.25–0.4
(high shear, ∼1000 s<sup>–1</sup>) with higher values
for the RM polymer with higher hydrophobe density. The swollen RM-water
shell substantially increases the effective volume fraction of the
dispersed latex particles. We find, however, that accounting for this
increase within the conventional effective hard-sphere (Krieger–Dougherty)
dispersion rheology model does not fully explain the higher viscosity
of the formulated mixture. We hypothesize the existence of latex–latex
interactions mediated by RM polymer bridges even at high shear. The
large-scale structure of the particle assembly will be reported in
a subsequent manuscript
Formulation-Controlled Positive and Negative First Normal Stress Differences in Waterborne Hydrophobically Modified Ethylene Oxide Urethane (HEUR)-Latex Suspensions
Hydrophobically modified ethylene
oxide urethane (HEUR) associative
thickeners are widely used to modify the rheology of waterborne paints.
Understanding the normal stress behavior of the HEUR-based paints
under high shear is critical for many applications such as brush drag
and spreading. We observed that the first normal stress difference, <i>N</i><sub>1</sub>, at high shear (large Weissenberg number)
can be positive or negative depending on the HEUR hydrophobe strength
and concentration. We propose that the algebraic sign of the <i>N</i><sub>1</sub> is primarily controlled by two factors: (a)
adsorption of HEURs on the latex surface and (b) the ability of HEURs
to form transient molecular bridges between latex particles. Such
transient bridges are favored for dispersions with small interparticle
distances and dense surface coverages; in these systems; HEUR-bridged
latex microstructures flow-align in high shear and exhibit positive <i>N</i><sub>1</sub>. In the absence of transient bridges (large
interparticle distances, low surface coverage), the dispersion rheology
is similar to that of weakly interacting spheres, exhibiting negative <i>N</i><sub>1</sub>. The results are summarized in a simplified
phase diagram connecting formulation, microstructure, and the <i>N</i><sub>1</sub> behavior
Shear-Dependent Interactions in Hydrophobically Modified Ethylene Oxide Urethane (HEUR) Based Coatings: Mesoscale Structure and Viscosity
We
have investigated the in situ mesoscale structure of paint formulations
under shear using ultra small-angle neutron scattering (rheo-USANS).
Contrast match conditions were utilized to independently probe the
latex binder particle aggregates and the TiO<sub>2</sub> pigment particle
aggregates. Two different latex chemistries and two different hydrophobically
modified ethylene oxide urethane (HEUR) rheology modifiers were studied.
The rheo-USANS data reveal that both the latex particles and the TiO<sub>2</sub> particles form transient aggregates which are fractal in
nature. The structures depend on the chemistry of the binder particles,
the type of rheology modifier present and the shear stress imposed
upon the formulation. The aggregate size of both the latex and pigment
generally decreases with increasing shear stress. In two of the formulations
studied, the latex and TiO<sub>2</sub> correlation lengths remain
large even at high shear stress and are characteristic of TiO<sub>2</sub> crowding. In a third formulation, shear induces string-like
aggregate structures of TiO<sub>2</sub>, and a further increase in
shear leads to pigment particles becoming more uniformly dispersed.
The changes in the latex and pigment transient aggregate structures
correlate with the changes observed in their viscosity flow curve
profiles. We have used this correlation to develop an elementary viscosity
prediction model based on the structural parameters extracted from
the rheo-USANS data. Using a single fitting parameter and only the
latex transient fractal aggregate structural parameters, good agreement
between the measured and calculated viscosity is obtained. This implies
that the structural parameters extracted from the scattering data
are representative of the colloidal structure under shear and that
energy dissipation from transient fractal aggregates of latex is the
predominant mechanism of viscosity creation in HEUR thickened latex
paints