823 research outputs found
Piloting a commercial broiler production model for smallholders in Rwanda
Increasing food security is premised on improving economic empowerment as well as nutrition across the household. As such, developmentprojects across Africa are integrating nutrition objectives into pro-poor value chain development interventions toincrease dietary diversity and incomes. To meet the micronutrient demands of a growingpopulation, Rwanda seeks to increase the production of and access to meat-basedproteins, including chicken production. Despite Rwandaâs recent rapid economic growth,there is a limited supply of and access to animal-sourced protein nationally. A hybridbroiler model, which integrates elements of smallholder and larger intensive poultrymodels, could be a sustainable approach. A model piloted in Musanze District, Rwanda.Tworore Inkoko, Twunguke (TI) (Letâs raise chickens for profit!) uses an intensive, 100-bird model with the aim of training and supporting 750 smallholder farmers through aninnovative private-sector-based train-the-trainer approach. This study examines the initial evidence from TI production data to determine (a) the performance of improved broiler breeds in a Rwandan smallholder context, (b) farmer profitability, and (c) household consumption of broilers. With 18 months of flock data, average livability of flocks was 89%, similar to large-scale, modern broiler sector averages globally. Tworore Inkoko smallholders have been profitable, with average profit increasing as they gain experience and grow-out new flocks (profit ranging between 28 and 89 USD per flock). Birds set aside for consumption by farmers ranged from an average of 0.31 to 4.00 birds per flock, settling at closer to three per flock by the end of the first 18 months. Smallholder farmers in Rwanda have the potential to be successful through this model. Lessons learned from the rollout of this pilot project will be used to inform potential scale-up of this hybrid model across Rwanda, as well as other pro-poor value chains looking to increase food security by generating incomes and increasing access to highly nutritious and balanced diets. 
Induced Polyakov supergravity on Riemann surfaces of higher genus
An effective action is obtained for the , induced supergravity on a
compact super Riemann surface (without boundary) of genus ,
as the general solution of the corresponding superconformal Ward identity. This
is accomplished by defining a new super integration theory on
which includes a new formulation of the super Stokes theorem and residue
calculus in the superfield formalism. Another crucial ingredient is the notion
of polydromic fields. The resulting action is shown to be well-defined and free
of singularities on \sig. As a by-product, we point out a morphism between
the diffeomorphism symmetry and holomorphic properties.Comment: LPTB 93-10, Latex file 20 page
HOW FAST α PARTICLES ARE EMITTED IN "MASSIVE TRANSFER" REACTIONS ?
No abstract availabl
W-algebras from symplectomorphisms
It is shown how -algebras emerge from very peculiar canonical
transformations with respect to the canonical symplectic structure on a compact
Riemann surface. The action of smooth diffeomorphisms of the cotangent bundle
on suitable generating functions is written in the BRS framework while a
-symmetry is exhibited. Subsequently, the complex structure of the symmetry
spaces is studied and the related BRS properties are discussed. The specific
example of the so-called -algebra is treated in relation to some other
different approaches.Comment: LaTex, 25 pages, no figures, to appear in Journ. Math. Phy
Supersymmetric structure of the induced W gravities
We derive the supersymmetric structure present in W-gravities which has been
already observed in various contexts as Yang-Mills theory, topological field
theories, bosonic string and chiral W_{3}-gravity. This derivation which is
made in the geometrical framework of Zucchini, necessitates the introduction of
an appropriate new basis of variables which replace the canonical fields and
their derivatives. This construction is used, in the W_{2}-case, to deduce from
the Chern-Simons action the Wess-Zumino-Polyakov action.Comment: 17 pages, Latex. To appear in Class. Quantum. Gravit
d=2, N=2 Superconformal Symmetries and Models
We discuss the following aspects of two-dimensional N=2 supersymmetric
theories defined on compact super Riemann surfaces: parametrization of (2,0)
and (2,2) superconformal structures in terms of Beltrami coefficients and
formulation of superconformal models on such surfaces (invariant actions,
anomalies and compensating actions, Ward identities).Comment: 43 pages, late
Four-quark stability
The physics of charm has become one of the best laboratories exposing the
limitations of the naive constituent quark model and also giving hints into a
more mature description of meson spectroscopy, beyond the simple
quark--antiquark configurations. In this talk we review some recent studies of
multiquark components in the charm sector and discuss in particular exotic and
non-exotic four-quark systems, both with pairwise and many-body forces.Comment: 6 pages. Article based on the presentations by J. Vijande and J.-M.
Richard at the Fifth Workshop on Critical Stability, Erice, Sicil
Improved imaging of magnetically labeled cells using rotational magnetomotive optical coherence tomography
In this paper, we present a reliable and robust method for magnetomotive optical coherence tomography (MM-OCT) imaging of single cells labeled with iron oxide particles. This method employs modulated longitudinal and transverse magnetic fields to evoke alignment and rotation of anisotropic magnetic structures in the sample volume. Experimental evidence suggests that magnetic particles assemble themselves in elongated chains when exposed to a permanent magnetic field. Magnetomotion in the intracellular space was detected and visualized by means of 3D OCT as well as laser speckle reflectometry as a 2D reference imaging method. Our experiments on mesenchymal stem cells embedded in agar scaffolds show that the magnetomotive signal in rotational MM-OCT is significantly increased by a factor of Ë3 compared to previous pulsed MM-OCT, although the solenoid's power consumption was 16 times lower. Finally, we use our novel method to image ARPE-19 cells, a human retinal pigment epithelium cell line. Our results permit magnetomotive imaging with higher sensitivity and the use of low power magnetic fields or larger working distances for future three-dimensional cell tracking in target tissues and organs
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