745 research outputs found
Unexploited Agricultural Growth: The Case of CropâLivestock Production Systems in Zimbabwe
Livestock is the most important source of cash for small-scale farmers in the semi-arid tropics of southern Africa. However, with limited access to markets, farmers do not have the incentive to invest in improved livestock management. Livestock production and off-takes remain low and farmers are unable to realize the full potential of their herds. We believe that improved market access will be the driver to increase technology adoption for income growth and poverty reduction. In Zimbabwe, a recent baseline diagnosis by ICRISAT and partners found that cash income from goats is crucial to cover day-to-day expenditures for food, education and human health. Cattle are more important for draft power and milk, and support subsistence cropping activities. Major production constraints include high mortality rates attributed to dry season feed shortages, particularly affecting farmers with small herds. An increasing demand for livestock products in rural and urban areas offers small-scale farmers opportunities for market participation. However, the existing markets are underdeveloped, with high transaction costs implying low producer prices and poor access to information for farmers. The challenge is to sustain livestock production, develop more effective market facilities, and thereby increase off-take. The potential of market-led technology development in cropâlivestock systems has not been sufficiently exploited by research and development. To have an impact on incomes and poverty, we develop an innovative approach that would first evaluate local constraints in production and marketing, and then test alternative livestock markets and management strategies, with a strong linkage between private and public sectorsAgricultural and Food Policy, Consumer/Household Economics, Environmental Economics and Policy, Farm Management, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Livestock Production/Industries, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,
Reconciling thermal leptogenesis with the gravitino problem in SUSY models with mixed axion/axino dark matter
Successful implementation of thermal leptogenesis requires re-heat
temperatures T_R\agt 2\times 10^9 GeV, in apparent conflict with SUSY models
with TeV-scale gravitinos, which require much lower T_R in order to avoid Big
Bang Nucleosynthesis (BBN) constraints. We show that mixed axion/axino dark
matter can reconcile thermal leptogenesis with the gravitino problem in models
with m_{\tG}\agt 30 TeV, a rather high Peccei-Quinn breaking scale and an
initial mis-alignment angle \theta_i < 1. We calculate axion and axino dark
matter production from four sources, and impose BBN constraints on long-lived
gravitinos and neutralinos. Moreover, we discuss several SUSY models which
naturally have gravitino masses of the order of tens of TeV. We find a
reconciliation difficult in Yukawa-unified SUSY and in AMSB with a wino-like
lightest neutralino. However, T_R\sim 10^{10}-10^{12} GeV can easily be
achieved in effective SUSY and in models based on mixed moduli-anomaly
mediation. Consequences of this scenario include: 1. an LHC SUSY discovery
should be consistent with SUSY models with a large gravitino mass, 2. an
apparent neutralino relic abundance \Omega_{\tz_1}h^2\alt 1, 3. no WIMP direct
or indirect detection signals should be found, and 4. the axion mass should be
less than \sim 10^{-6} eV, somewhat below the conventional range which is
explored by microwave cavity axion detection experiments.Comment: 25 pages including 15 .eps figures; updated version to coincide with
published versio
Thermal leptogenesis and the gravitino problem in the Asaka-Yanagida axion/axino dark matter scenario
A successful implementation of thermal leptogenesis requires the re-heat
temperature after inflation T_R to exceed ~2\times 10^9 GeV. Such a high T_R
value typically leads to an overproduction of gravitinos in the early universe,
which will cause conflicts, mainly with BBN constraints. Asaka and Yanagida
(AY) have proposed that these two issues can be reconciled in the context of
the Peccei-Quinn augmented MSSM (PQMSSM) if one adopts a mass hierarchy
m(sparticle)>m(gravitino)>m(axino), with m(axino) keV. We calculate the relic
abundance of mixed axion/axino dark matter in the AY scenario, and investigate
under what conditions a value of T_R sufficient for thermal leptogenesis can be
generated. A high value of PQ breaking scale f_a is needed to suppress
overproduction of axinos, while a small vacuum misalignment angle \theta_i is
needed to suppress overproduction of axions. The large value of f_a results in
late decaying neutralinos. To avoid BBN constraints, the AY scenario requires a
low thermal abundance of neutralinos and high values of neutralino mass. We
include entropy production from late decaying saxions, and find the saxion
needs to be typically at least several times heavier than the gravitino. A
viable AY scenario suggests that LHC should discover a spectrum of SUSY
particles consistent with weak scale supergravity; that the apparent neutralino
abundance is low; that a possible axion detection signal (probably with m_axion
in the sub-micro-eV range) should occur, but no direct or indirect signals for
WIMP dark matter should be observed.Comment: 28 pages including 21 .eps figures; high resolution pdf version
available at http://www.nhn.ou.edu/~bae
Effective Supersymmetry at the LHC
We investigate the phenomenology of Effective Supersymmetry (ESUSY) models
wherein electroweak gauginos and third generation scalars have masses up to
about 1~TeV while first and second generation scalars lie in the multi-TeV
range. Such models ameliorate the SUSY flavor and CP problems via a decoupling
solution, while at the same time maintaining naturalness. In our analysis, we
assume independent GUT scale mass parameters for third and first/second
generation scalars and for the Higgs scalars, in addition to m_{1/2}, \tan\beta
and A_0, and require radiative electroweak symmetry breaking as usual. We
analyse the parameter space which is consistent with current constraints, by
means of a Markov Chain Monte Carlo scan. The lightest MSSM particle (LMP) is
mostly, but not always the lightest neutralino, and moreover, the thermal relic
density of the neutralino LMP is frequently very large. These models may
phenomenologically be perfectly viable if the LMP before nucleosynthesis decays
into the axino plus SM particles. Dark matter is then an axion/axino mixture.
At the LHC, the most important production mechanisms are gluino production (for
m_{1/2} ~<700~GeV) and third generation squark production, while SUSY events
rich in b-jets are the hallmark of the ESUSY scenario. We present a set of
ESUSY benchmark points with characteristic features and discuss their LHC
phenomenology.Comment: 26 pages including 13 figure
SModelS: a tool for interpreting simplified-model results from the LHC and its application to supersymmetry
We present a general procedure to decompose Beyond the Standard Model (BSM)
collider signatures presenting a Z2 symmetry into Simplified Model Spectrum
(SMS) topologies. Our method provides a way to cast BSM predictions for the LHC
in a model independent framework, which can be directly confronted with the
relevant experimental constraints. Our concrete implementation currently
focusses on supersymmetry searches with missing energy, for which a large
variety of SMS results from ATLAS and CMS are available. As show-case examples
we apply our procedure to two scans of the minimal supersymmetric standard
model. We discuss how the SMS limits constrain various particle masses and
which regions of parameter space remain unchallenged by the current SMS
interpretations of the LHC results.Comment: v3: Version published in EPJ
Assisting Smallholder Farmers in Mixed Crop-Livestock Systems to Understand the Potential Effects of Technologies and Climate Change through Participatory Modelling
Smallholder farming systems in the semi-arid areas of Zimbabwe are characterized by low production. This low production is not solely due to lack of technologies but is also due to a lack of integrating a diversity of viewpoints belonging to local, expert and specialized stakeholders during technology development. Participatory approaches combined with computer-based modelling are increasingly being recognized as valuable approaches to jointly develop sustainable agricultural pathways. The application of this integrated and iterative process in developing and evaluating the impact of interventions aimed at improving food and feed production is discussed. The process allows farmers to determine the impact of their decisions, evaluate new options and define realistic production and management options tailored to their particular circumstances. Scientists and other stakeholders in-turn learn more about the farmersâ decision-making process, input and managerial potentials as well as knowledge gaps
SModelS v1.0: a short user guide
SModelS is a tool for the automatic interpretation of simplified-model
results from the LHC. Version 1.0 of the code is now publicly available. This
document provides a quick user guide for installing and running SModelS v1.0.Comment: The code is available for download at http://smodels.hephy.at
Prognostic significance of endogenous adhesion/growth-regulatory lectins in lung cancer
Objective: To determine the expression of endogenous adhesion/growth-regulatory lectins and their binding sites using labeled tissue lectins as well as the binding profile of hyaluronic acid as an approach to define new prognostic markers. Methods: Sections of paraffin-embedded histological material of 481 lungs from lung tumor patients following radical lung excision processed by a routine immunohistochemical method (avidin-biotin labeling, DAB chromogen). Specific antibodies against galectins-1 and - 3 and the heparin-binding lectin were tested. Staining by labeled galectins and hyaluronic acid was similarly visualized by a routine protocol. After semiquantitative assessment of staining, the results were compared with the pT and pN stages and the histological type. Survival was calculated by univariate and multivariate methods. Results: Binding of galectin-1 and its expression tended to increase, whereas the parameters for galectin-3 decreased in advanced pT and pN stages at a statistically significant level. The number of positive cases was considerably smaller among the cases with small cell lung cancer than in the group with non-small-cell lung cancer, among which adenocarcinomas figured prominently with the exception of galectin-1 expression. Kaplan-Meier computations revealed that the survival rate of patients with galectin-3-binding or galectin-1-expressing tumors was significantly poorer than that of the negative cases. In the multivariate calculations of survival lymph node metastases ( p < 0.0001), histological type ( p = 0.003), galectin-3-binding capacity ( p = 0.01), galectin-3 expression ( p = 0.03) and pT status ( p = 0.003) proved to be independent prognostic factors, not correlated with the pN stage. Conclusion: The expression and the capacity to bind the adhesion/growth regulatory galectin-3 is defined as an unfavorable prognostic factor not correlated with the pTN stage. Copyright (C) 2005 S. Karger AG, Basel
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