Women and Agroforestry: A Human Ecology Approach to Understanding The Needs and Priorities of Women Farmers in Africa

This study examined rural Ugandan women's lives to discover reasons why they may or may not practice agroforestry. These women are responsible for the triple roles of reproduction, production and community maintenance work, all carried out within the context of a gendered social environment. From the perspective of the social manifestations of gender, six key factors were identified. The findings were used to create a theoretical model of the interaction between rural women's lives and agroforestry systems. The model shows that agroforestry is not only a biophysical farming system; There is a human component in that interacts with other components to determine the success or failure of an agroforestry initiative. The model can be used to identify and understand the human component of the agroforestry system on an individual and community level.women in development, agroforestry programs, human ecology, women and work, Crop Production/Industries, Labor and Human Capital,

Gender and the Value of Trees in Mutoko Communal Area, Zimbabwe

This study examined the gender based differences in valuation of trees, as indicated by differences between men and women in the planting, care and use of tree resources. An analysis of differences in tree related behaviours between male headed households and female headed households was also undertaken. The study used a combination of quantitative and qualitative methodologies, including an interview schedule and card sort, supplemented by open-ended interviews and observations. The survey data were analysed using SPSS Windows. The study results indicate that trees were being planted and cared for in both male and female headed households and the majority of heads of households preferred multipurpose, fruit bearing tree species. There were differences in the types of tasks undertaken by men and women in both male and female headed households, the locus of decision making authority in the two types of households, and the uses of tree resources by men and women.Labor and Human Capital,

Increased tolerance of Litopenaeus vannamei to white spot syndrome virus (WSSV) infection after oral application of the viral envelope protein VP28

It has been generally accepted that invertebrates such as shrimp do not have an adaptive immune response system comparable to that of vertebrates. However, in the last few years, several studies have suggested the existence of such a response in invertebrates. In one of these studies, the shrimp Penaeus monodon showed increased protection against white spot syndrome virus (WSSV) using a recombinant VP28 envelope protein of WSSV. In an effort to further investigate whether this increased protection is limited to P. monodon or can be extended to other penaeid shrimp, experiments were performed using the Pacific white shrimp Litopenaeus vannamei. As found with P. monodon, a significantly lower cumulative mortality for VP28-fed shrimp was found compared to the controls. These experiments demonstrate that there is potential to use oral application of specific proteins to protect the 2 most important cultured shrimp species, P. monodon and L. vannamei, against WSSV. Most likely, this increased protection is based on a shared and, therefore, general defence mechanism present in all shrimp species. This makes the design of intervention strategies against pathogens based on defined proteins a viable option for shrimp cultur

Coexisting patterns of population oscillations: the degenerate Neimark Sacker bifurcation as a generic mechanism

We investigate a population dynamics model that exhibits a Neimark Sacker bifurcation with a period that is naturally close to 4. Beyond the bifurcation, the period becomes soon locked at 4 due to a strong resonance, and a second attractor of period 2 emerges, which coexists with the first attractor over a considerable parameter range. A linear stability analysis and a numerical investigation of the second attractor reveal that the bifurcations producing the second attractor occur naturally in this type of system.Comment: 8 pages, 3 figure

THE DISTRIBUTIONAL EFFECTS OF LAND CONTROLS IN AGRICULTURE

The paper introduces a framework for analyzing the impacts of land control programs on agricultural production under heterogenous land qualities, heterogenous production technologies and imperfect capital markets. It shows that the introduction of diversion programs tends to benefit land owners while harming operators. Moreover, it tends to increase the separation of land ownership and operation and increase concentration among operators. Diversion programs tend to raise land prices lass than proportional to the increases in rental rates. They encourage the adoption of yield increasing technologies, and may also encourage adoption of cost reducing technologies when credit is a binding constraint. Participation in voluntary government programs tends to be greater in regions with higher costs, less efficient marginal technology and less efficient marginal land.Land Economics/Use,

An evolutionary disc model of the edge-on galaxy NGC 5907

We present a physical model that explains the two disparate observational facts: 1) the exponential vertical disc structure in the optical and NIR of the non-obscured part of the stellar disc and 2) the enhanced FIR/submm luminosity by about a factor of four near the obscured mid-plane, which requires additional dust and also stellar light to heat the dust component. We use multi-band photometry in U, B, V, R, and I- band combined with radiative transfer through a dust component to fit simultaneously the vertical surface-brightness and colour index profiles in all bands adopting a reasonable star formation history and dynamical heating function. The final disc model reproduces the surface-brightness profiles in all bands with a moderately declining star formation rate and a slowly starting heating function for young stars. The total dust mass is 57 million solar masses as required from the FIR/submm measurements. Without a recent star burst we find in the midplane an excess of 5.2-, 4.0-, and 3.0-times more stellar light in the U-, B-, and V-band, respectively. The corresponding stellar mass-to-light ratios are 0.91 in V- and 1.0 in R-band. The central face-on optical depth in V-band is 0.81 and the radial scale length of the dust is 40% larger than that of the stellar disc. Evolutionary disc models are a powerful method to understand the vertical structure of edge-on galaxies. Insights to the star formation history and the dynamical evolution of stellar discs can be gained. FIR/submm observations are necessary to restrict the parameter space for the models.Comment: 17 pages, 12 figures (24 files), A&A in pres

DSCOVR-EPIC MAIAC AOD - A Proxy for Understanding Aerosol Diurnal Patterns from Space

The Deep Space Climate Observatory (DSCOVR) spacecraft was launched on 11 February 2015 and in June 2015 achieved its orbit at the first Lagrange point (L1), 1.5 million km from Earth toward the sun. The Earth Polychromatic Imaging Camera (EPIC) onboard DSCOVR views the entire sunlit Earth from sunrise to sunset, every 1-2 hours, at scattering angles between 168.5 and 175.5 with 10 narrowband filters in the range of 317-779 nm. NASA Multiangle Implementation of Atmospheric Correction (MAIAC) algorithm, originally developed for MODIS, has been applied to EPIC data with an Aerosol Optical Depth (AOD) product at 440nm with a 10km spatial resolution. This high temporal resolution product is a unique dataset for investigating diurnal patterns in aerosols from space. Our work analyzed the capability of the satellite-borne data to capture the aerosol diurnal variation by associating it with AERONET AOD at 440nm data over the contiguous US. We validated the DSCOVR MAIAC AOD data over 100 AERONET stations during 2015-2018, and examined the contribution of the surface reflectance and relevant acquisition angles, derived by the MAIAC algorithm, to the predicted error. We used over 180,000 hourly DSCOVR-EPIC MAIAC AOD observations with collocated with AERONET AOD observations averaged over +-30 minutes from the satellite overpass time. The AERONET and DSCOVR AOD temporal patterns show that the diurnal variation is different across US AERONET sites, with higher diurnal variation in the DSCOVR dataset in general

The Isomorphism Relation Between Tree-Automatic Structures

An $\omega$-tree-automatic structure is a relational structure whose domain and relations are accepted by Muller or Rabin tree automata. We investigate in this paper the isomorphism problem for $\omega$-tree-automatic structures. We prove first that the isomorphism relation for $\omega$-tree-automatic boolean algebras (respectively, partial orders, rings, commutative rings, non commutative rings, non commutative groups, nilpotent groups of class n >1) is not determined by the axiomatic system ZFC. Then we prove that the isomorphism problem for $\omega$-tree-automatic boolean algebras (respectively, partial orders, rings, commutative rings, non commutative rings, non commutative groups, nilpotent groups of class n >1) is neither a $\Sigma_2^1$-set nor a $\Pi_2^1$-set

Time--delay autosynchronization of the spatio-temporal dynamics in resonant tunneling diodes

The double barrier resonant tunneling diode exhibits complex spatio-temporal patterns including low-dimensional chaos when operated in an active external circuit. We demonstrate how autosynchronization by time--delayed feedback control can be used to select and stabilize specific current density patterns in a noninvasive way. We compare the efficiency of different control schemes involving feedback in either local spatial or global degrees of freedom. The numerically obtained Floquet exponents are explained by analytical results from linear stability analysis.Comment: 10 pages, 16 figure

Compensation and Political Feasibility: Facilitating Welfare Improving Policies

There is a broad consensus among economists, policymakers, and informed citizens that free-market economics do not preclude many inefficiencies in resource allocation. There are many circumstances where policy interventions have the potential to achieve a Pareto improvement in the sense of making some people better off without making others worse off. The challenge to any particular market-oriented society is to design those mechanisms, organizations and institutions that identify the limitations of free-markets and result in those reforms that seek Pareto-improved outcomes