1,119 research outputs found

    Participatory gender-sensitive approaches for addressing key climate change- related research issues: Evidence from Bangladesh, Ghana, and Uganda

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    Getting a better understanding of how climate variability affects rural men and women differently, and in different regions, is challenging. Since their ability to respond to change and take action that will make them more resilient and able to adapt to a changing climate (alongside all the other social and economic change they are dealing with) differs, we need to focus more research efforts on enhancing this understanding and linking this knowledge with actions aimed at enhancing livelihoods and food security. We examine how well existing participatory gender-sensitive research approaches address some key climate change-related research issues that CCAFS has prioritized. Bringing together gender experts and experienced agricultural research teams from Bangladesh, Ghana, and Uganda, multiple methods were tested in the field, and refined through the lessons learned, to help inform future action research and development efforts towards enhancing communities’ and individuals’ (particularly women’s) access to, and use of, information and knowledge to help them adapt to climate variability through more resilient livelihoods and agro-ecosystems

    Magnetoelectric Effect and Spontaneous Polarization in HoFe3_3(BO3_3)4_4 and Ho0.5_{0.5}Nd0.5_{0.5}Fe3_3(BO3_3)4_4

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    The thermodynamic, magnetic, dielectric, and magnetoelectric properties of HoFe3_3(BO3_3)4_4 and Ho0.5_{0.5}Nd0.5_{0.5}Fe3_3(BO3_3)4_4 are investigated. Both compounds show a second order Ne\'{e}l transition above 30 K and a first order spin reorientation transition below 10 K. HoFe3_3(BO3_3)4_4 develops a spontaneous electrical polarization below the Ne\'{e}l temperature (TN_N) which is diminished in external magnetic fields. No magnetoelectric effect could be observed in HoFe3_3(BO3_3)4_4. In contrast, the solid solution Ho0.5_{0.5}Nd0.5_{0.5}Fe3_3(BO3_3)4_4 exhibits both, a spontaneous polarization below TN_N and a magnetoelectric effect at higher fields that extends to high temperatures. The superposition of spontaneous polarization, induced by the internal magnetic field in the ordered state, and the magnetoelectric polarizations due to the external field results in a complex behavior of the total polarization measured as a function of temperature and field.Comment: 12 pages, 15 figure

    Dynamical Model for Chemically Driven Running Droplets

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    We propose coupled evolution equations for the thickness of a liquid film and the density of an adsorbate layer on a partially wetting solid substrate. Therein, running droplets are studied assuming a chemical reaction underneath the droplets that induces a wettability gradient on the substrate and provides the driving force for droplet motion. Two different regimes for moving droplets -- reaction-limited and saturated regime -- are described. They correspond to increasing and decreasing velocities with increasing reaction rates and droplet sizes, respectively. The existence of the two regimes offers a natural explanation of prior experimental observations.Comment: 4 pages, 5 figure

    Theoretical analysis of neutron scattering results for quasi-two dimensional ferromagnets

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    A theoretical study has been carried out to analyse the available results from the inelastic neutron scattering experiment performed on a quasi-two dimensional spin-1/2 ferromagnetic material K2CuF4K_2CuF_4. Our formalism is based on a conventional semi-classical like treatment involving a model of an ideal gas of vortices/anti-vortices corresponding to an anisotropic XY Heisenberg ferromagnet on a square lattice. The results for dynamical structure functions for our model corresponding to spin-1/2, show occurrence of negative values in a large range of energy transfer even encompassing the experimental range, when convoluted with a realistic spectral window function. This result indicates failure of the conventional theoretical framework to be applicable to the experimental situation corresponding to low spin systems. A full quantum formalism seems essential for treating such systems.Comment: 16 pages, 6 figures, 1 Table Submitted for publicatio

    Tautomeric mutation: A quantum spin modelling

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    A quantum spin model representing tautomeric mutation is proposed for any DNA molecule. Based on this model, the quantum mechanical calculations for mutational rate and complementarity restoring repair rate in the replication processes are carried out. A possible application to a real biological system is discussed.Comment: 7 pages (no figures

    Screwworms, Cochliomyia hominivorax, Reared for Mass Release Do Not Carry and Spread Foot-and-Mouth Disease Virus and Classical Swine Fever Virus

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    Experiments were done to determine if transporting live screwworms Cochliomyia hominivorax Coquerel (Diptera: Calliphoridae) for developing new strains from countries where foot-and-mouth disease and classical swine fever are endemic, to the mass rearing facilities in Mexico and Panama, may introduce these exotic diseases into these countries. Are screwworms capable of harboring and spreading foot-and-mouth disease virus (FMDV) and classical swine fever virus (CSFV) when they are grown in virus-inoculated larval rearing medium? In one experiment, screwworm larvae were reared in a FMDV-inoculated artificial medium containing either 0.1 % formaldehyde or antibiotics as an antimicrobial agent. In another experiment, larvae were similarly reared in a CSFV-inoculated artificial medium containing 0.1% formaldehyde. In each experiment, samples of larvae and the rearing media were collected daily until pupation occurred. The presence of FMDV was assayed by observing cytopathic effects on cell cultures and a conventional reverse transcription-polymerase chain reaction (RT-PCR); CSFV was assayed using an avidin-biotin complex assay and a conventional RT-PCR. For media containing antibiotics, FMDV was detected in a larval sample collected on day 1 and in media samples on days 1, 2 and 3. No FMDV was detected from larval and media samples collected on all other days. For media containing formaldehyde, FMDV and CSFV were not detectable in larval or media samples collected on all sampling days. These results indicate that FMDV and CSFV cannot survive in rearing medium containing formaldehyde as an antimicrobial agent. Therefore, insects collected in endemic regions and reared using formaldehyde-containing medium for at least one generation at the collection site should be free of FMDV and CSFV and can be transported safely to a strain development/mass rearing facility

    Self Running Droplet: Emergence of Regular Motion from Nonequilibrium Noise

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    Spontaneous motion of an oil droplet driven by chemical nonequilibricity is reported. It is shown that the droplet undergoes regular rhythmic motion under appropriately designed boundary conditions, whereas it exhibits random motion in an isotropic environment. This study is a novel manifestation on the direct energy transformation of chemical energy into regular spatial-motion under isothermal conditions. A simple mathematical equation including noise reproduces the essential feature of the transition from irregularity into periodic regular motion. Our results will inspire the theoretical study on the mechanism of molecular motors in living matter, working under significant influence of thermal fluctuation.Comment: 4 pages, 4 figure

    Feasibility of Using a Caribbean Screwworm for SIT Campaigns in Brazil

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    The screwworm, Cochliomyia hominivorax (Coquerel), remains one of the most damaging parasites of livestock in South America, causing millions of dollars in annual losses to producers. Recently, South American countries demonstrated interest in controlling this pest using the Sterile Insect Technique, and a pilot-project was conducted near the Brazil-Uruguay border in 2009. Since molecular studies have suggested the existence of C. hominivorax regional groups, crossing tests were conducted to evaluate mating competitiveness, mating preference and reproductive compatibility between a C. hominivorax strain from the Caribbean (Jamaica-06) and one from Brazil. Mating rates between Jamaican males and Brazilian females ranged between 82 and 100%, and each male inseminated from 3.3 to 3.95 females. Sterile males, regardless of the strain, competed equally against the fertile males for Brazilian females. Jamaican sterile males and Brazilian fertile males mated randomly with fertile or sterile females. No evidence of genetic incompatibility or hybrid dysgenesis was found in the hybridization crosses. Mating barriers should not compromise the use of Jamaican sterile males for Sterile Insect Technique campaigns in Brazil.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP

    Macroscopic transport by synthetic molecular machines

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    Nature uses molecular motors and machines in virtually every significant biological process, but demonstrating that simpler artificial structures operating through the same gross mechanisms can be interfaced with—and perform physical tasks in—the macroscopic world represents a significant hurdle for molecular nanotechnology. Here we describe a wholly synthetic molecular system that converts an external energy source (light) into biased brownian motion to transport a macroscopic cargo and do measurable work. The millimetre-scale directional transport of a liquid on a surface is achieved by using the biased brownian motion of stimuli-responsive rotaxanes (‘molecular shuttles’) to expose or conceal fluoroalkane residues and thereby modify surface tension. The collective operation of a monolayer of the molecular shuttles is sufficient to power the movement of a microlitre droplet of diiodomethane up a twelve-degree incline.
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