600 research outputs found
Gender roles and child nutrition in livestock production systems in developing countries: a critical review
The study of gender issues in agricultural production has become an important subject of inquiry, even since questions were raised on whether women and men benefited equally from economic development. The focus of the debate and empirical research has primarily been on the role of women in crop production to the virtual exclusion of the role of gender (women, men and children) in livestock farming. This review is based on the limited amount of available literature which shows that specific participation of women, men and children in animal husbandry is significant and varies from region to region according to the traditional gender division of labour, other variables, the farming systems and the demographic and environmental factors. The objectives of this review are to examine the gender division of labour, access to resources and benefits from smallholder ruminant livestock production systems; to evaluate the effects of ruminant livestock production on the nutritional status of children and to present two case studies that critically examine how gender analysis was included in smallholder ruminant livestock research projects
Melt compounding of rigid PVC formulations with hydrotalcites
Hydrotalcites, compounds of magnesiumâaluminiumâhydroxycarbonate, are promoted as
environmentally safe materials for costabilisation of PVC products. Commercial grades of
hydrotalcites have been added to rigid PVC formulations, containing a range of different stabiliser
types, to evaluate their contribution to heat stability and their effect on mechanical properties.
Hydrotalcites are confirmed to be effective costabilisers for rigid PVC: static thermal stability
(through oven testing) and dynamic thermal stability (via torque rheometry) of PVC compounds
are modified by their presence. The extent of change is determined by the primary stabiliser type
and the grade of the hydrotalcite. Detailed analysis of mechanical properties has been carried out
on compression moulded samples and on extruded compounds. With the former, no significant
change in tensile or impact performance was observed, for hydrotalcite levels up to 5 phr. Charpy
impact data on extruded PVC have shown significant increase in performance of compounds
containing an acrylate modifier when hydrotalcites are used
Profiles of the forms and functions of self-reported aggression in three adolescent samples
In the current study, we addressed several issues related to the forms (physical and relational) and functions (reactive and proactive) of aggression in community (n = 307), voluntary residential (n = 1,917) and involuntarily detained (n = 659) adolescents (ages 11 to 19 years). Across samples, boys self-reported more physical aggression and girls reported more relational aggression, with the exception of higher levels of both forms of aggression in detained girls. Further, few boys showed high rates of relational aggression without also showing high rates of physical aggression. In contrast, it was not uncommon for girls to show high rates of relational aggression alone and these girls tended to also have high levels of problem behavior (e.g., delinquency) and mental health problems (e.g., emotional dysregulation, callous-unemotional traits). Finally, for physical aggression in both boys and girls, and for relational aggression in girls, there was a clear pattern of aggressive behavior that emerged from cluster analyses across samples. Two aggression clusters emerged with one group showing moderately high reactive aggression and a second group showing both high reactive and high proactive aggression (combined group). On measures of severity (e.g., self-reported delinquency and arrests) and etiologically important variables (e.g., emotional regulation and callous-unemotional traits), the reactive aggression group was more severe than a non-aggressive cluster but less severe than the combined aggressive cluster
Efficient quantum algorithms for simulating sparse Hamiltonians
We present an efficient quantum algorithm for simulating the evolution of a
sparse Hamiltonian H for a given time t in terms of a procedure for computing
the matrix entries of H. In particular, when H acts on n qubits, has at most a
constant number of nonzero entries in each row/column, and |H| is bounded by a
constant, we may select any positive integer such that the simulation
requires O((\log^*n)t^{1+1/2k}) accesses to matrix entries of H. We show that
the temporal scaling cannot be significantly improved beyond this, because
sublinear time scaling is not possible.Comment: 9 pages, 2 figures, substantial revision
Trouble in Paradise - A disabled person's right to the satisfaction of a self-defined need:Some conceptual and practical problems
This paper questions the usefulness of the rights-based approach to ameliorating the social situation of disabled people in Britain and advances two criticisms. First, that rights and self-de? ned needs have been under-theorised by disability theorists to the extent that they have insuf? ciently appreciated the problems that these approaches pose. The paper suggests that rights to appropriate resources to satisfy self-de? ned needs will generate vast numbers of competing rights claims and that the resulting tendency of rights to con? ict has been under-appreciated. Secondly, that there has been little consideration of how these con? icts might be reconciled. The ? rst two sections of the paper look at the concepts of ascribed and self-de? ned needs, respectively, whilst the ? nal one looks at some of the problems of the rights approach and some of the dif? culties of making self-de? ned need the basis of rights claims
Gaussian quantum computation with oracle-decision problems
We study a simple-harmonic-oscillator quantum computer solving oracle
decision problems. We show that such computers can perform better by using
nonorthogonal Gaussian wave functions rather than orthogonal top-hat wave
functions as input to the information encoding process. Using the Deutsch-Jozsa
problem as an example, we demonstrate that Gaussian modulation with optimized
width parameter results in a lower error rate than for the top-hat encoding. We
conclude that Gaussian modulation can allow for an improved trade-off between
encoding, processing and measurement of the information.Comment: RevTeX4, 10 pages with 4 figure
Entanglement capability of self-inverse Hamiltonian evolution
We determine the entanglement capability of self-inverse Hamiltonian
evolution, which reduces to the known result for Ising Hamiltonian, and
identify optimal input states for yielding the maximal entanglement rate. We
introduce the concept of the operator entanglement rate, and find that the
maximal operator entanglement rate gives a lower bound on the entanglement
capability of a general Hamiltonian.Comment: 4 pages, no figures. Version 3: small change
High-voltage pulse generator based on sequentially charged MMC-SMs operating in a voltage-boost mode
Pulse forming networks and Marx generators are the classical rectangular waveform pulse generators (PGs). They are inflexible and their capacitors must be fully charged to the required voltage from 0V before delivering each high-voltage (HV) pulse. They are only able to generate unipolar pulses; if bipolar pulses are sought another generator fed from a negative supply voltage is added. Recently, several power electronics based PGs have been proposed. This paper presents an HV power electronics based PG, which is based on Half-Bridge Modular Multilevel Converter (HB-MMC) sub-modules (SMs) charged sequentially in a voltage boost mode. Each SM capacitor and main switch form a boost converter with the charging input supply and inductor. As a result, all SM capacitors are charged to a voltage greater than the input. During the discharging process the SM capacitors are connected in series, producing a rectangular HV pulse across the load. The proposed charging method allows a reduction in the converter footprint in comparison with recently proposed MMC sequentially charged PG topologies. Although only rectangular pulse waveforms are sought in this paper, a SM capacitor voltage balance method allows multilevel pulse generation. The viability of the proposed converter is confirmed by MATLAB/Simulink simulation and scaled-down experimentation
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