Biosecurity and disease control perceptions and practices of Vietnamese smallholder pig farmers

Pork is the most widely consumed meat in Vietnam and plays a key role in meeting the public demand for protein. It is estimated that 80% of pork consumed in Vietnam is sourced from smallholder farmers who can have their animal production and livelihood impacted by the introduction and spread of infectious diseases. Implementation of biosecurity and disease control practices can play a crucial role in negating these impacts. This study sampled 420 smallholder pig farmers in Vietnam to identify farmer perceptions and practices relating to biosecurity and disease control. The study found a majority (82%) of farmers reported experiencing one or more instances of pig disease in the last year, with self-treatment as the first response for 70% of farmers. Other measures such as disinfection mattresses and visitor control were used by 94% and 75% of the farmers respectively. Measures such as rodent control and quarantine of animals were poorly adopted, with respective adoption rates of 20% and 6%. Farmer perceptions revealed a desire to improve their knowledge and understanding of pig production and specifically biosecurity and disease control practices. Findings from this study will form part of a participatory approach to improving farm production and livelihoods through a understanding of current biosecurity and disease control practices and perceptions

Module Varieties over Canonical Algebras

AbstractThe main purpose of this paper is the study of module varieties over the class of canonical algebras, providing a rich source of examples of varieties with interesting properties. Our main tool is a stratification of module varieties, which was recently introduced by Richmond. This stratification does not require a precise knowledge of the module category. If it is finite, then it provides a method to classify irreducible components. We determine the canonical algebras for which this stratification is finite. In this case, we describe the algorithm for calculating the dimension of the variety and the number of irreducible components of maximal dimension. For an infinite family of examples we give easy combinatorial criteria for irreducibility, Cohen–Macaulay and normality

Hierarchical Bayes Estimation of Reliability Indexes of Cold Standby Series System under General Progressive Type II Censoring Scheme

In this paper, hierarchical Bayes approach is presented for estimation and prediction of reliability indexes and remaining lifetimes of a cold standby series system under general progressive Type II censoring scheme. A simulation study has been carried out for comparison purpose. The study will help reliability engineers in various industrial series system setups

Preference of Estimation Approach for Rayleigh Progressive Type II Data

This paper compare the performance of the empirical Bayes and generalized maximum likelihood estimation approaches in context of progressively Type II censored data from one parameter Rayleigh distribution. The generalized maximum likelihood and empirical Bayes estimates of scale parameter, reliability function, and failure rate function are compared using risk efficiency criterion. The empirical Bayes estimates are considered with respect to squared error loss function. The wind speed data is presented to illustrate the proposed estimation approaches, and an extensive Monte Carlo simulated study is done to compare the empirical Bayes and Generalized maximum likelihood estimates. The study indicates that the empirical Bayesian approach using squared error loss function is preferable than the generalized maximum likelihood approach for the estimation of reliability performances. Keywords: Progressively Type II censored samples, generalized maximum likelihood estimation, squared error loss function, empirical Bayes estimation, Risk efficiency, Monte Carlo simulation.

Biosecurity and diseases control practices and perceptions of smallholder pig farmers in Vietnam

Australian Centre for International Agricultural Researc

Reaction Norms for Age and Size at Maturation: Study of the Long-Term Trend (1970-1998) for Georges Bank and Gulf of Maine Cod Stocks

Average age and size at maturation have decreased in many commercially exploited fish stocks during the last decades. This phenomenon could be either a direct phenotypic response to some environmental variation, or the evolutionary consequence of some selective pressure. Traditionally used maturation indices, i.e., the age and size at which 50% of individuals are mature, are not appropriate to assess the causes of changes in maturation because they are influenced, in addition to maturation per se, by growth and survival. To make up for this shortcoming, we use a reaction norm based approach to disentangle evolutionary changes and phenotypic plasticity. A method is presented to estimate the reaction norm for age and size at maturation from data commonly gathered for the maturation of fisheries. This method is applied to data on Georges Bank Gulf of Maine stocks of Atlantic cod ("Gadus morhua"). The results show that maturation reaction norms in these stocks have shifted significantly downwards, resulting in a tendency to mature earlier at smaller size. These findings support the hypothesis that an evolutionary trend, probably caused by high fishing mortalities, is partially responsible for the observed decrease in age and size at maturation in these cod stocks. Two independent reasons justify this interpretation. First, there is no corresponding trend in growth that would suggest that improved feeding conditions could have facilitated maturation. Second, the results are based on maturation reaction norms, from which the known confounding effects of the growth and mortality variations are removed. Consequences of fisheries-induced evolution for the sustainability of the fisheries are discussed

Estimating Reaction Norms for Age and Size at Maturation When Age at First Reproduction is Unknown

We describe a novel method to estimate the probabilities of maturing at age as a function of size; these probabilities can often be interpreted as probabilistic reaction norms for age and size at maturation. Such estimations are useful for describing maturation process independently from the processes of growth and mortality, and they can also help to disentangle phenotypic plasticity from evolutionary changes in maturation. The estimation method can be used when mature and immature individuals are representatively sampled over two consecutive seasons, even when maturing individuals are not distinguished. Confidence intervals are derived for the reaction norm parameters using a bootstrap approach. Using simulated data, the method is shown to be asymptotically unbiased and robust to moderate violations of the main simplifying assumptions. However, it is relatively sensitive to small sample sizes: the method is not robust when fewer than about 100 individuals (mature and immature) are sampled from a cohort at a certain age. The method is illustrated by an application to Georges Bank cod stock (Gadus morhua) but can be used for any type of organism

Reflection group presentations arising from cluster algebras

We give a presentation of a finite crystallographic reflection group in terms of an arbitrary seed in the corresponding cluster algebra of finite type and interpret the presentation in terms of companion bases in the associated root system