Checking-in on Network Functions

When programming network functions, changes within a packet tend to have consequences---side effects which must be accounted for by network programmers or administrators via arbitrary logic and an innate understanding of dependencies. Examples of this include updating checksums when a packet's contents has been modified or adjusting a payload length field of a IPv6 header if another header is added or updated within a packet. While static-typing captures interface specifications and how packet contents should behave, it does not enforce precise invariants around runtime dependencies like the examples above. Instead, during the design phase of network functions, programmers should be given an easier way to specify checks up front, all without having to account for and keep track of these consequences at each and every step during the development cycle. In keeping with this view, we present a unique approach for adding and generating both static checks and dynamic contracts for specifying and checking packet processing operations. We develop our technique within an existing framework called NetBricks and demonstrate how our approach simplifies and checks common dependent packet and header processing logic that other systems take for granted, all without adding much overhead during development.Comment: ANRW 2019 ~ https://irtf.org/anrw/2019/program.htm

Approximate solution to a hybrid model with stochastic volatility: a singular-perturbation strategy

We study a hybrid model of Schobel-Zhu-Hull-White-type from a singular-perturbation-analysis perspective. The merit of the paper is twofold: On one hand, we find boundary conditions for the deterministic non-linear degenerate parabolic partial differential equation for the evolution of the stock price. On the other hand, we combine two-scales regular- and singular-perturbation techniques to find an approximate solution to the pricing PDE. The aim is to produce an expression that can be evaluated numerically very fast

The impact of smallholder commercialisation of organic crops on food consumption patterns, dietary diversity and consumption elasticities

The impact of smallholder commercialisation on food consumption patterns in a rural community of South Africa was investigated. The dietary diversity, nutrient intakes and consumption patterns of certified, partially certified and non-members of an organic farmers’ organisation were compared. Engagement in certified commercial organic farming promoted comparatively greater dietary diversity and improved nutrient intakes. While smallholder agriculture commercialisation has the potential to improve food consumption patterns and food quality through increased income and labour opportunities, caution should be exercised before claiming that such commercialisation can alleviate food insecurity and solve hunger in rural South Africa.agriculture, growth, smallholder, consumption, nutrition, Food Security and Poverty,

The Impact of Small Holder Commercialisation of Organic Crops on Food Consumption Patterns in KwaZulu-Natal, South Africa

The impact of smallholder commercialisation on food consumption patterns in a rural community of South Africa was investigated. The consumption patterns, dietary diversity and nutrient intakes of certified and partially certified members of an organic farmers' organisation were compared to data from a random sample of non-member households. Two consecutive survey rounds (n = 200) conducted in November 2004 and March 2005 enabled comparison of dietary diversity, nutrient adequacy (in terms of per household adult female equivalents for energy, iron, and vitamin A) and expenditure elasticities between seasons. Households with members engaged in certified comm ercial organic farming enjoyed greater dietary diversity, improved nutrient intakes com pared to households with members in conversion to organic production and households not engaged in commercial organic farming. Farm and non-farm income strongly and positively influenced nutritional adequacy for households of partially certified and certified members of the organisation. Marked differences in expenditure elasticities were found between the three groups. The results suggested that commercialisation of small holder agriculture has potential to improve food consumption patterns and food quality directly through income generated and indirectly through increased labour opportunities that result in wages and inkind food transfers. While commerciali sation of small holder agriculture shows potential for improving nutrition, caution should be exercised before claiming that such commercialisation can alleviate food insecurity and solve hunger in South Africa.food consumption, nutrition, farm households, small holder, Food Consumption/Nutrition/Food Safety, D1, Q12,

Expenditure elasticities for rural households in the Embo ward, Umbumbulu, KwaZulu-Natal

Household consumption patterns were investigated to determine the impact of an income shock on household expenditure and to establish the potential for demand-led growth in a rural area of KwaZulu-Natal. Household consumption data were collected from sample households in the Embo ward of Umbumbulu, KwaZulu-Natal during October 2004 and March 2005. Budget shares and expenditure elasticities were estimated for household consumption categories for the two study periods, allowing for a comparison of expenditure elasticities between the two seasons. Results suggest that expenditure elasticities for consumer expendables, durables and transport were highly elastic, while expenditure elasticities for the aggregate food category were negative (October) and highly inelastic (March). Analysis of the expenditure categories of tradable and non-tradable goods and services showed expenditure on tradable non-farm goods and services to have the greatest potential for demand-led growth with expenditure elasticities of 2.88 and 2.91, respectively. The category of non-tradable non-farm goods and services was not statistically significant for both periods and the category non-tradable farm goods and services was not statistically significant for October. A seasonal difference in expenditure patterns was apparent, suggesting that responses to income changes vary at different times of the year.Expenditure elasticities, demand-led growth, Umbumbulu region, KwaZulu-Natal, Consumer/Household Economics,

Transcription analysis of apple fruit development using cDNA microarrays

The knowledge of the molecular mechanisms underlying fruit quality traits is fundamental to devise efficient marker-assisted selection strategies and to improve apple breeding. In this study, cDNA microarray technology was used to identify genes whose expression changes during fruit development and maturation thus potentially involved in fruit quality traits. The expression profile of 1,536 transcripts was analysed by microarray hybridisation. A total of 177 genes resulted to be differentially expressed in at least one of the developmental stages considered. Gene ontology annotation was employed to univocally describe gene function, while cluster analysis allowed grouping genes according to their expression profile. An overview of the transcriptional changes and of the metabolic pathways involved in fruit development was obtained. As expected, August and September are the two months where the largest number of differentially expressed genes was observed. In particular, 85 genes resulted to be up-regulated in September. Even though most of the differentially expressed genes are involved in primary metabolism, several other interesting functions were detected and will be presented

Pentecostalism & schisms in the Reformed Church in Zambia 1996-2001: contextual and identity changes

This article analyzes the historical, contextual and identity changes that took place in the RCZ between 1996 and 2001 in order to find an answer to the question why it happened. The hypothesis is as follows: The leadership style of church leaders was influenced by the one-party state with its autocratic presidential powers that continued the missionary legacy of autocratic rule. The autocratic leadership style met head on with a new globalizing culture and with the Pentecostal tendencies in society. This created the conflict that caused the schisms. Pentecostal/charismatic tendencies challenged the long-inherited tradition with its autocratic church leadership style of mainline churches in general and the RCZ in particular. Subsequently, Pentecostal/charismatic movements caused intense conflict in the church between the pro-conservatives and pro-Pentecostals. In the RCZ, this led to the formation of the Christian Reformed Church (CRC) in 1999 and the Bible Gospel Church in Africa (BIGOCA) in 2001

Large-scale agricultural investments and household vulnerability to food insecurity: Evidence from Kenya, Madagascar and Mozambique

This study set out to estimate the role of large-scale agricultural investments on household vulnerability to food insecurity in sample communities in Kenya, Madagascar and Mozambique based on their adoption of coping strategies. The study used secondary data from the three countries (Kenya, Madagascar and Mozambique). The findings of the study revealed that households with members engaged in contract agreements with LSAIs adopted fewer coping strategies and were less food insecure than other households. Contract farming households seemed to cope better during food shortages (based on the marginal effects of the model). In comparison, households with members employed by a LSAI adopted more coping strategies than contract farming households. This might be because households with employed members had smaller numbers of livestock and smaller landholdings. Many LSAIs jobs were seasonal and low-paid, making the household less able to cope with food shortages. The study confirmed that households with more educated heads, smaller households, larger plot sizes and more livestock were less likely to slip into deeper levels of food insecurity should they face adversity. Most employed household heads had migrated from nearby districts. The job opportunities helped migrant workers mediate food insecurity. These results suggest that governments hosting LSAIs can promote plantation and contract farming that protect the land ownership of smallholder farmers, transfer good agricultural practices to improve agricultural production, household incomes and food security of smallholder farmers