Disentangling the ‘grass roots’ in Tonga: ‘traditional enterprise’ and autonomy in the moral and market economy

Semi–subsistence sectors predominate throughout Pacific Island countries. But the nature of the social organisation that characterises them, remains generally unexamined. This paper introduces the concept of ‘traditional enterprise’, based on observations in Tonga, to help analytically illuminate the sector. It also investigates processes of household dynamics that lead to selective upward social mobility and the consequent fragmentation of the generalised peasant household. Better understanding of the basic units, goals and means of achieving them among the traditional, rural, or the ‘grass roots’ sectors should help the current developmentalist emphasis on informal sector growth.     

Aflatoxin Accumulation and Associated Traits in QPM Maize Inbreds and their Testcrosses

Preharvest aflatoxin (AF) contamination by Aspergillus flavus Link:Fr is one of the main limitations for maize (Zea mays, L.) production in the southern USA, causing enormous economic losses and posing a risk to animal and human health. The objectives of this study were (1) to estimate aflatoxin accumulation and expression of associated traits in quality protein maize (QPM) inbreds and their testcrosses, (2) to compute their repeatabilities and correlations, and (3) to study the relationship between inbred lines and their testcrosses for aflatoxin accumulation. Forty-eight inbreds and their testcrosses plus checks were grown in one and three locations in south and central Texas, respectively. Aflatoxin concentration was evaluated in the plants following inoculation with A. flavus. Average aflatoxin concentration overall for inbreds was 286.3 ng g⁻¹, and for testcrosses 596.5 ng g⁻¹ at Corpus Christi, TX, 325.1 ng g⁻¹ at Weslaco, TX, and 105.1 ng g⁻¹ at College Station, TX. Flinty orange inbreds developed from CIMMYT Population 69 were the least susceptible to aflatoxin accumulation in both inbreds and testcrosses at all locations. Repeatability for aflatoxin was 0.67 in inbreds at Weslaco, TX and 0.54 in testcrosses across locations. Aflatoxin in testcrosses was positively correlated both phenotycally and genotypically with endosperm texture and kernel integrity, and negatively correlated with grain yield and silking date. Less aflatoxin accumulation was associated with flinty endosperm texture, better kernel integrity, and later maturities. Association between the expression of traits in inbreds and aflatoxin in testcrosses was relatively high for endosperm texture (R ² = 0.62), silking date (R ² = 0.44), kernel integrity (R ² = 0.39), and aflatoxin (R ² = 0.60 for log ng g⁻¹). It seems plausible to select for associated traits having high heritabilities and strong correlation with aflatoxin, in addition to low aflatoxin accumulation in inbreds and hybrids to reduce the risk of aflatoxin contamination.     

Mercury methylation by sulphate-reducing bacteria from sediments of an acid stressed lake

The role of freshwater sulphate-reducing bacteria in McHg production was examined by adding specific microbial inhibitors to anoxic lake sediments spiked with ²⁰³HgCl₂ and measuring net methylation. The effect of increased sulphate (such as would arise from acid deposition in the area) on the activity of sulphate-reducing bacteria both in terms of sulphate reduction rate and methylation of Hg was examined by adding sulphate to ²⁰³HgCl₂ spiked sediments. Sodium molybdate (10 mM), a specific inhibitor for sulphate-reducing bacteria, reduced the amount of MeHg produced from anoxic lake sediments by 75% compared with controls over a 7 d period. In contrast, 2-bromoethane sulfonic acid (15 mM), a specific inhibitor for methanogenic bacteria, did not alter the amount of McHg produced. Additions of sulphate that were “realistic” in terms of the normal range of the area (5 to 30 mg.L^?), increased the sulphate reduction rate of sediment slurries. However, in the experimental system, these additions did not stimulate McHg production. In our study, methylation of Hg in sediments was primarily due to the activity of sulphate-reducing bacteria. However, the methylation rate does not appear to be sensitive to the concentration of sulphate over the range typical of softwater, Precambrian Shield lakes. This could be due to reduced availability of Hg due to the formation of insoluble HgS or to the fact that the overall activity of sulphate reducers not being stimulated even if sulphate reduction rate is, or both.     

Vaccination of boars with a GnRH vaccine (Improvac) eliminates boar taint and increases growth performance.

Peri- and postpubertal boars accumulate substances (e.g., androstenone and skatole) in their fatty tissue that are responsible for boar taint in pork. The objective of this study was to assess the efficacy of a GnRH vaccine, Improvac, in eliminating boar taint. Three hundred male (200 intact boars, 100 barrows) crossbred (Large White x Landrace) pigs were used in a 2 x 3 factorially arranged experiment. The respective factors were sex group (barrows, boars treated with placebo, or boars treated with Improvac) and slaughter age (23 or 26 wk). Vaccines were administered 8 and 4 wk before slaughter. All Improvac-treated pigs exhibited anti-GnRH titers. Testes and bulbo-urethral gland weights in treated pigs were reduced by approximately 50% (P < 0.001) and serum testosterone levels were below 2 ng/mL in the majority of treated boars (94 and 92% across both age groups at 2 and 4 wk, respectively). Boar taint, as assessed by the concentration of androstenone and skatole in s.c. fat, was suppressed to low or undetectable levels in 100% of Improvac-treated boars. No Improvac-treated pigs had significant concentrations of either androstenone (> 1.0 microg/g) or skatole (> 0.20 microg/g). In contrast, 49.5% of placebo-treated controls had significant androstenone and 10.8% had significant skatole levels, resulting in 10% of the control boars with high concentrations of both compounds. The mean concentrations of taint compounds in the Improvac-treated pigs were not significantly different from those in barrows. Improvac-treated boars grew more rapidly (P = 0.051 and < 0.001 for pigs slaughtered at 23 and 26 wk of age, respectively) than control boars over the 4 wk after the secondary vaccination, possibly because of reduced sexual and aggressive activities. Compared with barrows, Improvac-treated boars were leaner and had superior feed conversion efficiency. The vaccine was well tolerated by the pigs, and no observable site reactions could be detected at the time of slaughter. Vaccination of boars with Improvac allows production of heavy boars with improved meat quality through prevention and control of boar taint.     

Associations between air emissions from sour gas processing plants and indices of cow retainment and survival in dairy herds in Alberta

This paper describes the results of an investigation into the effects of air emissions from sour gas processing plants on indices of retainment or survival of adult female dairy cattle on farms in Alberta; namely, the productive lifespan of individual animals, and annual herd-level risks for culling and mortality. Using a geographical information system, 2 dispersion models — 1 simple and 1 complex — were used to assess historical exposures to sour gas emissions at 1382 dairy farm sites from 1985 through to 1994. Multivariable survival models, adjusting for the dependence of survival responses within a herd over time, as well as potential confounding variables, were utilized to determine associations between sour gas exposure estimates and the time from the first calving date to either death or culling of 150 210 dairy cows. Generalized linear models were used to model the relationship between herd-level risks for culling and mortality and levels of sour gas exposure. No significant (P < 0.05) associations were found with the time to culling (n = 70 052). However, both dispersion model exposure estimates were significantly associated (P < 0.05) with a decreased hazard for mortality; that is, in cases where cattle had died on-farm (n = 8743). There were no significant associations (P > 0.05) between herd culling risks and the 2 dispersion model exposure estimates. There was no measurable impact of plant emissions on the annual herd risk of mortality.     

The 2002 Denali fault earthquake,Alaska: a large magnitude,slip-partitioned event

The MW (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. It illuminates earthquake mechanics and hazards of large strike-slip faults. It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip on the Denali fault, then took a right step and continued with right-slip on the Totschunda fault. There is good correlation between geologically observed and geophysically inferred moment release. The earthquake produced unusually strong distal effects in the rupture propagation direction, including triggered seismicity.     

Variograms of Ancillary Data to Aid Sampling for Soil Surveys

To provide reliable estimates for mapping soil properties for precision agriculture requires intensive sampling and costly laboratory analyses. If the spatial structure of ancillary data, such as yield, digital information from aerial photographs, and soil electrical conductivity (EC) measurements, relates to that of soil properties they could be used to guide the sampling intensity for soil surveys. Variograms of permanent soil properties at two study sites on different parent materials were compared with each other and with those for ancillary data. The ranges of spatial dependence identified by the variograms of both sets of properties are of similar orders of magnitude for each study site. Maps of the ancillary data appear to show similar patterns of variation and these seem to relate to those of the permanent properties of the soil. Correlation analysis has confirmed these relations. Maps of kriged estimates from sub-sampled data and the original variograms showed that the main patterns of variation were preserved when a sampling interval of less than half the average variogram range of ancillary data was used. Digital data from aerial photographs for different years and EC appear to show a more consistent relation with the soil properties than does yield. Aerial photographs, in particular those of bare soil, seem to be the most useful ancillary data and they are often cheaper to obtain than yield and EC data.