Commuting distances to local non‐farm workplaces and out‐migration: The case of Northeast Thailand

The relationship between commuting distances and where people work has been studied for urban contexts in both developed countries and developing countries. However, few studies have examined the situation in rural areas, and none look at commuting distances to non‐farm workplaces in rural areas of developing countries. This paper investigates how commuting distance, and thus accessibility, to local non‐farm work influences non‐farm employment and out‐migration from rural villages in Northeast Thailand. The main issues examined are: (i) the distance that rural residents travel to work in local non‐farm jobs; and (ii) the influence that local non‐farm employment has on the number of outmigrants from rural villages. The study finds: (i) distance between villages and non‐farm work sites impact the number of villagers who are employed in regular wage work; (ii) beyond 20 km villagers are less likely to travel to non‐farm employment using their own means of transportation; and (iii) employment in regular wage work decreases outmigration. The findings from this study contribute to the debates over the drivers of rural out‐migration, rural livelihood changes, and agrarian changes that are taking place in Southeast Asia.     

Remote Sensing of Spatial and Temporal Vegetation Patterns in Two Grazing Systems

One constraint that range scientists must face in grazing studies is the lack of accurate and repeatable techniques for discriminating grazing effects from both temporal variability and spatial heterogeneity of vegetation. Both forms of variability contribute to inconsistent grazing system effects on vegetation response and forage production in semiarid ecosystems. Remote sensing may be an efficient tool for detecting differences in spatial and temporal patterns of grazing impact on vegetation. The purpose of this study was to evaluate the spectral data derived from satellite images as a tool for comparing grazing system impacts on spatial and temporal vegetation patterns. We evaluated the effect of two grazing systems, “Continuous” (C) and “Two-Paddocks Rest-Rotation” (TPRR), on vegetation cover from 1996 to 2006 in a semiarid ecosystem of Argentina. We compared grazing effects on vegetation cover using two indices derived from the Normalized Difference of Vegetation Index (NDVI) data from Landsat Thematic Mapper images. We observed a slight advantage in NDVI improvement for the TPRR over the C. Even though, in both grazing systems, an upward vegetation trend occurred only in areas located far from the watering points, TPRR showed higher relative vegetation cover near the watering point than C. We consider this methodology an important step for monitoring vegetation changes and making management decisions in livestock systems of semiarid regions because grazing system impacts may be compared for both spatial and temporal vegetation patterns. However, we think that the key next step is to develop procedures that discriminate between forage and nonforage components.     

A Case Study Evaluating Economic Implications of Two Grazing Strategies for Cattle Ranches in Northwest Argentina

In the Argentinean Chaco Arido region, cattle production based on cow–calf operations is the principal source of agricultural income, and rangeland is the main forage source for cattle. Traditional grazing strategy (TGS, high stocking rate and continuous grazing) is considered the main cause of current rangeland degradation. Research shows that rangeland and cattle production improvements are possible when using a conservative grazing strategy (CGS, moderate stocking rate and rest rotation grazing). The aim of this research was to compare the effects of TGS and CGS applications on economic results for a cattle ranch in the region. To achieve this objective we used an approach that included estimations of forage and cattle production, and economic results. The study period was 1972/73–1983/84. Results showed that during the study period forage production and herd size were almost doubled with CGS, but maintained with TGS. The difference in net income between CGS and TGS (in Argentinean pesos, $), increased linearly from negative (-$2.88 · ha^-1) to positive ($4.48 · ha^-1) in the first 4 yr, and then was maintained at positive values (averaging $4.48 · ha^-1). Data suggest that CGS leads to higher productivity and better economic results than TGS in the medium and long terms.En la región del Chaco Árido Argentino, la ganadería de cría es la actividad agropecuaria más difundida. Esta actividad se basa principalmente en el forraje que proporciona el pastizal nativo. La estrategia de pastoreo tradicional (EPT, consistente de alta carga animal y pastoreo continuo), se considera la causa principal del estado de degradación actual del pastizal nativo. Varios estudios han mostrado que el mejoramiento de la productividad del pastizal y del ganado es posible cuando se utiliza una estrategia de pastoreo conservativa (EPC, consistente en carga animal moderada y un pastoreo que permita descanso del pastizal en época de crecimiento). El objetivo de esta investigación fue comparar el efecto de la EPT y la EPC sobre el aspecto económico de un rancho ganadero de la región del Chaco Árido. Para lograr dicho objetivo se hizo un análisis en distintas etapas, estimación de la producción forrajera, estimación de la producción ganadera, y estimación del resultado económico. El periodo de estudio fue desde 1972/73 hasta 1983/84. Los resultados mostraron que durante el periodo de estudio la producción de forraje y el tamaño del rodeo se duplicaron para la EPC, mientras que para EPT se mantuvieron. La diferencia en el resultado económico neto entre la EPC y la EPT (en pesos Argentinos, $), se incrementó linealmente desde valores negativos (-$2.88 · ha^-1) a valores positivos ($4.48 · ha^-1) en los cuatro primeros años, para luego mantenerse en un valor promedio de $4.48 · ha^-1. Los resultados sugieren que la EPC permite obtener una productividad más alta y mejores resultados económicos que la EPT a mediano y largo plazo.     

Crystal structure of the ribonucleoprotein core of the signal recognition particle

The signal recognition particle (SRP), a protein-RNA complex conserved in all three kingdoms of life, recognizes and transports specific proteins to cellular membranes for insertion or secretion. We describe here the 1.8 angstrom crystal structure of the universal core of the SRP, revealing protein recognition of a distorted RNA minor groove. Nucleotide analog interference mapping demonstrates the biological importance of observed interactions, and genetic results show that this core is functional in vivo. The structure explains why the conserved residues in the protein and RNA are required for SRP assembly and defines a signal sequence recognition surface composed of both protein and RNA.     

Canopy microclimate response to pattern and density of thinning in a Sierra Nevada forest

Restoring Sierra Nevada mixed-conifer forests after a century of fire suppression has become an important management priority as fuel reduction thinning has been mandated by the Healthy Forests Restoration Act. However, in mechanically thinned stands there is little information on the effects of different patterns and densities of live-tree retention on forest canopy microclimate. This study compared gradients of air temperature and vapor pressure deficit (VPD) through the vertical forest profile among an overstory-thin, an understory-thin, an un-thinned control, and a riparian environment in a Sierra Nevada mixed-conifer forest. Temperature and humidity were recorded for a year by 60 data loggers arrayed in 12 trees at 5, 15, 25, 35, and 45 m above the forest floor. Both thinning treatments had significantly more extreme summer daily ranges of temperature and VPD than the control across heights. The overstory-thin resulted in the greatest maximum temperatures, VPDs, and VPD range among all sensors at 5 m, and significantly higher summer maximum temperatures and VPDs than the control in lower strata (≤15 m). The understory-thin also had significantly higher summer maximum temperatures than the control (≤15 m), but these too were significantly less than in the overstory-thin nearest the surface at 5 m. Understory thinning did not alter the mean or range of microclimate as much as overstory thinning. Riparian microclimate had significantly lower minimums and means, and greater daily ranges of temperatures and VPDs than the control. Results suggest that thinning canopy cover significantly increases the extremes and variability of understory microclimate compared to thinning from below and no-thin treatments.     

11S and 7S globulins of coconut (Cocos nucifera L.): purification and characterization

Total globulins extracted with 0.4 M NaCl in buffer from coconut endosperm separated into two peaks on gel filtration: peak I corresponding to 11S globulin or cocosin and peak II to 7S globulin with native molecular weights of 326 000 and 156 000, respectively. The percent composition of total globulins was estimated to be 11S, 86% and 7S, 14%. On SDS-PAGE, cocosin resolved into two closely migrating bands at approximately 34 000 (acidic polypeptide) and another set of 2 bands at 24 000 (basic polypeptide). Each set consisted of one darkly stained band and one lightly stained band. The 7S globulin consisted of three bands of 16 000, 22 000, and 24 000. Three isoforms of cocosin were identified after anion exchange chromatography. Cocosin, but not the 7S, was found to have disulfide bonds. Using periodic acid-Schiff's reagent, all of the bands of cocosin on SDS-PAGE were positive for carbohydrate. However, when con A-peroxidase was used, only the basic polypeptide stained positively for carbohydrate. For the 7S globulin, no carbohydrate group was detected using the PAS and con A-peroxidase tests. The 7S globulin was easily extracted with 0.10-0.15 M NaCl, whereas cocosin was extracted with 0.35 M NaCl. The N-terminal amino acid sequences of the 34 k band and 24 k band of cocosin were SVRSVNEFRXE and GLEETQ, respectively, and that of the 7S was EQEDPELQK.     

Impact of manganese amino acid complex on tissue-specific trace mineral distribution and corpus luteum function in gilts

Functional corpora lutea (CL) are required for pregnancy establishment and gestational maintenance in swine, and CL function is susceptible to environmental influences. Manganese (Mn) could be critical in regulating CL function since it is a component of the antioxidant enzyme Mn superoxide dismutase (MnSOD) as well as enzymes involved in cholesterol and steroid hormone synthesis. We hypothesized that a more bioavailable dietary Mn source would increase Mn content in the CL thereby influencing luteal function during the mid-luteal phase of the estrous cycle. Postpubertal gilts (n = 32) were assigned to one of four gestation diets. The control diet (CON) met or exceeded National Research Council (2012) requirements and was formulated to contain 20 parts per million (ppm) of added Mn in the form of Mn sulfate. Three additional diets included 20 (treatment [TRT]1), 40 (TRT2), or 60 (TRT3) ppm of added Mn from a Mn–amino acid complex (Availa-Mn; Zinpro Corporation) instead of Mn sulfate. Dietary treatment began at estrus synchronization onset and continued through 12 days post estrus (dpe) of the ensuing estrous cycle. Blood samples were collected at estrus onset, which was assigned as 0 dpe, as well as 4, 8, and 12 dpe. Gilts were euthanized and tissues were collected at 12 dpe. Serum progesterone (P₄) increased (P < 0.01) from 0 to 12 dpe but was unaffected by dietary treatment (P = 0.15) and there was no effect of the interaction between day and treatment (P = 0.85). Luteal Mn content increased (P ≤ 0.05) by 19%, 21%, and 24% in gilts fed TRT1, TRT2, and TRT3, respectively, compared to CON. Luteal P₄ concentrations decreased (P = 0.03) 25%, 26%, and 32% in gilts fed TRT1, TRT2, and TRT3, respectively, compared to CON. Relative to CON gilts, CL calcium content decreased (P = 0.02) by 36%, 24%, and 34% for TRT1, TRT2, and TRT3 gilts, respectively. Collectively, these data support the hypothesis that feeding a more bioavailable Mn source increases Mn accumulation in CL tissue. If and how this influences CL function may be related to altered luteal P₄ concentrations.     

Energetic radiation produced during rocket-triggered lightning

Using a NaI(Tl) scintillation detector designed to operate in electrically noisy environments, we observed intense bursts of energetic radiation (> 10 kiloelectron volts) during the dart leader phase of rocket-triggered lightning, just before and possibly at the very start of 31 out of the 37 return strokes measured. The bursts had typical durations of less than 100 microseconds and deposited many tens of megaelectron volts into the detector. These results provide strong evidence that the production of runaway electrons is an important process during lightning.