Root architecture of provenances, seedlings and cuttings of Melia volkensii: implications for crop yield in dryland agroforestry

Melia volkensii (Gürke) is being increasingly promoted as an on-farm tree in Kenya. Researchers’ and farmers’ views on its competitiveness with crops differ; research station studies have found it to be highly competitive whereas farmers do not consider it to be so. Because of difficulties in seed germination, it is probable that dissemination programmes will rely upon plants produced from root and stem cuttings, rather than on seedlings. This study evaluates differences in root system architecture of plants raised from seed (of four provenances), stem or root cuttings and the relationships between the competitivity index (CI) and crop yield. Cuttings were more shallowly rooting than seedlings, and had higher competitivity indices, and there was a negative relationship between CI and crop yield. No differences in root architecture between provenances were found. Therefore, to reduce tree-crop competition, the use of seedlings rather than cuttings should be recommended when promoting the use of this species on dryland farms. If cuttings are used to circumvent the problems of seed germination, alternative methods of controlling competition, such as root pruning, need to be considered

The Afen Slide

Summary Identified in 1996, as part of an environmental survey for the Atlantic Frontiers Environment Network (Graham et al 1996, Masson et al 1996), the Afen Slide lies around 95 km northwest off the Shetland Islands. Using seabed picks from 3D exploration seismics reveals the detailed morphology of the slide (Bulat 2001) enabling interpretations about the phases and nature of movement to be made. The head of the slide is at water depth of 830 mbsl and the debris lobe stretches to over 1120 mbsl along a slope varying from >2o to <1o. The overall length is in excess of 12 km and the maximum width attained is around 4.5 km. The relative timing of the various phases can be determined with some certainty although the absolute age of the slide or the various phases is more difficult to confirm. There are two 14C dates from the area, one from the surficial sediments within the slide scar (Holmes et al 1997) and the other from within the debris lobe. These suggest a possible first movement at around 16,000 –13,000 years BP with the later retrogressive phases occurring after 5,800 years BP. These are highly speculative, as the exact relationship of the dated material to the post slide stratigraphy is not known. The seismic data combined with information from previous studies indicates that sedimentation in the area is controlled by along slope processes; mounded elongate contourites can be traced through the surrounding area. The seismic record suggests that the depositional environment has remained remarkably consistent since the onset of the last glacial. This may have contributed to the conditions that combined to produce slope failure in this particular area. An abundance of contouritic sands predisposed to liquefaction interspersed with fine-grained low permeability muds would provide a plane of weakness along which failure could propagate. However, the seismicity, necessary to cause liquefaction, during the period in question is not known although threshold values for failure have been calculated to be within the 10,000 yr return period (Hobbs et al 1997)

TSPA Model for the Yucca Mountain Unsaturated Zone

Yucca Mountain, Nevada, is being considered as a potential site for a repository for spent nuclear fuel and high-level radioactive waste. Total-system performance-assessment (TSPA) calculations are performed to evaluate the safety of the site. Such calculations require submodels for all important engineered and natural components of the disposal system. There are five submodels related to the unsaturated zone: climate, infiltration, mountain-scale flow of water, seepage into emplacement drifts, and radionuclide transport. For each of these areas, models have been developed and implemented for use in TSPA. The climate model is very simple (a set of climate states have been deduced from paleoclimate data, and the times when climate changes occur in the future have been estimated), but the other four models make use of complex process models involving time-consuming computer runs. An important goal is to evaluate the impact of uncertainties (e.g., incomplete knowledge of the site) on the estimates of potential repository performance, so particular attention is given to the key uncertainties for each area. Uncertainties in climate, infiltration, and mountain-scale flow are represented in TSPA simulations by means of discrete high, medium, and low cases, Uncertainties in seepage and radionuclide transport are represented by means of continuous probability distributions for several key parameters

ENERGY ACQUISITION AND ALLOCATION IN PLANTS AND INSECTS: A HYPOTHESIS FOR THE POSSIBLE ROLE OF HORMONES IN INSECT FEEDING PATTERNS

A distributed delay age structure model is presented for plants and insects that describes the dynamics of per capita energy (dry matter) acquisition and allocation patterns, and the within-organism subunit (e.g. leaves, fruit, ova) number dynamics that occur during growth, reproduction, and development. Four species of plants (common bean, cassava, cotton, and tomato) and two species of insects (pea aphid and a ladybird beetle) are modeled. A common acquisition (i.e. functional response) submodel is used to estimate the daily photosynthetic rates in plants and consumption rates in pea aphid and the ladybird beetle. The focus of this work is to capture the essence of the common attributes between trophic levels across this wide range of taxa. The models are compared with field or laboratory data. A hypothesis is proposed for the observed patterns of reproduction in pea aphid and in a ladybird beetl

UNDERSTANDING THE DETERMINANTS OF BLOCKCHAIN ADOPTION IN SUPPLY CHAINS: AN EMPIRICAL STUDY IN CHINA

This study adopts affordance approach to understand how supply chain managers interpret the possible benefits that can be performed within blockchain-enabled supply chain applications. With a focus on governance efficiency improvement, the impacts of traceability and transparency affordance on uncertainty reduction were examined from the perspective of transaction cost theory in supply chain industry. Partial least squares – structural equation modelling (PLS-SEM) was used to analyze the data collected from 364 experienced supply chain managers in China. The results revealed that traceability affordance exerted significant impacts on environmental and trading partner uncertainty rather than transparency affordance, which in turn affected the adoption intention. This study contributes to the extant literature by embedding transaction cost in blockchain affordances. The findings are useful in guiding practitioners to improve blockchain system design for reducing uncertainties in supply chain environment, leading to a higher adoption rate of blockchain technology

Encapsulated bacteria deform lipid vesicles into flagellated swimmers

We study a synthetic system of motile Escherichia coli bacteria encapsulated inside giant lipid vesicles. Forces exerted by the bacteria on the inner side of the membrane are sufficient to extrude membrane tubes filled with one or several bacteria. We show that a physical coupling between the membrane tube and the flagella of the enclosed cells transforms the tube into an effective helical flagellum propelling the vesicle. We develop a simple theoretical model to estimate the propulsive force from the speed of the vesicles and demonstrate the good efficiency of this coupling mechanism. Together, these results point to design principles for conferring motility to synthetic cells

Granulation and suspension rheology: A unified treatment

Mixing a small amount of liquid into a powder can give rise to dry-looking granules; increasing the amount of liquid eventually produces a flowing suspension. We perform experiments on these phenomena using Spheriglass, an industrially realistic model powder. Drawing on recent advances in understanding friction-induced shear thickening and jamming in suspensions, we offer a unified description of granulation and suspension rheology. A "liquid incorporation phase diagram"explains the existence of permanent and transient granules and the increase of granule size with liquid content. Our results point to rheology-based design principles for industrial granulation

Draft genome sequence of a harveyi clade bacterium isolated from lolliguncula brevis squid

Vibrio species of the Harveyi clade are commonly found in free-living and host-associated marine habitats. Here, we report the draft genome sequence for a Harveyi clade bacterium, Vibrio sp. strain LB10LO1, which was isolated from the Atlantic brief squid Lolliguncula brevis