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Encroachment by host communities on pipeline right-of-way (PROW) constitutes a major problem for the oil and gas sector of the economy. This paper uses remote sensing and geographic information system (GIS) technologies to assess the level of vulnerability of people living along the PROW in Arepo, Ogun State, Nigeria. A satellite imagery of the community was acquired and processed using ArcGIS computer software. A GIS buffering operation was performed on the PROW using 15 m, 30 m, 60 m, and 90 m distances, respectively. Three hundred and forty buildings were identified in the buffered zones, out of which 200 (60%) were randomly selected for the study. A structured questionnaire was administered to household heads in the sampled buildings. Empirical analysis shows that 140 buildings (70%) observed less than a 30 m setback to the pipeline. Also, residents benefit from incidents of oil spillage and see these as an avenue to vandalize the pipeline, making them more vulnerable. GIS analysis shows that more than 30% of respondents are highly vulnerable to the hazard of pipeline explosion incidents. Enforcement of setback regulations by the Town Planning Authority and public education and awareness of risks associated with encroachment on the PROW are canvassed among others.

This paper assessed encroachment of streams due to physical development in Wa Urban Area of the Upper West Region of Ghana. The assessment was informed by the recognition that the roles played by streams in flood control are undermined by physical developments. This affects sustainable urban development and renders the urban area vulnerable to floods. The assessment was based on the 300m buffer zone standard set by the Ghana Water Resources Commission as a protective zone for such streams in the country. It is mandatory to offset all physical development from this zone but that is not the situation on the ground. For the purpose of this study each buffer zone was divided into sub-buffer zones of 100m in order to appreciate how far development has moved into the prohibited buffer zone. The streams and physical structures were mapped with a Trimble GPS receiver while land owners and tenants were purposively selected and interviewed. The buffer zone and sub-buffer zones were defined using GIS and overlaid with map of the physical structures. The categories of structures found in the buffer zones were residential (93.4 %), commercial (5.1%), public (1.3%) and agriculture (0.2%). The results of the study indicates that more than 50 % of physical structures mapped are located in the inner buffer and the land acquisition process for development of these structures amongst others in Wa is mostly initiated by developers.

It is conventional wisdom that a manufacturer's encroachment into retail space will likely hurt an existing retailer. In contrast to this conventional belief, current research indicates that a retailer may welcome a manufacturer's encroachment despite the new competition in the final market. The encroachment may help the manufacturer have some 'skin in the game' at the retail level, which will cause the manufacturer to make a selfish cost-reducing investment that spills over to the retailer as a lower wholesale price. Such a spillover effect enhances the retailer's profit as long as the encroachment does not result in extreme retail competition by a certain degree of product differentiation, and ultimately generates Pareto gains in the supply chain. The spillover effect is so robust that the retailer's benefit from the encroachment remains even after considering potential mitigating factors such as selling costs, a nonlinear form of cost reduction, decentralized encroachment, additional retail competition, price competition, and a negotiation between the manufacturer and the retailer. [ABSTRACT FROM AUTHOR]

We study a supply chain with manufacturer encroachment in which product quality is endogenous and customers have heterogeneous preferences for quality. It is known that, when quality is exogenous, encroachment could make the retailer better off. Yet, when quality is endogenous and the manufacturer has enough flexibility in adjusting quality, we find that encroachment always makes the retailer worse off in a large variety of scenarios. We also establish that, while a higher manufacturer's cost of quality hurts the retailer in absence of encroachment, it could benefit the retailer with encroachment. In addition, we show that a manufacturer offering differentiated products through two channels prefers to sell its high-quality product through the direct channel. Contrary to conventional wisdom, quality differentiation does not always benefit either manufacturer or retailer. Our results may explain why, despite extant theoretical predictions, retailers almost always resent encroachment. These findings also suggest that firms must be cautious when adopting quality differentiation as a strategy to ease channel conflict caused by encroachment. [ABSTRACT FROM AUTHOR]

We used a set of large-eddy simulations to investigate the effect of one-dimensional stripe-like surface heat-flux heterogeneities on mixed-layer top entrainment. The profiles of sensible heat flux and the temporal evolution of the boundary-layer depth revealed decreased entrainment for small heat-flux amplitudes and increased entrainment for large heat-flux amplitudes, compared to the homogeneously-heated mixed layer. For large heat-flux amplitudes the largest entrainment was observed for patch sizes in the order of the boundary-layer depth, while for significantly smaller or larger patch sizes entrainment was similar as in the homogeneous case. In order to understand the underlying physics of this impact, a new approach was developed to infer local information on entrainment by means of the local flux divergence. We found an entrainment maximum over the centre of the stronger heated surface patch, where thermal energy is accumulated by the secondary circulation (SC) that was induced by the surface heterogeneity. Furthermore, we observed an entrainment maximum over the less heated patch as well, which we suppose is to be linked to the SC-induced horizontal flow convergence at the top of the convective boundary layer (CBL). For small heat-flux amplitudes a counteracting effect dominates that decreases entrainment, which we suppose is the horizontal advection of cold air in the lower, and warm air in the upper, CBL by the SC, stabilizing the CBL and thus weakening thermal convection. Moreover, we found that a mean wind can reduce the heterogeneity-induced impact on entrainment. If the flow is aligned perpendicular to the border between the differentially-heated patches, the SC and thus its impact on entrainment vanishes due to increased horizontal mixing, even for moderate wind speeds. However, if the flow is directed parallel to the border between the differentially-heated patches, the SC and thus its impact on entrainment persists. [ABSTRACT FROM AUTHOR]

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Most remote sensing studies in deserts focus solely on vegetation monitoring to assess the extent of desertification. However, the application of sand dune encroachment into such studies would greatly improve the accuracy in the prediction criteria of risk-prone areas. This study applies the latter methodology for tracking desertification using sand dunes in the Kelso Dunes (in Newberry-Baker, CA, USA). The approach involves the comparison of spectral characteristics of the dunes in Landsat Thematic Mapper (TM) images over a 24-year period (1982, 1988, 1994, 2000, and 2006). During this 24-year period, two El Niño events occurred (1983 and 1993); it was concluded that despite the shift in predominant winds, the short-term variation in wind direction did not make a noticeable change in dune formation, but greatly influences vegetation cover. Therefore, relying solely on vegetation monitoring to assess desertification can lead to overestimations in prediction analysis. Results from this study indicate that the Kelso Dunes are experiencing an encroachment rate of approximately 5.9 m3/m/yr over the 24-year period. While quantifying the Kelso Dunes or any natural dynamic system is subject to uncertainties, the encroachment rate approach reflects the highly heterogeneous nature of the sand dunes (in regards to spectral variability in brightness) at Kelso Dunes and serves as an exemplar for future research. [ABSTRACT FROM AUTHOR]

This study has examined the driving forces behind forest encroachment in Tabora region, Tanzania. The study focused on two Forest Reserves (FRs), namely Igombe River and Simbo. While both FRs are undergoing degradation, the later FR is more severely encroached upon than the later. The information gathered covered both socio economic and biophysical aspects. The study observed that the major reasons contributing to forestry degradation through encroachment were mainly three: (i) socio-economic factors including migration, scarcity of arable land, fuel wood extraction for tobacco drying, livestock keeping and charcoal and timber business (ii) policy related factors such as unclear and conflicting laws on natural resource utilisation and (iii) biophysical factors such as soil fertility gradients within or near forestry reserves, vegetation types and distribution and micro climatic variations. [ABSTRACT FROM AUTHOR]

Little is known about the relationship between fire regimes and plant diversity in Australia's temperate grassy woodlands. The effect of fire frequency on shrubs in grassy woodland remnants across Western Sydney's Cumberland Plain was examined. Shrub species richness and composition were compared in sites that had experienced a high, moderate or low frequency of fire over the previous 20 years. Nine sites were surveyed, three in each fire frequency category; most sites, including all low-fire-frequency sites, had burnt 9–36 months prior to sampling. Fire frequency had a profound effect on the composition and structure of the shrub layer. Per cent frequency and density of the prickly shrub Bursaria spinosa (Pittosporaceae) was considerably higher in low-fire-frequency sites than where fires had occurred at least once a decade. In sites where fire had been absent for decades prior to a recent fire, this species dominated the landscape, while elsewhere it occurred as clumps in a grassy matrix. Per cent frequency of other native shrubs, particularly obligate seeders, was greatest at moderate fire frequencies. Exotic shrubs were recorded most often where fire had been rare. While ordination clearly separated out the low-fire-frequency sites, complete separation between high- and moderate-fire-frequency blocks was not achieved. The increase in Bursaria in the absence of fire mirrors the encroachment of woody plants into a range of grassy ecosystems around the world. The sensitivity of obligate seeder species, many of them short-lived legumes with fire-cued seeds, to both very frequent and very infrequent fire shows the vulnerability of these species to extreme fire regimes, despite the safeguards conferred by hard-seededness. Competition from Bursaria, as well as loss of viable seed in the soil, may have contributed to the low frequency of these species after a long inter-fire interval. [ABSTRACT FROM AUTHOR]

As track density increases, it has become even more critical to understand the track edge. In this study, the impact of media design on the track edges in perpendicular magnetic recording has been investigated. This study shows that soft under layer thickness and intergranular exchange coupling have significant impact on both track edge erasure and write width. In the range we studied, head-to- keeper spacing and media coercivity have a strong impact on write width, but not on track edge erasure. On the other hand, media design does not impact transition curvature significantly. Experimental observations were supported by media micromagnetic modeling results and write field simulation using a finite element model. Analyzing the write bubble helps to understand the dependence of adjacent track encroachment on media design. Cross track profiles of various signal-to-noise ratio (SNR) components can provide valuable insights into different track edge mechanisms. [ABSTRACT FROM AUTHOR]

Woody plants have been increasing in many woodland and savanna ecosystems owing to land use changes in recent decades. We examined the effects of encroachment by the indigenous shrub Leptospermum scoparium (Myrtaceae) on herb-rich Eucalyptus camaldulensis woodlands in southern Australia. Species richness and compositional patterns were examined under the canopy of L. scoparium and in surrounding open areas to determine the species most susceptible to structural changes. Richness was significantly lower in areas of moderate to high L. scoparium cover (>15%), suggesting that a threshold shrub cover caused major change in this ecosystem. Shrubs were associated with a significant reduction in above-ground biomass of the ground-layer flora and a significant shift in community composition. The few species that were positively associated with high L. scoparium cover were also common in the woodland flora; no new species were recorded under the shrub canopy. Important environmental changes associated with L. scoparium cover were decreased light availability and increased litter cover, which were likely a consequence of encroachment. Leptospermum scoparium cover was also associated with greater surface soil moisture, which may be a consequence of increased shading under the shrub canopy or indicate favourable soil conditions for L. scoparium establishment. Reductions in species richness and abundance of the germinable seed bank were found in soil samples taken from under L. scoparium. With ongoing recruitment of L. scoparium and consequent increases in shrub cover, ground-layer diversity in these species-rich woodlands should continue to decline over time. [ABSTRACT FROM AUTHOR]

The common wisdom is that a retailer suffers when its wholesale supplier encroaches on the retailer's operations by selling directly to final consumers. We demonstrate that the retailer can benefit from encroachment even when encroachment admits no synergies and does not facilitate product differentiation or price discrimination. The retailer benefits because encroachment induces the encroaching supplier to reduce the wholesale price in order not to diminish unduly the retailer's demand for the manufacturer's wholesale product. The lower wholesale price and increased downstream competition mitigate double marginalization problems and promote efficiency gains that can secure Pareto improvements. [ABSTRACT FROM AUTHOR]

Successful new products typically encroach in some fashion on an existing market, impacting prices, sales, and profits for the old product(s). We present a framework in which encroachment takes one of two forms, either high-end or low-end. High-end encroachment is exemplified by Intel's Pentium III, which encroached on the Pentium II by first catering to high-end customers before diffusing to the low end to fully displace the Pentium II. Low-end encroachment is illustrated by disk drives with smaller form factors, which first catered to low-end customers desiring lower-cost, but eventually diffused upward to the high end. Our low-end encroachment framework may help clarify how a disruptive innovation impacts the market, in terms of sales prices, volumes, and profits. Similarly, our high-end encroachment results may lend insight into the market impact of a sustaining technology. [ABSTRACT FROM AUTHOR]

Our study aimed at identifying mechanisms that permit the long-term persistence of Sarcopoterium spinosum, a dwarf-shrub that dominates large areas of hilly landscape in eastern Mediterranean countries. Data were obtained from 16 1×1 m quadrats distributed among well-established S. spinosum communities in Israel that had not been burned or otherwise disturbed for well over 20 years. We sampled three communities that represent different climatic and habitat conditions and analysed the growth rings in the root crowns of 604 uprooted plants, to determine the age structures of the sampled stands. Many older ‘shrubs’ that appeared to be individual plants were in fact clusters of ramets with their root crowns concentrated in a very small area. The morphology of these ramets indicates that they arose by rooting of peripheral stems. Seedlings and young plants were rare. Ramets seldom exceeded 17 years of age, although a few were 18–21 years old and one had 34 growth rings. The average ramet age on the different sites varied between 9 and 11 years. The ramets appeared to separate from the mother plant when they were older than 7 years, after which they had an estimated average half-life of ca. 2.8 years. Young shrubs grew rapidly in height, but their basal cover was low; it increased when they were much older, presumably as the older plants died. Consequently, three or four cohorts of older ramets between 12 and 17 years old often dominated stand cover. The continuing profuse production of seeds even where seedling recruitment is normally rare could be related to the relatively short average life-span of the ramets. We conclude that where resources are irregularly distributed and establishment sites are fully occupied by perennial species, localised phalanx-type clonal proliferation can reduce the risk of genet extinction. On favourable sites this strategy confers upon S. spinosum genets the tenacity required to hold off replacement by other species and to dominate large areas of the landscape for much longer than the average life span of individual ramets. [ABSTRACT FROM AUTHOR]

Abstract This study examines the regeneration of indigenous tree species in the formerly encroached area in Mgahinga Gorilla National Park (MGNP), south-western Uganda. Before gazetting in 1992, MGNP had basically been agricultural land for well over 50 years. The distribution of exotic vegetation was established using a Geographical Positioning System receiver and indigenous vegetation was sampled by establishment of quadrats along transect lines. Observations indicated that approximately 2% of the old cropland was covered by exotic woodlots. Black wattle (Acacia mearnsii) and Eucalyptus trees were found to be the most widely distributed and Pinus patula the least distributed species in the park. Species numbers of indigenous trees (n = 26) were high in the old cropland, compared with twelve species observed in exotic woodlots. The natural forest supported the highest (75%) stem density and the lowest (4%) stem density was recorded in exotic woodlots. Seedling class (< 2 cm, d.b.h.) accounted for the majority of juveniles, with the lowest stem density (1350 seedlings ha-1) recorded in exotic woodlots compared with 6609 seedlings ha-1 in the old cropland and 24,625 seedlings ha-1 in the natural forest. The levels of tree diversity and stocking characteristics recorded under the exotic species suggest that a low diverse community of native species may exploit this environment. [ABSTRACT FROM AUTHOR]

Eastern redcedar (Juniperus virginiana L., redcedar) encroachment is transitioning the oak-dominated Cross-Timbers of the southern Great Plain of the USA into mixed-species forests. However, it remains unknown how the re-assemblage of tree species in a semiarid to sub-humid climate affects species-specific water use and competition, and ultimately the ecosystem-level water budget. We selected three sites representative of oak, redcedar, and oak and redcedar mixed stands with a similar total basal area (BA) in a Cross-Timbers forest near Stillwater, Oklahoma. Sap flow sensors were installed in a subset of trees in each stand representing the distribution of diameter at breast height (DBH). Sap flow of each selected tree was continuously monitored over a period of 20 months, encompassing two growing seasons between May 2017 and December 2018. Results showed that the mean sap flow density (Sd) of redcedar was usually higher than post oaks (Quercus stellata Wangenh.). A structural equation model showed a significant correlation between Sd and shallow soil moisture for redcedar but not for post oak. At the stand level, the annual water use of the mixed species stand was greater than the redcedar or oak stand of similar total BA. The transition of oak-dominated Cross-Timbers to redcedar and oak mixed forest will increase stand-level transpiration, potentially reducing the water available for runoff or recharge to groundwater. [ABSTRACT FROM AUTHOR]