Designing a virtual-memory implementation using the Motorola MC68010 16 bit microprocessor with multi-processor capability interfaced to the VMEbus

The primary purpose of this thesis is to explore and discuss the hardware design of a bus-oriented microprocessor system. A bus-oriented microprocessor system permits it to be expanded to a multi-processor system. Through the use of a bus controller and bus arbiter, as discussed in this thesis, the necessary logic is in place to control bus access by system users. Bus access may be initiated to share another sub-system's resource, such as memory. To accommodate memory sharing between two systems, a dual-port memory controller can be used to resolve memory access between the two systems. This thesis discusses the design of a MC68010 microprocessor system integrated on the VMEbus with dual-ported memory capability. Additional features of the MC68010 microprocessor system include memory-management and interrupt control. The memory-management features permit protected memory and virtual-memory to be implemented on the system, while an interrupt handler is used to assist the MC68010 microprocessor in exception processing.http://archive.org/details/designingvirtual1094534827Lieutenant, United States NavyApproved for public release; distribution is unlimited

Ecological Impacts of Alien Species: Quantification, Scope, Caveats, and Recommendations

Despite intensive research during the past decade on the effects of alien species, invasion science still lacks the capacity to accurately predict the impacts of those species and, therefore, to provide timely advice to managers on where limited resources should be allocated. This capacity has been limited partly by the context-dependent nature of ecological impacts, research highly skewed toward certain taxa and habitat types, and the lack of standardized methods for detecting and quantifying impacts. We review different strategies, including specific experimental and observational approaches, for detecting and quantifying the ecological impacts of alien species. These include a four-way experimental plot design for comparing impact studies of different organisms. Furthermore, we identify hypothesis-driven parameters that should be measured at invaded sites to maximize insights into the nature of the impact. We also present strategies for recognizing high-impact species. Our recommendations provide a foundation for developing systematic quantitative measurements to allow comparisons of impacts across alien species, sites, and tim

Ecological impacts of alien species: quantification, scope, caveats, and recommendations

Despite intensive research during the past decade on the effects of alien species, invasion science still lacks the capacity to accurately predict the impacts of those species and, therefore, to provide timely advice to managers on where limited resources should be allocated. This capacity has been limited partly by the context-dependent nature of ecological impacts, research highly skewed toward certain taxa and habitat types, and the lack of standardized methods for detecting and quantifying impacts. We review different strategies, including specific experimental and observational approaches, for detecting and quantifying the ecological impacts of alien species. These include a four-way experimental plot design for comparing impact studies of different organisms. Furthermore, we identify hypothesis-driven parameters that should be measured at invaded sites to maximize insights into the nature of the impact. We also present strategies for recognizing high-impact species. Our recommendations provide a foundation for developing systematic quantitative measurements to allow comparisons of impacts across alien species, sites, and time

Form Appro ed

Approved for public release; distribution is unlimited

Defining the Impact of Non-Native Species

Non-native species cause changes in the ecosystems to which they are introduced. These changes, or some of them, are usually termed impacts; they can be manifold and potentially damaging to ecosystems and biodiversity. However, the impacts of most non-native species are poorly understood, and a synthesis of available information is being hindered because authors often do not clearly define impact. We argue that explicitly defining the impact of non-native species will promote progress toward a better understanding of the implications of changes to biodiversity and ecosystems caused by non-native species; help disentangle which aspects of scientific debates about non-native species are due to disparate definitions and which represent true scientific discord; and improve communication between scientists from different research disciplines and between scientists, managers, and policy makers. For these reasons and based on examples from the literature, we devised seven key questions that fall into 4 categories: directionality, classification and measurement, ecological or socio-economic changes, and scale. These questions should help in formulating clear and practical definitions of impact to suit specific scientific, stakeholder, or legislative contexts.Peer Reviewe

Impact scheme of the Global Invasive Species Database, implemented by the IUCN Species Survival Commission (SSC) Invasive Species Specialist Group.

<p>The GISD stores detailed information on more than 800 invasive alien species, including on the impacts they cause. The GISD has recently been redesigned, and all information has been re-classified in order to improve the searching functionalities of the database. The schema developed for the revised GISD has allowed all species stored in the database to be coded in respect of the direct mechanisms by which their impacts occur (e.g., predation), and by the outcomes of those impact mechanisms on the environment or on human activities. For example, the grass <i>Imperata cylindrica</i> (Poales: Poaceae) almost doubles litter biomass in invaded locations, which increases potential fuel for fires (impact mechanism coded as flammability, and impact outcome as modification of fire regime). The plant <i>Schinus terebinthifolius</i> (Sapindales: Anacardiaceae) is a bio-fouling agent, forming dense thickets in gullies and river bottoms, with the ultimate effect of changing the hydrology of river streams of invaded freshwater bodies (mechanism coded as bio-fouling, and impact outcome described as modification of hydrology). The insect <i>Adelges piceae</i> (Hemiptera: Adelgidae) releases a toxin causing stress to trees, which eventually die. The impact outcome of <i>A. piceae</i> is described in GISD as damage to forestry, with its mechanism of impact coded as poisoning/toxicity, but it can also be coded as having an environmental impact on plant/animal health, as it has been here. In the table, mechanisms and outcomes are reported in two separate columns, and the three examples of the connections between mechanisms and outcomes are shown. Impact outcomes in the GISD database can be environmental or socio-economic, but our categorisation scheme of species in terms of the magnitudes of their impacts (<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001850#pbio-1001850-g002" target="_blank">Figure 2</a>; <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001850#pbio-1001850-t001" target="_blank">Table 1</a>) concerns only the former.</p

Impact criteria for assigning alien species to different categories in the classification scheme (Box 2).

<p>These categories are for species that have been evaluated, have alien populations (i.e., are known to have been introduced outside their native range), and for which there is adequate data to allow classification (see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001850#pbio-1001850-g002" target="_blank">Figure 2</a>). Classification follows the general principle outlined in the first row. However, we specifically outlined the different mechanisms through which an alien species can cause impacts in order to help assessors to look at the different aspects and to identify potential research gaps. Numbers next to different impact classes reference the numbering of impacts in the classification of impact mechanisms in the GISD (<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001850#pbio-1001850-g001" target="_blank">Figure 1</a>).</p

The different categories in the alien species impact scheme, and the relationship between them.

<p>Descriptions of the categories are provided in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001850#pbio-1001850-box002" target="_blank">Box 2</a>. The CG category is not represented in this diagram as CG taxa may be found in any category.</p