Privatpersoner och företag hyr i allt större utsträckning molntjänster snarare än att själva driva ett datacenter. Kunder som använder molntjänster förväntar sig att dessa alltid är tillgängliga och säkra i ett datacenters händer. För att möta kunders förväntningar designas dagens datacenter med hög tillgänglighet, skalbarhet och säkerhet. Dagens datacenter designas utifrån hierarkiska trädtopologier med redundanta enheter och protokoll, vilket möjliggör både hög tillgänglighet och skalbarhet. Säkerheten uppnås via flera delar såsom brandväggar, spam- och DoS-skydd samt med ständigt uppdaterade enheter. Företaget TwigNET var i behov av en förnyad brandväggslösning och omstrukturering av sitt datacenter. Med målsättningen att ta fram den bästa brandväggslösningen för företaget så analyserades den befintliga brandväggslösningen i kombination med hur trafiken flödar till och från datacentret.Analysen användes som grund för att ta fram en ny lösning som designades för att kunna användas samtidigt som företagets befintliga lösning. I den gamla lösningen så delade alla servrar på en broadcast-domän. Den nya brandväggslösningen designades till att dela in varje server-kategori i en egen broadcast-domän, subnätverk och zon. Företagets redan etablerade policy för internetkommunikation återanvändes på de nya zonerna, men anpassades även för filtrering mellan dessa. Teknikerna chassis cluster, LACP och vPC användes för att uppnå hög tillgänglighet för brandväggarna utan att behöva använda active/active. När den nya brandväggslösningen var färdigställd så jämfördes Juniper SRX mot Cisco ASA för att belysa likheter och skillnader.

Piñon and juniper tree species have species-specific climatic requirements, resulting in unique distributions and differential responses to climate change. Piñons and junipers co-dominate the arid woodlands of North America as groups with widespread hybridization. Two piñons, Pinus edulis; P. monophylla, and four junipers, Juniperus deppeana var. deppeana; J. monosperma; J. occidentalis; J. osteosperma, are endemic to the midlatitude interior west and form three groups of hybridizing sister species, P. edulis-P. monophylla; J. deppeana var. deppeana-J. monosperma; J. occidentalis-J. osteosperma. Recent droughts have caused widespread mortality among piñons, but have had less impact on junipers and indicate shifts in co-occurrence have already begun in response to global climate change. Within these groups hybridization likely plays an important role in such distribution changes. The central objective of this thesis is to forecast the distributions of piñons and junipers endemic to the US under modeled climate change for the 21st century. Species distribution models are built with an emphasis placed on aligning the life cycle dynamics of the species within the temporal and spatial resolution of predictor variables, and within the modeling technique. Two concerns surrounding species distribution modeling are addressed. First, concerns regarding the extent to which species are at equilibrium with the current climate are addressed by incorporating dispersal into the model building process. Second, concerns regarding the potential role of hybridization between closely related species are addressed by building distribution models for each of the three sister species groups as well as the six component species. Species distribution models exhibited individualistic responses to modeled climate change. Modeled areal loss was greater than gain for all species, which is reflected in changes of co-occurrence. Piñon-juniper richness is forecast to increase in the northern Colorado Plateau, eastern Great Basin, and Rocky Mountains. The sister-species models forecast greater areal gain, and less areal loss, along hybridization zones for P. edulis-P. monophylla and for J. occidentalis-J. osteosperma, but forecast greater areal loss along the periphery of the component species distributions. The sister-species model for J. deppeana var. deppeana-J. monosperma forecasts overall greater areal loss than the component species. In general, forecast changes in latitude and elevation are about one third of the changes inferred, from the fossil record, to have occurred following the transition to the current interglacial ~10,000 years ago.

Pinyon-juniper woodland encroachment threatens ecosystem function and diversity on sagebrush steppe. Decreased fire frequency likely favors proliferation of pinyon-juniper woodlands and subsequent decline in desirable understory species. Increased tree cover produces hazardous canopy fuel loads that contribute to severe crown fires and threaten life and property at the wildland-urban-interface. Mechanical mastication converts large canopy fuels into small woody debris, altering wildfire dynamics from a potential crown fire to a more controllable surface fire. We measured fuel loading and cover on untreated, masticated, and masticated + burned treatments on 30-m transects within 30 X 33-m subplots, representing 45 different sites throughout Utah. All variables were analyzed using mixed-model analysis of covariance with untreated or pretreatment tree cover as the covariate. Shredding trees reduced large-diameter fuels to primarily 10-hour fuels (6.4-25.4 mm diameter). Reduced fuel sizes, fuel redistribution, and fuelbed compactness resulting from mastication treatments can aid wildfire suppression. Masticated + burned treatments effectively reduced woody surface fuel loading to that of pretreatment conditions. Prescribed burning could be used outside the growing season in cool-weather, high-moisture conditions to remove surface fuels, mitigating lethal soil heating and plant mortality. Shrub loading was not adversely affected by mastication treatments, but was significantly reduced with masticated + burned treatments. Masticated and masticated + burned treatments significantly increased herbaceous fuel loading. Treating at lower tree cover values reduced fuel buildup, and provided more opportunity for a positive herbaceous response. Fuel loading estimates measured in this study were provided to populate fire behavior models for mastication treatments on our study sites when such models become available.

No description available.

The spread of fruiting tree species is strongly determined by the behavior and range of fruit-eating animals, particularly birds. Birds either consume and digest seeds or carry and cache them at some distance from the source tree. These carried and settled seeds provide some form of distribution which generates tree spread to the new location. Firstly, we modal seed dispersal by birds and introduce it in a dispersal model to estimate seed distribution. Using this distribution, we create a population model to estimate the speed at which juniper and pinyon forest boundaries move. Secondly, we introduce a fact that bird movement occurs based on local habitat type to receive modified dispersal model. Birds can easily move many kilometers but habitat changes on the scale of tens of meters with rapidly varying. We develop a new technique to solve the modified dispersal model and approximate the form of transported seed distributions in highly variable landscapes. Using a tree population model, we investigate the rate of forest migration in variable landscapes. We show that speeds calculated using average motility of animals and mean seed handling times accurately predict the migration rate of trees. Regional scale forest distribution models are frequently used to project tree migration based on climate and geographic variables such as elevation, and regional presence-absence data. It is difficult to accurately use dispersal models based on large-scale presence-absence data, particularly for tree species dispersed by birds. The challenge is that variables associated with seed dispersal by birds are represented only few meters while the smallest pixel size for the distribution models begins with few kilometers. Transported seed distribution estimated in the variable landscape offers a tool to make use of this scale separation. Finally, we develop a scenarios that allows us to find large scale dispersal probabilities based on small scale environmental variables.

Anthropogenic activities are responsible for increases in atmospheric CO₂ and climate change. These increases are partly counterbalanced by natural processes, such as carbon uptake in land surfaces. These processes are themselves subject to climate change, creating a coupled carbon-climate system. I investigated the carbon sink that woody encroachment represents, using a Central Texas savanna as study site, and studied how climatic factors influence this carbon sink. Woody plant encroachment, a worldwide structural change in grassland and savanna ecosystems, alters many ecosystem properties, but the net effect on the carbon balance is uncertain. Woody encroachment represents one of the key uncertainties in the US carbon balance, and demands a more detailed understanding. To come to a process-based understanding of the encroachment effect on carbon dynamics, I analyzed patterns of carbon exchange using eddy-covariance technology. I expected the imbalance between carbon uptake and release processes associated with the encroaching trees specifically, to be responsible for the carbon sink. I also expected that the sink would vary in time, due to strong links between carbon fluxes and soil water in this semi-arid ecosystem. I further studied the ecophysiology of the dominant species, as well as soil respiration processes under different vegetation types, and scaled these findings in space and time. I found that the ecosystem was a significant carbon sink of 405 g C m⁻² yr⁻¹. The encroaching trees increased photosynthesis by 180% and decreased soil respiration by 14%, compared to the grassland, resulting in a strong carbon sink due to the encroachment process. The encroaching process also altered carbon dynamics in relation to climatic drivers. The evergreen species Ashe juniper effectively lengthened the growing season and widened the temperature range over which the ecosystem acts as a carbon sink. The drought resistance of the encroaching trees reduced the sensitivity of this savanna to drought. I conclude that encroachment in Central Texas savannas increased the carbon sink strength by increasing the carbon inputs into the ecosystem. Woody encroachment also reduced the sensitivity to climatic drivers. These two effects constitute a direct effect, as well as a negative feedback to the coupled carbon-climate system. / text

No description available.

Common juniper (Juniperus communis subs. Communis) is a shrub or a tree original in Czech Republic which was widespread there in the past. It grows either in lowlands or in mountains and it is undemanding to the soil. Nowadays, there is a lower number of it because of economic transformation in landscape. In consequence of this, it is on the list of endangered species of Czech Republic. The aim of this project was to chart the current state of population of common juniper in region "Mšály" (in The Protected Landscape Area of Třeboňsko). 144 living specimens were founded there. Dendrometry, mensuration of the specimens by GPS and drawing the new maps was realised. Another aim was comparison of the new data with the results of the research in 2004 2007. It was ascertained, that the observed population has a decreasing tendency in it's quantity. The average height of a specimen in the population has grew from 0,8 m to 4,9 m since 2007.

The paper maps the community of Common Juniper (Juniperus Communis) encountered at Konrac, a site included in the Česká Kanada Nature Preserve. The site itself, or rather the common juniper growing there, does not have the benefit of special legal protection; consequently, no targeted steps have been taken to maintain the juniper community intact in the Konrac landscape - still, the site allowed to monitor the natural development of the community in conditions typical of the current methods of farming. The locality is described to encompass four main types of habitats: stony islands amid meadows; unplowed strips of land around former small fields; peripheries of open stands; and peripheries of close stands. The acquired (and subsequently processed) data point to the conclusion that the habitat at the unplowed margins of fields suits the common juniper communities quite well, even without any human intervention in the farming practices beyond what is implemented on the site now.

No description available.