The emerald ash borer (EAB, Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is a non-native wood boring beetle that is causing extensive ash (Fraxinus spp.) mortality in eastern North America, affecting both urban and wildland forests and drastically altering forest structure and composition. As EAB-induced ash mortality progresses, native arthropod associates of ash forests are impacted by the effects of rapid and broad scale tree mortality. These include loss of food source, increased canopy gap formation, alterations in litter inputs causing shifting temperature and moisture regimes on the forest floor, and significant accumulation of coarse woody debris. I assessed the sub-canopy arthropod community in five forests, all in different stages of the invasion process, from introduction through impact. Additionally, I assessed the ground level arthropod community in a post EAB-invaded forest with 100% mature ash mortality. Arthropod communities were assessed at the ordinal level, and with a focus on coleopterans, they were further classified to families and trophic guilds to analyze abundance, richness, and diversity. Due to their overwhelming abundance, I identified scolytines collected in the post EAB-invaded forest to species to see if the EAB-invasion was part of a greater invasional meltdown. My results indicate that the EAB-invasion in North America is affecting the native coleopteran communities associated with these forests.

Historically, performance has been the most important feature when optimizing computer hardware. Modern processors are so highly optimized that every cycle of computation time matters. However, this practice of optimizing for performance at all costs has been called into question by new microarchitectural attacks, e.g. Meltdown and Spectre. Microarchitectural attacks exploit the effects of microarchitectural components or optimizations in order to leak data to an attacker. These attacks have caused processor manufacturers to introduce performance impacting mitigations in both software and silicon. To investigate the performance impact of the various mitigations, a test suite of forty-seven different tests was created. This suite was run on a series of virtual machines that tested both Ubuntu 16 and Ubuntu 18. These tests investigated the performance change across version updates and the performance impact of CPU core number vs. default microarchitectural mitigations. The testing proved that the performance impact of the microarchitectural mitigations is non-trivial, as the percent difference in performance can be as high as 200%.

With the introduction of Spectre and Meltdown, two new attacks thattarget the speculative instructions due to Out-of-Order execution intoday's processors, a new way to handle speculative loads has beenproposed. Instead of performing the speculative load, the approach isto predict them. This is a new way to use value predictors. In thiswork, the Last Value Predictor, which predicts based on the previouslyseen value, Value TAgged GEometric history length Predictor (VTAGE),which predicts based on the global branch history, and a stridepredictor, which predicts with help of strides, has been compared tosee which one has the best fit for this new use. They have been runwith the SPEC CPU 2017 benchmark suite in three different tests,different sizes, different threshold confidence and for VTAGE,different associativity. The VTAGE predictor performed best in terms ofvalues predicted and values correctly predicted. The thresholdconfidence level plays an important role in how many incorrectpredictions were made. The associativity in the VTAGE did not do muchdifference to the results.

Genetic changes likely occur in wild fish populations as a consequence of interactions with cultured fish, but to what extent do those changes threaten the maintenance of natural genetic diversity and population viability? Following a review and categorization of numerous processes suspected of being agents of post-release genetic change in recipient wild populations (Chapter 1), I focus on risks relating to the magnitude and duration of releases -- but with a twist. That is, I assume that the mean fitness of released, cultured individuals does not differ from that of the recipient natural population. Throughout, attention is devoted to potential post-release changes in inbreeding (NeI) and variance (NeV) effective population sizes -- indicators of expected rates of population-level change in inbreeding and drift variance, respectively. The reductive effect that large-scale releases exert on NeI in recipient populations can be significant. The effect is shown to be a threshold process (Chapter 2) and thus suggestive of an approach for determining risk-adverse stocking (or release) rates. This approach is utilized in Chapter 3, which describes genetic recommendations for an incipient marine stocking program. Several discordant contemporary NeI models are examined mathematically and by computer simulation (Chapter 4). I show that certain published results pertaining to the effect of multiple paternity on NeI are erroneous; a general model is described which accounts for inbreeding and relatedness in and among parents. That model is utilized in an empirical study of gene correlation in a hatchery cohort (Chapter 5). Propagation-related causes of reductions in NeI are also investigated in this cohort. Finally, extending mutational meltdown theory to accommodate fluctuating population sizes and recessive selective effects, I show that when large reductions in NeV occur (such as those that accompany admixtures of cultured and wild fish), the expected time to population inviability is significantly reduced (Chapter 6). Although a more comprehensive theoretical approach is needed, a precautionary inference may be drawn -- aquaculture-induced reductions in Ne, even though they may be transient, can lead to adverse genetic impacts. Avoidance of Ne-reductions cannot be accomplished, in a practical sense, without considering the stocking or release rates of cultured fish.

With Spectre and Meltdown out in the public, a rushed effort was made to patch these vulnerabilities by operating system vendors. However, with the mitigations against said vulnerabilities there will be some form of performance impact. This study aims to find out how much of an impact the software mitigations against Spectre and Meltdown have on database management systems during an online transaction processing workload. An experiment was carried out to evaluate two popular open-source database management systems and see how they were affected before and after the software mitigations against Spectre and Meltdown was applied. The study found that there is an average of 4-5% impact on the performance when the software mitigations is applied. The study also compared the two database management systems with each other and found that PostgreSQL can have a reduced performance of about 27% when both a hypervisor and the operating system is patched against Spectre and Meltdown. / När Spectre och Meltdown tillkännagavs gjordes en snabb insats för att korrigera dessa sårbarheter av operativsystemleverantörer. Men med mildringarna mot dessa sårbarheter kommer det att finnas någon form av prestationspåverkan. Denna studie syftar till att ta reda på hur mycket av en påverkan uppdateringarna mot Spectre och Meltdown har på databashanteringssystem under en online-transaktionsbehandlings arbetsbelastning. Ett experiment gjordes för att utvärdera två populära databashanteringssystem baserad på fri mjukvara och se hur de påverkades före och efter att uppdateringarna mot Spectre och Meltdown applicerats i en Linux maskin. Studien fann att det i genomsnitt är 4–5% påverkan på prestandan när uppdateringarna tillämpas. Studien jämförde också de två databashanteringssystemen med varandra och fann att PostgreSQL kan ha en reducerad prestanda på cirka 27% när både det virtuella maskinhanteringssystemet och operativsystemet är uppdaterad mot Spectre och Meltdown.

The aim of this study is to compare the cause of the, to date, three onlycommercial nuclear power plant accidents. These are very complex incidents,which have dire impact on society and the environment and therefore benefitfrom further investigation, if there lays a possibility of identifying factors thatcould prevent further accidents in the future. In order to investigate this theactions and decisions that lead up to each nuclear meltdown was identified andcompared.The investigation was based on a qualitative study on three cases of nuclearmeltdown accidents. They are based on text analysis of official reports anddocumentaries on the subject. The theoretical background for this study wasKajtazi’s (2011) work on Information Inadequacy. The study was limited to theevents leading up to the accidents and do not include activities afterwards.The study shows that each case had different underlying reasons. It alsoshows that we seem to have learned something from our previous mistakes, andacted on them accordingly. From the Fukushima Daiichi accident we canrecommend that organizations in charge should take early warnings seriouslyand act upon them as soon as they are presented.

Univ., Diss--Bielefeld, 2007.

Examensarbetet behandlar problematik som uppstår vid härdsmältningsförlopp i en kärnkraftsreaktor av typen kokvattensreaktor. Resultatet ska användas som riktlinjer till strategier som utvecklas av Severe Accident Management Guidelines (SAMG) där arbetets uppdrag är ett delmoment i framtagning av strategier för att bemästra de olika fenomen som uppstår vid härdsmälta.   Syftet med arbetet är att undersöka begränsningar för att bevara reaktortanken intakt vid haveri, genom att undersöka den minsta mängd vatten som behövs för att undvika tankgenomsmältning. Undersöka fallen som leder till härdsmälta och gruppera dem efter händelsesekvenser. Undersöka metall/vatten-reaktionen som uppstår då härden blir över 800°C och undersök om fallen kan grupperas i händelsesekvenser.  Metoder som används i arbetet är PSA-dokumentation, händelseutvecklingsträd, teoretiska beräkningar och MAAPv5.03. Resultatet beskriver att grupperingar av fallen som slutar i härdsmälta och grupperingar av metall/vatten-reaktionen hos de olika fallen kan genomföras. Resultatet beskriver även ett minsta flöde som kan föras in i reaktortanken för att hindra tankgenomsmältning och flöden upp till 100 kg/s så det finns resultat för olika flöden beroende på vilka kylmedel som är tillgängliga.  Slutsatsen av arbetet är att fall kan grupperas efter händelsesekvenser och påverkan hos metall/vattenreaktion, grupperingarna sparar tid vid ett haveriförlopp. I varje grupp kunde det svåraste fallet beräknas för minsta flöde för att klara tankgenomsmältning och flöden upp till 100 kg/s.  Framtida arbeten bör undersöka trycket och vätgasen som skapas vid vatteninmatning samt dess påverkan på reaktorinneslutningen. / The master thesis deals with problems that arise during nuclear meltdown in a nuclear powerplant of the type boiling water reactor. The work will be used as guidelines for strategies developed by Severe Accident Management Guidelines (SAMG), this master thesis is a sub-element in the development of strategies for mastering the various phenomena that arise during a meltdown.  The purpose of the work is to investigate limitations for maintaining the reactor tank intact during the meltdown by, examining the minimum amount of water needed to avoid the meltdown getting through the reactor tank. Examining the cases that lead to meltdown and group them according to the event sequences. Examine the metal/water-reaction that occurs when the core becomes over 800°C and examine if the cases can be grouped into event sequences.  Methods used in the master thesis is PSA-analysis, event development threes, theoretical calculations and MAAPv5.03.  The result describes the groupings of the cases ending in meltdown and the groupings of the metal/water-reaction of the various cases. The result also describes a minimum flow that is required to prevent meltdown of getting through the reactor tank and flow up to a 100 kg/s.  The conclusion of the master thesis is that cases can be grouped according to event sequences and the influence of the metal/water-reaction, the groupings save time in the event of a breakdown. In each group the most difficult case was calculated so that the lowest flow to prevent the meltdown from getting through the reactor tank was presented among with different flows up to 100 kg/s. Future work should investigate the pressure and hydrogen gas created by the water input and its influence on the reactor inclusion.

The diploma thesis clarifies main causes of the mortgage market meltdown in the USA as a starter to the global financial problems. The objective of the thesis is to analyze the American mortgage and housing market price bubble according to the views of the Austrian school of economics, which claims that problems were caused by inappropriate intervention of the U.S. Federal Government, Federal Reserve System and other government institutions in the markets. Furthermore, the thesis criticize the actions and measures taken by the U.S. government to stabilize the economy, which only seeks to alleviate the consequences, not to prevent the causes. Last chapter of the thesis analyze the impact of the subsequent financial crisis and global economic downturn on financial market, real economy and international trade of Czech republic.

Invasive exotic species threaten native biodiversity, alter ecosystem structure and function, and annually cost over $100 billion in the US alone. Determining the ecological traits and interactions that affect invasion success are thus critical for predicting, preventing, and mitigating the negative effects of biological invasions. Native herbivores are widely assumed to facilitate exotic plant invasions by preferentially consuming native plants and avoiding exotic plants. Here, I use freshwater plant communities scattered broadly across the Southeastern U.S. to show that herbivory is an important force driving the ecology and evolution of freshwater systems. However, native consumers often preferentially consume rather than avoid exotic over native plants. Analyses of 3 terrestrial datasets showed similar patterns, with native herbivores generally preferring exotic plants. Thus, exotic plants appear defensively nave against these evolutionarily novel consumers, and exotic plants may escape their coevolved, specialist herbivores only to be preferentially consumed by the native generalist herbivores in their new ranges. In further support of this hypothesis, a meta-analysis of 71 manipulative field studies including over 100 exotic plant species and 400 native plant species from terrestrial, aquatic, and marine systems revealed that native herbivores strongly suppressed exotic plants, while exotic herbivores enhanced the abundance and species richness of exotic plants by suppressing native plants. Both outcomes are consistent with the hypothesis that prey are susceptible to evolutionarily novel consumers. Thus, native herbivores provide biotic resistance to plant invasions, but the widespread replacement of native with exotic herbivores eliminates this ecosystem service, facilitates plant invasions, and triggers an invasional meltdown. Consequently, rather than thriving because they escape their co-evolved specialist herbivores, exotic plants may thrive because their co-evolved generalist herbivores have stronger negative effects on evolutionarily nave, native plants.