On The Origin of Super-Hot Electrons from Intense Laser Interactions with Solid Targets having Moderate Scale Length Preformed Plasmas

We use PIC modeling to identify the acceleration mechanism responsible for the observed generation of super-hot electrons in ultra-intense laser-plasma interactions with solid targets with pre-formed plasma. We identify several features of direct laser acceleration (DLA) that drive the generation of super-hot electrons. We find that, in this regime, electrons that become super-hot are primarily injected by a looping mechanism that we call loop-injected direct acceleration (LIDA)

Essays on systemic risk and financial market volatility

This doctoral thesis consists of four independent research papers. All papers are empirical and cover the area of financial market risk, with a particular focus on systemic risk and volatility in financial markets.The first paper analyzes the joint effect of centrality and other characteristics that are essential in determining banks’ systemic importance. Specifically, centrality is treated as a moderator variable and the paper analyzes whether characteristics such as size and Value-at-Risk become more, or less, important in determining a bank’s contribution to systemic risk. The main finding is that a bank’s contribution to systemic risk, measured by ΔCoVaR, given a certain level of VaR, is about four times higher for a bank with two standard deviations above average estimated centrality, compared to a bank with average centrality. Neglecting this indirect moderation effect severely underestimates the importance of centrality for “risky” banks and overestimates it for “safer” banks.The second paper considers the relationship between the concept of implicit government guarantees and bank equity returns. In alignment with the risk-return trade off, riskier firms should earn higher expected returns. However, risky financial institutions also pose a threat to financial stability and can be considered ‘too big to fail’. From this perspective it can be argued that the risk-adjusted expected return should be lower for highly systemic financial institutions than for less systemic institutions. The paper examines this conjecture from an asset pricing perspective by sorting bank stocks according to the systemic risk measures ΔCoVaR and MES, and compares their risk-adjusted returns. No clear evidence is found that points towards the perception that implicit government guarantees incurred lower risk-adjusted returns during the period 1987-2013 for highly systemic bank holding companies.The third paper investigates the relationship between equity volatility and financial leverage on the firm level. The paper uses a comprehensive dataset of large syndicated loans with a total loan amount in excess of USD12tn. This allows for a precise identification of the date when a company experiences a large change in leverage. In contrast to several previous studies that have relied only on accounting data, the paper finds very clear results that increased financial leverage increases equity volatility. The findings are robust to controlling for time trends in variance as well as the type and purpose of the loan.The fourth paper considers volatility dynamics in the Bitcoin market. Bitcoin is the world’s largest cryptocurrency by market capitalization. Bitcoin is also considered extremely volatile and predicting the volatility of any currency or asset is one of the most fundamental tasks for anyone dealing with investment decisions and risk. The paper studies Bitcoin volatility by looking at the link between the volatility in the Bitcoin market and the volatility in other related traditional markets, as well as the general risk level in the financial system. Retail investor driven search volumes on Google, as a possible proxy for investor sentiment, are also considered. The main finding is that there is a relatively strong positive link between Bitcoin volatility and search pressures on Bitcoin-related words on Google, particularly for the search word “bitcoin”. Overall, the results point at retail investors, rather than large institutional investors, being major drivers of Bitcoin volatility dynamics

Measuring systemic risk in the Nordic countries - An application of CoVaR

Spillover effects and systemic risk contribution of institutions, as measured by their CoVaR and delta-CoVaR respectively, is one way of assessing risk both for an institution in isolation, as well as for regulators and the economy as a whole. CoVaR is the q%-VaR of an institution conditional on another institution already being at its q%-VaR level, whereas delta-CoVaR measures each institution’s marginal risk contribution. This essay applies the CoVaR methodology proposed by Adrian and Brunnermeier (2011) on the Nordic stock market (OMX Nordic 40 Index) in order to measure systemic risk contribution of 36 firms on this market, during the period January 2002 to March 2014. Publicly available stock market data is used to estimate abovementioned measures by applying quantile regression. The results, which are aggregated at sector level, suggest that systemic risk contribution is higher during times of financial distress and sectors generally show a similar pattern in how risky they are over time. VaR is further not positively correlated with CoVaR, i.e. even if a sector is considered risky in isolation as measured by its VaR, it is not necessarily the case that it spills over this risk to other sectors/institutions. However, there are some sectors that contribute more to systemic risk than they are risky in isolation, as measured by their delta-CoVaR and VaR. Sectors contributing the most to Nordic systemic risk are Forestry and Construction, as well as the European stock market as measured by the EuroStoxx50 Index. The banks included in the OMX Nordic 40 Index are also examined in a separate case study, finding Swedbank the most risky and Nordea the least risky in isolation, but the other way around when measuring risk contribution (delta-CoVaR) of these two banks, to other banks

Seeds in the Forest Floor of the Ponderosa Pine Type

Regeneration of forest stands is often complicated by the establishment and competition of brush on logged and burned-over areas. The encroachment of brush in the ponderosa pine type of Idaho, particularly Ceanothus velutinus, Dougl. presents a difficult problem to the forest manager. The brush competition severely reduces the growth rate of associated trees, thus extending the period necessary to grow a crop of trees. This situation may seriously limit the economic production of a wood crop of ponderosa pine. Any approach to the solution of brush problems should include a thorough understanding of brush ecology. Those phases of ecology dealing with reproduction and distribution of brush need special emphasis. It has been assumed that most of the brush on logged or burned-over areas originated from seed stored in the forest floor; yet little is known of the quantity or distribution of these seeds. This study was carried out to learn what kind, number and variability of seed is present in the forest floor, and to investigate the number of seed located in different forest conditions, aspects and soil layers. To achieve the above objectives, 48 square-foot, duff-soil samples were taken in the ponderosa pine type of the Boise Basin Experimental Forest in Idaho. Seeds were separated from the samples and major species identified, pretreated and germinated. Appropriate statistical techniques were employed to determine significant results among the different forest conditions, aspects and soil layers sampled