Malgré les évolutions significatives des systèmes de retraite, notamment le passage de systèmes par répartition à des systèmes par capitalisation, plusieurs problèmes subsistent. La structure démographique est un des principaux facteurs de risque systémique, menaçant l’équilibre des caisses de retraite et favorisant l’instabilité et les moindres performances économiques. Dans cette thèse, nous mobilisons l’analyse empirique et théorique afin d’apporter une réponse en termes de stratégie d’investissement à ce problème. Nous synthétisons tout d’abord les éléments de littérature existants et mettons en avant l’importance du partage intergénérationnel du risque et les différences entre les investissements individuels et collectifs. En nous appuyant sur un modèle à générations imbriquées, nous étudions les effets de la structure démographique sur le prix des actifs. Nous identifions une corrélation positive entre l’inverse du ratio de dépendance et le prix de ces derniers (asset meltdown). Puis, en nous basant sur des contrats de retraites simulés, nous étudions les effets de l’augmentation de l’espérance de vie et de la diminution du taux de fécondité sur le partage intergénérationnel du risque. Bien que le régime collectif de retraite à cotisations définies (CDC) amortisse mieux les risques démographiques, des performances analogues peuvent être obtenues au moyen d’une capitalisation individuelle. De plus, la capitalisation individuelle supplante le régime collectif lorsque la réglementation est fortement contraignante. Nos résultats suggèrent la nécessité de la mise en place d’un processus de réforme continu basé sur les stratégies d’investissement. Ainsi, l’efficacité des méthodes de sélection des fonds telles que celle basée sur le taux de faux positifs semble être confirmée. / Despite the substantial evolution of pension systems shifting away from pay-as-you-go scemes at the end of the last century, some significant issues still subsist. Demographic structure is one of the main systemic risks threatening the asset-liability balance and causing insolvability and unsustainable performance. In this dissertation, we use both theoretical and empirical analysis to address this issue and to propose a possible solution based on investment strategy. We first conduct a detailed literature survey, aiming to highlight the importance of inter-generation risk sharing and to characterize the differences between collective and individual investment. Based on a theoretical overlapping generation model we study the effect of demographic structure on the asset prices. We identify a positive correlation between the inverse dependency ratio and the asset price, known as the asset meltdown. Then, focusing on diverse stylized pension contracts, we investigate the effect on inter-generation risk sharing of both an increase in life-expectancy and a decrease in fertility rate. Although the collective defined contribution (CDC) plan better amortizes the demographic risk compared to other contracts, its performance can be replicated by individual investment. Moreover, when regulation imposes strict policy safety constraints, individual investment outperforms the collective plan participation. Our results suggest the need for a continuous reforming process, especially on investment-based strategies. Hence, the efficiency of fund selection methods such as the one based on False Discovery Rate seems to be confirmed.

This research attempts to construct the dynamic model of forming process in Subprime Crisis by systemic thinking and find out the solution by using Archetype. We extensively review literature concerning Subprime Mortgage, Credit transaction, System Dynamics, and Finance. Then based on these literature, this research would construct Causal Feedback Loop Diagram to search for Leverage Solution and hopes to resolve the financial problem fundamentally. After reviewing previous literature, most articles only focus on short-term and limited discussion, so this research attempts to put them together by Causal Feedback Loop Diagram. Through analysis, this research find out the concealed Values behind Subprime Crisis, that is the pursuit of capitalism ,in other words, it means decision-makers only care about short-term benefits lack of consideration of the consequence. So the more effective strategy is ¡§to hold Management Flight Simulator Seminar for managers¡¨ and ¡§to increase the opportunity for the general public to get access to system thinking.¡¨ Furthermore, we also discover that ¡§Moral Courage¡¨ cannot be neglected in the recent Subprime Crisis. If we continue to limit our thinking, the financial crisis would never end and would happen again and again. The better way is to strengthen risk control and to hold a value system when facing chain reaction of the Subprime Crisis.

<div> <p><a>Biotic interactions play key roles in determining invasive species’ establishment success in receiving ecosystems (Tilman 2004). The invasional meltdown hypothesis suggests that initial invaders can facilitate subsequent invasions through direct (e.g., commensalism, mutualism) and indirect (e.g., changes in habitat and energy flow) pathways (Simberloff & Holle 1999; Simberloff 2006). Such positive interactions among invaders can alter community-level processes, but little research on this has been done in aquatic-terrestrial landscapes. My dissertation explores the links between reciprocal facilitation of invasive species and ecosystem change in a desert river system in the southwest USA. </a></p> <p> Like most rivers in the southwestern United States, the San Juan River has been altered by hydrologic regulation and biological invasions that affect ecosystem function and act synergistically to induce substantial ecosystem change. Invasion of channel catfish (<i>Ictalurus punctatus</i>) has drastically altered the fish assemblage of the San Juan River, yet the impacts of riparian invasion by a fruit-bearing tree, Russian olive (<i>Elaeaganus agustifolia</i>) have largely been ignored. Channel catfish have been observed consuming Russian olive fruits, but the level of facilitation between species and corresponding impact on the ecosystem is unclear. </p> <p>Channel catfish may benefit directly from Russian olive invasion by feeding on fallen fruits and/or indirectly from habitat alteration and invertebrate prey production from Russian olive detritus. Additionally, channel catfish may facilitate germination, growth, and seed dispersal of Russian olive. Mutualism between these invaders could increase the fitness of each species, thereby facilitating invasion success. Plant-animal mutualism is the most common form of facilitation among invaders, but no studies, to our knowledge, have evaluated facilitation between invasive riparian plants and aquatic invaders and their combined impact on ecosystem function. My goal preparing this dissertation is to determine whether mutual facilitation between riparian and aquatic invasive species influences ecosystem change through biotic interactions. </p> <p>To test for mutual facilitation, I first determined the contribution of Russian olive fruits to channel catfish growth by evaluating seasonal diet composition across four sites and six time periods. I then used replicated growth experiments to determine assimilation rates of Russian olive fruits consumed by channel catfish. Using bioenergetics models, I then determined how Russian olive subsidies in San Juan River contribute to channel catfish biomass. To determine whether channel catfish benefit Russian olive reproduction, I compared germination rates of seeds consumed by channel catfish to seeds consumed by terrestrial mammals and control seeds that had not been eaten. </p> <p>Russian olive fruits were the most important diet item for channel catfish during the fall and spring, comprising up to 57 and 70% of stomach contents by mass, respectively, and were consumed throughout the year. Feeding trials revealed that Russian olive fruits contributed little to growth or lipid deposition, but they did provide metabolic energy allowing channel catfish fed exclusively Russian olive fruits to maintain weight. In addition, Russian olive trees received a reproductive benefit through increased germination success of seeds consumed by channel catfish over those transported by water. Using bioenergetic models, I showed that Russian olive fruits subsidized 46% of San Juan River channel catfish biomass, indicating that the subsidy from Russian olive fruits had a population-level impact. This dissertation thus establishes mutual facilitation by non-native species across ecosystem boundaries, a phenomenon that few studies heretofore have demonstrated in the ecology or invasion biology literature.</p> </div> <br>

Meltdown och Spectre är två säkerhetshål som har upptäckts i moderna processorer. För att säkra sig mot dessa säkerhetshål är företagen tvungna att uppdatera sina system med de säkerhetsuppdateringar som släpps även om prestandan eventuellt kan försämras. Studien har som syfte att undersöka huruvida svenska hostingföretag har blivit påverkade av uppdateringarna mot säkerhetshålen. Företagen kan påverkas prestandamässigt men även få problem med de uppdateringsprocesser som har genomgåtts. Hostingföretagen är de företag som ansetts vara ett av de mer påverkade. Urvalet för de medverkande företagen i studien blev små till medelstora hostingföretag lokaliserade på olika platser i Sverige. Undersökningen använder en kvalitativ intervjustudie. Företagen kontaktades med E-post, för att sedan bli vidarebefordrad till en person som har varit involverad i arbetet med Meltdown och Spectre. Totalt var det 59 företag som kontaktades och det var fyra företag som ställde upp på att vara delaktiga i studien. Ett av företagen kunde inte utföra en intervju över Skype, men medverkande genom att svara på frågorna över E-post. Svaren från intervjuerna sammanställdes och analyserades sedan och de analyserade svaren visar att: Företagen har blivit påverkade prestandamässigt av uppdateringarna men inte i den utsträckning att det skulle påverka den dagliga verksamheten. Den del som påverkade företagen mest var den arbetsprocess utfördes för att applicera uppdateringarna samt komplikationerna från leverantörernas sida att leverera en fungerade och skyddande uppdatering i tid. / This studies focus is to analyze the impact on Swedish hosting companies after the announcement about Meltdown and Spectre. Meltdown and Spectre are two security issues that reside on modern processors today. It has been said that the hosting business will take most of the impact generated by the patches to fix the problem. The effects that it could have on the companies are performance degradation but also questions arising during the patching process. The companies that were chosen to be part of this study were small to medium sized hosting companies located in different places in Sweden. A qualitative interview study was used to collect data. An email was used to contact companies to be redirected to the person that had been involved with the work around Meltdown and Spectre. Totally 59 companies were contacted to see if there were interest in participating in the study. Out of those 59 companies, there were four contributors, where three of these were real interviews over Skype and one over email. The data collected from the interviews were analyzed and showed that: The companies have been affected by the updates, but not to the extent that it would change the day-today operations. The part that touched the companies the most was the work process that had to be performed to apply the updates, as well as the complications from the supplier's side to deliver a secure working patch in time.

With the progress of the times, the international financial market link is becoming more and more closely, while the probability of extreme events more and more high, if there are some indicators can be used as a prediction of the crash, as whether to sell the stocks, it can be very useful. The study process for the use of the Fama-French five-factor model, as well as the VaR model, with the cluster analysis method, and clustering for Taiwan 50 constituent stocks in accordance with the five-factor characteristics of the individual stocks, the similar nature of stock into the same group, the establishment of portfolio, the use of portfolio daily returns to calculate the the VaR, and observe the VaR spread before the crash, how the trend, and whether certain characteristics. Comparison of the cluster group for the predictive ability of the collapse events, as well as the relationship between risk factors and predictive ability. The results of VaR spread movements are often subject to fluctuations significantly change the situation before the crash occurs. By intense will be stable or from stable will be severe. Good predictive ability of the cluster, often its constituent stocks and the collapse of the reasons more closely the relationship. Financial stocks sensitive to the financial tsunami; Electronic stocks are subject to exchange rate affect.Overall, the group with the best predictive ability is more sensitive to momentum effects and investor sentiment indicators ,but non-sensitive to book-to-market factor.To use the Var spread as a predictor of reference,choosing to meet the aforementioned conditions of stocks to the portfolio is a nice way.

This thesis deals with the severe accident of the gas-cooled fast reactor GFR. At the beginning of the study there is a review of the gas-cooled fast reactor subject. Next part is focused on description of possible solutions for severe accidents with emphasis on the solution applied in the Generation III+ reactors. Chapters that deal with material and thermal balance with severe accident of GFR demonstration unit, along with the chapter which analyses features of the corium, create a basis for the conceptual design of core catcher of GFR demonstration unit, which forms the final part of this thesis.

Context. The paradigm of virtualization is rapidly changing due to hardware optimization and capabilities, while also due to rapid development and deployment strategies used in the modern day IT industry. Just like the positive changes, negative effects are necessary to occur in order to improve modern day technologies.This final year project takes a look at both the positive and negatives by exploring how containers are relevant to modern day computing and how they are affected by the patch that mitigates the Meltdown CPU vulnerabilities discovered in mid-2017 in terms of performance. Looking at the trade-off between information security and performance by taking an in-depth approach with a take on the core functionalities of the Linux Kernel. This paper succeeded to identify system call costs that between a secure and non-secure Linux kernel in the context of a containerized environment. Objectives. This study examines the effects of the KAISER security patch aimed to mitigate microprocessor vulnerabilities related to Meltdown. The investigated effect is the performance as the cost of system calls under the condition of a non-KAISER and a KAISER enabled Linux kernel. The intent is to increase the transparency of how a major security patch such as KAISER affects the system. Methods. A quantitative experimental study is conducted. One single Debian Stretch node is used with two different treatments. First micro-benchmarks are run without a KAISER enabled kernel which later is compared with a KAISER enabled kernel. The measuring point is the time one single system call takes in a sequence of 1 000 000 system calls. Results. First macro-benchmarks were conducted to see what a performance loss would look like on an application level. This proved to introduce many superfluous factors which made it difficult to use system calls as a measuring point. In the end a comparison between the two kernels was done. This indicated that the cost per system differed roughly 29% in time. Conclusions. The results indicate that a large performance loss is identified. However, this does not indicate that all activities on a computer will suffer from this loss. The performance loss the end-user will experience all depends on the amount of system calls generated from one single set of instructions. The performance loss can be neglected if these instructions generating a low amount of system calls. These results should notbe used as evidence to favor performance over information security in real life applications and implementations but rather as a motivation to meet the two aspects. / Kontext. Användning kring virtualisering håller snabbt på att förändras tack vare bättre hårdvaruoptimeringar och förmågor. Samtidigt ändras många olika utplaceringstrategier av datorresurser iden moderna IT industrin. Likväl alla positiva förändringar så introduceras det även effekter med negativa följder. Det här är ett examensarbete som ämnar att utforska båda dessa positiva och negativa effekter. Genom att titta på hur den populära virtualiserings tekniken som består av containers påverkas av uppdateringen som ska lösa sårbarhter i moderna processorer som går under namnet Meltdown. Påverkningarna definieras i form av prestanda vilket tillåter en djupare inspektering av de fundementala funktioner av Linux kärnan, där systemanrop kan användas som mätningspunkt. Metoden samt resultat i det här examensarbetet har med framgång lyckats hitta en kostnads skillnad per systemanrop under förhållandetav en osäker samt en säker Linux kärnna i en miljö som består av containers. Mål. Examensarbetet tittar på effekterna av uppdateringen som ska åtgärda sårbarheterna i moderna mikroprocessorer relaterade till Meltdown. De investigerade effekterna är definierade som prestandan där kostanden av systemanrop används som mätningspunkt. Meningen med det här examensarbetet att öka transparansen av vad en stor säkerhetsuppdatering gör med ett modernt datorsystem. Metod. En kvantitativ experimental studie utförs där en Debian Stretch nod används för att observera två olika behandlingar. Till början så körs det ”mikrobenchmarks” under förhållandet av en osäker Linux kärna. Sedan så följs detta upp med en säker Linux kärna. Till slut jämförs de olika resultat med varandra för att identifera hur mycket ett system anrop kostar under en sekvens av 10’000’000 systemanrop. Resultat. Som pilot studie utfördes det en rad olika tester som använder många olika verktyg för att se om det går att identifiera en prestanda förlust på applikations nivå. Genom att utföra tester utav den karaktären blev det tydligt att överflödiga faktorer förhindrade ett utfall som ansågs vara tillräcklig. Till slut hittades rätt typ av verktyg för att få fram ett utfall som visade att en prestanda skillnad på ~29% existerade mellan en osäker samt en säker Linux kärna. Sammanfattning. Resultatet indikerar att en prestanda förlust existerar. Dock påverkas inte den generella prestandan nödvändigtvis. Prestanda förlusten en slutanvändare kommer att uppleva beror helt på av hur stort antal systemanrop som genereras under sekvensen av aktiviteten som utförs. Resultatet som redovisas i detta examensarbete bör inte användas som motivation att prioritera prestanda över informations säkerhet i produktions miljöer men hellre som en motivation att kunna bemöta båda aspekterna.

Most of today's widely used operating systems are based on a monolithic design and have a very large code size which complicates verification of security-critical applications. One approach to solving this problem is to use a microkernel, i.e., a small kernel which only implements the bare necessities. A system usinga microkernel can be constructed using the operating-system framework Genode, which provides security features and a strict process hierarchy. However, these systems may still be vulnerable to microarchitectural attacks, which can bypassan operating system's security features, exploiting vulnerable hardware. This thesis aims to investigate whether microkernels are vulnerable to the microarchitectural attacks Meltdown and Spectre version 1 in the context of Genode. Furthermore, the thesis analyzes the execution cost of mitigating Spectre version 1 in a Genode's remote procedure call. The result shows how Genode does not mitigate the Meltdown attack, which will be confirmed by demonstrating a working Meltdown attack on Genode+Linux. We also determine that microkernels are vulnerable to Spectre by demonstrating a working attack against two microkernels. However, we show that the cost of mitigating this Spectre attack is small, with a cost of &lt; 3 slowdown for remote procedure calls in Genode.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 241 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: 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. / ABSTRACT: 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. / ABSTRACT: 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. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Meltdown and Spectre are two vulnerabilities discovered in 2017. These vulnerabilities allow unauthorized users to extract confidential information from systems. Security patches have been developed to resolve these vulnerabilities, but with a potental performance loss. This report investigates how PHP is affected by Microsofts web server IIS, with the security patch developed by Microsoft to protect systems against Meltdown and Spectre applied. In a practical laboratory experiment, the JMeter tool has been used to create a simulated load on the web server system, where PHPts CPU usage is monitored and noted for further analysis. The result shows that there has been a 13.74% performance loss with Microsofts security patch applied. This opens up for discussion about what Microsofts security patch actually does in a system, and if there is a suffciently large degradation to consider a transition to another solution.