19,585 research outputs found
Stock Repurchase Agreements: Close Corporation Use of Designee Provision Permits Repurchase Despite Insufficient Earned Surplus
Statistical random number testing is a well studied field focusing on pseudo-random number generators, that is to say algorithms that produce random-looking sequences of numbers. These generators tend to have certain kinds of flaws, which have been exploited through rigorous testing. Such testing has led to advancements, and today pseudo random number generators are both very high-speed and produce seemingly random numbers. Recent advancements in quantum physics have opened up new doors, where products called quantum random number generators that produce acclaimed true randomness have emerged. Of course, scientists want to test such randomness, and turn to the old tests used for pseudo random number generators to do this. The main question this thesis seeks to answer is if publicly available such tests are good enough to evaluate a quantum random number generator. We also seek to compare sequences from such generators with those produced by state of the art pseudo random number generators, in an attempt to compare their quality. Another potential problem with quantum random number generators is the possibility of them breaking without the user knowing. Such a breakdown could have dire consequences. For example, if such a generator were to control the output of a slot machine, an malfunction could cause the machine to generate double earnings for a player compared to what was planned. Thus, we look at the possibilities to implement live tests to quantum random number generators, and propose such tests. Our study has covered six commonly available tools for random number testing, and we show that in particular one of these stands out in that it has a series of tests that fail our quantum random number generator as not random enough, despite passing an pseudo random number generator. This implies that the quantum random number generator behave differently from the pseudo random number ones, and that we need to think carefully about how we test, what we expect from an random sequence and what we want to use it for.Statistisk slumptalstestning är ett väl studerat ämne som fokuserar på så kallade pseudoslumpgeneatorer, det vill säga algorithmer som producerar slump-liknande sekvenser med tal. Sådana generatorer tenderar att ha vissa defekter, som har exploaterats genom rigorös tesning. Sådan testning har lett till framsteg och idag är pseudoslumpgeneratorer både otroligt snabba och producerar till synes slumpade tal. Framsteg inom kvantfysiken har lett till utvecklingen av kvantslumpgeneratorer, som producerar vad som hävdas vara äkta slump. Självklart vill forskare utvärdera sådan slump, och har då vänt sig till de gamla testerna som utvecklats för pseudoslumpgeneratorer. Den här uppsatsen söker utvärdera hurvida allmänt tillgängliga slumptester är nog bra för att utvärdera kvantslumpgeneratorer. Vi jämför även kvantslumpsekvenser med pseudoslumpsekvenser för att se om dessa väsentligen skiljer sig från varandra och på vilket sätt. Ett annat potentiellt problem med kvantslumpgeneratorer är möjligheten att dessa går sönder under drift. Om till exempel en kvantslumpgenerator används för att slumpgenerera resultatet hos en enarmad bandit kan ett fel göra så att maskinen ger dubbel vinst för en spelare jämfört med planerat. Därmed ser vi över möjligheten att implementera live-tester i kvantslumpgeneratorer, och föreslår några sådana tester. Vår studie har täckt sex allmänt tillgängliga verktyg för slumptalstestning, och vi visar att i synnerhet ett av dessa står ut på så sätt att det har en serie av tester som slumptalen från vår kvantslumpgenerator inte anser är nog slumpade. Trots det visar samma test att sekvensen från pseudoslumpgeneratorerna är bra nog. Detta antyder att kvantslumpgeneratorn beter sig annorlunda mot pseudoslumpgeneratorerna, och att vi behöver tänka över ordentligt kring hur vi testar slumpgeneratorer, vad vi förväntar oss att få ut och hurvida detta påverkar det vi skall använda slumpgeneratorn till
The International Bathymetric Chart of the Arctic Ocean (IBCAO): An Improved Morphological Framework for Oceanographic Investigations
The IBCAO initiative set out in late 1997 to assemble and merge all available bathymetric observations from northern regions, with the intent of constructing a reliable and up-to-date portrayal of the Arctic seabed in digital and printed form. In early 2000, a provisional grid and map were placed in circulation for public review and comment. Available for free downloading from a website hosted by the U.S. National Geophysical Data Center, these products won immediate acceptance from a broad spectrum of Arctic investigators who recognized the potential worth of the new information in a variety of applications ranging from straightforward map production to analysing the influence of underwater topography on ocean circulation. At the same time, error reports and new data sets were being forwarded to the creators of IBCAO, so that by the middle of 2002 a new and more definitive grid was ready to be placed into circulation. This was soon followed by the construction of a prototype shaded relief map that has been proposed as a successor to Sheet 5.17 of the General Bathymetric Chart of the Oceans (GEBCO)
Classics Illustrated: Limits of Spacetimes
We carefully study the and limits of the
Reissner-Nordstr\"om spacetime using Geroch's definition of limits of
spacetimes. This is implemented by embedding the one-parameter family of
spacetimes in anti-de Sitter space, and as a result we obtain metrically
correct Penrose diagrams. For two distinct limits are
studied.Comment: 23 pages, 13 figure
Estimating Sparse Signals Using Integrated Wideband Dictionaries
In this paper, we introduce a wideband dictionary framework for estimating
sparse signals. By formulating integrated dictionary elements spanning bands of
the considered parameter space, one may efficiently find and discard large
parts of the parameter space not active in the signal. After each iteration,
the zero-valued parts of the dictionary may be discarded to allow a refined
dictionary to be formed around the active elements, resulting in a zoomed
dictionary to be used in the following iterations. Implementing this scheme
allows for more accurate estimates, at a much lower computational cost, as
compared to directly forming a larger dictionary spanning the whole parameter
space or performing a zooming procedure using standard dictionary elements.
Different from traditional dictionaries, the wideband dictionary allows for the
use of dictionaries with fewer elements than the number of available samples
without loss of resolution. The technique may be used on both one- and
multi-dimensional signals, and may be exploited to refine several traditional
sparse estimators, here illustrated with the LASSO and the SPICE estimators.
Numerical examples illustrate the improved performance
The Swedish Corporate Control Model: Convergence, Persistence or Decline?
This paper explores the effects of deregulation and globalization on the dominant mode of corporate governance in Swedish public firms. The effects are multidimensional—the direction of change in corporate governance cannot be determined by simply examining whether a convergence towards the Anglo-Saxon model is occurring. Dispersed ownership with management control has not proven to be a viable model of corporate governance for Swedish listed companies. Instead, the control models with the most rapid growth in the most recent decades are found outside the stock market, notably private equity and foreign ownership. After a major revival of the Swedish stock market its importance for the Swedish economy is again in decline. Instead of adjustments in pertinent institutions and practices to ensure effectiveness of the corporate governance of Swedish public firms under these new conditions, a great deal of endogenous adjustment of the ownership structure has taken place.Corporate control; Corporate governance; Corporatism; Entrepreneurship; Ownership policy; Ownership structure; Swedish model
The Swedish Model of Corporate Ownership and Control in Transition
We analyze the development of the Swedish ownership model after World War II. The controlling ownership in Swedish firms is typically concentrated to one or two owners. Often, but not always, the controlling owners are Swedish families. Thus, the model resembles the typical corporate control model of Continental Europe. A distinguishing feature of the Swedish model is that control is typically based on a smaller capital base than in other European countries. This feature is a result of a seemingly paradoxical policy concerning private ownership. Tax policy has consistently disfavored the accumulation of private wealth, but at the same time corporate law has greatly facilitated the wielding of control based on a small equity base. Our analysis shows that the large gap between ownership and control makes the Swedish corporate control model both politically and economically unstable. The major political threat to date has been the proposal of the Swedish Trade Union Congress (the LO) and the Social Democratic Party to introduce a scheme that would result in the gradual takeover of the Swedish corporate sector by union-controlled wage-earner funds. After the political defeat of this proposal in the 1980’s economic policy was changed in a more market liberal direction. This policy change has uncovered the economic instability of the model. The weak financial base of the controlling owners makes it difficult for them to take an active part in the current international restructuring of the corporate sector. Two forces are now seen as the major threat to the Swedish ownership model: (a) a rapidly increasing foreign takeover of Swedish firms and (b) large state and corporatist pension funds. Their financial assets are far larger than those of today’s dominant control owners and extensive mandatory and/or tax-favored systems for pensions saving ascertain that their relative financial strength will continue to grow sharply in the future.Corporate control; Corporate governance; Corporatism; Entrepreneurship; Ownership policy; Ownership structure; Swedish Model
A Modeling Experiment on the Grounding of an Ice Shelf in the Central Arctic Ocean During MIS 6
High-resolution chirp sonar subbottom profiles from the Lomonosov Ridge in the central Arctic Ocean, acquired from the Swedish icebreaker Oden in 1996, revealed large-scale erosion of the ridge crest down to depths of 1000 m below present sea level [Jakobsson, 1999]. Subsequent acoustic mapping during the SCICEX nuclear submarine expedition in 1999 showed glacial fluting at the deepest eroded areas and subparallel ice scours from 950 m water depth to the shallowest parts of the ridge crest [Polyak et al., 2001]. The directions of the mapped glaciogenic bed-forms and the redeposition of eroded material on the Amerasian side of the ridge indicate ice flow from the Barents-Kara Sea area. Core studies revealed that sediment drape the eroded areas from Marine Isotope Stage (MIS) 5.5 and, thus, it was proposed that the major erosional event took place during Marine Isotope Stage (MIS) 6 [Jakobsson et al., 2001]. Glacial geological evidence suggests strongly that the Late Saalian (MIS 6) ice sheet margin reached the shelf break of the Barents-Kara Sea [Svendsen et al. in press] and this gives us two possible ways to explain the ice erosional features on the Lomonosov Ridge. One is the grounding of a floating ice shelf and the other is the scouring from large deep tabular iceberg. Here we apply numerical ice sheet modeling to test the hypothesis that an ice shelf emanating from the Barents/Kara seas grounded across part of the Lomonsov Ridge and caused the extensive erosion down to a depth of around 1000 m below present sea level. A series of model experiments was undertaken in which the ice shelf mass balance (surface accumulation and basal melting) and ice shelf strain rates were adjusted. Grounding of the Lomonosov Ridge was not achieved when the ice shelf strain rate was 0.005 yr-1 (i.e. a free flowing ice shelf). However this model produced two interesting findings. First, with basal melt rates of up to 50 cm yr-1 an ice shelf grew from the St. Anna Trough ice stream across the section of the ridge where there is evidence for grounding. Second, even with ultra low rates of basal melting, the ice shelf thickness was always less than 200 m over the ridge. We conclude that grounding of the Lomonosov Ridge by a free-flowing ice shelf is not possible. When the strain rate was reduced to zero, however, the shelf thickness increased substantially. Such conditions are likely only to have occurred during periods of large-scale glaciation across the Eurasian Arctic such as in the Saalian, and if a substantial stagnant thickened sea ice was present in the ocean, buttressing the shelf flowing from the Barents Sea. Our results are interpreted using new techniques for dynamic 3Dvisualization
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