Finite subgroups of simple algebraic groups with irreducible centralizers

We determine all finite subgroups of simple algebraic groups that have irreducible centralizers - that is, centralizers whose connected component does not lie in a parabolic subgroup.Comment: 24 page

Strengthening Fairness and Funding in the Canada Pension Plan: Is Raising the Retirement Age an Option?

This paper seeks to contribute to a forward-looking debate on possible reform options for the Canada Pension Plan (CPP) and the Quebec Pension Plan (QPP). Even though it focuses on the CPP, most of its analysis applies to the QPP as well since the two programs are largely identical. This paper does not provide a broad survey of all possible reform options, but rather analyzes one vital option that has received insufficient attention in previous debates: raising the normal retirement age from 65 to 67 years. A discussion of this option is warranted not only because it could prevent future financing problems in Canada’s public pension insurance programs, but also because it could improve fairness across generations. The significant increase in life expectancy raises the question of whether the current retirement ages of 60 years, for earliest CPP and QPP benefits, and 65 years, for full benefits, are too low. Should future generations pay for the longevity increases of the current generation of workers, or should current workers share the costs by retiring at a later age? We conclude that raising the normal age from 65 to 67 years—and the earliest age from 60 to 62 years—is a financially effective, intergenerationally fair, and politically acceptable option for improving the CPP and for addressing the QPP’s problems. We suggest that the option of raising the retirement age needs to be discussed well before longevity increases or funding problems occur and that a broad consultation with stakeholders and citizens would be an essential part of a debate on raising the retirement age in Canada.pension systems, pensions, retirement, retirement age, life expectancy, Canada

Online revenue model adoption in the media sector: in-depth results from an exploratory study in the Netherlands

Especially for companies in the media sector such as publishers, the Internet has created new strategic and commercial opportunities. However, many companies in the media sector are struggling with how to adapt their business and revenue model for doing profitable business online. This exploratory study goes into the success factors and the level of adoption of online revenue models by media sector companies. We use Chaffey (2002) in determining online revenue models in which we included Osterwalder’s (2001) four ‘pillars’ of business models. These four pillars cover the twelve critical success factors for e-businesses as identified by Sung (2004). This theoretical framework was used for in-depth interviews with 20 senior managers within the media sector in the Netherlands. From this, it appeared that advertising is the most used online revenue model, with targeting advertising, lead generation and a combination of content and customer profiles as most promising. Ease of use is distinguished by all senior managers as success factor. Still, in order to be successful, all factors should be applied, and this appears not to be the case. Organizations in the media sector need to invest in technical and organizational expertise by hiring the right employees with the right knowledge. Emphasis on target advertising and lead generation are most promising. A combination of content and customer profiles is a focus-point for the near future

Feasibility of UV lasing without inversion in mercury vapor

We investigate the feasibility of UV lasing without inversion at a wavelength of $253.7$ nm utilizing interacting dark resonances in mercury vapor. Our theoretical analysis starts with radiation damped optical Bloch equations for all relevant 13 atomic levels. These master equations are generalized by considering technical phase noise of the driving lasers. From the Doppler broadened complex susceptibility we obtain the stationary output power from semiclassical laser theory. The finite overlap of the driving Gaussian laser beams defines an ellipsoidal inhomogeneous gain distribution. Therefore, we evaluate the intra-cavity field inside a ring laser self-consistently with Fourier optics. This analysis confirms the feasibility of UV lasing and reveals its dependence on experimental parameters.Comment: changes were made according to reviewer comments (accepted for publication in JOSA B

Kinematically redundant robot manipulators

Research on control, design and programming of kinematically redundant robot manipulators (KRRM) is discussed. These are devices in which there are more joint space degrees of freedom than are required to achieve every position and orientation of the end-effector necessary for a given task in a given workspace. The technological developments described here deal with: kinematic programming techniques for automatically generating joint-space trajectories to execute prescribed tasks; control of redundant manipulators to optimize dynamic criteria (e.g., applications of forces and moments at the end-effector that optimally distribute the loading of actuators); and design of KRRMs to optimize functionality in congested work environments or to achieve other goals unattainable with non-redundant manipulators. Kinematic programming techniques are discussed, which show that some pseudo-inverse techniques that have been proposed for redundant manipulator control fail to achieve the goals of avoiding kinematic singularities and also generating closed joint-space paths corresponding to close paths of the end effector in the workspace. The extended Jacobian is proposed as an alternative to pseudo-inverse techniques

Why Did the Greek Polis Originally Need Coins?

Why did the ancient Greek polis originally need coins? This question, so simple to pose and so difficult to answer, leads to more specific queries such as what practical purposes coins served in the polis and what messages they communicated either explicitly through their types and legends or implicitly by their very creation as products of the political community of the polis

Sovereignty and Coinage in Classical Greece

This book examines the common assumption that coins were produced in classical Greece to serve as symbols of the political sovereignty of the state, much like flags of modern nations. Since the beginning of modern numismatics studies, scholars have used this assumption to establish the chronology of numerous Greek coinages and, in turn, to make hypotheses about important historical events, especially the intervention in Greek affairs of Philip II, Alexander the Great, and their early successors. The author challenges the standard opinion , refuting the notion that a conquered state automatically lost its right of coinage and establishing that the minting of classical Greek coinage was primarily motivated by economic concerns.https://crossworks.holycross.edu/hc_books/1002/thumbnail.jp