How Fluids Bend: the Elastic Expansion for Higher-Dimensional Black Holes

Hydrodynamics can be consistently formulated on surfaces of arbitrary co-dimension in a background space-time, providing the effective theory describing long-wavelength perturbations of black branes. When the co-dimension is non-zero, the system acquires fluid-elastic properties and constitutes what is called a fluid brane. Applying an effective action approach, the most general form of the free energy quadratic in the extrinsic curvature and extrinsic twist potential of stationary fluid brane configurations is constructed to second order in a derivative expansion. This construction generalizes the Helfrich-Canham bending energy for fluid membranes studied in theoretical biology to the case in which the fluid is rotating. It is found that stationary fluid brane configurations are characterized by a set of 3 elastic response coefficients, 3 hydrodynamic response coefficients and 1 spin response coefficient for co-dimension greater than one. Moreover, the elastic degrees of freedom present in the system are coupled to the hydrodynamic degrees of freedom. For co-dimension-1 surfaces we find a 8 independent parameter family of stationary fluid branes. It is further shown that elastic and spin corrections to (non)-extremal brane effective actions can be accounted for by a multipole expansion of the stress-energy tensor, therefore establishing a relation between the different formalisms of Carter, Capovilla-Guven and Vasilic-Vojinovic and between gravity and the effective description of stationary fluid branes. Finally, it is shown that the Young modulus found in the literature for black branes falls into the class predicted by this approach - a relation which is then used to make a proposal for the second order effective action of stationary blackfolds and to find the corrected horizon angular velocity of thin black rings.Comment: v3: 50pp; minor corrections in Sec. 3.2; typos fixed; published in JHE

Writing Sumerian, Creating Texts: Reflections on Text-building Practices in Old Babylonian Schools

Sumerian lexical and literary compositions both emerged from the same social sphere, namely scribal education. The complexities of inter-compositional dependence in these two corpora have not been thoroughly explored, particularly as relevant to questions of text-building during the Old Babylonian period (c. 1800–1600 bce). Copying practices evident in lexical texts indicate that students and scholars adopted various methods of replication, including visual copying, copying from memory, and ad hoc innovation. They were not confined to reproducing a received text. Such practices extend to copying literary compositions. A study of compositions from Advanced Lexical Education in comparison with several literary compositions shows a complex inter-dialectic between the corpora, in which lexical compositions demonstrate dependence on literary compositions and vice versa. Thus, Old Babylonian students and scholars could experiment with multiple text-building practices, drawing on their knowledge of the lexical and the literary, regularly creating new versions of familiar compositions

The Generation of Memory: Reflections on the “Memory Boom” in Contemporary Historical Studies

Jay Winter delivered the following in the form of a lecture at the Canadian War Museum on 31 October 2000. A distinguished academic, Winter has been writing about the cultural history of the First World War for nearly three decades. He has taught at the University of Cambridge in England and is presently at Yale University. Since 1988, he has been a director of the Historial de la grande guerre in Peronne, an important war museum in northern France. In this capacity, he has become familiar with a great many institutions of war and military history around the world and he has great knowledge and familiarity with the important historical and intellectual debates that will be fundamental to the creation of a new Canadian War Museum, which is now slated to open in May 2005. Probably Winter’s best-known book is Sites of Memory, Sites of Mourning: the Great War in European Cultural History published in 1995. In it, he argues that the rituals of mourning associated with commemoration after the First World War had a history stretching far back in human life and experience. In this he contradicts the thinking of Canadian historian Modris Eksteins who argued that the Great War marked the birth of the modern age. Lately, Daniel Sherman has proposed that commemorative ceremonies and memorials are significantly politicized in the interests of state control. In the following paper Winter warns against the dangers of collective memory being collapsed into “a set of stories formed by or about the state” while also providing a rich overview of the great importance that attention to memory and culture studies has taken on in contemporary thought. These cannot be ignored in any serious attempt to lay the intellectual foundation of any new museum, and perhaps especially may have specific relevance to a new war museum

E-mail, computer usage and college students: a case study

The explosive growth of the Internet and electronic mail (E-mail) is causing many educators to try integrating electronic materials and communication into their classrooms. Many of these educators are implicitly assuming that all students will use these new electronic resources once they are available. This paper tests this assumption and finds that even when students are given large incentives to use E-mail, over a quarter of the students in this case study did not.Accepted manuscrip

Gender Swapping in World of Warcraft: A look into personal relationships and gender identity in the gaming environment

Massively multi player online role-playing games (MMORPGs) are virtual environments that allow thousands of players to come together at one time to interact, fight monsters, and solve challenges. Role-playing in particular offers some unique benefits and opportunities that are not spared in its virtual equivalent. Gender-swapping, that is when a player chooses to play as a character that is the opposite gender of him or her is one of those benefits. This study will explore the phenomenon of gender-swapping, looking for the diverse reasons players may have to assume an identity so extremely opposite of their own. The purpose of this research is to answer the question “Why do people gender-swap in MMORPGs and how does that effect their interpersonal relationships within the game?” In order to answer this question it has been broken into three parts. First, how does gender-swapping affect the player in a casual group? Second this study looks at how gender swapping affects a closer group; in game these groups are called guilds. Last will be a quick analysis of class, the chosen job (i.e. Mage, Priest) taken on by a player in order to perform within their group; and group roll, the players job as either one who takes damage, deals damage or heals the group; as a form of non-verbal communication within the game

Beginner Modeling Exercises

The goal of this paper written as part of the MIT Systems Dynamics in Education Project is to teach the reader how to distinguish between stocks and flows. A stock is an accumulation that is changed over time by inflows and outflows. The reader will gain intuition about stocks and flow through and extensive list of different examples and will practice modeling simple systems with constant flows. STELLA modeling examples include, but are not restricted to, skunks populations, landfills, a bank account and nuclear weapons. Educational levels: High school, Middle school, Undergraduate lower division, Undergraduate upper division