Interpretation is Evolution: Whose History?

When I try to explain to non-history people what my degree means, I used to hit wall after all. It was so hard explaining exactly what, Applied History, really means. People understand, History, but the idea of public history has a certain brand of special sauce added on top. I used to say something akin to, doing Park Ranger things, though that never really worked. When I had a group on an historical landscape, I\u27d often just say, Public History is this. It doesn\u27t work. Those definitions aren\u27t clear. [excerpt

Shared Agency Without Shared Intention

The leading reductive approaches to shared agency model that phenomenon in terms of complexes of individual intentions, understood as plan-laden commitments. Yet not all agents have such intentions, and non-planning agents such as small children and some non-human animals are clearly capable of sophisticated social interactions. But just how robust are their social capacities? Are non-planning agents capable of shared agency? Existing theories of shared agency have little to say about these important questions. I address this lacuna by developing a reductive account of the social capacities of non-planning agents, which I argue supports the conclusion that they can enjoy shared agency. The resulting discussion offers a fine-grained account of the psychological capacities that can underlie shared agency, and produces a recipe for generating novel hypotheses concerning why some agents do not engage in shared agency

FTAA: What's in It for the South?

Not everyone in the Americas thinks that negotiating an FTAA is desirable. Some argue that the timing of the negotiations is being set by the agenda of the developed countries, particularly the US, and not that of the rest of the region. Others say that negotiating tariff reductions will do little to increase exports. The argument is that non-tariff barriers to trade must be part of the package, or the whole idea is a waste of time. These are just some of the opinions coming from the South. Interestingly, a number of these ideas are coming from Brazil, the hemisphere's most populous country after the US, and clearly a leader in the region. Presidential elections in Brazil took place in the fall of 2002 just prior to an FTAA Ministerial in Quito. In the lead up to the election, the FTAA positions of the opposition candidates, including the eventual winner, were much more protectionist than that of the outgoing government. If the protectionism carries through to official government policy, then the FTAA process will be much more difficult. However, this might just have been electoral talk. This paper will attempt to sort out truth from rhetoric.Brazil, non-tariff barriers, FTAA, South, International Relations/Trade,

Teens, social media, and privacy

This report finds that teens are sharing more information about themselves on social media sites than they have in the past, but they are also taking a variety of technical and non-technical steps to manage the privacy of that information. Despite taking these privacy-protective actions, teen social media users do not express a high level of concern about third-parties (such as businesses or advertisers) accessing their data; just 9% say they are “very” concerned. Key findings include: Teens are sharing more information about themselves on their social media profiles than they did when we last surveyed in 2006: 91% post a photo of themselves, up from 79% in 2006. 71% post their school name, up from 49%. 71% post the city or town where they live, up from 61%. 53% post their email address, up from 29%. 20% post their cell phone number, up from 2%. 60% of teen Facebook users set their Facebook profiles to private (friends only), and most report high levels of confidence in their ability to manage their settings. 56% of teen Facebook users say it’s “not difficult at all” to manage the privacy controls on their Facebook profile. 33% Facebook-using teens say it’s “not too difficult.” 8% of teen Facebook users say that managing their privacy controls is “somewhat difficult,” while less than 1% describe the process as “very difficult.” Authored by Mary Madden, Amanda Lenhart, Sandra Cortesi, Urs Gasser, Maeve Duggan, and Aaron Smith

Neutrinos Have Mass - So What?

In this brief review, I discuss the new physics unveiled by neutrino oscillation experiments over the past several years, and discuss several attempts at understanding the mechanism behind neutrino masses and lepton mixing. It is fair to say that, while significant theoretical progress has been made, we are yet to construct a coherent picture that naturally explains non-zero, yet tiny, neutrino masses and the newly revealed, puzzling patterns of lepton mixing. I discuss what the challenges are, and point to the fact that more experimental input (from both neutrino and non-neutrino experiments) is dearly required - and that new data is expected to reveal, in the next several years, new information. Finally, I draw attention to the fact that neutrinos may have only just begun to reshape fundamental physics, given the fact that we are still to explain the LSND anomaly and because the neutrino oscillation phenomenon is ultimately sensitive to very small new-physics effects.Comment: invited brief review, 15 pages, 1 eps figure, typo corrected, reference adde

Expansion of a compressible gas in vacuum

Tai-Ping Liu \cite{Liu\_JJ} introduced the notion of "physical solution' of the isentropic Euler system when the gas is surrounded by vacuum. This notion can be interpreted by saying that the front is driven by a force resulting from a H\"older singularity of the sound speed. We address the question of when this acceleration appears or when the front just move at constant velocity. We know from \cite{Gra,SerAIF} that smooth isentropic flows with a non-accelerated front exist globally in time, for suitable initial data. In even space dimension, these solutions may persist for all $t\in\R$ ; we say that they are {\em eternal}. We derive a sufficient condition in terms of the initial data, under which the boundary singularity must appear. As a consequence, we show that, in contrast to the even-dimensional case, eternal flows with a non-accelerated front don't exist in odd space dimension. In one space dimension, we give a refined definition of physical solutions. We show that for a shock-free flow, their asymptotics as both ends $t\rightarrow\pm\infty$ are intimately related to each other

A block Hankel generalized confluent Vandermonde matrix

Vandermonde matrices are well known. They have a number of interesting properties and play a role in (Lagrange) interpolation problems, partial fraction expansions, and finding solutions to linear ordinary differential equations, to mention just a few applications. Usually, one takes these matrices square, $q\times q$ say, in which case the $i$-th column is given by $u(z_i)$, where we write $u(z)=(1,z,...,z^{q-1})^\top$. If all the $z_i$ ($i=1,...,q$) are different, the Vandermonde matrix is non-singular, otherwise not. The latter case obviously takes place when all $z_i$ are the same, $z$ say, in which case one could speak of a confluent Vandermonde matrix. Non-singularity is obtained if one considers the matrix $V(z)$ whose $i$-th column ($i=1,...,q$) is given by the $(i-1)$-th derivative $u^{(i-1)}(z)^\top$. We will consider generalizations of the confluent Vandermonde matrix $V(z)$ by considering matrices obtained by using as building blocks the matrices $M(z)=u(z)w(z)$, with $u(z)$ as above and $w(z)=(1,z,...,z^{r-1})$, together with its derivatives $M^{(k)}(z)$. Specifically, we will look at matrices whose $ij$-th block is given by $M^{(i+j)}(z)$, where the indices $i,j$ by convention have initial value zero. These in general non-square matrices exhibit a block-Hankel structure. We will answer a number of elementary questions for this matrix. What is the rank? What is the null-space? Can the latter be parametrized in a simple way? Does it depend on $z$? What are left or right inverses? It turns out that answers can be obtained by factorizing the matrix into a product of other matrix polynomials having a simple structure. The answers depend on the size of the matrix $M(z)$ and the number of derivatives $M^{(k)}(z)$ that is involved. The results are obtained by mostly elementary methods, no specific knowledge of the theory of matrix polynomials is needed