Sharp Oracle Inequalities for Square Root Regularization

We study a set of regularization methods for high-dimensional linear regression models. These penalized estimators have the square root of the residual sum of squared errors as loss function, and any weakly decomposable norm as penalty function. This fit measure is chosen because of its property that the estimator does not depend on the unknown standard deviation of the noise. On the other hand, a generalized weakly decomposable norm penalty is very useful in being able to deal with different underlying sparsity structures. We can choose a different sparsity inducing norm depending on how we want to interpret the unknown parameter vector $\beta$. Structured sparsity norms, as defined in Micchelli et al. [18], are special cases of weakly decomposable norms, therefore we also include the square root LASSO (Belloni et al. [3]), the group square root LASSO (Bunea et al. [10]) and a new method called the square root SLOPE (in a similar fashion to the SLOPE from Bogdan et al. [6]). For this collection of estimators our results provide sharp oracle inequalities with the Karush-Kuhn-Tucker conditions. We discuss some examples of estimators. Based on a simulation we illustrate some advantages of the square root SLOPE

χ2\chi^2-confidence sets in high-dimensional regression

We study a high-dimensional regression model. Aim is to construct a confidence set for a given group of regression coefficients, treating all other regression coefficients as nuisance parameters. We apply a one-step procedure with the square-root Lasso as initial estimator and a multivariate square-root Lasso for constructing a surrogate Fisher information matrix. The multivariate square-root Lasso is based on nuclear norm loss with $\ell_1$-penalty. We show that this procedure leads to an asymptotically $\chi^2$-distributed pivot, with a remainder term depending only on the $\ell_1$-error of the initial estimator. We show that under $\ell_1$-sparsity conditions on the regression coefficients $\beta^0$ the square-root Lasso produces to a consistent estimator of the noise variance and we establish sharp oracle inequalities which show that the remainder term is small under further sparsity conditions on $\beta^0$ and compatibility conditions on the design.Comment: 22 page

Autonomy and Symbolic Capital in an Academic Social Movement: The March 9 Group in Egypt

Qualities that can make activism possible under an authoritarian regime can become disadvantages when restrictions on the political field are eased. Under the Mubarak regime in Egypt, the March 9 Group for University Autonomy, a small group of academics, campaigned against the interference of the state security apparatus and the ruling party in academic affairs and campus life. This article suggests that the group’s survival in that context, and its ability to organize successful campaigns within certain limits, depended on the involvement of highly accomplished academics, some of whom are well-known outside academia, on its practice of a particular type of participatory democracy, and on its focus on institutional autonomy from the state. All these assets became liabilities following the revolutionary uprising of January 2011, and the group has to a large extent demobilized as a result

Al-Istiqlaliyya wa-l-Ra'simal al-Ramzi dimn Haraka Ijtima`iyya Akadimiyya: Majmu`at 9 Maris fi Misr

Arabic translation of "Autonomy and Symbolic Capital in an Academic Social Movement: The March 9 Group in Egypt"

Autonomy and Symbolic Capital in an Academic Social Movement: The March 9 Group in Egypt

Qualities that can make activism possible under an authoritarian regime can become disadvantages when restrictions on the political field are eased. Under the Mubarak regime in Egypt, the March 9 Group for University Autonomy, a small group of academics, campaigned against the interference of the state security apparatus and the ruling party in academic affairs and campus life. This article suggests that the group’s survival in that context, and its ability to organize successful campaigns within certain limits, depended on the involvement of highly accomplished academics, some of whom are well-known outside academia, on its practice of a particular type of participatory democracy, and on its focus on institutional autonomy from the state. All these assets became liabilities following the revolutionary uprising of January 2011, and the group has to a large extent demobilized as a result

Wolfram Syndrome protein, Miner1, regulates sulphydryl redox status, the unfolded protein response, and Ca2+ homeostasis.

Miner1 is a redox-active 2Fe2S cluster protein. Mutations in Miner1 result in Wolfram Syndrome, a metabolic disease associated with diabetes, blindness, deafness, and a shortened lifespan. Embryonic fibroblasts from Miner1(-/-) mice displayed ER stress and showed hallmarks of the unfolded protein response. In addition, loss of Miner1 caused a depletion of ER Ca(2+) stores, a dramatic increase in mitochondrial Ca(2+) load, increased reactive oxygen and nitrogen species, an increase in the GSSG/GSH and NAD(+)/NADH ratios, and an increase in the ADP/ATP ratio consistent with enhanced ATP utilization. Furthermore, mitochondria in fibroblasts lacking Miner1 displayed ultrastructural alterations, such as increased cristae density and punctate morphology, and an increase in O2 consumption. Treatment with the sulphydryl anti-oxidant N-acetylcysteine reversed the abnormalities in the Miner1 deficient cells, suggesting that sulphydryl reducing agents should be explored as a treatment for this rare genetic disease

Prophets and Priests of the Nation: Naguib Mahfouz’s Karnak Café and the 1967 Crisis in Egypt

Similarities between religion and nationalism are well known but not well understood. They can be explained by drawing on Pierre Bourdieu's sociological theory in order to consider symbolic interests and the strategies employed to advance them. In both religion and nationalism, the “strategy of the prophets” relies on charisma while the “strategy of the priests” relies on cultural capital. In 20th-century Egypt, nationalism permitted intellectuals whose cultural capital was mainly secular, such as Naguib Mahfouz, to become “priests of the nation” in order to compete with the ʿulamaʾ for prestige and influence. However, it severely limited their autonomy, particularly after Nasser took power and became a successful nationalist prophet. Mahfouz's novel Al-Karnak, which explores the fate of the Nasser regime's political prisoners and the effects of Egypt's 1967 military defeat, reflects this limitation. Under a nationalist regime, the film adaptation of the novel contributed to Mahfouz's heteronomy