Insights into enzymatic halogenation from computational studies

The halogenases are a group of enzymes that have only come to the fore over the last 10 years thanks to the discovery and characterization of several novel representatives. They have revealed the fascinating variety of distinct chemical mechanisms that nature utilizes to activate halogens and introduce them into organic substrates. Computational studies using a range of approaches have already elucidated many details of the mechanisms of these enzymes, often in synergistic combination with experiment. This Review summarizes the main insights gained from these studies. It also seeks to identify open questions that are amenable to computational investigations. The studies discussed herein serve to illustrate some of the limitations of the current computational approaches and the challenges encountered in computational mechanistic enzymology

The Effectiveness of Paraphrasing Strategy in Increasing University Students' Reading Comprehension and Writing Achievement

Reading comprehension and writing as the crucial skills must be instructed effectively in order to engage the students in the meaningful teaching and learning process. One of the ways to increase students' reading comprehension and writing achievement is by the use of paraphrasing strategy in the classroom instruction. Through the application of the paraphrasing strategy, it is easy for the students to internalize the information of the original source comprehensively; thus, students' reading comprehension achievement is increased. In relation to the improvement of students' reading comprehension achievement, students' writing achievement is also increased by the use of paraphrasing strategy since the students can rewrite the text in to their own writing style. Therefore, the use of paraphrasing strategy is considered as one of the beneficial ways used to enhance students' reading comprehension and writing achievement

Comment on Ferejohn’s “Judicializing Politics, Politicizing Law”

Munger comments on John Ferejohn\u27s recent article in which Ferejohn examines some key issues raised by the exercise of legislative power by the judicial branch. Ferejohn claims that Americans have chosen to accept the judicialization of politics, leaving the courts the option of exercising power inappropriately. Munger argues that while the courts do have power, they forebear from exercising it for long periods of time

Iwahori-Hecke algebras of type A at roots of unity

In this paper, we explore the use of path idempotents for the Hecke algebra of type $A$ at roots of unity. For $q$ a primitive $\ell$-th root of unity we obain a non-unital imbedding of (a quotient of) the group algebra of $S_m$ into (a quotient of) the Hecke algebra $H_n(q)$ for certain $m$ and $n$. From this we recover certain instances of irreducibility criteria of Dipper, James, and Mathas, and we derive estimates on the decomposition numbers for the Hecke algebra at roots of unity. The bounds are easily computed, provide a good geometric picture of the pairs of diagrams $\lambda$, $\mu$ for which the decomposition number $d_{\lambda, \mu}$ is non-zero, and also appers to be a useful adjunct to the exact computation of the decomposition numbers.Comment: **Second** substantial revision of previously submitted manuscript. 38 pages, TeX, with figures in EPS, requires macro BoxedEP

On Approximations of the Curve Shortening Flow and of the Mean Curvature Flow based on the DeTurck trick

In this paper we discuss novel numerical schemes for the computation of the curve shortening and mean curvature flows that are based on special reparametrizations. The main idea is to use special solutions to the harmonic map heat flow in order to reparametrize the equations of motion. This idea is widely known from the Ricci flow as the DeTurck trick. By introducing a variable time scale for the harmonic map heat flow, we obtain families of numerical schemes for the reparametrized flows. For the curve shortening flow this family unveils a surprising geometric connection between the numerical schemes in [5] and [9]. For the mean curvature flow we obtain families of schemes with good mesh properties similar to those in [3]. We prove error estimates for the semi-discrete scheme of the curve shortening flow. The behaviour of the fully-discrete schemes with respect to the redistribution of mesh points is studied in numerical experiments. We also discuss possible generalizations of our ideas to other extrinsic flows