How Diverse Schools Affect Student Mobility: Charter, Magnet, and Newly Built Campuses in Los Angeles

Analyzes how student attributes, including race/ethnicity, language, and nativity, and school type (public, charter, pilot, magnet), size, and mix affect which students leave and which schools they transfer to. Considers pros and cons of student mobility

Teacher Stability and Turnover in Los Angeles: The Influence of Teacher and School Characteristics

Analyzes how teacher and school characteristics - including demographics, quality and qualification, specialty, school type (public, magnet, charter) and size, academic climate, and teacher-student racial match - influence teacher turnover

Proteins Do Not Have Strong Spines After All

In this issue of Structure, Berkholz et al. show that the detailed backbone geometry of proteins depends on the local conformation and suggest how this information can be practically used in modeling and refining protein structures

N-{N-[2-(3,5-Difluoro­phenyl)acetyl]-(S)-alanyl}-(S)-phenyl­glycine tert-butyl ester (DAPT): an inhibitor of γ-secretase, revealing fine electronic and hydrogen-bonding features

The title compound, C23H26F2N2O4, is a dipeptidic inhibitor of γ-secretase, one of the enzymes involved in Alzheimer’s dis­ease. The mol­ecule adopts a compact conformation, without intra­molecular hydrogen bonds. In the crystal structure, one of the amide N atoms forms the only inter­molecular N—H⋯O hydrogen bond; the second amide N atom does not form hydrogen bonds. High-resolution synchrotron diffraction data permitted the unequivocal location and refinement without restraints of all H atoms, and the identification of the characteristic shift of the amide H atom engaged in the hydrogen bond from its ideal position, resulting in a more linear hydrogen bond. Significant residual densities for bonding electrons were revealed after the usual SHELXL refinement, and modeling of these features as additional inter­atomic scatterers (IAS) using the program PHENIX led to a significant decrease in the R factor from 0.0411 to 0.0325 and diminished the r.m.s. deviation level of noise in the final difference Fourier map from 0.063 to 0.037 e Å−3

Carrying out an optimal experiment

Diffraction data collection parameters leading to optimal data quality are discussed in the context of different applications of these data

SU(2) Cosmological Solitons

We present a class of numerical solutions to the SU(2) nonlinear $\sigma$-model coupled to the Einstein equations with cosmological constant $\Lambda\geq 0$ in spherical symmetry. These solutions are characterized by the presence of a regular static region which includes a center of symmetry. They are parameterized by a dimensionless ``coupling constant'' $\beta$, the sign of the cosmological constant, and an integer ``excitation number'' $n$. The phenomenology we find is compared to the corresponding solutions found for the Einstein-Yang-Mills (EYM) equations with positive $\Lambda$ (EYM$\Lambda$). If we choose $\Lambda$ positive and fix $n$, we find a family of static spacetimes with a Killing horizon for $0 \leq \beta < \beta_{max}$. As a limiting solution for $\beta = \beta_{max}$ we find a {\em globally} static spacetime with $\Lambda=0$, the lowest excitation being the Einstein static universe. To interpret the physical significance of the Killing horizon in the cosmological context, we apply the concept of a trapping horizon as formulated by Hayward. For small values of $\beta$ an asymptotically de Sitter dynamic region contains the static region within a Killing horizon of cosmological type. For strong coupling the static region contains an ``eternal cosmological black hole''.Comment: 20 pages, 6 figures, Revte

Impact of synchrotron radiation on macromolecular crystallography: a personal view

This article, largely based on personal experiences of the authors, reviews the early history of the application of synchrotron radiation to structural biology, and particularly protein crystallography, to show the tremendous impact that this experimental innovation has had on these disciplines

Solvent content of protein crystals from diffraction intensities by Independent Component Analysis

An analysis of the protein content of several crystal forms of proteins has been performed. We apply a new numerical technique, the Independent Component Analysis (ICA), to determine the volume fraction of the asymmetric unit occupied by the protein. This technique requires only the crystallographic data of structure factors as input.Comment: 9 pages, 2 figures, 1 tabl