From which world is your graph?

Discovering statistical structure from links is a fundamental problem in the analysis of social networks. Choosing a misspecified model, or equivalently, an incorrect inference algorithm will result in an invalid analysis or even falsely uncover patterns that are in fact artifacts of the model. This work focuses on unifying two of the most widely used link-formation models: the stochastic blockmodel (SBM) and the small world (or latent space) model (SWM). Integrating techniques from kernel learning, spectral graph theory, and nonlinear dimensionality reduction, we develop the first statistically sound polynomial-time algorithm to discover latent patterns in sparse graphs for both models. When the network comes from an SBM, the algorithm outputs a block structure. When it is from an SWM, the algorithm outputs estimates of each node's latent position.Comment: To appear in NIPS 201

Adaptive Reduced Rank Regression

We study the low rank regression problem $\mathbf{y} = M\mathbf{x} + \epsilon$, where $\mathbf{x}$ and $\mathbf{y}$ are $d_1$ and $d_2$ dimensional vectors respectively. We consider the extreme high-dimensional setting where the number of observations $n$ is less than $d_1 + d_2$. Existing algorithms are designed for settings where $n$ is typically as large as $\mathrm{rank}(M)(d_1+d_2)$. This work provides an efficient algorithm which only involves two SVD, and establishes statistical guarantees on its performance. The algorithm decouples the problem by first estimating the precision matrix of the features, and then solving the matrix denoising problem. To complement the upper bound, we introduce new techniques for establishing lower bounds on the performance of any algorithm for this problem. Our preliminary experiments confirm that our algorithm often out-performs existing baselines, and is always at least competitive.Comment: 40 page

Autogenous shrinkage induced stress of alkali activated slag and fly ash concrete under restraint condition

Autogenous shrinkage is an important engineering property for construction materials since it can induce internal tensile stress and consequent micro- or macro- cracking of the concrete. Alkali activated slag and fly ash (AASF), as a promising alternative to ordinary Portland cement (OPC), has shown many interesting properties such as high early age strength, good durability and fire resistance, but it also shows high autogenous shrinkage in the meantime, which hinders a wider application of this eco-friendly binder material. However, high autogenous shrinkage doesn’t necessarily mean high stress of the material under restraint condition, since there are creep and associated stress relaxation happening simultaneously. Therefore, the creep of AASF needs to be considered in order to better understand the stress induced by autogenous shrinkage. In this study, the autogenous shrinkage induced stress of AASF concrete (with a liquid/binder ratio of 0.5) under restraint condition is measured by Thermal Stress Testing Machine (TSTM). The free autogenous shrinkage of a twin specimen is measured by Autogenous Deformation Testing Machine (ADTM). The elastic modulus of AASF concrete is tested on prisms. The creep coefficient of AASF concrete is calculated based on the stress, free autogenous shrinkage and elastic modulus. It is found that the creep coefficient of AASF concrete is much higher than that of OPC concrete, and creep plays an important role in relaxing the shrinkage induced stress and thus reducing the cracking potential of AASF concrete. Please click Additional Files below to see the full abstract

Dichloridobis(4-pyridylmethyl 1H-pyrrole-2-carboxyl­ate-κN)zinc

In the title mol­ecule, [ZnCl2(C11H10N2O2)2], the ZnII ion, situated on a twofold axis, is in a distorted tetra­hedral coordination environment formed by two chloride anions and two pyridine N atoms of the two organic ligands. In the pyrrole-2-carboxyl­ate unit, the pyrrole N—H group and the carbonyl group point approximately in the same direction. The dihedral angle between the two pyridine rings is 54.8 (3)°. The complex mol­ecules are connected into chains extending along [101] by N—H⋯Cl hydrogen bonds. The chains are further assembled into (-101) layers by C—H⋯O and C—H⋯Cl inter­actions

Why is son preference so persistent in East and South Asia? a cross-country study of China, India, and the Republic of Korea

Son preference has persisted in the face of sweeping economic and social changes in China, India, and the Republic of Korea. The authors attribute this to their similar family systems, which generate strong disincentives to raise daughters while valuing adult women's contributions to the household. Urbanization, female education, and employment can only slowly change these incentives without more direct efforts by the state and civil society to increase the flexibility of the kinship system such that daughters and sons can be perceived as being more equally valuable. Much can be done to this end through social movements, legislation, and the mass media.Gender and Development,Health Monitoring&Evaluation,Anthropology,Public Health Promotion,Population&Development,Adolescent Health,Anthropology,Life Sciences&Biotechnology,Health Monitoring&Evaluation,Population&Development

meso-5,5′-Bis[(4-fluoro­phen­yl)diazen­yl]-2,2′-(pentane-3,3-di­yl)di-1H-pyrrole

There are two independent molecules in the asymmetric unit of the title compound, C25H24F2N6, in which the N=N bonds adopt a trans configuration with distances in the range 1.262 (2)–1.269 (3) Å. The dihedral angles between heterocycles are 86.7 (2) and 85.6 (2)° in the two molecules while the dihedral angles between the heterocylic rings and the adjacent benzene rings are 13.4 (2) and 13.4 (2)° in one molecule and 5.3 (2) and 6.5 (2)° in the other. In the crystal, pairs of independent mol­ecules are held together by four N—H⋯N hydrogen bonds, forming inter­locked dimers

Comparison of the Ground-Motion Attenuation Relationship Between the Wenchuan, China, Area and the Central and Eastern United States

An Mw-7.9 earthquake occurred in Wenchuan, China, in 2008, along the Longmenshan Fault, which is located on the western border of the South China stable continental region. A detailed comparison of the Wenchuan ground-motion attenuation relationships with the relationships for the central and eastern United States (also a stable continental region) showed that the ground-motion prediction equation for the Wenchuan area is similar to those for the central and eastern United States. Thus, the strong-motion records from the Wenchuan earthquake can be used for constraining the ground-motion prediction equation and engineering analysis for the central and eastern United States