Visualizing probabilistic models: Intensive Principal Component Analysis

Unsupervised learning makes manifest the underlying structure of data without curated training and specific problem definitions. However, the inference of relationships between data points is frustrated by the `curse of dimensionality' in high-dimensions. Inspired by replica theory from statistical mechanics, we consider replicas of the system to tune the dimensionality and take the limit as the number of replicas goes to zero. The result is the intensive embedding, which is not only isometric (preserving local distances) but allows global structure to be more transparently visualized. We develop the Intensive Principal Component Analysis (InPCA) and demonstrate clear improvements in visualizations of the Ising model of magnetic spins, a neural network, and the dark energy cold dark matter ({\Lambda}CDM) model as applied to the Cosmic Microwave Background.Comment: 6 pages, 5 figure

Poly[[tetra­kis­(μ2-pyrazine N,N′-dioxide-κ2 O:O′)erbium(III)] tris­(perchlorate)]

The title three-dimensional coordination network, {[Er(C4H4N2O2)4](ClO4)3}n, is isostructural to that of other lanthanides. The Er+3 cation lies on a fourfold roto-inversion axis. It is coordinated in a distorted square-anti­prismatic fashion by eight O atoms from bridging pyrazine N,N′-dioxide ligands. There are two unique pyrazine N,N′-dioxide ligands. One ring is located around an inversion center, and there is a a twofold rotation axis at the center of the other ring. There are also two unique perchlorate anions. One is centered on a twofold rotation axis and the other on a fourfold roto-inversion axis. The perchlorate anions are located in channels that run perpendicular to (001) and (110) and inter­act with the coordination network through C—H⋯O hydrogen bonds

Attributes of researchers and their strategies to recruit minority populations: Results of a national survey

Despite NIH mandates for inclusion, recruiting minorities is challenging for biomedical and public health researchers. Little is known about how attributes of researchers affect their choice of recruitment strategies. The purpose of this study was to address this gap by examining how use of recruitment strategies relates to other researcher characteristics. To do this, we conducted an online survey from May to August 2010 with researchers (principal investigators, research staff, and IRB members) in which we measured the number and types of recruitment strategies utilized, along with other characteristics of the researchers and their research. We identified two clusters of researchers: comprehensive researchers who utilized a greater number and more diverse and active recruitment strategies, and traditional researchers, who utilized fewer and more passive strategies. Additional characteristics that distinguished the two groups were that comprehensive researchers were more likely than traditional researchers to 1) report racial and ethnic differences as one of their specific aims or hypotheses, 2) receive federal (CDC and NIH) funding, 3) conduct behavioral or epidemiological research, and 4) have received training in conducting research with and recruiting minorities. Traditional researchers, on the other hand, were more likely to conduct clinical research and a greater (though non-significant) percentage received funding from pharmaceutical sources. This study provides a novel description of how researcher attributes are related to their recruitment strategies and raises a number of future research questions to further examine the implications of this relationship.http://dx.doi.org/10.1016/j.cct.2012.06.01

Aquatic biosurvey of the Lovell River on UNH land

We assessed the physical, chemical and biological conditions at two sites along the Lovell River on University of New Hampshire (UNH) -owned conservation land. The discharge was 4.4 m3 s-1 at Site 1 and 5.7 m3 s -1 downstream at Site 2. Canopy coverage ranged from 8-25%. Canopy was dominated by Eastern Hemlock (79-84%). Much of the stream was strewn with large boulders and the substrate consisted of rocks of highly variable sizes ( 3-549 cm dia.). Specific conductivity (22.1-23.3 µS), pH (6.4) and temperature (7.9-8.3 °C) varied little between sites. Macro-invertebrate bio-indices indicated either excellent water quality with no apparent organic pollution (3.0/10) or good water quality with possible slight organic pollution (4.4/10)