Learning and Exposure Affect Environmental Perception Less than Evolutionary Navigation Costs

Russell E. Jackson is with University of Idaho, Chéla R. Willey is with University of California Los Angeles, Lawrence K. Cormack is with UT Austin.Most behaviors are conditional upon successful navigation of the environment, which depends upon distance perception learned over repeated trials. Unfortunately, we understand little about how learning affects distance perception–especially in the most common human navigational scenario, that of adult navigation in familiar environments. Further, dominant theories predict mutually exclusive effects of learning on distance perception, especially when the risks or costs of navigation differ. We tested these competing predictions in four experiments in which we also presented evolutionarily relevant navigation costs. Methods included within- and between-subjects comparisons and longitudinal designs in laboratory and real-world settings. Data suggested that adult distance estimation rapidly reflects evolutionarily relevant navigation costs and repeated exposure does little to change this. Human distance perception may have evolved to reflect navigation costs quickly and reliably in order to provide a stable signal to other behaviors and with little regard for objective accuracy.Psycholog

Spectral and Structural Characterization of 5,6-Chrysenequinone Diimine Complexes of Rhodium(III): Evidence for a pH-Dependent Ligand Conformational Switch

Rhodium(III) complexes containing 9,10-phenanthrenequinone diimine (phi) ligands have been broadly applied for the construction of DNA binding and recognition molecules, and more recently, derivatives containing the 5,6-chrysenequinone diimine (chrysi) ligand have been shown specifically to recognize base mismatches in DNA. Here the structural properties of [Rh(bpy)_2(chrysi)]Cl_3 and spectroscopic properties of derivatives are examined and compared to those of phi complexes of rhodium. Although similar in many respects, phi and chrysi complexes display distinctly different protonation behavior. The pK_a values of chrysi complexes are as much as 1 unit lower than analogous phi compounds, and visible spectra of the chrysi complexes differ markedly from the phi counterparts in acidic but not basic solution. This protonation behavior is traced to the presence of a steric clash between a proton on the aromatic ring of the chrysi ligand and the acidic immino proton of the metal complex. In avoidance of this steric clash, a significant disruption in the planarity of the chrysi ligand is evident crystallographically in the structure of [Rh(bpy)_2(chrysi)]Cl_3·3CH_3CN·2H_2O (triclinic crystal system, space group P1̄ (No. 2), Z = 2, a = 9.079(3) Å, b = 10.970(3) Å, c = 21.192(8) Å, α = 86.71(3)°, β = 89.21(3)°, γ = 78.58(3)°, V = 2065.4(12) Å^3). Phi complexes, lacking the additional aromatic ring, require no similar distortion from ligand planarity. NMR spectra support this pH-dependent structural distortion for the chrysi complex. Rhodium complexes of chrysenequinone diimine, therefore, not only represent new DNA binding molecules targeted to mismatches but also provide an illustration of a pH “gated” ligand conformational switch

Fluorescent amplified fragment length polymorphism analysis of Norwegian Bacillus cereus and Bacillus thuringiensis soil isolates

We examined 154 Norwegian B. cereus and B. thuringiensis soil isolates (collected from five different locations), 8 B. cereus and 2 B. thuringiensis reference strains, and 2 Bacillus anthracis strains by using fluorescent amplified fragment length polymorphism (AFLP). We employed a novel fragment identification approach based on a hierarchical agglomerative clustering routine that identifies fragments in an automated fashion. No method is free of error, and we identified the major sources so that experiments can be designed to minimize its effect. Phylogenetic analysis of the fluorescent AFLP results reveals five genetic groups in these group 1 bacilli. The ATCC reference strains were restricted to two of the genetic groups, clearly not representative of the diversity in these bacteria. Both B. anthracis strains analyzed were closely related and affiliated with a B. cereus milk isolate (ATCC 4342) and a B. cereus human pathogenic strain (periodontitis). Across the entire study, pathogenic strains, including B. anthracis, were more closely related to one another than to the environmental isolates. Eight strains representing the five distinct phylogenetic clusters were further analyzed by comparison of their 16S rRNA gene sequences to confirm the phylogenetic status of these groups. This analysis was consistent with the AFLP analysis, although of much lower resolution. The innovation of automated genotype analysis by using a replicated and statistical approach to fragment identification will allow very large sample analyses in the future

China and the CNOOC Bid for Unocal: Issues for Congress

The bid by the China National Offshore Oil Corporation (CNOOC) to acquire the U.S. energy company Unocal for $18.5 billion raised many issues with U.S. policymakers. This report provides an overview and analysis of the CNOOC bid, U.S. interests, implications for U.S. energy security, U.S. investment in the PRC’s (People’s Republic of China’s) oil industry, the process for reviewing the security and other implications of foreign investment in the United States, Congressional activity, and a listing of unresolved issues

China and the CNOOC Bid for Unocal: Issues for Congress

The bid by the China National Offshore Oil Corporation (CNOOC) to acquire the U.S. energy company Unocal for $18.5 billion raised many issues with U.S. policymakers. This report provides an overview and analysis of the CNOOC bid, U.S. interests, implications for U.S. energy security, U.S. investment in the PRC’s (People’s Republic of China’s) oil industry, the process for reviewing the security and other implications of foreign investment in the United States, Congressional activity, and a listing of unresolved issues

Reconnection of Colliding Cosmic Strings

For vortex strings in the Abelian Higgs model and D-strings in superstring theory, both of which can be regarded as cosmic strings, we give analytical study of reconnection (recombination, inter-commutation) when they collide, by using effective field theories on the strings. First, for the vortex strings, via a string sigma model, we verify analytically that the reconnection is classically inevitable for small collision velocity and small relative angle. Evolution of the shape of the reconnected strings provides an upper bound on the collision velocity in order for the reconnection to occur. These analytical results are in agreement with previous numerical results. On the other hand, reconnection of the D-strings is not classical but probabilistic. We show that a quantum calculation of the reconnection probability using a D-string action reproduces the nonperturbative nature of the worldsheet results by Jackson, Jones and Polchinski. The difference on the reconnection -- classically inevitable for the vortex strings while quantum mechanical for the D-strings -- is suggested to originate from the difference between the effective field theories on the strings.Comment: 29 pages, 14 eps figures, JHEP style; references added, typos correcte

Molecular Insights into Division of Single Human Cancer Cells in On-Chip Transparent Microtubes.

In vivo, mammalian cells proliferate within 3D environments consisting of numerous microcavities and channels, which contain a variety of chemical and physical cues. External environments often differ between normal and pathological states, such as the unique spatial constraints that metastasizing cancer cells experience as they circulate the vasculature through arterioles and narrow capillaries, where they can divide and acquire elongated cylindrical shapes. While metastatic tumors cause most cancer deaths, factors impacting early cancer cell proliferation inside the vasculature and those that can promote the formation of secondary tumors remain largely unknown. Prior studies investigating confined mitosis have mainly used 2D cell culture systems. Here, we mimic aspects of metastasizing tumor cells dividing inside blood capillaries by investigating single-cell divisions of living human cancer cells, trapped inside 3D rolled-up, transparent nanomembranes. We assess the molecular effects of tubular confinement on key mitotic features, using optical high- and super-resolution microscopy. Our experiments show that tubular confinement affects the morphology and dynamics of the mitotic spindle, chromosome arrangements, and the organization of the cell cortex. Moreover, we reveal that membrane blebbing and/or associated processes act as a potential genome-safety mechanism, limiting the extent of genomic instability caused by mitosis in confined circumstances, especially in tubular 3D microenvironments. Collectively, our study demonstrates the potential of rolled-up nanomembranes for gaining molecular insights into key cellular events occurring in tubular 3D microenvironments in vivo.The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 311529 (S.S.) and the Volkswagen Foundation no. 86 362 (S.S. and W.X.), a FEBS Return-to-Europe fellowship (C.K.S.), the Wellcome Trust (092096/Z/10/Z for N.L.; 094587/Z/10/Z for R.B.), and a European Research Council (ERC) Starting Researcher Grant (R.E.C.-S.; SYSGRO). O.G.S. acknowledges financial support from the DFG Research Unit 1713 “Sensorische Mikro und Nanosysteme”. D.H.G. acknowledges funding from the Alexander von Humboldt Foundation and the U.S. National Science Foundation (Grants: CMMI 1200241 and CBET-1442014). Research in the S.P.J. laboratory is funded by Cancer Research U.K., the ERC, and the European Community Seventh Framework Programme (DDResponse), with core infrastructure provided by Cancer Research U.K. and the Wellcome Trust.This is the final version of the article. It first appeared from the American Chemical Society via http://dx.doi.org/10.1021/acsnano.6b0046

CMBPol Mission Concept Study: Prospects for polarized foreground removal

In this report we discuss the impact of polarized foregrounds on a future CMBPol satellite mission. We review our current knowledge of Galactic polarized emission at microwave frequencies, including synchrotron and thermal dust emission. We use existing data and our understanding of the physical behavior of the sources of foreground emission to generate sky templates, and start to assess how well primordial gravitational wave signals can be separated from foreground contaminants for a CMBPol mission. At the estimated foreground minimum of ~100 GHz, the polarized foregrounds are expected to be lower than a primordial polarization signal with tensor-to-scalar ratio r=0.01, in a small patch (~1%) of the sky known to have low Galactic emission. Over 75% of the sky we expect the foreground amplitude to exceed the primordial signal by about a factor of eight at the foreground minimum and on scales of two degrees. Only on the largest scales does the polarized foreground amplitude exceed the primordial signal by a larger factor of about 20. The prospects for detecting an r=0.01 signal including degree-scale measurements appear promising, with 5 sigma_r ~0.003 forecast from multiple methods. A mission that observes a range of scales offers better prospects from the foregrounds perspective than one targeting only the lowest few multipoles. We begin to explore how optimizing the composition of frequency channels in the focal plane can maximize our ability to perform component separation, with a range of typically 40 < nu < 300 GHz preferred for ten channels. Foreground cleaning methods are already in place to tackle a CMBPol mission data set, and further investigation of the optimization and detectability of the primordial signal will be useful for mission design.Comment: 42 pages, 14 figures, Foreground Removal Working Group contribution to the CMBPol Mission Concept Study, v2, matches AIP versio