H-Band Spectroscopic Classification of OB Stars

We present a new spectroscopic classification for OB stars based on H-band (1.5 micron to 1.8 micron) observations of a sample of stars with optical spectral types. Our initial sample of nine stars demonstrates that the combination of He I 1.7002 micron and H Brackett series absorption can be used to determine spectral types for stars between about O4 and B7 (to within about +/- 2 sub-types). We find that the Brackett series exhibits luminosity effects similar to the Balmer series for the B stars. This classification scheme will be useful in studies of optically obscured high mass star forming regions. In addition, we present spectra for the OB stars near 1.1 micron and 1.3 micron which may be of use in analyzing their atmospheres and winds.Comment: Accepted by AJ, 16 pages Latex (aastex4.0) including 4 figures and 2 tables. A complete PostScript copy is available at ftp://degobah.colorado.edu/pub/rblum/Hband

Stem clutch for motor driven valve

Development of mechanical device to reduce possibility of damage to motor driven needle valve is discussed. Mechanical clutch is employed to allow slippage when needle valve reaches limit of travel. Operation of system for various conditions is described

Active Semi-Supervised Learning Using Sampling Theory for Graph Signals

We consider the problem of offline, pool-based active semi-supervised learning on graphs. This problem is important when the labeled data is scarce and expensive whereas unlabeled data is easily available. The data points are represented by the vertices of an undirected graph with the similarity between them captured by the edge weights. Given a target number of nodes to label, the goal is to choose those nodes that are most informative and then predict the unknown labels. We propose a novel framework for this problem based on our recent results on sampling theory for graph signals. A graph signal is a real-valued function defined on each node of the graph. A notion of frequency for such signals can be defined using the spectrum of the graph Laplacian matrix. The sampling theory for graph signals aims to extend the traditional Nyquist-Shannon sampling theory by allowing us to identify the class of graph signals that can be reconstructed from their values on a subset of vertices. This approach allows us to define a criterion for active learning based on sampling set selection which aims at maximizing the frequency of the signals that can be reconstructed from their samples on the set. Experiments show the effectiveness of our method.Comment: 10 pages, 6 figures, To appear in KDD'1

Primary education for global learning and sustainability

This is one of a series of research reports commissioned by the Cambridge Primary Review Trust (CPRT), a notfor-profit company established in December 2012 with the aim of consolidating and building on the evidence, findings and principles of the Cambridge Primary Review. Cambridge Primary Review Trust is supported by Pearson Education, based at the University of York and chaired by Professor Robin Alexander. A briefing which summarises key issues from this report is also available. The report and briefing may be downloaded from the Trust’s website: www.cprtrust.org.uk. The website also provides information and other reports in this series, and about the many publications of the Cambridge Primary Review

End states, ladder compounds, and domain wall fermions

A magnetic field applied to a cross linked ladder compound can generate isolated electronic states bound to the ends of the chain. After exploring the interference phenomena responsible, I discuss a connection to the domain wall approach to chiral fermions in lattice gauge theory. The robust nature of the states under small variations of the bond strengths is tied to chiral symmetry and the multiplicative renormalization of fermion masses.Comment: 10 pages, 4 figures; final version for Phys. Rev. Let

Local electronic structure of the peptide bond probed by resonant inelastic soft X-ray scattering.

The local valence orbital structure of solid glycine, diglycine, and triglycine is studied using soft X-ray emission spectroscopy (XES), resonant inelastic soft X-ray scattering (RIXS) maps, and spectra calculations based on density-functional theory. Using a building block approach, the contributions of the different functional groups of the peptides are separated. Cuts through the RIXS maps furthermore allow monitoring selective excitations of the amino and peptide functional units, leading to a modification of the currently established assignment of spectral contributions. The results thus paint a new-and-improved picture of the peptide bond, enhance the understanding of larger molecules with peptide bonds, and simplify the investigation of such molecules in aqueous environment

The Stellar Initial Mass Function in the Galactic Center

Massive stars define the upper limits of the star formation process, dominate the energetics of their local environs, and significantly affect the chemical evolution of galaxies. Their role in starburst galaxies and the early Universe is likely to be important, but we still do not know the maximum mass that a star can possess, i.e.``the upper mass cutoff.'' I will discuss results from a program to measure the upper mass cutoff and IMF slope in the Galactic Center. The results suggest that the IMF in the Galactic center may deviate significantly from the Salpeter value, and that there may be an upper mass cutoff to the initial mass function of $\sim$150 Msun.Comment: To be published in the IMF@50 conference proceeding

Synthesis of Gold Nanoparticles Attached to Polypyrrole Nanofibers

Polypyrrole is a frequently studied conducting polymer due to its application in sensing and catalysis.1 Polypyrrole is considered among the most promising conductive polymers due to its stability and ease of conversion between conducting and insulating forms.2 Different chemical and electrochemical methods are generally used in the synthesis of polypyrrole.2 Despite many interesting applications, the use of polypyrrole is limited because of difficulty in processing it. Several approaches have been explored to improve the ability to process polypyrrole, including the use of emulsion, inverse emulsion, steric stabilizer, and microemulsion methods.1 Several reports have also been published on the synthesis of polypyrrole-metal nanocomposites.3 the sensing and catalytic abilities of the polypyrrole composites are significantly better than those for polymer alone.4 as most of the important properties of the noble metals depend on their dispersion and surface properties in the surrounding medium, it is important to obtain evenly distributed Au nanoparticles in conducting polymer matrix. Here we report a simple and convenient procedure for the synthesis of polypyrrole and gold composites, where both polymer and metal morphologies can be controlled in a single set-up