113 research outputs found
Metal-Interface-Elastomer (MINE) Structures for Stretchable Electronics
The future of soft, conformable, and robust wearable electronics will require elastomers to provide mechanical stabilization, a soft surface to interact with human wearers, and a crucial physical barrier to protect stretchable devices from the environment. It is a difficult challenge, however, for a single elastomer to fulfill each of these needs. Here, we present a new approach that fuses a membrane of poly(dimethylsiloxane) (PDMS) onto the surface of a transparent butyl rubber (T-IIR) substrate using an organosilane-based molecular glue. The resulting membrane-interface-elastomer (MINE) structures uniquely combine the surface chemistry of PDMS with the intrinsically low gas permeability of T-IIR for the fabrication of robust stretchable devices. Our most intriguing finding, however, is that the T-IIR-PDMS interface, buried microns below the PDMS surface, exerts a remarkable influence on metal films deposited on the PDMS membrane surface from below, improving stretching and conductance performance by orders of magnitude
Composition and Analysis of Music Using Mathematica
In this paper we demonstrate how to create and analyze musical compositions using Mathematica. In §1, we begin by demonstrating how to create a musical composition for an orchestra based on the butterfly curve using traditional means. In §2, we then show how a computer generated piece based on any curve can be composed using Mathematica. Finally, in §3, we show how Mathematica can be used to analyze musical compositions using the methods from nonlinear time series analysis
How to Find Young Massive Cluster Progenitors
We propose that bound, young massive stellar clusters form from dense clouds
that have escape speeds greater than the sound speed in photo-ionized gas. In
these clumps, radiative feedback in the form of gas ionization is bottled up,
enabling star formation to proceed to sufficiently high efficiency so that the
resulting star cluster remains bound even after gas removal. We estimate the
observable properties of the massive proto-clusters (MPCs) for existing
Galactic plane surveys and suggest how they may be sought in recent and
upcoming extragalactic observations. These surveys will potentially provide a
significant sample of MPC candidates that will allow us to better understand
extreme star-formation and massive cluster formation in the Local Universe.Comment: 5 pages, 1 figure, 1 table, accepted for publication in ApJ
A Mid-Infrared Census of Star Formation Activity in Bolocam Galactic Plane Survey Sources
We present the results of a search for mid-infrared signs of star formation
activity in the 1.1 mm sources in the Bolocam Galactic Plane Survey (BGPS). We
have correlated the BGPS catalog with available mid-IR Galactic plane catalogs
based on the Spitzer Space Telescope GLIMPSE legacy survey and the Midcourse
Space Experiment (MSX) Galactic plane survey. We find that 44% (3,712 of 8,358)
of the BGPS sources contain at least one mid-IR source, including 2,457 of
5,067 (49%) within the area where all surveys overlap (10 deg < l < 65 deg).
Accounting for chance alignments between the BGPS and mid-IR sources, we
conservatively estimate that 20% of the BPGS sources within the area where all
surveys overlap show signs of active star formation. We separate the BGPS
sources into four groups based on their probability of star formation activity.
Extended Green Objects (EGOs) and Red MSX Sources (RMS) make up the highest
probability group, while the lowest probability group is comprised of
"starless" BGPS sources which were not matched to any mid-IR sources. The mean
1.1 mm flux of each group increases with increasing probability of active star
formation. We also find that the "starless" BGPS sources are the most compact,
while the sources with the highest probability of star formation activity are
on average more extended with large skirts of emission. A subsample of 280 BGPS
sources with known distances demonstrates that mass and mean H_2 column density
also increase with probability of star formation activity.Comment: 20 pages, 12 figures, 3 tables. Accepted for publication in ApJ. Full
Table 2 will be available online through Ap
A Survey of Local Group Galaxies Currently Forming Stars. I. UBVRI Photometry of Stars in M31 and M33
We present UBVRI photometry obtained from Mosaic images of M31 and M33 using
the KPNO 4-m telescope. The survey covers 2.2 sq degrees of M31, and 0.8 sq
degrees of M33, chosen so as to include all of the regions currently active in
forming massive stars. The catalog contains 371,781 and 146,622 stars in M31
and M33, respectively, where every star has a counterpart (at least) in B, V,
and R. We compare our photometry to previous studies. We provide cross
references to the stars confirmed as members by spectroscopy, and compare the
location of these to the complete set in color-magnitude diagrams. While
follow-up spectroscopy is needed for many projects, we demonstrate the success
of our photometry in being able to distinguish M31/M33 members from foreground
Galactic stars. We also present the results of newly obtained spectroscopy,
which identifies 34 newly confirmed members, including B-A supergiants, the
earliest O star known in M31, and two new Luminous Blue Variable candidates
whose spectra are similar to that of P Cygni.Comment: Accepted by the Astronomical Journal. A version with higher
resolution figures can be found at:
http://www.lowell.edu/users/massey/M3133.pdf.g
A New Lecture-Tutorial for Teaching about Molecular Excitations and Synchrotron Radiation
Light and spectroscopy are among the most important and frequently taught
topics in introductory, college-level, general education astronomy courses.
This is due to the fact that the vast majority of observational data studied by
astronomers arrives at Earth in the form of light. While there are many
processes by which matter can emit and absorb light, Astro 101 courses
typically limit their instruction to the Bohr model of the atom and electron
energy level transitions. In this paper, we report on the development of a new
Lecture-Tutorial to help students learn about other processes that are
responsible for the emission and absorption of light, namely molecular
rotations, molecular vibrations, and the acceleration of charged particles by
magnetic fields.Comment: 13 pages, 7 figures Accepted for publication in The Physics Teache
An Infrared through Radio Study of the Properties and Evolution of IRDC Clumps
We examine the physical properties and evolutionary stages of a sample of 17
clumps within 8 Infrared Dark Clouds (IRDCs) by combining existing infrared,
millimeter, and radio data with new Bolocam Galactic Plane Survey (BGPS) 1.1 mm
data, VLA radio continuum data, and HHT dense gas (HCO+ and N2H+) spectroscopic
data. We combine literature studies of star formation tracers and dust
temperatures within IRDCs with our search for ultra-compact (UC) HII regions to
discuss a possible evolutionary sequence for IRDC clumps. In addition, we
perform an analysis of mass tracers in IRDCs and find that 8 micron extinction
masses and 1.1 mm Bolocam Galactic Plane Survey (BGPS) masses are complementary
mass tracers in IRDCs except for the most active clumps (notably those
containing UCHII regions), for which both mass tracers suffer biases. We find
that the measured virial masses in IRDC clumps are uniformly higher than the
measured dust continuum masses on the scale of ~1 pc. We use 13CO, HCO+, and
N2H+ to study the molecular gas properties of IRDCs and do not see any evidence
of chemical differentiation between hot and cold clumps on the scale of ~1 pc.
However, both HCO+ and N2H+ are brighter in active clumps, due to an increase
in temperature and/or density. We report the identification of four UCHII
regions embedded within IRDC clumps and find that UCHII regions are associated
with bright (>1 Jy) 24 micron point sources, and that the brightest UCHII
regions are associated with "diffuse red clumps" (an extended enhancement at 8
micron). The broad stages of the discussed evolutionary sequence (from a
quiescent clump to an embedded HII region) are supported by literature dust
temperature estimates; however, no sequential nature can be inferred between
the individual star formation tracers.Comment: 33 pages, 26 figures, 6 tables, accepted for publication in ApJ. Full
resolution version available here:
http://casa.colorado.edu/~battersb/Publications.htm
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