3,682 research outputs found
Honoring Veterans Means Funding Suicide Prevention
Many Americans may not know that it was Dwight D. Eisenhower who in 1954 issued the official proclamation celebrating the service of all veterans by designating Nov. 11, formerly known as Armistice Day, in honor of our vets. Eisenhower, of course, was supreme commander of Allied Forces in Europe during World War II and commander in chief as the 34th president of the United States.
In Ike’s words, “on that day let us solemnly remember the sacrifices of all those who fought so valiantly, on the seas, in the air, and on foreign shores, to preserve our heritage of freedom, and let us reconsecrate ourselves to the task of promoting an enduring peace so that their efforts shall not have been in vain.”
This Veterans Day, millions of Americans thank a veteran for serving our nation, but during the hour-long service at the local elementary school or church cemetery, a veteran or active-duty member of the armed forces will take his own life: The harsh reality is that the average suicide rate today among all those who are serving or have served is more than 20 per day — 17 are veterans. [excerpt
Tax and Spending Policy and Economic Mobility
Surveys the literature on how economic mobility is affected by federal tax policies such as the Earned Income Tax Credit and deductions for home ownership; government spending on education and health care; and income supports such as Social Security
Induction flowmeter for dielectric fluids, experimental verification final report
Experimental verification of induction flow meter for use with dielectric fluid
The Collapse of the Wien Tail in the Coldest Brown Dwarf? Hubble Space Telescope Near-Infrared Photometry of WISE J085510.83-071442.5
We present Hubble Space Telescope (HST) near-infrared photometry of the
coldest known brown dwarf, WISE J085510.83071442.5 (WISE 08550714). WISE
08550714 was observed with the Wide Field Camera 3 (WFC3) aboard HST using
the F105W, F125W, and F160W filters, which approximate the , , and
near-infrared bands. WISE 08550714 is undetected at F105W with a
corresponding 2 magnitude limit of 26.9. We marginally detect
WISE 08550714 in the F125W images (S/N 4), with a measured magnitude
of 26.41 0.27, more than a magnitude fainter than the band magnitude
reported by Faherty and coworkers. WISE J08550714 is clearly detected in the
F160W band, with a magnitude of 23.90 0.02, the first secure detection of
WISE 08550714 in the near-infrared. Based on these data, we find that WISE
08550714 has extremely red F105WF125W and F125WF160W colors relative
to other known Y dwarfs. We find that when compared to the models of Saumon et
al. and Morley et al., the F105WF125W and F125WF160W colors of WISE
08550714 cannot be accounted for simultaneously. These colors likely
indicate that we are seeing the collapse of flux on the Wien tail for this
extremely cold object.Comment: Accepted for publication in ApJ Letter
FeH Absorption in the Near-Infrared Spectra of Late M and L Dwarfs
We present medium-resolution z-, J-, and H-band spectra of four late-type
dwarfs with spectral types ranging from M8 to L7.5. In an attempt to determine
the origin of numerous weak absorption features throughout their near-infrared
spectra, and motivated by the recent tentative identification of the E 4\Pi- A
^4\Pi system of FeH near 1.6 microns in umbral and cool star spectra, we have
compared the dwarf spectra to a laboratory FeH emission spectrum. We have
identified nearly 100 FeH absorption features in the z-, J-, and H-band spectra
of the dwarfs. In particular, we have identified 34 features which dominate the
appearance of the H-band spectra of the dwarfs and which appear in the
laboratory FeH spectrum. Finally, all of the features are either weaker or
absent in the spectrum of the L7.5 dwarf which is consistent with the weakening
of the known FeH bandheads in the spectra of the latest L dwarfs.Comment: accepted by Ap
Three New Cool Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer (WISE) and an Improved Spectrum of the Y0 Dwarf WISE J041022.71+150248.4
As part of a larger search of Wide-field Infrared Survey Explorer (WISE) data
for cool brown dwarfs with effective temperatures less than 1000 K, we present
the discovery of three new cool brown dwarfs with spectral types later than T7.
Using low-resolution, near-infrared spectra obtained with the NASA Infrared
Telescope Facility and the Hubble Space Telescope we derive spectral types of
T9.5 for WISE J094305.98+360723.5, T8 for WISE J200050.19+362950.1, and Y0: for
WISE J220905.73+271143.9. The identification of WISE J220905.73+271143.9 as a Y
dwarf brings the total number of spectroscopically confirmed Y dwarfs to
seventeen. In addition, we present an improved spectrum (i.e. higher
signal-to-noise ratio) of the Y0 dwarf WISE J041022.71+150248.4 that confirms
the Cushing et al. classification of Y0. Spectrophotometric distance estimates
place all three new brown dwarfs at distances less than 12 pc, with WISE
J200050.19+362950.1 lying at a distance of only 3.9-8.0 pc. Finally, we note
that brown dwarfs like WISE J200050.19+362950.1 that lie in or near the
Galactic plane offer an exciting opportunity to measure their mass via
astrometric microlensing.Comment: Accepted for publication in the Astronomical Journa
Layer-Resolved Ultrafast XUV Measurement of Hole Transport in a Ni-TiO2-Si Photoanode
Metal-oxide-semiconductor junctions are central to most electronic and
optoelectronic devices. Here, the element-specificity of broadband extreme
ultraviolet (XUV) ultrafast pulses is used to measure the charge transport and
recombination kinetics in each layer of a Ni-TiO2-Si junction. After
photoexcitation of silicon, holes are inferred to transport from Si to Ni
ballistically in ~100 fs, resulting in spectral shifts in the Ni M2,3 XUV edge
that are characteristic of holes and the absence of holes initially in TiO2.
Meanwhile, the electrons are observed to remain on Si. After picoseconds, the
transient hole population on Ni is observed to back-diffuse through the TiO2,
shifting the Ti spectrum to higher oxidation state, followed by electron-hole
recombination at the Si-TiO2 interface and in the Si bulk. Electrical
properties, such as the hole diffusion constant in TiO2 and the initial hole
mobility in Si, are fit from these transient spectra and match well with values
reported previously
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