618 research outputs found
The Future of Soft Money in Federal Elections: The 527 Reform Act of 2005 and the First Amendment
President George W. Bush signed the Bipartisan Campaign Finance Reform Act of 2002 (âBCRAâ) into law on March 27, 2002, and when it became law on November 6, 2002, BCRA marked the first significant revision of the federal laws controlling the financing of campaigns for federal office since the Federal Election Campaign Act of 1971 (âFECAâ). Title I of BCRA banned national parties and officeholders from raising and spending âsoft money.â Soft money can be defined simply as contributions that are not subject to FECAâs contribution regulations while âhard moneyâ refers to contributions that do fall under FECAâs domain. FECA established a series of mandatory limits on contributions to candidates and mandatory ceilings on expenditures. Senator John McCain (R-AZ), one of the billâs co-sponsors who has fought for significant campaign finance reform for more than half a decade, hoped the law would ârestore the publicâs faith in government.â President Bush hailed BCRA by stating that â[a]ll of the American electorate will benefit from these measures to strengthen our democracy.
Bayesian High-Redshift Quasar Classification from Optical and Mid-IR Photometry
We identify 885,503 type 1 quasar candidates to i<22 using the combination of
optical and mid-IR photometry. Optical photometry is taken from the Sloan
Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey
(SDSS-III/BOSS), while mid-IR photometry comes from a combination of data from
the Wide-Field Infrared Survey Explorer (WISE) "ALLWISE" data release and
several large-area Spitzer Space Telescope fields. Selection is based on a
Bayesian kernel density algorithm with a training sample of 157,701
spectroscopically-confirmed type-1 quasars with both optical and mid-IR data.
Of the quasar candidates, 733,713 lack spectroscopic confirmation (and 305,623
are objects that we have not previously classified as photometric quasar
candidates). These candidates include 7874 objects targeted as high probability
potential quasars with 3.5<z<5 (of which 6779 are new photometric candidates).
Our algorithm is more complete to z>3.5 than the traditional mid-IR selection
"wedges" and to 2.2<z<3.5 quasars than the SDSS-III/BOSS project. Number counts
and luminosity function analysis suggests that the resulting catalog is
relatively complete to known quasars and is identifying new high-z quasars at
z>3. This catalog paves the way for luminosity-dependent clustering
investigations of large numbers of faint, high-redshift quasars and for further
machine learning quasar selection using Spitzer and WISE data combined with
other large-area optical imaging surveys.Comment: 54 pages, 17 figures; accepted by ApJS Data for tables 1 and 2
available at
http://www.physics.drexel.edu/~gtr/outgoing/optirqsos/data/master_quasar_catalogs.011414.fits.bz2
and
http://www.physics.drexel.edu/~gtr/outgoing/optirqsos/data/optical_ir_quasar_candidates.052015.fits.bz
A long gamma-ray burst from a merger of compact objects
Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from
energetic cosmic explosions. Bursts of long (>2 s) duration are produced by the
core-collapse of massive stars, those of short (< 2 s) duration by the merger
of two neutron stars (NSs). A third class of events with hybrid high-energy
properties was identified, but never conclusively linked to a stellar
progenitor. The lack of bright supernovae rules out typical core-collapse
explosions, but their distance scales prevent sensitive searches for direct
signatures of a progenitor system. Only tentative evidence for a kilonova has
been presented. Here we report observations of the exceptionally bright
GRB211211A that classify it as a hybrid event and constrain its distance scale
to only 346 Mpc. Our measurements indicate that its lower-energy (from
ultraviolet to near-infrared) counterpart is powered by a luminous (~1E42
erg/s) kilonova possibly formed in the ejecta of a compact binary merger.Comment: original version, accepted for publication after revisio
Phytoplankton composition from sPACE: Requirements, opportunities, and challenges
Ocean color satellites have provided a synoptic view of global phytoplankton for over 25 years through near surface measurements of the concentration of chlorophyll a. While remote sensing of ocean color has revolutionized our understanding of phytoplankton and their role in the oceanic and freshwater ecosystems, it is important to consider both total phytoplankton biomass and changes in phytoplankton community composition in order to fully understand the dynamics of the aquatic ecosystems. With the upcoming launch of NASA\u27s Plankton, Aerosol, Clouds, ocean Ecosystem (PACE) mission, we will be entering into a new era of global hyperspectral data, and with it, increased capabilities to monitor phytoplankton diversity from space. In this paper, we analyze the needs of the user community, review existing approaches for detecting phytoplankton community composition in situ and from space, and highlight the benefits that the PACE mission will bring. Using this three-pronged approach, we highlight the challenges and gaps to be addressed by the community going forward, while offering a vision of what global phytoplankton community composition will look like through the âeyesâ of PACE
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of
continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a
fully coherent search, based on matched filtering, which uses the position and rotational parameters
obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto-
noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch
between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have
been developed, allowing a fully coherent search for gravitational waves from known pulsars over a
fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of
11 pulsars using data from Advanced LIGOâs first observing run. Although we have found several initial
outliers, further studies show no significant evidence for the presence of a gravitational wave signal.
Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of
the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for
the first time. For an additional 3 targets, the median upper limit across the search bands is below the
spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried
out so far
No iron fertilization in the equatorial Pacific Ocean during the last ice age
The equatorial Pacific Ocean is one of the major high-nutrient, low-chlorophyll regions in the global ocean. In such regions, the consumption of the available macro-nutrients such as nitrate and phosphate is thought to be limited in part by the low abundance of the critical micro-nutrient iron1. Greater atmospheric dust deposition2 could have fertilized the equatorial Pacific with iron during the last ice ageâthe Last Glacial Period (LGP) but the effect of increased ice-age dust fluxes on primary productivity in the equatorial Pacific remains uncertain. Here we present meridional transects of dust (derived from the 232Th proxy), phytoplankton productivity (using opal, 231Pa/230Th and excess Ba), and the degree of nitrate consumption (using foraminifera-bound ÎŽ15N) from six cores in the central equatorial Pacific for the Holocene (0â10,000 years ago) and the LGP (17,000â27,000 years ago). We find that, although dust deposition in the central equatorial Pacific was two to three times greater in the LGP than in the Holocene, productivity was the same or lower, and the degree of nitrate consumption was the same. These biogeochemical findings suggest that the relatively greater ice-age dust fluxes were not large enough to provide substantial iron fertilization to the central equatorial Pacific. This may have been because the absolute rate of dust deposition in the LGP (although greater than the Holocene rate) was very low. The lower productivity coupled with unchanged nitrate consumption suggests that the subsurface major nutrient concentrations were lower in the central equatorial Pacific during the LGP. As these nutrients are today dominantly sourced from the Subantarctic Zone of the Southern Ocean, we propose that the central equatorial Pacific data are consistent with more nutrient consumption in the Subantarctic Zone, possibly owing to iron fertilization as a result of higher absolute dust fluxes in this region7,8. Thus, ice-age iron fertilization in the Subantarctic Zone would have ultimately worked to lower, not raise, equatorial Pacific productivity
When Music and Long-Term Memory Interact: Effects of Musical Expertise on Functional and Structural Plasticity in the Hippocampus
The development of musical skills by musicians results in specific structural and functional modifications in the brain. Surprisingly, no functional magnetic resonance imaging (fMRI) study has investigated the impact of musical training on brain function during long-term memory retrieval, a faculty particularly important in music. Thus, using fMRI, we examined for the first time this process during a musical familiarity task (i.e., semantic memory for music). Musical expertise induced supplementary activations in the hippocampus, medial frontal gyrus, and superior temporal areas on both sides, suggesting a constant interaction between episodic and semantic memory during this task in musicians. In addition, a voxel-based morphometry (VBM) investigation was performed within these areas and revealed that gray matter density of the hippocampus was higher in musicians than in nonmusicians. Our data indicate that musical expertise critically modifies long-term memory processes and induces structural and functional plasticity in the hippocampus
Multiple Molecular Mechanisms Cause Reproductive Isolation between Three Yeast Species
Incompatibility between nuclear and mitochondrial genomes in yeast species may represent a general mechanism of reproductive isolation during yeast evolution
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