357 research outputs found
An institutional explanation for the stickiness of federal grants
Researchers have struggled to understand why federal block grants, contrary to economic theory, have a large stimulative effect on the spending of state and local governments. This article proposes and tests an institutional explanation for this effect. We argue that certain budgetary rules, by limiting the ability of subnational governments to respond to voter demands for increased spending, may systematically force lawmakers to under-provide public goods. When this occurs, governments are likely to treat grant revenue as a supplement to total expenditures and not return this money to voters in the form of a tax cut as suggested by existing theory. To evaluate our hypothesis, we use data on the Community Development Block Grant program and municipal tax and expenditure limitations. Results show that restrictive fiscal institutions significantly increase the stimulative power of federal grant revenue. (JEL H7, H4, R5
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Photoplethysmographic measurements from the esophagus using a new fiber-optic reflectance sensor
A prototype fiber-optic reflectance-mode pulse oximetry sensor and measurement system is developed for the purposes of estimating arterial oxygen saturation in the esophagus. A dedicated probe containing miniature right-angled glass prisms coupled to light sources and a photodetector by means of optical fibers is designed and used to record photoplethysmographic (PPG) signals from the esophageal epithelium in anesthetized patients. The probe is inserted simply by an anesthesiologist in all cases, and signals are recorded successfully in all but one of 20 subjects, demonstrating that esophageal PPG signals can be reliably obtained. The mean value of the oxygen saturation recorded from the esophagus for all subjects is 94.0 Ā± 4.0%. These results demonstrate that SpO2 may be estimated in the esophagus using a fiber-optic probe
Spitzer infrared spectrometer 16Ī¼m observations of the GOODS fields
We present Spitzer 16Ī¼m imaging of the Great Observatories Origins Deep Survey (GOODS) fields. We survey
150 arcmin^2 in each of the two GOODS fields (North and South), to an average 3Ļ depth of 40 and 65 Ī¼Jy,
respectively. We detect ~1300 sources in both fields combined. We validate the photometry using the 3ā24Ī¼m
spectral energy distribution of stars in the fields compared to Spitzer spectroscopic templates. Comparison with
ISOCAM and AKARI observations in the same fields shows reasonable agreement, though the uncertainties are
large. We provide a catalog of photometry, with sources cross-correlated with available Spitzer, Chandra, and
Hubble Space Telescope data. Galaxy number counts show good agreement with previous results from ISOCAM
and AKARI with improved uncertainties. We examine the 16ā24Ī¼m flux ratio and find that for most sources it
lies within the expected locus for starbursts and infrared luminous galaxies. A color cut of S_(16)/S_(24) > 1.4 selects
mostly sources which lie at 1.1 < z < 1.6, where the 24Ī¼m passband contains both the redshifted 9.7 Ī¼m silicate
absorption and the minimum between polycyclic aromatic hydrocarbon emission peaks. We measure the integrated
galaxy light of 16Ī¼m sources and find a lower limit on the galaxy contribution to the extragalactic background
light at this wavelength to be 2.2 Ā± 0.2 nW m^(ā2) sr^(ā1)
Oceanids C2: An Integrated Command, Control, and Data Infrastructure for the Over-the-Horizon Operation of Marine Autonomous Systems
Long-range Marine Autonomous Systems (MAS), operating beyond the visual line-of-sight of a human pilot or research ship, are creating unprecedented opportunities for oceanographic data collection. Able to operate for up to months at a time, periodically communicating with a remote pilot via satellite, long-range MAS vehicles significantly reduce the need for an expensive research ship presence within the operating area. Heterogeneous fleets of MAS vehicles, operating simultaneously in an area for an extended period of time, are becoming increasingly popular due to their ability to provide an improved composite picture of the marine environment. However, at present, the expansion of the size and complexity of these multi-vehicle operations is limited by a number of factors: (1) custom control-interfaces require pilots to be trained in the use of each individual vehicle, with limited cross-platform standardization; (2) the data produced by each vehicle are typically in a custom vehicle-specific format, making the automated ingestion of observational data for near-real-time analysis and assimilation into operational ocean models very difficult; (3) the majority of MAS vehicles do not provide machine-to-machine interfaces, limiting the development and usage of common piloting tools, multi-vehicle operating strategies, autonomous control algorithms and automated data delivery. In this paper, we describe a novel piloting and data management system (C2) which provides a unified web-based infrastructure for the operation of long-range MAS vehicles within the UK's National Marine Equipment Pool. The system automates the archiving, standardization and delivery of near-real-time science data and associated metadata from the vehicles to end-users and Global Data Assembly Centers mid-mission. Through the use and promotion of standard data formats and machine interfaces throughout the C2 system, we seek to enable future opportunities to collaborate with both the marine science and robotics communities to maximize the delivery of high-quality oceanographic data for world-leading science
A Phase Glass is a Bose Metal: New Conducting State in 2D
In the quantum rotor model with random exchange interactions having a
non-zero mean, three phases, a 1) phase (Bose) glass, 2) superfluid, and 3)
Mott insulator, meet at a bi-critical point. We demonstrate that proximity to
the bi-critical point and the coupling between the energy landscape and the
dissipative degrees of freedom of the phase glass lead to a metallic state at
T=0. Consequently, the phase glass is unique in that it represents a concrete
example of a metallic state that is mediated by disorder, even in 2D. We
propose that the experimentally observed metallic phase which intervenes
between the insulator and the superconductor in a wide range of thin films is
in actuality a phase glass.Comment: 4 pages, 1 .eps figure, final version to appear in Phys. Rev. Let
Bats of St. Vincent, Lesser Antilles
The chiropteran fauna of the island of Saint Vincent, represented by 12 species, is among the most complex in the Lesser Antilles, being represented by four families including Noctilionidae (1 species), Mormoopidae (1), Phyllostomidae (8), and Molossidae (2). This fauna includes four trophic guilds as represented by Noctilio leporinus (piscivore/insectivore); Glossophaga longirostris and Monophyllus plethodon (nectarivore/pollenivore); Artibeus lituratus, A. schwartzi, Brachyphylla cavernarum, Ardops nichollsi, and Sturnira paulsoni (frugivore); and Pteronotus fuscus, Micronycteris buriri, Molossus molossus, and Tadarida brasiliensis (insectivore). One speciesāMicronycteris buririāand two subspeciesāSturnira paulsoni paulsoni and Ardops nichollsi vincentensisāare endemic to the island. Recent advancements in population genomics have led to the discovery of the reticulated evolutionary history of Artibeus schwartzi and it is likely that the formation of the hybrid evolutionary trajectory of this species is linked with classical island biogeography. The bat fauna of St. Vincent is unique in the West Indies, characterized by being a crossroads for species, an outpost for both northern and southern species, the boundary for a multi-island bat fauna as marked by Koopmanās Line, and a site of endemism. Based on our studies, we place the bat fauna of St. Vincent as the southern-most island in the Lesser Antillean Faunal Core
Evolution of predator dispersal in relation to spatio-temporal prey dynamics : how not to get stuck in the wrong place!
Peer reviewedPublisher PD
A Survey of Galaxy Kinematics to z ~ 1 in the TKRS/GOODS-N Field. I. Rotation and Dispersion Properties
We present kinematic measurements of a large sample of galaxies from the TKRS
Survey in the GOODS-N field. We measure line-of-sight velocity dispersions from
integrated emission for 1089 galaxies with median z=0.637, and spatially
resolved kinematics for a subsample of 380 galaxies. This is the largest sample
of galaxies to z ~ 1 with kinematics to date, and allows us to measure
kinematic properties without morphological pre-selection. Emission linewidths
provide kinematics for the bulk of blue galaxies. To fit the spatially resolved
kinematics, we fit models with both line-of-sight rotation amplitude and
velocity dispersion. Integrated linewidth correlates well with a combination of
the rotation gradient and dispersion, and is a robust measure of galaxy
kinematics. The spatial extents of emission and continuum are similar and there
is no evidence that linewidths are affected by nuclear or clumpy emission. The
measured rotation gradient depends strongly on slit PA alignment with galaxy
major axis, but integrated linewidth does not. Even for galaxies with
well-aligned slits, some have kinematics dominated by dispersion (V/sigma<1)
rather than rotation. These are probably objects with disordered velocity
fields, not dynamically hot stellar systems. About 35% of the resolved sample
are dispersion dominated; galaxies that are both dispersion dominated and
bright exist at high redshift but appear rare at low redshift. This kinematic
morphology is linked to photometric morphology in HST/ACS images: dispersion
dominated galaxies include a higher fraction of irregulars and chain galaxies,
while rotation dominated galaxies are mostly disks and irregulars. Only
one-third of chain/hyphen galaxies are dominated by rotation; high-z elongated
objects cannot be assumed to be inclined disks. (Abridged)Comment: ApJ in press. 23 pages, 23 figures. Full data tables available from
http://www.astro.umd.edu/~bjw/tkrs_kinematics
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