166 research outputs found
The State Response to Climate Change: 50 State Survey
This survey accompanies Global Climate Change and U.S. Law, Second Edition (Michael B. Gerrard and Jody Freeman, eds, 2014). It compiles state legislation, rules and executive orders that specifically address climate change as of the end of April 2014. It also includes a wide variety of state activities that may have an impact on greenhouse gases including legislation related to energy efficiency and renewable energy. The focus of this material is to provide readers with an understanding of the range of state activity that may contribute to greenhouse gas reduction and climate change. Some types of energy efficiency, alternative fuels and renewable energy legislation (such as tax credits for hybrid vehicles) are very similar from state to state; some laws have a short duration and therefore may not be codified (such as temporary tax credits); energy legislation is being enacted at an increasing pace. As a result, not all energy efficiency, alternative fuels and renewable energy legislation and other activity in every state are included in this compilation
The Arizona CDFS Environment Survey (ACES): A Magellan/IMACS Spectroscopic Survey of the Chandra Deep Field South
We present the Arizona CDFS Environment Survey (ACES), a recently-completed
spectroscopic redshift survey of the Chandra Deep Field South (CDFS) conducted
using IMACS on the Magellan-Baade telescope. In total, the survey targeted 7277
unique sources down to a limiting magnitude of R = 24.1, yielding 5080 secure
redshifts across the ~30' x 30' extended CDFS region. The ACES dataset delivers
a significant increase to both the spatial coverage and the sampling density of
the spectroscopic observations in the field. Combined with
previously-published, spectroscopic redshifts, ACES now creates a
highly-complete survey of the galaxy population at R < 23, enabling the local
galaxy density (or environment) on relatively small scales (~1 Mpc) to be
measured at z < 1 in one of the most heavily-studied and data-rich fields in
the sky. Here, we describe the motivation, design, and implementation of the
survey and present a preliminary redshift and environment catalog. In addition,
we utilize the ACES spectroscopic redshift catalog to assess the quality of
photometric redshifts from both the COMBO-17 and MUSYC imaging surveys of the
CDFS.Comment: resubmitted to MNRAS; 12 pages, 12 figures, and 3 tables; updated
redshift catalog available at http://mur.ps.uci.edu/~cooper/ACES
The Dense Gas Mass Fraction and the Relationship to Star Formation in M51
Observations of 12CO J = 1 - 0 and HCN J = 1 - 0 emission from NGC 5194 (M51) made with the 50 m Large Millimeter Telescope and the SEQUOIA focal plane array are presented. Using the HCN-to-CO ratio, we examine the dense gas mass fraction over a range of environmental conditions within the galaxy. Within the disk, the dense gas mass fraction varies along the spiral arms but the average value over all spiral arms is comparable to the mean value of interarm regions. We suggest that the near-constant dense gas mass fraction throughout the disk arises from a population of density-stratified, self-gravitating molecular clouds and the required density threshold to detect each spectral line. The measured dense gas fraction significantly increases in the central bulge in response to the effective pressure, P e , from the weight of the stellar and gas components. This pressure modifies the dynamical state of the molecular cloud population and, possibly, the HCN-emitting regions in the central bulge from self-gravitating to diffuse configurations in which P e is greater than the gravitational energy density of individual clouds. Diffuse molecular clouds comprise a significant fraction of the molecular gas mass in the central bulge, which may account for the measured sublinear relationships between the surface densities of the star formation rate and molecular and dense gas
The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts
We describe the design and data sample from the DEEP2 Galaxy Redshift Survey,
the densest and largest precision-redshift survey of galaxies at z ~ 1
completed to date. The survey has conducted a comprehensive census of massive
galaxies, their properties, environments, and large-scale structure down to
absolute magnitude M_B = -20 at z ~ 1 via ~90 nights of observation on the
DEIMOS spectrograph at Keck Observatory. DEEP2 covers an area of 2.8 deg^2
divided into four separate fields, observed to a limiting apparent magnitude of
R_AB=24.1. Objects with z < 0.7 are rejected based on BRI photometry in three
of the four DEEP2 fields, allowing galaxies with z > 0.7 to be targeted ~2.5
times more efficiently than in a purely magnitude-limited sample. Approximately
sixty percent of eligible targets are chosen for spectroscopy, yielding nearly
53,000 spectra and more than 38,000 reliable redshift measurements. Most of the
targets which fail to yield secure redshifts are blue objects that lie beyond z
~ 1.45. The DEIMOS 1200-line/mm grating used for the survey delivers high
spectral resolution (R~6000), accurate and secure redshifts, and unique
internal kinematic information. Extensive ancillary data are available in the
DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into
one of the richest multiwavelength regions on the sky. DEEP2 surpasses other
deep precision-redshift surveys at z ~ 1 in terms of galaxy numbers, redshift
accuracy, sample number density, and amount of spectral information. We also
provide an overview of the scientific highlights of the DEEP2 survey thus far.
This paper is intended as a handbook for users of the DEEP2 Data Release 4,
which includes all DEEP2 spectra and redshifts, as well as for the
publicly-available DEEP2 DEIMOS data reduction pipelines. [Abridged]Comment: submitted to ApJS; data products available for download at
http://deep.berkeley.edu/DR4
Two Lensed Lyman-alpha Emitting Galaxies at z~5
We present observations of two strongly lensed Lyman-
Emitting (LAE) galaxies that were discovered in the Sloan Giant Arcs Survey
(SGAS). We identify the two sources as SGAS J091541+382655, at , and
SGAS J134331+415455 at . We measure their AB magnitudes at
) mags and
) mags, and the rest-frame
equivalent widths of the Lyman- emission at \AA~and
\AA~for SGAS J091541+382655 and SGAS J134331+415455,
respectively. Each source is strongly lensed by a massive galaxy cluster in the
foreground, and the magnifications due to gravitational lensing are recovered
from strong lens modeling of the foreground lensing potentials. We use the
magnification to calculate the intrinsic, unlensed Lyman- and UV
continuum luminosities for both sources, as well as the implied star formation
rates (SFR). We find SGAS J091541+382655 and SGAS J134341+415455 to be galaxies
with (L, LLL) and
(L, LLL),
respectively. Comparison of the spectral energy distributions (SEDs) of both
sources against stellar population models produces estimates of the mass in
young stars in each galaxy: we report an upper limit of M M_{\sun} h_{0.7}^{-1} for SGAS
J091531+382655, and a range of viable masses for SGAS J134331+415455 of
M_{\sun} h_{0.7}^{-1} < M M_{\sun}
h_{0.7}^{-1}.Comment: 10 pages, 8 figures, emulate apj format, Accepted to Ap
Paper 1: The JWST PEARLS View of the El Gordo Galaxy Cluster and of the Structure It Magnifies
The massive galaxy cluster El Gordo (z=0.87) imprints multitudes of
gravitationally lensed arcs onto James Webb Space Telescope (JWST)
Near-Infrared Camera (NIRCam) images. Eight bands of NIRCam imaging were
obtained in the ``Prime Extragalactic Areas for Reionization and Lensing
Science'' (``PEARLS'') program. PSF-matched photometry across Hubble Space
Telescope (HST) and NIRCam filters supplies new photometric redshifts. A new
light-traces-mass lens model based on 56 image multiplicities identifies the
two mass peaks and yields a mass estimate within 500 kpc of ~(7.0 +/- 0.30) x
10^14 Msun. A search for substructure in the 140 cluster members with
spectroscopic redshifts confirms the two main mass components. The southeastern
mass peak that contains the BCG is more tightly bound than the northwestern
one. The virial mass within 1.7 Mpc is (5.1 +/- 0.60) x 10^14 Msun, lower than
the lensing mass. A significant transverse velocity component could mean the
virial mass is underestimated. We contribute one new member to the previously
known z=4.32 galaxy group. Intrinsic (delensed) positions of the five secure
group members span a physical extent of ~60 kpc. Thirteen additional candidates
selected by spectroscopic/photometric constraints are small and faint with a
mean intrinsic luminosity ~2.2 mag fainter than L*. NIRCam imaging admits a
fairly wide range of brightnesses and morphologies for the group members,
suggesting a more diverse galaxy population in this galaxy overdensity.Comment: 24 pages, accepted by Ap
Gain through losses in nonlinear optics
Instabilities of uniform states are ubiquitous processes occurring in a variety of spatially extended nonlinear systems. These instabilities are at the heart of symmetry breaking, condensate dynamics, self-organization, pattern formation and noise amplification across diverse disciplines, including physics, chemistry, engineering and biology. In nonlinear optics, modulation instabilities are generally linked to the so-called parametric amplification process, which occurs when certain phase-matching or quasi-phase-matching conditions are satisfied. In the present review article, we summarize the principle results on modulation instabilities and parametric amplification in nonlinear optics, with special emphasis on optical fibres. We then review state-of-the-art research about a peculiar class of modulation instabilities and signal amplification processes induced by dissipation in nonlinear optical systems. Losses applied to certain parts of the spectrum counterintuitively lead to the exponential growth of the damped mode themselves, causing gain through losses. We discuss the concept of imaging of losses into gain, showing how to map a given spectral loss profile into a gain spectrum. We demonstrate with concrete examples that dissipation-induced modulation instability, apart from being of fundamental theoretical interest, may pave the way towards the design of a new class of tuneable fibre-based optical amplifiers, optical parametric oscillators, frequency comb sources and pulsed lasers
Dealing with femtorisks in international relations
The contemporary global community is increasingly interdependent and confronted with systemic risks posed by the actions and interactions of actors existing beneath the level of formal institutions, often operating outside effective governance structures. Frequently, these actors are human agents, such as rogue traders or aggressive financial innovators, terrorists, groups of dissidents, or unauthorized sources of sensitive or secret information about government or private sector activities. In other instances, influential .actors. take the form of climate change, communications technologies, or socioeconomic globalization. Although these individual forces may be small relative to state governments or international institutions, or may operate on long time scales, the changes they catalyze can pose significant challenges to the analysis and practice of international relations through the operation of complex feedbacks and interactions of individual agents and interconnected systems. We call these challenges "femtorisks," and emphasize their importance for two reasons. First, in isolation, they may be inconsequential and semiautonomous; but when embedded in complex adaptive systems, characterized by individual agents able to change, learn from experience, and pursue their own agendas, the strategic interaction between actors can propel systems down paths of increasing, even global, instability. Second, because their influence stems from complex interactions at interfaces of multiple systems (e.g., social, financial, political, technological, ecological, etc.), femtorisks challenge standard approaches to risk assessment, as higher-order consequences cascade across the boundaries of socially constructed complex systems. We argue that new approaches to assessing and managing systemic risk in international relations are required, inspired by principles of evolutionary theory and development of resilient ecological systems
The State Response to Climate Change: 50 State Survey
This survey accompanies Global Climate Change and U.S. Law, Second Edition (Michael B. Gerrard and Jody Freeman, eds, 2014). It compiles state legislation, rules and executive orders that specifically address climate change as of the end of April 2014. It also includes a wide variety of state activities that may have an impact on greenhouse gases including legislation related to energy efficiency and renewable energy. The focus of this material is to provide readers with an understanding of the range of state activity that may contribute to greenhouse gas reduction and climate change. Some types of energy efficiency, alternative fuels and renewable energy legislation (such as tax credits for hybrid vehicles) are very similar from state to state; some laws have a short duration and therefore may not be codified (such as temporary tax credits); energy legislation is being enacted at an increasing pace. As a result, not all energy efficiency, alternative fuels and renewable energy legislation and other activity in every state are included in this compilation
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