370 research outputs found
Comparing Ecological Sensitivity with Stream Flow Rates in the Apalachicola-Chattahoochee-Flint River Basin
Environmental Economics and Policy, Resource /Energy Economics and Policy,
Climate change adaptation, flood risks and policy coherence in integrated water resources management in England
Integrated water resources management (IWRM) assumes coherence between cognate aspects of water governance at the river basin scale, for example water quality, energy production and agriculture objectives. But critics argue that IWRM is often less âintegratedâ in practice, raising concerns over inter-sectoral coherence between implementing institutions. One increasingly significant aspect of IWRM is adaptation to climate change-related risks, including threats from flooding, which are particularly salient in England. Although multiple institutional mechanisms exist for flood risk management (FRM), their coherence remains a critical question for national adaptation. This paper therefore (1) maps the multi-level institutional frameworks determining both IWRM and FRM in England; (2) examines their interaction via various inter-institutional coordinating mechanisms; and (3) assesses the degree of coherence. The analysis suggests that cognate EU strategic objectives for flood risk assessment demonstrate relatively high vertical and horizontal coherence with river basin planning. However, there is less coherence with flood risk requirements for land-use planning and national flood protection objectives. Overall, this complex governance arrangement actually demonstrates de-coherence over time due to ongoing institutional fragmentation. Recommendations for increasing IWRM coherence in England or re-coherence based on greater spatial planning and coordination of water-use and land-use strategies are proposed
Perspectives for a mixed two-qubit system with binomial quantum states
The problem of the relationship between entanglement and two-qubit systems in
which it is embedded is central to the quantum information theory. This paper
suggests that the concurrence hierarchy as an entanglement measure provides an
alternative view of how to think about this problem. We consider mixed states
of two qubits and obtain an exact solution of the time-dependent master
equation that describes the evolution of two two-level qubits (or atoms) within
a perfect cavity for the case of multiphoton transition. We consider the
situation for which the field may start from a binomial state. Employing this
solution, the significant features of the entanglement when a second qubit is
weakly coupled to the field and becomes entangled with the first qubit, is
investigated. We also describe the response of the atomic system as it varies
between the Rabi oscillations and the collapse-revival mode and investigate the
atomic inversion and the Q-function. We identify and numerically demonstrate
the region of parameters where significantly large entanglement can be
obtained. Most interestingly, it is shown that features of the entanglement is
influenced significantly when the multi-photon process is involved. Finally, we
obtain illustrative examples of some novel aspects of this system and show how
the off-resonant case can sensitize entanglement to the role of initial state
setting.Comment: 18 pages, 9 figure
An efficient method for generalized linear multiplicative programming problem with multiplicative constraints
Perturbative expansion for master equation and it applications
We construct generally applicable small-loss rate expansions for the density
operator of an open system. Successive terms of those expansions yield
characteristic loss rates for dissipation processes. Three applications are
presented in order to give further insight into the context of those
expansions. The first application, of a two-level atom coupling to a bosonic
environment, shows the procedure and the advantage of the expansion, whereas
the second application that consists of a single mode field in a cavity with
linewidth due to partial transmission through one mirror illustrates a
practical use of those expansions in quantum measurements, and the third one,
for an atom coupled to modes of a lossy cavity shows the another use of the
perturbative expansion.Comment: 10 pages, 1 figur
Electro-elastic tuning of single particles in individual self-assembled quantum dots
We investigate the effect of uniaxial stress on InGaAs quantum dots in a
charge tunable device. Using Coulomb blockade and photoluminescence, we observe
that significant tuning of single particle energies (~ -0.5 meV/MPa) leads to
variable tuning of exciton energies (+18 to -0.9 micro-eV/MPa) under tensile
stress. Modest tuning of the permanent dipole, Coulomb interaction and
fine-structure splitting energies is also measured. We exploit the variable
exciton response to tune multiple quantum dots on the same chip into resonance.Comment: 16 pages, 4 figures, 1 table. Final versio
The K20 survey. VI. The Distribution of the Stellar Masses in Galaxies up to z~2
We present a detailed analysis of the stellar mass content of galaxies up to
z=2.5 in the K20 galaxy sample, that has a 92% spectroscopic completeness and a
complete multicolor coverage. We find that the M/L ratio decreases
with redshift: in particular, the average M/L ratio of early type galaxies
decreases with , with a scatter that is indicative of a range of
star--formation time-scales and redshift of formation. More important, the
typical M/L of massive early type galaxies is larger than that of less massive
ones, suggesting that their stellar population formed at higher z. The final
K20 galaxy sample spans a range of stellar masses from M*=10^9Msun to
M*=10^12Msun, with massive galaxies ($M*>10^11Msun) detected up to z~2. We
compute the Galaxy Stellar Mass Function at various z, of which we observe only
a mild evolution (i.e. by 20-30%) up to z~1. At z>1, the evolution of the GSMF
appears to be much faster: at z~2, about 35% of the present day stellar mass in
objects with M*~10^11Msun appear to have assembled. We also detect a change in
the physical nature of the most massive galaxies, since at z>1 a population of
massive star--forming galaxies progressively appears. We finally analyze our
results in the framework of Lambda-CDM hierarchical models. First, we show that
the large number of massive galaxies detected at high z does not violate any
fundamental Lambda-CDM constraint based on the number of massive DM halos.
Then, we compare our results with the predictions of renditions of both
semianalytic and hydro-dynamical models, that range from severe underestimates
to slight overestimates of the observed mass density at z<~2. We discuss how
the differences among these models are due to the different implementation of
the main physical processes. (Abridged)Comment: Accepted for publication on Astronomy & Astrophysic
Adolescent Religiosity and Selective Exposure to Television
Relying on the Adolescent Media Practice Model and selective exposure theory, this study investigated whether religious adolescents watch less mature television entertainment programs than their less religious peers. Program maturity was measured using V-chip ratings, with higher maturity scores indicating content that included more sexuality, violence, and/or adult and sexual language. The responses from 1,335 16- to 18-year-olds who completed Wave 2 of the National Study of Youth and Religion (NSYR) survey were analyzed. Findings indicate that religiosity contributes to explaining the variance in television maturity means, with more religious adolescents indicating a preference for less mature television entertainment. Gender, race, income, and parentsâ monitoring of teensâ media were also found to influence television maturity. Teensâ attitudes toward premarital sex appeared to mediate the effect of religiosity on their television entertainment choices
Toward Understanding Environmental Effects in SDSS Clusters
We find clusters and superclusters of galaxies using the Data Release 1 of
the Sloan Digital Sky Survey. We determine the luminosity function of clusters
and find that clusters in a high-density environment have a luminosity a factor
of ~5 higher than in a low-density environment. We also study clusters and
superclusters in numerical simulations. Simulated clusters in a high-density
environment are also more massive than those in a low-density environment.
Comparison of the density distribution at various epochs in simulations shows
that in large low-density regions (voids) dynamical evolution is very slow and
stops at an early epoch. In contrast, in large regions of higher density
(superclusters) dynamical evolution starts early and continues until the
present; here particles cluster early, and by merging of smaller groups very
rich systems of galaxies form.Comment: 12 pages, 8 figures, submitted for Astronomy and Astrophysic
- âŠ