2,242 research outputs found
Expanding the role of participatory mapping to assess ecosystem service provision in local coastal environments
There has been increasing international effort to better understand the diversity and quality of marine natural capital, ecosystem services and their associated societal benefits. However, there is an evidence gap as to how these benefits are identified at the local scale, where benefits are provided and to whom, trade-offs in development decisions, and understanding how benefits support well-being. Often the benefits of conservation are poorly understood at the local scale, are not effectively integrated into policy and are rarely included meaningfully in public discourse. This paper addresses this disjuncture and responds to the demand for improving dialogue with local communities and stakeholders. Participatory GIS mapping is used as a direct means of co-producing knowledge with stakeholder and community interests. This paper drives a shift from development of participatory approaches to adaptive applications in real-world case studies of local, national and international policy relevance. The results from four sites along the UK North Sea coast are presented. This paper showcases a robust stakeholder-driven approach that can be used to inform marine planning, conservation management and coastal development. Although the demonstration sites are UK-focused, the methodology presented is of global significance and can be applied across spatial and temporal scales
Spatial mapping of band bending in semiconductor devices using in-situ quantum sensors
Band bending is a central concept in solid-state physics that arises from
local variations in charge distribution especially near semiconductor
interfaces and surfaces. Its precision measurement is vital in a variety of
contexts from the optimisation of field effect transistors to the engineering
of qubit devices with enhanced stability and coherence. Existing methods are
surface sensitive and are unable to probe band bending at depth from surface or
bulk charges related to crystal defects. Here we propose an in-situ method for
probing band bending in a semiconductor device by imaging an array of
atomic-sized quantum sensing defects to report on the local electric field. We
implement the concept using the nitrogen-vacancy centre in diamond, and map the
electric field at different depths under various surface terminations. We then
fabricate a two-terminal device based on the conductive two-dimensional hole
gas formed at a hydrogen-terminated diamond surface, and observe an unexpected
spatial modulation of the electric field attributed to a complex interplay
between charge injection and photo-ionisation effects. Our method opens the way
to three-dimensional mapping of band bending in diamond and other
semiconductors hosting suitable quantum sensors, combined with simultaneous
imaging of charge transport in complex operating devices.Comment: This is a pre-print of an article published in Nature Electronics.
The final authenticated version is available online at
https://dx.doi.org/10.1038/s41928-018-0130-
Preheating and Affleck-Dine leptogenesis after thermal inflation
Previously, we proposed a model of low energy Affleck-Dine leptogenesis in
the context of thermal inflation. The lepton asymmetry is generated at the end
of thermal inflation, which occurs at a relatively low energy scale with the
Hubble parameter somewhere in the range 1 \keV \lesssim H \lesssim 1 \MeV.
Thus Hubble damping will be ineffective in bringing the Affleck-Dine field into
the lepton conserving region near the origin, leaving the possibility that the
lepton number could be washed out. Previously, we suggested that preheating
could damp the amplitude of the Affleck-Dine field allowing conservation of the
lepton number. In this paper, we demonstrate numerically that preheating does
efficiently damp the amplitude of the Affleck-Dine field and that the lepton
number is conserved as the result. In addition to demonstrating a crucial
aspect of our model, it also opens the more general possibility of low energy
Affleck-Dine baryogenesis.Comment: 38 pages, 17 figure
Hemispherical power asymmetry: parameter estimation from CMB WMAP5 data
We reexamine the evidence of the hemispherical power asymmetry, detected in
the CMB WMAP data using a new method. At first, we analyze the hemispherical
variance ratios and compare these with simulated distributions. Secondly,
working within a previously-proposed CMB bipolar modulation model, we constrain
model parameters: the amplitude and the orientation of the modulation field as
a function of various multipole bins. Finally, we select three ranges of
multipoles leading to the most anomalous signals, and we process corresponding
100 Gaussian, random field (GRF) simulations, treated as observational data, to
further test the statistical significance and robustness of the hemispherical
power asymmetry. For our analysis we use the Internally-Linearly-Coadded (ILC)
full sky map, and KQ75 cut-sky V channel, foregrounds reduced map of the WMAP
five year data (V5). We constrain the modulation parameters using a generic
maximum a posteriori method.
In particular, we find differences in hemispherical power distribution, which
when described in terms of a model with bipolar modulation field, exclude the
field amplitude value of the isotropic model A=0 at confidence level of ~99.5%
(~99.4%) in the multipole range l=[7,19] (l=[7,79]) in the V5 data, and at the
confidence level ~99.9% in the multipole range l=[7,39] in the ILC5 data, with
the best fit (modal PDF) values in these particular multipole ranges of A=0.21
(A=0.21) and A=0.15 respectively. However, we also point out that similar or
larger significances (in terms of rejecting the isotropic model), and large
best-fit modulation amplitudes are obtained in GRF simulations as well, which
reduces the overall significance of the CMB power asymmetry down to only about
94% (95%) in the V5 data, in the range l=[7,19] (l=[7,79]).Comment: 24 pages, 10 figures; few typos corrected; published in JCA
Using quantile regression to understand visitor spending
A common approach to assessing visitor expenditures is to use least-squares regression analysis to determine statistically significant variables upon which key market segments are identified for marketing purposes. This was done by Wang (2004) for survey data based on expenditures by Mainland Chinese visitors to Hong Kong. In this research note we use this same dataset to demonstrate the benefits of using quantile regression analysis to better identify tourist spending patterns and market segments. The quantile regression method measures tourist spending in different categories against a fixed range of dependent variables, which distinguishes between lower, medium, and higher spenders. The results show that quantile regression is less susceptible to influence by outlier values and is better able to target finer tourist spending market segments
The Rho GDI Rdi1 regulates Rho GTPases by distinct mechanisms
© 2008 by The American Society for Cell Biology. Under the License and Publishing Agreement, authors grant to the general public, effective two months after publication of (i.e.,. the appearance of) the edited manuscript in an online issue of MBoC, the nonexclusive right to copy, distribute, or display the manuscript subject to the terms of the Creative Commons–Noncommercial–Share Alike 3.0 Unported license (http://creativecommons.org/licenses/by-nc-sa/3.0).The small guanosine triphosphate (GTP)-binding proteins of the Rho family are implicated in various cell functions, including establishment and maintenance of cell polarity. Activity of Rho guanosine triphosphatases (GTPases) is not only regulated by guanine nucleotide exchange factors and GTPase-activating proteins but also by guanine nucleotide dissociation inhibitors (GDIs). These proteins have the ability to extract Rho proteins from membranes and keep them in an inactive cytosolic complex. Here, we show that Rdi1, the sole Rho GDI of the yeast Saccharomyces cerevisiae, contributes to pseudohyphal growth and mitotic exit. Rdi1 interacts only with Cdc42, Rho1, and Rho4, and it regulates these Rho GTPases by distinct mechanisms. Binding between Rdi1 and Cdc42 as well as Rho1 is modulated by the Cdc42 effector and p21-activated kinase Cla4. After membrane extraction mediated by Rdi1, Rho4 is degraded by a novel mechanism, which includes the glycogen synthase kinase 3β homologue Ygk3, vacuolar proteases, and the proteasome. Together, these results indicate that Rdi1 uses distinct modes of regulation for different Rho GTPases.Deutsche Forschungsgemeinschaf
From START to FINISH : the influence of osmotic stress on the cell cycle
Peer reviewedPublisher PD
Effect of pre-existing baryon inhomogeneities on the dynamics of quark-hadron transition
Baryon number inhomogeneities may be generated during the epoch when the
baryon asymmetry of the universe is produced, e.g. at the electroweak phase
transition. The regions with excess baryon number will have a lower temperature
than the background temperature of the universe. Also the value of the quark
hadron transition temperature will be different in these regions as
compared to the background region. Since a first-order quark hadron transition
is very susceptible to small changes in temperature, we investigate the effect
of the presence of such baryonic lumps on the dynamics of quark-hadron
transition. We find that the phase transition is delayed in these lumps for
significant overdensities. Consequently, we argue that baryon concentration in
these regions grows by the end of the transition. We briefly discuss some
models which may give rise to such high overdensities at the onset of the
quark-hadron transition.Comment: 16 pages, no figures, minor changes, version to appear in Phys. Rev.
Consequences of local gauge symmetry in empirical tight-binding theory
A method for incorporating electromagnetic fields into empirical
tight-binding theory is derived from the principle of local gauge symmetry.
Gauge invariance is shown to be incompatible with empirical tight-binding
theory unless a representation exists in which the coordinate operator is
diagonal. The present approach takes this basis as fundamental and uses group
theory to construct symmetrized linear combinations of discrete coordinate
eigenkets. This produces orthogonal atomic-like "orbitals" that may be used as
a tight-binding basis. The coordinate matrix in the latter basis includes
intra-atomic matrix elements between different orbitals on the same atom.
Lattice gauge theory is then used to define discrete electromagnetic fields and
their interaction with electrons. Local gauge symmetry is shown to impose
strong restrictions limiting the range of the Hamiltonian in the coordinate
basis. The theory is applied to the semiconductors Ge and Si, for which it is
shown that a basis of 15 orbitals per atom provides a satisfactory description
of the valence bands and the lowest conduction bands. Calculations of the
dielectric function demonstrate that this model yields an accurate joint
density of states, but underestimates the oscillator strength by about 20% in
comparison to a nonlocal empirical pseudopotential calculation.Comment: 23 pages, 7 figures, RevTeX4; submitted to Phys. Rev.
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