1,111 research outputs found
The potential of open-access data for flood estimations: uncovering inundation hotspots in Ho Chi Minh City, Vietnam, through a normalized flood severity index
Hydro-numerical models are increasingly important to
determine the adequacy and evaluate the effectiveness of potential flood
protection measures. However, a significant obstacle in setting up
hydro-numerical and associated flood damage models is the tedious and
oftentimes prohibitively costly process of acquiring reliable input data,
which particularly applies to coastal megacities in developing countries and
emerging economies. To help alleviate this problem, this paper explores the
usability and reliability of flood models built on open-access data in
regions where highly resolved (geo)data are either unavailable or difficult
to access yet where knowledge about elements at risk is crucial for
mitigation planning. The example of Ho Chi Minh City, Vietnam, is taken to
describe a comprehensive but generic methodology for obtaining, processing
and applying the required open-access data. The overarching goal of this
study is to produce preliminary flood hazard maps that provide first insights
into potential flooding hotspots demanding closer attention in subsequent,
more detailed risk analyses. As a key novelty, a normalized flood severity
index (INFS), which combines flood depth and duration, is proposed to
deliver key information in a preliminary flood hazard assessment. This index
serves as an indicator that further narrows down the focus to areas where
flood hazard is significant. Our approach is validated by a comparison with
more than 300 flood samples locally observed during three heavy-rain events
in 2010 and 2012 which correspond to INFS-based inundation hotspots in
over 73 % of all cases. These findings corroborate the high potential of
open-access data in hydro-numerical modeling and the robustness of the newly
introduced flood severity index, which may significantly enhance the
interpretation and trustworthiness of risk assessments in the future. The
proposed approach and developed indicators are generic and may be replicated
and adopted in other coastal megacities around the globe.</p
Plants Attract Parasitic Wasps to Defend Themselves against Insect Pests by Releasing Hexenol
Plant volatiles play an important role in defending plants against insect attacks by attracting their natural enemies. For example, green leaf volatiles (GLVs) and terpenoids emitted from herbivore-damaged plants were found to be important in the host location of parasitic wasps. However, evidence of the functional roles and mechanisms of these semio-chemicals from a system of multiple plants in prey location by the parasitoid is limited. Little is known about the potential evolutionary trends between herbivore-induced host plant volatiles and the host location of their parasitoids.. Specifically, we found that volatile profiles from healthy plants revealed a partly phylogenetic signal, while the inducible compounds of the infested-plants did not result from the fact that the induced plant volatiles dominate most of the volatile blends of the host and non-host plants of the leafminer pests. We further show that the parasitoids are capable of distinguishing the damaged host plant from the non-host plant of the leafminers.Our results suggest that, as the most passive scenario of plant involvement, leafminers and mechanical damages evoke similar semio-chemicals. Using ubiquitous compounds, such as hexenol, for host location by general parasitoids could be an adaptation of the most conservative evolution of tritrophic interaction. Although for this, other compounds may be used to improve the precision of the host location by the parasitoids
Low-regret climate change adaptation in coastal megacities – evaluating large-scale flood protection and small-scale rainwater detention measures for Ho Chi Minh City, Vietnam
Urban flooding is a major challenge for many megacities
in low-elevation coastal zones (LECZs), especially in Southeast Asia. In
these regions, the effects of environmental stressors overlap with rapid
urbanization, which significantly aggravates the hazard potential. Ho Chi
Minh City (HCMC) in southern Vietnam is a prime example of this set of
problems and therefore a suitable case study to apply the concept of
low-regret disaster risk adaptation as defined by the Intergovernmental
Panel on Climate Change (IPCC). In order to explore and evaluate potential
options of hazard mitigation, a hydro-numerical model was employed to
scrutinize the effectiveness of two adaptation strategies: (1) a classic
flood protection scheme including a large-scale ring dike as currently
constructed in HCMC and (2) the widespread installation of small-scale
rainwater detention as envisioned in the framework of the Chinese Sponge
City Program (SCP). A third adaptation scenario (3) assesses the combination of both approaches (1) and (2).
From a hydrological point of view, the reduction in various flood intensity
proxies that were computed within this study suggests that large-scale flood protection is comparable but slightly more effective than small-scale
rainwater storage: for instance, the two adaptation options could reduce the normalized flood severity index (INFS), which is a measure combining flood depth and duration, by 17.9 % and 17.7 %, respectively. The
number of flood-prone manufacturing firms that would be protected after
adaptation, in turn, is nearly 2 times higher for the ring dike than for
the Sponge City approach. However, the numerical results also reveal that
both response options can be implemented in parallel, not only without
reducing their individual effectiveness but also complementarily with
considerable added value. Additionally, from a governance perspective,
decentralized rainwater storage conforms ideally to the low-regret paradigm:
while the existing large-scale ring dike depends on a binary commitment (to
build or not to build), decentralized small- and micro-scale solutions can
be implemented gradually (for example through targeted subsidies) and add
technical redundancy to the overall system. In the end, both strategies are
highly complementary in their spatial and temporal reduction in flood
intensity. Local decision-makers may hence specifically seek combined
strategies, adding to singular approaches, and design multi-faceted
adaptation pathways in order to successfully prepare for a deeply uncertain
future.</p
Observation of excited Lambda_b0 baryons
Using pp collision data corresponding to 1.0 fb-1 integrated luminosity
collected by the LHCb detector, two narrow states are observed in the
Lambda_b0pi+pi- spectrum with masses 5911.97 +- 0.12(stat) +- 0.02(syst) +-
0.66(Lambda_b0 mass) MeV/c^2 and 5919.77 +- 0.08(stat) +- 0.02(syst) +-
0.66(Lambda_b0 mass) MeV/c^2. The significances of the observations are 5.2 and
10.2 standard deviations, respectively. These states are interpreted as the
orbitally-excited Lambda_b0 baryons, Lambda_b*0(5912) and Lambda_b*0(5920).Comment: Replaced by version published in Phys. Rev. Lett, modified fit with
better mass resolution treatmen
Observation of two new baryon resonances
Two structures are observed close to the kinematic threshold in the mass spectrum in a sample of proton-proton collision data, corresponding
to an integrated luminosity of 3.0 fb recorded by the LHCb experiment.
In the quark model, two baryonic resonances with quark content are
expected in this mass region: the spin-parity and
states, denoted and .
Interpreting the structures as these resonances, we measure the mass
differences and the width of the heavier state to be
MeV,
MeV,
MeV, where the first and second
uncertainties are statistical and systematic, respectively. The width of the
lighter state is consistent with zero, and we place an upper limit of
MeV at 95% confidence level. Relative
production rates of these states are also reported.Comment: 17 pages, 2 figure
Prey and Non-prey Arthropods Sharing a Host Plant: Effects on Induced Volatile Emission and Predator Attraction
It is well established that plants infested with a single herbivore species can attract specific natural enemies through the emission of herbivore-induced volatiles. However, it is less clear what happens when plants are simultaneously attacked by more than one species. We analyzed volatile emissions of lima bean and cucumber plants upon multi-species herbivory by spider mites (Tetranychus urticae) and caterpillars (Spodoptera exigua) in comparison to single-species herbivory. Upon herbivory by single or multiple species, lima bean and cucumber plants emitted volatile blends that comprised mostly the same compounds. To detect additive, synergistic, or antagonistic effects, we compared the multi-species herbivory volatile blend with the sum of the volatile blends induced by each of the herbivore species feeding alone. In lima bean, the majority of compounds were more strongly induced by multi-species herbivory than expected based on the sum of volatile emissions by each of the herbivores separately, potentially caused by synergistic effects. In contrast, in cucumber, two compounds were suppressed by multi-species herbivory, suggesting the potential for antagonistic effects. We also studied the behavioral responses of the predatory mite Phytoseiulus persimilis, a specialized natural enemy of spider mites. Olfactometer experiments showed that P. persimilis preferred volatiles induced by multi-species herbivory to volatiles induced by S. exigua alone or by prey mites alone. We conclude that both lima bean and cucumber plants effectively attract predatory mites upon multi-species herbivory, but the underlying mechanisms appear different between these species
Observation of resonances consistent with pentaquark states in decays
Observations of exotic structures in the channel, that we refer to
as pentaquark-charmonium states, in decays are
presented. The data sample corresponds to an integrated luminosity of 3/fb
acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude
analysis is performed on the three-body final-state that reproduces the
two-body mass and angular distributions. To obtain a satisfactory fit of the
structures seen in the mass spectrum, it is necessary to include two
Breit-Wigner amplitudes that each describe a resonant state. The significance
of each of these resonances is more than 9 standard deviations. One has a mass
of MeV and a width of MeV, while the second
is narrower, with a mass of MeV and a width of MeV. The preferred assignments are of opposite parity, with one
state having spin 3/2 and the other 5/2.Comment: 48 pages, 18 figures including the supplementary material, v2 after
referee's comments, now 19 figure
Study of and decays and determination of the CKM angle
We report a study of the suppressed and favored
decays, where the neutral meson is detected
through its decays to the and CP-even and
final states. The measurement is carried out using a proton-proton
collision data sample collected by the LHCb experiment, corresponding to an
integrated luminosity of 3.0~fb. We observe the first significant
signals in the CP-even final states of the meson for both the suppressed
and favored modes, as well as
in the doubly Cabibbo-suppressed final state of the decay. Evidence for the ADS suppressed decay , with , is also presented. From the observed
yields in the , and their
charge conjugate decay modes, we measure the value of the weak phase to be
. This is one of the most precise
single-measurement determinations of to date.Comment: 22 pages, 9 figures; All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-020.htm
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