2,399 research outputs found
Ecology and conservation of marine turtles in Kenya
Conservation requires comprehensive data about the target species or ecosystem. For marine turtles, obtaining such data can be challenging due to their migratory and cryptic nature, as well as their long and complex life histories. This hampers our ability to assess fundamental parameters such as population size and reproductive output, and to design adequate spatial conservation measures. In this thesis, I aim to comprehensively synthesize the available information regarding marine turtles along the African continental east coast and address several of the identified knowledge gaps with multiple long- term data sets from Watamu, Kenya, that were collected by a grassroots community-based organisation. More specifically, in Chapter 1, I combine results from a systematic literature review with perspectives from Kenya, Tanzania, Mozambique, South Africa and the Western Indian Ocean (WIO) region, provided by marine turtle experts, to create a comprehensive assessment of the biology and conservation of marine turtles along the African continental east coast. I highlight the importance of this sub-region as foraging and nesting grounds, identify knowledge gaps and threats to turtles, and discuss strengths and impediments in turtle conservation. In Chapter 2, I analyse turtle nesting data collected at Watamu between 2000 and 2020 and show promising signs of recovery for green (Chelonia mydas) and olive ridley turtle (Lepidochelys olivacea) nesting. I also present information crucial to the conservation of turtle populations in the WIO. Following this, in Chapter 3, I present the first empirical data on estimated green turtle primary sex ratios in Kenya. The analysis I present demonstrates balanced sex ratios are achieved in clutches that incubate in-situ and that the conservation intervention of clutch relocation induces a female-biased sex ratio. Lastly, in Chapter 4, I examine the data from an incentive-based bycatch mortality mitigation program that has been in operation in Watamu since 1998. I provide insights into small-scale fisheries turtle bycatch and show the importance of coastal areas as foraging grounds for juvenile green and hawksbill turtles (Eretmochelys imbricata). In conclusion, this thesis has identified and addressed fundamental knowledge gaps about marine turtles along the African continental east coast and Kenya, whilst demonstrating the potential of community-based conservation in achieving conservation outcomes and bolstering ecological knowledge
Terminal Phosphanido Rhodium Complexes Mediating Catalytic P—P and P—C Bond Formation
Complexes with terminal phosphanido (M-PR2) functionalities are believed to be crucial intermediates in new catalytic processes involving the formation of P-P and P-C bonds. We showcase here the isolation and characterization of mononuclear phosphanide rhodium complexes ([RhTp(H)(PR2)L]) that result from the oxidative addition of secondary phosphanes, a reaction that was also explored computationally. These compounds are active catalysts for the dehydrocoupling of PHPh2 to Ph2P-PPh2. The hydrophosphination of dimethyl maleate and the unactivated olefin ethylene is also reported. Reliable evidence for the prominent role of mononuclear phosphanido rhodium species in these reactions is also provided.The generous financial support from MICINN/FEDER (Project CTQ2011-22516), Gobierno de Aragón/FSE (GA/FSE, Inorganic Molecular Architecture Group, E70), and NWO-CW (VICI project 016.122.613; BdB) is gratefully acknowledged. A.M.G. and A.L.S. thank Gobierno de Aragón and MEC, respectively, for fellowships.Peer reviewe
Including Limited Partners in the Diversity Jurisdiction Analysis
This paper presents the results of the Dynamic Pricing Challenge, held on the occasion of the 17th INFORMS Revenue Management and Pricing Section Conference on June 29–30, 2017 in Amsterdam, The Netherlands. For this challenge, participants submitted algorithms for pricing and demand learning of which the numerical performance was analyzed in simulated market environments. This allows consideration of market dynamics that are not analytically tractable or can not be empirically analyzed due to practical complications. Our findings implicate that the relative performance of algorithms varies substantially across different market dynamics, which confirms the intrinsic complexity of pricing and learning in the presence of competition
Large-scale groundwater modeling using global datasets: a test case for the Rhine-Meuse basin
The current generation of large-scale hydrological models does not include a groundwater flow component. Large-scale groundwater models, involving aquifers and basins of multiple countries, are still rare mainly due to a lack of hydro-geological data which are usually only available in developed countries. In this study, we propose a novel approach to construct large-scale groundwater models by using global datasets that are readily available. As the test-bed, we use the combined Rhine-Meuse basin that contains groundwater head data used to verify the model output. We start by building a distributed land surface model (30 arc-second resolution) to estimate groundwater recharge and river discharge. Subsequently, a MODFLOW transient groundwater model is built and forced by the recharge and surface water levels calculated by the land surface model. Results are promising despite the fact that we still use an offline procedure to couple the land surface and MODFLOW groundwater models (i.e. the simulations of both models are separately performed). The simulated river discharges compare well to the observations. Moreover, based on our sensitivity analysis, in which we run several groundwater model scenarios with various hydro-geological parameter settings, we observe that the model can reasonably well reproduce the observed groundwater head time series. However, we note that there are still some limitations in the current approach, specifically because the offline-coupling technique simplifies the dynamic feedbacks between surface water levels and groundwater heads, and between soil moisture states and groundwater heads. Also the current sensitivity analysis ignores the uncertainty of the land surface model output. Despite these limitations, we argue that the results of the current model show a promise for large-scale groundwater modeling practices, including for data-poor environments and at the global scale
Long-Baseline Study of the Leading Neutrino Oscillation at a Neutrino Factory
Within the framework of three-flavor neutrino oscillations, we consider the
physics potential of \nu_e --> \nu_\mu appearance and \nu_\mu --> \nu_\mu
survival measurements at a neutrino factory for a leading oscillation scale
\delta m^2 ~ 3.5 \times 10^{-3} eV^2. Event rates are evaluated versus baseline
and stored muon energy, and optimal values discussed. Over a sizeable region of
oscillation parameter space, matter effects would enable the sign of \delta m^2
to be determined from a comparison of \nu_e --> \nu_\mu with \bar\nu_e -->
\bar\nu_\mu event rates and energy distributions. It is important, therefore,
that both positive and negative muons can be stored in the ring. Measurements
of the \nu_\mu --> \nu_\mu survival spectrum could determine the magnitude of
\delta m^2 and the leading oscillation amplitude with a precision of O(1%--2%).Comment: 33 pages, single-spaced Revtex, uses epsf.sty, 14 postscript figures.
Added references, expanded conclusions, improved figs. 13 and 14. Version to
be published in Phys. Rev.
Signals of R-parity violating supersymmetry in neutrino scattering at muon storage rings
Neutrino oscillation signals at muon storage rings can be faked by
supersymmetric (SUSY) interactions in an R-parity violating scenario. We
investigate the -appearance signals for both long-baseline and near-site
experiments, and conclude that the latter is of great use in distinguishing
between oscillation and SUSY effects. On the other hand, SUSY can cause a
manifold increase in the event rate for wrong-sign muons at a long-baseline
setting, thereby providing us with signatures of new physics.Comment: 7 pages LaTeX, 4 ps figures, accepted for publication in Phys. Rev.
An ultrashort pulse ultra-violet radiation undulator source driven by a laser plasma wakefield accelerator
Narrow band undulator radiation tuneable over the wavelength range of 150–260 nm has been produced by short electron bunches from a 2 mm long laser plasma wakefield accelerator based on a 20 TW femtosecond laser system. The number of photons measured is up to 9 × 106 per shot for a 100 period undulator, with a mean peak brilliance of 1 × 1018 photons/s/mrad2/mm2/0.1% bandwidth. Simulations estimate that the driving electron bunch r.m.s. duration is as short as 3 fs when the electron beam has energy of 120–130 MeV with the radiation pulse duration in the range of 50–100 fs
That was a great commercial, but what were they selling?: Effects of violence and sex on memory for products in televisioncommercials
College students (N = 324) watched a television program containing violence, sex, or no violence or sex. Each program contained 3 violent ads, 3 sexual ads, and 3 neutral ads. Participants were less likely to remember the advertised brands when the ads were embedded in a violent or sexual program than when the ads were embedded in a neutral program. Violent ads were the least memorable. This memory impairment occurred for both males and females, regardless of the content of the ads. If advertisers want viewers to remember advertised brands, they should think twice about sponsoring programs containing violence and sex. © 2007 Copyright the Authors; Journal compilation © 2007 Blackwell Publishing, Inc
The Blanco Cosmology Survey: Data Acquisition, Processing, Calibration, Quality Diagnostics and Data Release
The Blanco Cosmology Survey (BCS) is a 60 night imaging survey of 80
deg of the southern sky located in two fields: (,)= (5 hr,
) and (23 hr, ). The survey was carried out between
2005 and 2008 in bands with the Mosaic2 imager on the Blanco 4m
telescope. The primary aim of the BCS survey is to provide the data required to
optically confirm and measure photometric redshifts for Sunyaev-Zel'dovich
effect selected galaxy clusters from the South Pole Telescope and the Atacama
Cosmology Telescope. We process and calibrate the BCS data, carrying out PSF
corrected model fitting photometry for all detected objects. The median
10 galaxy (point source) depths over the survey in are
approximately 23.3 (23.9), 23.4 (24.0), 23.0 (23.6) and 21.3 (22.1),
respectively. The astrometric accuracy relative to the USNO-B survey is
milli-arcsec. We calibrate our absolute photometry using the stellar
locus in bands, and thus our absolute photometric scale derives from
2MASS which has % accuracy. The scatter of stars about the stellar locus
indicates a systematics floor in the relative stellar photometric scatter in
that is 1.9%, 2.2%, 2.7% and2.7%, respectively.
A simple cut in the AstrOmatic star-galaxy classifier {\tt spread\_model}
produces a star sample with good spatial uniformity. We use the resulting
photometric catalogs to calibrate photometric redshifts for the survey and
demonstrate scatter with an outlier fraction %
to . We highlight some selected science results to date and provide a
full description of the released data products.Comment: 23 pages, 23 figures . Response to referee comments. Paper accepted
for publication. BCS catalogs and images available for download from
http://www.usm.uni-muenchen.de/BC
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