872 research outputs found
Pforams@microtax: Anew online taxonomic database for planktonic foraminifera
A new relational taxonomic database for planktonic foraminifera (“pforams@mikrotax�) has been constructed and is now freely available online at http://www.mikrotax.org. It represents amajor advance from its predecessor, the CHRONOS online taxonomic database, which has served the research community since 2005. The benefits of the new database to the research and industrial biostratigraphic communities are many, as it will serve as an immediately accessible taxonomic guide and reference for specialists and non-specialists alike by providing access to a wealth of information and images from original authors and from expertswho have inserted recent authoritative updates to planktonic foraminiferal taxonomy, phylogeny and biostratigraphy. The database will be continually updated and used as a guide for training current and future generations of students and professionals who will be able to self-educate on planktonic foraminiferal taxonomy and biostratigraphy. Further investigation of species traditionally included in the Cretaceous genera Heterohelix, Globigerinelloides, Marginotruncana, and Globotruncana is required to exclude the use of polyphyletic morphotaxa. The taxonomy for Paleogene planktonic foraminifera is quite stable following publication of the Paleocene, Eocene, and Oligocene taxonomic atlases, but revisions to the taxonomy and phylogeny of Neogene taxa are needed to incorporate results from genetic sequencing studies and recent biostratigraphic observations
Reducing Constraints in a Higher Dimensional Extension of the Randall and Sundrum Model
In order to investigate the phenomenological implications of warped spaces in
more than five dimensions, we consider a dimensional extension to
the Randall and Sundrum model in which the space is warped with respect to a
single direction by the presence of an anisotropic bulk cosmological constant.
The Einstein equations are solved, giving rise to a range of possible spaces in
which the additional spaces are warped. Here we consider models in
which the gauge fields are free to propagate into such spaces. After carrying
out the Kaluza Klein (KK) decomposition of such fields it is found that the KK
mass spectrum changes significantly depending on how the additional
dimensions are warped. We proceed to compute the lower bound on the KK mass
scale from electroweak observables for models with a bulk
gauge symmetry and models with a bulk gauge
symmetry. It is found that in both cases the most favourable bounds are
approximately TeV, corresponding to a mass of the first gauge
boson excitation of about 4-6 TeV. Hence additional warped dimensions offer a
new way of reducing the constraints on the KK scale.Comment: 27 pages, 15 figures, v3: Additional comments in sections 1, 2 and 4.
New appendix added. Five additional figures. References adde
Suppressing Electroweak Precision Observables in 5D Warped Models
We elaborate on a recently proposed mechanism to suppress large contributions
to the electroweak precision observables in five dimensional (5D) warped
models, without the need for an extended 5D gauge sector. The main ingredient
is a modification of the AdS metric in the vicinity of the infrared (IR) brane
corresponding to a strong deviation from conformality in the IR of the 4D
holographic dual. We compute the general low energy effective theory of the 5D
warped Standard Model, emphasizing additional IR contributions to the wave
function renormalization of the light Higgs mode. We also derive expressions
for the S and T parameters as a function of a generic 5D metric and zero-mode
wave functions. We give an approximate formula for the mass of the radion that
works even for strong deviation from the AdS background. We proceed to work out
the details of an explicit model and derive bounds for the first KK masses of
the various bulk fields. The radion is the lightest new particle although its
mass is already at about 1/3 of the mass of the lightest resonances, the KK
states of the gauge bosons. We examine carefully various issues that can arise
for extreme choices of parameters such as the possible reintroduction of the
hierarchy problem, the onset of nonperturbative physics due to strong IR
curvature or the creation of new hierarchies near the Planck scale. We conclude
that a KK scale of 1 TeV is compatible with all these constraints.Comment: 44 pages, 11 figures, references adde
Neutrino Mixing from Wilson Lines in Warped Space
We consider the generation of the hierarchical charged lepton spectrum and
anarchic neutrino masses and mixing angles in warped extra dimensional models
with Randall-Sundrum metric. We have classified all possible cases giving rise
to realistic spectra for both Dirac and Majorana neutrinos. An anarchic
neutrino spectrum requires a convenient bulk symmetry broken by boundary
conditions on both UV and IR branes. We have in particular considered the case
of Majorana neutrinos with a continuous bulk symmetry. To avoid unwanted
massless extra gauge bosons the 4D group should be empty. If the 4D coset is
not vanishing it can provide a Wilson Line description of the neutrino Majorana
mass matrix. We have studied an example based on the bulk gauge group U(3)_{L}
\otimes U(3)_{N} \otimes_{i} U(1)_{E^i} with the Wilson Line in SO(3)_{N}
satisfying all required conditions. A \chi^2-fit to experimental data exhibits
the 95% CL region in the parameter space with no fine-tuning. As a consequence
of the symmetries of the theory there is no tree-level induced lepton flavor
violation and so one-loop processes are consistent with experimental data for
KK-modes about a few TeV. The model is easily generalizable to models with IR
deformed metrics with similar conclusions.Comment: 28 pages, 9 eps plots, uses axodraw; v2 Title changed, comments on
phenomenology added, version to be published in JHE
Evolutionary Dead End in the Galápagos: Divergence of Sexual Signals in the Rarest of Darwin's Finches
Understanding the mechanisms underlying speciation remains a challenge in evolutionary biology. The adaptive radiation of Darwin's finches is a prime example of species formation, and their study has revealed many important insights into evolutionary processes. Here, we report striking differences in mating signals (songs), morphology and genetics between the two remnant populations of Darwin's mangrove finch Camarhynchus heliobates, one of the rarest species in the world. We also show that territorial males exhibited strong discrimination of sexual signals by locality: in response to foreign songs, males responded weaker than to songs from their own population. Female responses were infrequent and weak but gave approximately similar results. Our findings not only suggest speciation in the mangrove finch, thereby providing strong support for the central role of sexual signals during speciation, but they have also implications for the conservation of this iconic bird. If speciation is complete, the eastern species will face imminent extinction, because it has a population size of only 5–10 individuals
Experimental Demonstration of the Fitness Consequences of an Introduced Parasite of Darwin's Finches
Introduced parasites are a particular threat to small populations of hosts living on islands because extinction can occur before hosts have a chance to evolve effective defenses. An experimental approach in which parasite abundance is manipulated in the field can be the most informative means of assessing a parasite's impact on the host. The parasitic fly Philornis downsi, recently introduced to the Galápagos Islands, feeds on nestling Darwin's finches and other land birds. Several correlational studies, and one experimental study of mixed species over several years, reported that the flies reduce host fitness. Here we report the results of a larger scale experimental study of a single species at a single site over a single breeding season.We manipulated the abundance of flies in the nests of medium ground finches (Geospiza fortis) and quantified the impact of the parasites on nestling growth and fledging success. We used nylon nest liners to reduce the number of parasites in 24 nests, leaving another 24 nests as controls. A significant reduction in mean parasite abundance led to a significant increase in the number of nests that successfully fledged young. Nestlings in parasite-reduced nests also tended to be larger prior to fledging.Our results confirm that P. downsi has significant negative effects on the fitness of medium ground finches, and they may pose a serious threat to other species of Darwin's finches. These data can help in the design of management plans for controlling P. downsi in Darwin's finch breeding populations
Are migraineur women really more vulnerable to stress and less able to cope?
Abstract Background In this study, we aimed to investigate the differences between a sample of migraineurs and non-migraineurs with regard to their stress symptoms, tendency to stress, coping styles and life satisfaction. Methods This study was carried out on a migraineur group (n = 62, mean age: 37.5 ± 11.3, range: 18 to 61 years) and a non-migraineur group (n = 58, mean age: 32.0 ± 11.2, range: 18 to 61 years). Stress Audit (Symptoms), Stress Audit (Vulnerability), Turkish version of Ways of Coping Inventory Scales and Life Satisfaction were applied to the migraineur and non-migraineur groups. Results No significant differences were found between the groups in the scores of the stress symptoms except in the sub scores of the sympathetic system. There was no significant difference between the groups in the tendency to stress and life satisfaction (p > .05). For scores of the coping styles, the mean scores of the seeking social support subscale was higher in the control group than that of the migraineur group. However, migraineur women had higher mean scores in the submissive and the optimistic subscales. Conclusion We consider that, these outcomes may emphasize the necessity to be careful when using negative expressions about stress relating to migraineurs. Further comprehensive studies are required considering the multiple triggers of the disease in various cultural contexts.</p
The Effective Lagrangian for Bulk Fermions in Models with Extra Dimensions
We compute the dimension 6 effective Lagrangian arising from the tree level
integration of an arbitrary number of bulk fermions in models with warped extra
dimensions. The coefficients of the effective operators are written in terms of
simple integrals of the metric and are valid for arbitrary warp factors, with
or without an infrared brane, and for a general Higgs profile. All relevant
tree level fermion effects in electroweak and flavor observables can be
computed using this effective Lagrangian.Comment: 22 pages. V2: typos corrected, matches published versio
Impact of the provision of safe drinking water on school absence rates in Cambodia:a quasi-experimental study
Education is one of the most important drivers behind helping people in developing countries lift themselves out of poverty. However, even when schooling is available absenteeism rates can be high. Recently interest has focussed on whether or not WASH interventions can help reduce absenteeism in developing countries. However, none has focused exclusively on the role of drinking water provision. We report a study of the association between absenteeism and provision of treated water in containers into schools
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