14,946 research outputs found
Integrating Species Traits into Species Pools
Despite decades of research on the speciesâpool concept and the recent explosion of interest in traitâbased frameworks in ecology and biogeography, surprisingly little is known about how spatial and temporal changes in speciesâpool functional diversity (SPFD) influence biodiversity and the processes underlying community assembly. Current traitâbased frameworks focus primarily on community assembly from a static regional species pool, without considering how spatial or temporal variation in SPFD alters the relative importance of deterministic and stochastic assembly processes. Likewise, speciesâpool concepts primarily focus on how the number of species in the species pool influences local biodiversity. However, species pools with similar richness can vary substantially in functionalâtrait diversity, which can strongly influence community assembly and biodiversity responses to environmental change. Here, we integrate recent advances in community ecology, traitâbased ecology, and biogeography to provide a more comprehensive framework that explicitly considers how variation in SPFD, among regions and within regions through time, influences the relative importance of community assembly processes and patterns of biodiversity. First, we provide a brief overview of the primary ecological and evolutionary processes that create differences in SPFD among regions and within regions through time. We then illustrate how SPFD may influence fundamental processes of local community assembly (dispersal, ecological drift, niche selection). Higher SPFD may increase the relative importance of deterministic community assembly when greater functional diversity in the species pool increases niche selection across environmental gradients. In contrast, lower SPFD may increase the relative importance of stochastic community assembly when high functional redundancy in the species pool increases the influence of dispersal history or ecological drift. Next, we outline experimental and observational approaches for testing the influence of SPFD on assembly processes and biodiversity. Finally, we highlight applications of this framework for restoration and conservation. This speciesâpool functional diversity framework has the potential to advance our understanding of how localâ and regionalâscale processes jointly influence patterns of biodiversity across biogeographic regions, changes in biodiversity within regions over time, and restoration outcomes and conservation efforts in ecosystems altered by environmental change
Close-up of primary and secondary asteroseismic CoRoT targets and the ground-based follow-up observations
To optimise the science results of the asteroseismic part of the CoRoT
satellite mission a complementary simultaneous ground-based observational
campaign is organised for selected CoRoT targets. The observations include both
high-resolution spectroscopic and multi-colour photometric data. We present the
preliminary results of the analysis of the ground-based observations of three
targets. A line-profile analysis of 216 high-resolution FEROS spectra of the
delta Sct star HD 50844 reveals more than ten pulsation frequencies in the
frequency range 5-18 c/d, including possibly one radial fundamental mode (6.92
c/d). Based on more than 600 multi-colour photometric datapoints of the beta
Cep star HD180642, spanning about three years and obtained with different
telescopes and different instruments, we confirm the presence of a dominant
radial mode nu1=5.48695 c/d, and detect also its first two harmonics. We find
evidence for a second mode nu2=0.3017 c/d, possibly a g-mode, and indications
for two more frequencies in the 7-8 c/d domain. From Stromgren photometry we
find evidence for the hybrid delta Sct/gamma Dor character of the F0 star HD
44195, as frequencies near 3 c/d and 21 c/d are detected simultaneously in the
different filters.Comment: 7 pages, 6 figures, HELAS II International Conference
"Helioseismology, Asteroseismology and MHD Connections", 2008, J.Phys.: Conf.
Ser. 118, 01207
Present status and future prospects for a Higgs boson discovery at the Tevatron and LHC
Discovering the Higgs boson is one of the primary goals of both the Tevatron
and the Large Hadron Collider (LHC). The present status of the Higgs search is
reviewed and future prospects for discovery at the Tevatron and LHC are
considered. This talk focuses primarily on the Higgs boson of the Standard
Model and its minimal supersymmetric extension. Theoretical expectations for
the Higgs boson and its phenomenological consequences are reviewed.Comment: 13 pages, 9 figures, 2 tables, jpconf documentclass file, invited
talk at PASCOS 2010, the 16th International Symposium on Particles, Strings
and Cosmology, Valencia, Spain, 19--23 July 201
Simple predictions from ALCOR_c for rehadronisation of charmed quark matter
We study the production of charmed hadrons with the help of ALCOR_c, the
algebraic coalescence model for rehadronisation of charmed quark matter.
Mesonic ratios are introduced as factors connecting various antibaryon to
baryon ratios. The resulting simple relations could serve as tests of quark
matter formation and coalescence type rehadronization in heavy ion collisions.Comment: 7 pages in Latex, 1 PS figur
Academic motherhood and fieldwork: Juggling time, emotions and competing demands
The idea and practice of going âinto the fieldâ to conduct research and gather data is a deeply rooted aspect of Geography as a discipline. For global North Development Geographers, amongst others, this usually entails travelling to, and spending periods of time in, often far-flung parts of the global South. Forging a successful academic career as a Development Geographer in the UK, is therefore to some extent predicated on mobility. This paper aims to critically engage with the gendered aspects of this expected mobility, focusing on the challenges and time constraints that are apparent when conducting overseas fieldwork as a mother, unaccompanied by her children. The paper emphasises the emotion work that is entailed in balancing the competing demands of overseas fieldwork and mothering, and begins to think through the implications of these challenges in terms of the types of knowledge we produce, as well as in relation to gender equality within the academy
Towards resolution of the scalar meson nonet enigma
By the application of a linear mass spectrum to a composite system of both
the pseudoscalar and scalar meson nonets, we find three mass relations for the
masses of the scalar states which suggest the assignment for the
scalar meson nonet: Comment: 16 pages, LaTe
Decay constants and form factors of s-wave and p-wave mesons in the covariant light-front quark model
We reanalyze the decay constants of s-wave and p-wave mesons and D, B ->M
form factors, where M represents a pseudoscalar meson, a vector meson, a scalar
meson, or an axial vector meson within a covariant light-front quark model. The
parameter \beta for wave-functions of most of s-wave mesons and of a few
axial-vector mesons are fixed with latest experimental information, wherever
available or using the lattice calculations. The treatment of masses and mixing
angles for strange axial vector mesons is improved for the purpose. We extend
our analysis to determine the form factors appearing in the transition of D_s,
B_s->M transitions, and to the isoscalar final state mesons. Numerical results
of the form factors for transitions between a heavy pseudoscalar meson and an
s-wave or p-wave light meson and their momentum dependence are presented in
detail. Further, their sensitivity to uncertainties of beta parameters of the
initial as well as the final mesons is investigated. Some experimental
measurements of the charmed and bottom meson decays are employed to compare the
decay constants and transition form factors obtained in this and other works.Comment: 36 pages, 2 figure
Hadronization of massive quark matter
We present a fast hadronization model for the constituent quark plasma (CQP)
produced in relativistic heavy ion collisions at SPS. The model is based on
rate equations and on an equation of state inspired by the string
phenomenology. This equation of state has a confining character. We display the
time evolution of the relevant physical quantities during the hadronization
process and the final hadron multiplicities. The results indicate that the
hadronization of CQP is fast.Comment: 12 pages, Latex, 2 EPS figures, contribution to the Proceedings of
the 4th International Conference on Strangeness in Quark Matter (SQM'98),
Padova, Italy, 20-24 July 199
Application of Jain and Munczek's bound-state approach to gamma gamma-processes of pi0, eta_c and eta_b
We point out the problems affecting most quark--antiquark bound state
approaches when they are faced with the electromagnetic processes dominated by
Abelian axial anomaly. However, these problems are resolved in the consistently
coupled Schwinger-Dyson and Bethe-Salpeter approach. Using one of the most
successful variants of this approach, we find the dynamically dressed
propagators of the light u and d quarks, as well as the heavy c and b quarks,
and find the Bethe-Salpeter amplitudes for their bound states pi0, eta_c and
\eta_b. Thanks to incorporating the dynamical chiral symmetry breaking, the
pion simultaneously appears as the (pseudo)Goldstone boson. We give the
theoretical predictions for the gamma-gamma decay widths of pi0, eta_c and
eta_b, and for the pi0 gamma* -> gamma transition form factor, and compare them
with experiment. In the chiral limit, the axial-anomaly result for
pi0->gamma-gamma is reproduced analytically in the consistently coupled
Schwinger-Dyson and Bethe-Salpeter approach, provided that the quark-photon
vertex is dressed consistently with the quark propagator, so that the vector
Ward-Takahashi identity of QED is obeyed. On the other hand, the present
approach is also capable of quantitatively describing systems of heavy quarks,
concretely eta_c and possibly eta_b, and their gamma-gamma decays. We discuss
the reasons for the broad phenomenological success of the bound-state approach
of Jain and Munczek.Comment: RevTeX, 37 pages, 7 eps figures, submitted to Int. J. Mod. Phys.
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