8,321 research outputs found
Elysia timida (Risso, 1818) three decades of research
Elysia timida (Risso, 1818) three decades of research.— During the last 30 years, studies on Elysia timida (Risso,
1818) have addressed various aspects related to food sources, photosynthetic efficiency of kleptoplasts, population
genetics, chemical ecology and reproductive biology, both in the Mediterranean Sea and in the Mar Menor
coastal lagoon. E. timida shows a strong specific interaction with Acetabularia acetabulum, retaining functional
chloroplasts for at least 45 days and obtaining extra energy in periods when food resources are scarce. It shows
control of parapodia, avoiding pigment photodestruction under oversaturated light conditions. The chemical ecological
relationships established between E. timida and its potential predator fish, Thalassoma pavo, have also
been evaluated, and it has been found that that the extracts of the mollusc contain repellent and unpalatable
polypropionate compounds. Population genetics has demonstrated the genetic divergence between populations
showing high and significant values of FST and genetic distances, and at least six privative alleles that are not
shared with Mediterranean populations have been detected in lagoon populations. This sacoglossan is a poecilogonic
species, and its lagoon populations show a greater reproductive output than Mediterranean populations; they
produce a greater number of egg masses and embyros per individual, and the capsules have a wider diameter
Non-Perturbative Renormalisation using Domain Wall Fermions
The viability of the Non-Perturbative Renormalisation (NPR) method of the
Rome/Southampton group is studied, for the first time, in the context of domain
wall fermions. The procedure is used to extract the renormalisation
coefficients of the various quark bilinears, as well as the four-fermion
operators relevant to the effective Hamiltonian. The
renormalisation of the Hamiltonian is also discussed.Comment: LATTICE99(Improvement and Renormalization),3 pages, LaTeX2e; minor
typos correcte
Context-aware systems architecture (CaSA)
Context-aware systems are becoming increasingly mainstream as more and more technology allows real-time collection of daily life data and it is more and more affordable to provide useful services to citizens in various situations of need. However, developers in this field are not well supported. Naturally we have inherited a number of methods and tools from past software engineering efforts to create previous computing systems. However the most recent generation of systems dominated by sensing supported context-awareness integrating a variety of data sources and with a higher expectation of personalized services delivered at the right time, place and in the right form, are not well supported. Developers need more guidance and support to pinpoint those valuable contexts and to work out ways of detecting them and activating the right services associated with these contexts. Our community has reported on various systems they created however not much is emerging in a way of a methodology, a standard, a transferable body of advice and guidance which can help teams next time they need to develop a new system. In this article we explain a couple of complementary methodologies which we have tried and tested through development of different context-aware projects. We argue these are of practical usefulness and provide an initial valid point of discussion for our community to create evolved versions of these which can be tested more widely to identify good practice in the area
Achieving multi-user capabilities through an indoor positioning system based on BLE beacons
The multiple user challenge is one of the issues that need to be addressed in order to facilitate the adoption of intelligent environments in everyday activities. The development of multi-user capabilities in smart homes is closely related to the creation of effective indoor positioning systems. This research work reports on the development and evaluation of an indoor positioning system that allows multi-user management in a smart home environment. The design of the BLE based system is presented, as well as its implementation and evaluation in the Smart Spaces Lab at Middlesex University. The validation of the system is shown as a case study in which it is used to develop multi-user capabilities in two context-aware systems of the laboratory. Video demonstrations are provided to illustrate the multi-user capabilities that were developed in the validation
B-physics from lattice QCD...with a twist
We present a precise lattice QCD determination of the b-quark mass, of the B
and Bs decay constants and first results for the B-meson bag parameters. For
our computation we employ the so-called ratio method and our results benefit
from the use of improved interpolating operators for the B-mesons. QCD
calculations are performed with Nf = 2 dynamical light-quarks at four values of
the lattice spacing and the results are extrapolated to the continuum limit.
The preliminary results are mb(mb) = 4.35(12) GeV for the MSbar b-quark mass,
fBs = 234(6) MeV and fB = 197(10) MeV for the B-meson decay constants, BBs(mb)
= 0.90(5) and BB(mb) = 0.87(5) for the B-meson bag parameters.Comment: 6 pages, 3 figures. Proceedings of the 36th International Conference
on High Energy Physics - ICHEP 2012; July 4-11 2012; Melbourne, Australi
K^0-\bar{K}^0 mixing in the Standard Model from Nf=2+1+1 Twisted Mass Lattice QCD
We present preliminary results at {\beta} = 1.95 (a = 0.077 fm) on the first
unquenched N_f=2+1+1 lattice computation of the B_K parameter which controls
the neutral kaon oscillations in the Standard Model. Using N_f=2+1+1 maximally
twisted sea quarks and Osterwalder-Seiler valence quarks we achieve O(a)
improvement and a continuum-like renormalization pattern for the four-fermion
operator. Our results are extrapolated/interpolated to the physical
light/strange quark mass but not yet to the continuum limit. The computation of
the relevant renormalization constants is performed non perturbatively in the
RI'-MOM scheme using dedicated simulations with N_f=4 degenerate sea quark
flavours produced by the ETM collaboration.
We get B_K^{RGI} (a = 0.077) = 0.747(18), which when compared to our previous
unquenched N_f=2 determination and most of the existing results, suggests a
rather weak B_K^{RGI} dependence on the number of dynamical flavours. We are at
the moment analysing lattice data at two additional {\beta} values which will
allow us to perform an extrapolation to the continuum limit.Comment: 7 pages, 8 figures, Proceedings of Lattice 2011, XXIX International
Symposium on Lattice Field Theory, Squaw Valley, Lake Tahoe, Californi
Large pion pole in Z_{S}^{MOM}/Z_{P}^{MOM} from Wilson action data
We show that, contrarily to recent claims, data from the Wilson (unimproved)
fermionic action at three different beta values demonstrate the presence of a
large Goldstone boson contribution in the quark pseudoscalar vertex,
quantitatively close to our previous estimate based on the SW action with
c_{SW}=1.769. We show that discretisation errors on Z_{S}^{MOM}/Z_{P}^{MOM}
seem to be much smaller than the Goldstone pole contribution over a very large
range of momenta. The subtraction of this non perturbative contribution leads
to numbers close to one-loop BPT.Comment: 12 pages, 5 figures, laTeX, minor corrections of typos, beta
dependence made more explicit, added one table giving the contribution of the
Goldstone vs. the discretisation errors at ap=
Forecasting ocean warming impacts on seabird demography: a case study on the European storm petrel
Bottom-up climatic forcing has been shown to be influential for a variety of marine
taxa, but evidence on seabird populations is scarce. Seasonal variation in environmental conditions
can have an indirect effect on subsequent reproduction, which, given the longevity and
single-brooding of seabirds, may affect population dynamics. Our study focuses on linking the
effect of oceanographic conditions (from 1991 to 2013) to the fecundity and consequently pop -
ulation growth rate of the Mediterranean subspecies of the European storm petrel Hydrobates
pelagicus melitensis. In this study, we examined 23 yr of > 5400 capture–mark−recaptures (CMR)
and modelled the probability of skipping reproduction as a function of oceanographic variables
using CMR models. We demonstrate that a decrease in sea surface temperature in the pre-breeding
period negatively influences skipping propensity, and therefore hypothesize that this behaviour
would have significant influence on population abundance over time. For this reason, we analysed
population growth as a function of skipping probability as affected by oceanographic
conditions. We used stochastic demographic models to forecast the fate of the population, and
evaluated contrasted environmental condition scenarios. As a result, we found that a decrease in
frequency of cold winter events would probably reduce skipping propensity, with a positive effect
on the population as a whole
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