Search results for "selection"
showing 10 items of 1940 documents
First results on dark matter annihilation in the Sun using the ANTARES neutrino telescope
2013
A search for high-energy neutrinos coming from the direction of the Sun has been performed using the data recorded by the ANTARES neutrino telescope during 2007 and 2008. The neutrino selection criteria have been chosen to maximize the selection of possible signals produced by the self-annihilation of weakly interacting massive particles accumulated in the centre of the Sun with respect to the atmospheric background. After data unblinding, the number of neutrinos observed towards the Sun was found to be compatible with background expectations. The 90% CL upper limits in terms of spin-dependent and spin-independent WIMP-proton cross-sections are derived and compared to predictions of two sup…
Optimization of the KNN Supervised Classification Algorithm as a Support Tool for the Implantation of Deep Brain Stimulators in Patients with Parkins…
2019
Deep Brain Stimulation (DBS) of the Subthalamic Nuclei (STN) is the most used surgical treatment to improve motor skills in patients with Parkinson&rsquo
Spin alignment and violation of the OZI rule in exclusive ω and ϕ production in pp collisions
2014
Exclusive production of the isoscalar vector mesons $\omega$ and $\phi$ is measured with a 190 GeV$/c$ proton beam impinging on a liquid hydrogen target. Cross section ratios are determined in three intervals of the Feynman variable $x_{F}$ of the fast proton. A significant violation of the OZI rule is found, confirming earlier findings. Its kinematic dependence on $x_{F}$ and on the invariant mass $M_{p\mathrm{V}}$ of the system formed by fast proton $p_\mathrm{fast}$ and vector meson $V$ is discussed in terms of diffractive production of $p_\mathrm{fast}V$ resonances in competition with central production. The measurement of the spin density matrix element $\rho_{00}$ of the vector mesons…
Co-mimics have a mutualistic relationship despite unequal defences
2007
Defensive mimicry, where species have evolved to resemble others in order to evade predators, is quite common in the animal kingdom. The two extremes of the mimicry spectrum are known as 'batesian' and 'mullerian'. Batesian mimics develop signals — visual cues for instance — that are similar to those of species being mimicked, but stop short of adopting the attribute that makes it unprofitable prey to predators. Mullerian mimics both resemble the model species and share the anti-predation attribute — by being dangerous or unpalatable. These different types of mimic were identified a century ago, but the dynamics of mimicry between unequally defended prey remain unresolved. In an experiment …
Strong antiapostatic selection against novel rare aposematic prey
2001
The evolution of aposematism, a phenomenon where prey species conspicuously advertise their unprofitability to predators, is puzzling. How did conspicuousness evolve, if it simultaneously increased the likelihood of an inexperienced predator to detect the prey and presumably kill it? Antiapostatic selection, where rare prey is predated relatively more often, is considered as another major difficulty for aposematism to evolve. However, the risk of being conspicuous in low frequencies has not been experimentally tested. We designed an experiment to test how frequency (4%, 12%, 32%) of conspicuous aposematic prey and its dispersion type (solitary vs. aggregated) affect an initial predation ri…
Selection for cryptic coloration in a visually heterogeneous habitat.
2001
We studied selection by predators for cryptic prey coloration in a visually heterogeneous habitat that consists of two microhabitats. It has been suggested that the probability of escaping detection in such habitats might be optimized by maximizing crypsis in one of the microhabitats. However, a recent model indicates that a coloration that compromises the requirements of different microhabitats might sometimes be the optimal solution. To experimentally study these hypotheses, we allowed great tits (Parus major L.) to search for artificial prey items in two different microhabitats (background boards): small patterned and large patterned. On each board there was one prey item that was either…
Can experienced birds select for Müllerian mimicry?
2008
Field experiments have shown that avian predators in the wild can select for similarity of warning signals in aposematic prey (Müllerian mimicry) because a common signal is better protected than a signal that is novel and rare. The original theory of Müllerian mimicry assumes that the mechanism promoting mimicry is predator learning; by sharing a signal, the comimic species share the mortality that is due to sampling by inexperienced predators. Predation events have not been observed in the wild, and learning experiments with naive bird predators in a laboratory have not unambiguously shown a benefit of a uniform signal compared with different signals. As predators in the field experiments …
Post-fledging survival of individual great tits: the effect of hatching date and fledging mass
2002
Pre-breeeding survival is one of the major sources of individual variation in lifetime reproductive success. However, very little is known about the reasons for differences in survival among individuals during this important phase of the life cycle. Some studies, using local return rates as indices of survival, have shown a relationship between post-fledging survival and fledging date and mass in birds, most of them suggesting directional selection towards heavy masses and early fledging dates. Recent development of capture-recapture models allows the separate estimate of survival and recapture probabilities, as well as the inclusion of individual covariates into the modelling process. We u…
Multiple benefits of gregariousness cover detectability costs in aposematic aggregations
2001
Understanding the early evolution of aposematic (warning) coloration has been a challenge for scientists, as a new conspicuous morph in a population of cryptic insects would have a high predation risk and would probably die out before local predators learnt to avoid it1,2,3,4. Fisher5 presented the idea of aggregation benefit through the survival of related individuals; however, his theory has been strongly debated6,7,8 as the mechanisms that favour grouping have never been explored experimentally with the incorporation of detectability costs. Here we create a comprehensive ‘novel world’ experiment with the great tit (Parus major) as a predator to explore simultaneously the predation-relate…
Quantification of the heterogeneity of prognostic cellular biomarkers in ewing sarcoma using automated image and random survival forest analysis
2014
Driven by genomic somatic variation, tumour tissues are typically heterogeneous, yet unbiased quantitative methods are rarely used to analyse heterogeneity at the protein level. Motivated by this problem, we developed automated image segmentation of images of multiple biomarkers in Ewing sarcoma to generate distributions of biomarkers between and within tumour cells. We further integrate high dimensional data with patient clinical outcomes utilising random survival forest (RSF) machine learning. Using material from cohorts of genetically diagnosed Ewing sarcoma with EWSR1 chromosomal translocations, confocal images of tissue microarrays were segmented with level sets and watershed algorithm…