To help constrain the algorithms used in reconstructing high-energy muon events incident on the Sudbury Neutrino Observatory (SNO), a muon tracking system was installed. The system consisted of four ...planes of wire chambers, which were triggered by scintillator panels. The system was integrated with SNO's main data acquisition system and took data for a total of 95 live days. Using cosmic-ray events reconstructed in both the wire chambers and in SNO's water Cherenkov detector, the external muon tracking system was able to constrain the uncertainty on the muon direction to better than 0.6°.
► This paper describes a novel technique for calibrating tracking algorithms. ► The experimental accuracy achieved by this system was better than 1°. ► The principle behind the technique can be used in future underground experiments.
Most previous attempts at reconstructing the past history of human populations did not explicitly take geography into account or considered very simple scenarios of migration and ignored ...environmental information. However, it is likely that the last glacial maximum (LGM) affected the demography and the range of many species, including our own. Moreover, long-distance dispersal (LDD) may have been an important component of human migrations, allowing fast colonization of new territories and preserving high levels of genetic diversity. Here, we use a high-quality microsatellite data set genotyped in 22 populations to estimate the posterior probabilities of several scenarios for the settlement of the Old World by modern humans. We considered models ranging from a simple spatial expansion to others including LDD and a LGM-induced range contraction, as well as Neolithic demographic expansions. We find that scenarios with LDD are much better supported by data than models without LDD. Nevertheless, we show evidence that LDD events to empty habitats were strongly prevented during the settlement of Eurasia. This unexpected absence of LDD ahead of the colonization wave front could have been caused by an Allee effect, either due to intrinsic causes such as an inbreeding depression built during the expansion or due to extrinsic causes such as direct competition with archaic humans. Overall, our results suggest only a relatively limited effect of the LGM contraction on current patterns of human diversity. This is in clear contrast with the major role of LDD migrations, which have potentially contributed to the intermingled genetic structure of Eurasian populations.
Introgression between domestic and wild taxa is a conservation issue because it can lead to the genetic extinction of wild taxa. Understanding the causes of introgression is thus a crucial task for ...conservation biologists. Here we provide evidence from biparentally, paternally and maternally inherited genetic markers in hybridizing European wildcats (Felis silvestris silvestris) and domestic cats (Felis silvestris catus) that one cause of introgression can be range expansion of the threatened species. We analyzed 68 autosomal, two Y-chromosomal and four mitochondrial diagnostic single nucleotide polymorphisms, and a sequence of 384 base pair of mitochondrial DNA, in 224 wild- and domestic cats from the Jura region of eastern Switzerland and western France. Using Bayesian estimation approaches, we found more gene flow from domestic cats to wildcats than vice versa (0.017 and 0.003 migrants per generation). Introgression of maternally inherited markers was higher than of paternally inherited markers. To test if these observed introgression patterns might be explained by wildcat expansion, we simulated neutral genetic data under various models of hybridization including spatial features such as range expansion. The most likely scenario represented an expansion of wildcats into domestic cat range. We also explored the geographic distribution of wildcats and hybrids. In comparison to wildcats, hybrids were found closer to the edge of the wildcat distribution range. Overall, the patterns we observed are compatible with the hypothesis that introgression is caused by wildcat range expansion, rather than by domestic cat invasion of wildcat habitat. That the threatened European wildcat is expanding is a positive sign, but careful monitoring of introgression and its fitness consequences is needed to ensure that the wildcat does not go genetically extinct in the generations to come.
Breakthrough technologies which now enable the sequencing of individual genomes will irreversibly modify the way diseases are diagnosed, predicted, prevented and treated. For these technologies to ...reach their full potential requires, upstream, access to high-quality biomedical data and samples from large number of properly informed and consenting individuals and, downstream, the possibility to transform the emerging knowledge into a clinical utility. The Lausanne Institutional Biobank was designed as an integrated, highly versatile infrastructure to harness the power of these emerging technologies and catalyse the discovery and development of innovative therapeutics and biomarkers, and advance the field of personalised medicine. Described here are its rationale, design and governance, as well as parallel initiatives which have been launched locally to address the societal, ethical and technological issues associated with this new bio-resource. Since January 2013, inpatients admitted at Lausanne CHUV University Hospital have been systematically invited to provide a general consent for the use of their biomedical data and samples for research, to complete a standardised questionnaire, to donate a 10-ml sample of blood for future DNA extraction and to be re-contacted for future clinical trials. Over the first 18 months of operation, 14,459 patients were contacted, and 11,051 accepted to participate in the study. This initial 18-month experience illustrates that a systematic hospital-based biobank is feasible; it shows a strong engagement in research from the patient population in this University Hospital setting, and the need for a broad, integrated approach for the future of medicine to reach its full potential.
A Geoneutrino Experiment at Homestake Tolich, N.; Chan, Y. -D.; Currat, C. A. ...
Earth, moon, and planets,
12/2006, Letnik:
99, Številka:
1-4
Journal Article
Recenzirano
Odprti dostop
A significant fraction of the 44TW of heat dissipation from the Earth’s interior is believed to originate from the decays of terrestrial uranium and thorium. The only estimates of this radiogenic ...heat, which is the driving force for mantle convection, come from Earth models based on meteorites, and have large systematic errors. The detection of electron antineutrinos produced by these uranium and thorium decays would allow a more direct measure of the total uranium and thorium content, and hence radiogenic heat production in the Earth. We discuss the prospect of building an electron antineutrino detector approximately 700 m3 in size in the Homestake mine at the 4850’ level. This would allow us to make a measurement of the total uranium and thorium content with a statistical error less than the systematic error from our current knowledge of neutrino oscillation parameters. It would also allow us to test the hypothesis of a naturally occurring nuclear reactor at the center of the Earth.
Aperiodic crystals which are long range ordered materials present original dynamics features due to the lack of translational symmetry formally implying the nonvalidity of the Brillouin zone concept. ...This Letter reports the observation by neutron scattering of an overdamped acousticlike mode at a Bragg peak position in a n-alkane-urea inclusion crystal. This result implies the existence of a gap in the dispersion branch. The gap and anomalous damping of these collective modes are discussed in terms of specific dynamics and interaction in aperiodic materials.
Mekel-Bobrov et al. and Evans et al. (Reports, 9 Sept. 2005, p. 1720 and p. 1717, respectively) examined sequence data from modern humans within two gene regions associated with brain development, ...ASPM and microcephalin, and concluded that selection of these genes must be ongoing. We show that models of human history that include both population growth and spatial structure can generate the observed patterns without selection.
A precise determination of the energy scale of jets at the Collider Detector at Fermilab at the Tevatron
p
p
¯
collider is described. Jets are used in many analyses to estimate the energies of ...partons resulting from the underlying physics process. Several correction factors are developed to estimate the original parton energy from the observed jet energy in the calorimeter. The jet energy response is compared between data and Monte Carlo simulation for various physics processes, and systematic uncertainties on the jet energy scale are determined. For jets with transverse momenta above 50
GeV the jet energy scale is determined with a
3
%
systematic uncertainty.
We present a coherent x-ray diffraction study of the antiferrodistortive displacive transition of SrTiO3, a prototypical example of a phase transition for which the critical fluctuations exhibit two ...length scales and two time scales. From the microbeam x-ray coherent diffraction patterns, we show that the broad (short-length scale) and the narrow (long-length scale) components can be spatially disentangled, due to 100-microm-scale spatial variations of the latter. Moreover, both components exhibit a speckle pattern, which is static on a approximately 10 mn time scale. This gives evidence that the narrow component corresponds to static ordered domains. We interpret the speckles in the broad component as due to a very slow dynamical process, corresponding to the well-known central peak seen in inelastic neutron scattering.
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