Red coral extinction risk enhanced by ocean acidification

The red coral Corallium rubrum is a habitat-forming species with a prominent and structural role in mesophotic habitats, which sustains biodiversity hotspots. This precious coral is threatened by both over-exploitation and temperature driven mass mortality events. We report here that biocalcification, growth rates and polyps’ (feeding) activity of Corallium rubrum are significantly reduced at pCO2 scenarios predicted for the end of this century (0.2 pH decrease). Since C. rubrum is a long-living species (.200 years), our results suggest that ocean acidification predicted for 2100 will significantly increases the risk of extinction of present populations. Given the functional role of these corals in the mesophotic zone, we predict that ocean acidification might have cascading effects on the functioning of these habitats worldwid

Are geometric morphometric analyses replicable? Evaluating landmark measurement error and its impact on extant and fossil Microtus classification.

Geometric morphometric analyses are frequently employed to quantify biological shape and shape variation. Despite the popularity of this technique, quantification of measurement error in geometric morphometric datasets and its impact on statistical results is seldom assessed in the literature. Here, we evaluate error on 2D landmark coordinate configurations of the lower first molar of five North American Microtus (vole) species. We acquired data from the same specimens several times to quantify error from four data acquisition sources: specimen presentation, imaging devices, interobserver variation, and intraobserver variation. We then evaluated the impact of those errors on linear discriminant analysis-based classifications of the five species using recent specimens of known species affinity and fossil specimens of unknown species affinity. Results indicate that data acquisition error can be substantial, sometimes explaining >30% of the total variation among datasets. Comparisons of datasets digitized by different individuals exhibit the greatest discrepancies in landmark precision, and comparison of datasets photographed from different presentation angles yields the greatest discrepancies in species classification results. All error sources impact statistical classification to some extent. For example, no two landmark dataset replicates exhibit the same predicted group memberships of recent or fossil specimens. Our findings emphasize the need to mitigate error as much as possible during geometric morphometric data collection. Though the impact of measurement error on statistical fidelity is likely analysis-specific, we recommend that all geometric morphometric studies standardize specimen imaging equipment, specimen presentations (if analyses are 2D), and landmark digitizers to reduce error and subsequent analytical misinterpretations

Test with cosmic rays of the GEM chambers for the LHCb muon system produced in Cagliari

The inner region of the first LHCb muon station will be equipped with twelve Gas Electron Multiplier chambers. The seven chambers produced in Cagliari were studied for several days each using cosmic rays. We measured the efficiency, timing resolution, and uniformity, cluster-size and out-of-time multiplicity. We find all seven chambers perform well

The discontinuous nature of chromospheric activity evolution

Chromospheric activity has been thought to decay smoothly with time and, hence, to be a viable age indicator. Measurements in solar type stars in open clusters seem to point to a different conclusion: chromospheric activity undergoes a fast transition from Hyades level to that of the Sun after about 1 Gyr of main--sequence lifetime and any decaying trend before or after this transition must be much less significant than the short term variations.Comment: 6 pages, 1 figure, to be published in Astrophysics and Space Scienc

The chromospheric emission of solar-type stars in the young open clusters IC 2391 and IC 2602

In this paper we present chromospheric emission levels of the solar-type stars in the young open clusters IC 2391 and IC 2602. High resolution spectroscopic data were obtained for over 50 F, G, and K stars from these clusters over several observing campaigns using the University College London Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope. Unlike older clusters, the majority (28/52) of the solar-type stars in the two clusters are rapid-rotators (vsini > 20 km/s) with five of the stars being classified as ultra-rapid rotators (vsini > 100 km/s). The emission levels in the Calcium infrared triplet lines were then used as a measure of the chromospheric activity of the stars. When plotted against Rossby number (NR) the star's chromospheric emission levels show a plateau in the emission for Log(NR) < -1.1 indicating chromospheric saturation similar to the coronal saturation seen in previously observed X-ray emission from the same stars. However, unlike the coronal emission, the chromospheric emission of the stars show little evidence of a reduction in emission (i.e. supersaturation) for the ultra-rapid rotators in the clusters. Thus we believe that coronal supersaturation is not the result of an overall decrease in magnetic dynamo efficiency for ultra-rapid rotators.Comment: 19 pages, 14 figures, Landscape tables in separate tex file, Accepted by MNRA

Measurement of the front-end dead-time of the LHCb muon detector and evaluation of its contribution to the muon detection inefficiency

A method is described which allows to deduce the dead-time of the front-end electronics of the LHCb muon detector from a series of measurements performed at different luminosities at a bunch-crossing rate of 20 MHz. The measured values of the dead-time range from 70 ns to 100 ns. These results allow to estimate the performance of the muon detector at the future bunch-crossing rate of 40 MHz and at higher luminosity

Anyone with a Long-Face? Craniofacial Evolutionary Allometry (CREA) in a Family of Short-Faced Mammals, the Felidae

Among adults of closely related species, a trend in craniofacial evolutionary allometry (CREA) for larger taxa to be long-faced and smaller ones to have paedomorphic aspects, such as proportionally smaller snouts and larger braincases, has been demonstrated in some mammals and two bird lineages. Nevertheless, whether this may represent a ‘rule’ with few exceptions is still an open question. In this context, Felidae is a particularly interesting family to study because, although its members are short-faced, previous research did suggest relative facial elongation in larger living representatives. Using geometric morphometrics, based on two sets of anatomical landmarks, and traditional morphometrics, for comparing relative lengths of the palate and basicranium, we performed a series of standard and comparative allometric regressions in the Felidae and its two subfamilies. All analyses consistently supported the CREA pattern, with only one minor exception in the geometric morphometric analysis of Pantherinae: the genus Neofelis. With its unusually long canines, Neofelis species seem to have a relatively narrow cranium and long face, despite being smaller than other big cats. In spite of this, overall, our findings strengthen the possibility that the CREA pattern might indeed be a ‘rule’ among mammals, raising questions on the processes behind it and suggesting future directions for its study

Performance of the LHCb muon system with cosmic rays

The LHCb Muon system performance is presented using cosmic ray events collected in 2009. These events allowed to test and optimize the detector configuration before the LHC start. The space and time alignment and the measurement of chamber efficiency, time resolution and cluster size are described in detail. The results are in agreement with the expected detector performance.Comment: Submitted to JINST and accepte

Inclusive production of ρ0(770),f0(980)\rho^{0}(770), f_0(980) and f2(1270)f_2(1270) mesons in νμ\nu_{\mu} charged current interactions

The inclusive production of the meson resonances $\rho^{0}(770)$, $f_0(980)$ and $f_2(1270)$ in neutrino-nucleus charged current interactions has been studied with the NOMAD detector exposed to the wide band neutrino beam generated by 450 GeV protons at the CERN SPS. For the first time the $f_{0}(980)$ meson is observed in neutrino interactions. The statistical significance of its observation is 6 standard deviations. The presence of $f_{2}(1270)$ in neutrino interactions is reliably established. The average multiplicity of these three resonances is measured as a function of several kinematic variables. The experimental results are compared to the multiplicities obtained from a simulation based on the Lund model. In addition, the average multiplicity of $\rho^{0}(770)$ in antineutrino - nucleus interactions is measured.Comment: 23 pages, 14 figures, 8 tables. To appear in Nucl. Phys.