Evaluating Mesolithic settlement patterns in mountain environments (Dolomites, Eastern Italian Alps): the role of research biases and locational strategies

The wealth of Mesolithic evidence in the Alpine environments makes it possible to attempt a reconstruction of highland settlement patterns based on the distribution of known sites. However, just how representative this site distribution is has not yet been fully tested and the impact of research biases on the spatial organisation of Mesolithic findspots is not clear. In order to tackle these issues the locational pattern of Mesolithic sites recorded in an upland area of the Venetian Dolomites (North-Eastern Italy) was analysed. Point pattern analysis was used to correlate site distribution with two sets of covariates mirroring research biases and prehistoric settlement preferences. Point-process models were created and compared using both standard Akaike and Bayesian Information Criteria. Results indicate that both factors equally influence the current site distribution. The low number of statistically significant variables - slope and land-use - suggests the existence of additional variables that were not considered. An additional model helped us explore the importance of alternative variables and provided new perspectives for future investigation of high-altitude Mesolithic landscapes, with particular attention to highland mobility

Charm and beauty of the Large Hadron Collider

With the acceleration of lead nuclei in the LHC, heavy-ion physics will enter a new energy domain. One of the main novelties introduced by the 30-fold energy-jump from RHIC to the LHC is the abundant heavy-quark production. After discussing a few examples of physics issues that can be addressed using heavy quarks, we present a selection of results on the expected experimental capability of ALICE, the dedicated heavy-ion experiment at the LHC, in the open-heavy-flavour sector.Comment: 10 pages, 5 figures. Invited talk at Strangeness in Quark Matter (SQM) 2004, Cape Town, South Africa, 15-20 September 2004. Submitted to J. Phys.

Asymmetry determines the effects of natural ceramides on model membranes

Ceramides can dramatically influence the lateral organization of biological membranes. In particular, ceramide-induced alterations of protein-lipid domains can be involved in several cellular processes, ranging from senescence to immune response. In this context, an important role is played by the length of the fatty acid bound to the sphingosine moiety. Asymmetric, heterogeneous ceramides,with more than 20 or less than 16 carbon atoms in the fatty acyl chain, in fact exert diverging effects in vivo if compared to their symmetric counterparts. In this work, we investigated the role of ceramide asymmetry and heterogeneity in model membranes showing raft-like phase separation, using a combination of fluorescence imaging, atomic force microscopy, fluorescence correlation spectroscopy and differential scanning calorimetry. We show that ceramide produced enzymatically from natural mixtures of sphingomyelin can dramatically alter the mixing behaviour of proteins and lipids in the membrane, inducing a homogenization of the bilayer. Furthermore, we characterized the physical properties of coexisting lipid phases at equilibrium in membranes with varying ceramide content, emphasizing the differences between symmetric-homogeneous and asymmetric-heterogeneous ceramides. While symmetric ceramides always produce enhanced order, asymmetric ceramides display a more complex behavior similar to that of cholesterol. Our results might help contribute to a more precise understanding of the rearrangements induced by different kinds of ceramide generation in cellular membranes

Growth form and leaf habit drive contrasting effects of Arctic amplification in long-lived woody species

Current global change is inducing heterogeneous warming trends worldwide, with faster rates at higher latitudes in the Northern Hemisphere. Consequently, tundra vegetation is experiencing an increase in growth rate and uneven but expanding distribution. Yet, the drivers of this heterogeneity in woody species responses are still unclear. Here, applying a retrospective approach and focusing on long-term responses, we aim to get insight into growth trends and climate sensitivity of long-lived woody species belonging to different functional types with contrasting growth forms and leaf habits (shrub vs. tree and deciduous vs. evergreen). A total of 530 samples from 7 species (common juniper, dwarf birch, woolly willow, Norway spruce, lodgepole pine, rowan, and downy birch) were collected in 10 sites across Iceland. We modelled growth trends and contrasted yearly ring-width measurements, filtering in high- and low-frequency components, with precipitation, land- and sea-surface temperature records (1967-2018). Shrubs and trees showed divergent growth trends, with shrubs closely tracking the recent warming, whereas trees, especially broadleaved, showed strong fluctuations but no long-term growth trends. Secondary growth, particularly the high-frequency component, was positively correlated with summer temperatures for most of the species. On the contrary, growth responses to sea surface temperature, especially in the low frequency, were highly diverging between growth forms, with a strong positive association for shrubs and a negative for trees. Within comparable vegetation assemblage, long-lived woody species could show contrasting responses to similar climatic conditions. Given the predominant role of oceanic masses in shaping climate patterns in the Arctic and Low Arctic, further investigations are needed to deepen the knowledge on the complex interplay between coastal tundra ecosystems and land-sea surface temperature dynamics

Mouse Panx1 Is Dispensable for Hearing Acquisition and Auditory Function

Panx1 forms plasma membrane channels in brain and several other organs, including the inner ear. Biophysical properties, activation mechanisms and modulators of Panx1 channels have been characterized in detail, however the impact of Panx1 on auditory function is unclear due to conflicts in published results. To address this issue, hearing performance and cochlear function of the Panx1−/− mouse strain, the first with a reported global ablation of Panx1, were scrutinized. Male and female homozygous (Panx1−/−), hemizygous (Panx1+/−) and their wild type (WT) siblings (Panx1+/+) were used for this study. Successful ablation of Panx1 was confirmed by RT-PCR and Western immunoblotting in the cochlea and brain of Panx1−/− mice. Furthermore, a previously validated Panx1-selective antibody revealed strong immunoreactivity in WT but not in Panx1−/− cochleae. Hearing sensitivity, outer hair cell-based “cochlear amplifier” and cochlear nerve function, analyzed by auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) recordings, were normal in Panx1+/− and Panx1−/− mice. In addition, we determined that global deletion of Panx1 impacts neither on connexin expression, nor on gap-junction coupling in the developing organ of Corti. Finally, spontaneous intercellular Ca2+ signal (ICS) activity in organotypic cochlear cultures, which is key to postnatal development of the organ of Corti and essential for hearing acquisition, was not affected by Panx1 ablation. Therefore, our results provide strong evidence that, in mice, Panx1 is dispensable for hearing acquisition and auditory function

Hydraulic traits of Juniperus communis L. along elevations and European populations

Plant hydraulics play an important role in determining plant distribution and performance, by influencing their growth and productivity. Knowledge of the hydraulic amplitude and plasticity of species is thus a prerequisite for estimating future performance under climate change. We investigated hydraulic safety and efficiency in Juniperus communis L. to estimate its intra-specific hydraulic variability. We analysed plants growing along an elevational transect (700-2000 m a.s.l., Tyrol, Austria) and plants grown in a common garden experiment from seeds collected in various European regions (France, Austria, Ireland, Germany and Sweden). Vulnerability to drought-induced embolism (i.e. hydraulic safety) was assessed via Cavitron and ultrasonic acoustic emission techniques while specific hydraulic conductivity (i.e. hydraulic efficiency) was measured with a flow meter. Hydraulic safety (water potentials inducing 12, 50 and 88% loss of conductivity) and efficiency did not differ significantly neither across elevations nor between European provenancies. Common juniper proved to a be a species with high resistance to drouht stress and showed surprisingly homogenous hydraulic traits, despite sub-species are formed at higher elevation and plant morphology differed widely across provenancies. Due to its overall high hydraulic safety, this species can be considered as less susceptible to the effects of a warmer climate

Hard probes in heavy ion collisions at the LHC: heavy flavour physics

We present the results from the heavy quarks and quarkonia working group. This report gives benchmark heavy quark and quarkonium cross sections for $pp$ and $pA$ collisions at the LHC against which the $AA$ rates can be compared in the study of the quark-gluon plasma. We also provide an assessment of the theoretical uncertainties in these benchmarks. We then discuss some of the cold matter effects on quarkonia production, including nuclear absorption, scattering by produced hadrons, and energy loss in the medium. Hot matter effects that could reduce the observed quarkonium rates such as color screening and thermal activation are then discussed. Possible quarkonium enhancement through coalescence of uncorrelated heavy quarks and antiquarks is also described. Finally, we discuss the capabilities of the LHC detectors to measure heavy quarks and quarkonia as well as the Monte Carlo generators used in the data analysis.Comment: 126 pages Latex; 96 figures included. Subgroup report, to appear in the CERN Yellow Book of the workshop: Hard Probes in Heavy Ion Collisions at the LHC. See also http://a.home.cern.ch/f/frixione/www/hvq.html for a version with better quality for a few plot

Contrasting Impacts of Climate Warming on Coastal Old-Growth Tree Species Reveal an Early Warning of Forest Decline

Old-growth forests in the Pacific Northwest are being fundamentally altered by climate change. A primary example of this is yellow-cedar (Callitropsis nootkatensis), a culturally and economically important species, which has suffered widespread decline across its range since the beginning of the twentieth century. We used tree rings to compare the climate-growth response of yellow-cedar to two co-occurring species; western hemlock (Tsuga heterophylla) and Sitka spruce (Picea sitchensis), in an old-growth forest on Haida Gwaii, Canada, to better understand the unique climatic drivers of a species that is declining across its range. We developed three species-specific chronologies spanning 560–770 years, reconstructing a long-term record of species growth and dynamics over time. The climate is strongly influenced by the Pacific Decadal Oscillation (PDO), a multi-decadal pattern of ocean-atmospheric climate variability. Climate varied across three time periods that have coincided with major shifts in the PDO during the twentieth century [1901–1945 (neutral/positive), 1946–1976 (negative) and 1977–2015 (positive)]. Conditions were significantly warmer and wetter during positive phases, with the greatest maximum temperatures in the most recent period. We used complimentary methods of comparison, including Morlet wavelet analysis, Pearson correlations, and linear-mixed effects modeling to investigate the relations between climate and species growth. All three species exhibited multi-decadal frequency variation, strongest for yellow-cedar, suggesting the influence of the PDO. Consistent with this, the strength and direction of climate-growth correlations varied among PDO phases. Growing season temperature in the year of ring formation was strongly positively correlated to yellow-cedar and western hemlock growth, most significantly in the latter two time periods, representing a release from a temperature limitation. Sitka spruce growth was only weakly associated with climate. Yellow-cedar responded negatively to winter temperature from 1977 to 2015, consistent with the decline mechanism. Increased yellow-cedar mortality has been linked to warmer winters and snow loss. This study provides new insights into yellow-cedar decline, finding the first evidence of decline-related growth patterns in an apparently healthy, productive coastal temperate rainforest

A Comment on Conical Flow Induced by Heavy-Quark Jets

The suppression of high transverse momentum particles, recently discovered at RHIC, is commonly interpreted as due to parton energy loss. In high energy nuclear collisions, QCD jets would deposit a large fraction of their energy and into the produced matter. The question of how this energy is degraded and whether we can use this phenomenon to probe the properties of the produced matter is now under active discussion. It has been proposed that if this matter, which is now being referred to as a {\em strongly coupled Quark-Gluon Plasma} (sQGP), may behave as a liquid with a very small viscosity. In this case, a very specific collective excitation should be produced, called the ``conical flow'', similar e.g. to the sonic booms generated by the shock waves produced by supersonic planes. The RHIC experiments seem indeed to be obtaining some indication that the production of particles emitted opposite to a high-$p_t$ jet may actually be peaked away from the quenched jet direction, at an angle roughly consistent with the direction expected in case a shock wave is produced (i.e. orthogonal to the Mach cone). In this note we speculate that for tagged heavy-quark jets one may observe a shrinkage of the Mach cone at moderate $p_t$. The experimental observation of such an effect would be a very good test for the validity of the whole picture currently emerging from the study of partonic matter in nuclear collisions