710 research outputs found
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
Measuring beauty production in Pb-Pb collisions at the LHC via single electrons in ALICE
We present the expected ALICE performance for the measurement of the
p_t-differential cross section of electrons from beauty decays in central Pb-Pb
collisions at the LHC.Comment: 4 pages, 2 figures, proceeding of poster presentation at "Quark
Matter 2005
Etnoarcheologia dei paesaggi alpini di alta quota nelle Alpi occidentali: un bilancio preliminare
The study of the interaction between human groups and mountain environment is crucial for archaeological research. Ethnoarchaeology contributes the analysis of this interaction in modern and contemporary contexts, aimed at creating analogical models for interpreting the past and understanding human strategies in historical and modern periods. The EthWAL project (Ethnoarchaeology of Western Alpine upland Landscapes), started in 2013, and aims to be a reference for the study of human activities in the alpine uplands during the modern and contemporary age. This is a multidisciplinary (associating archaeological methods to ethnography, historiography, spatial analysis and soil analysis) and multiscalar project (small to large scale). Specific attention is given to traditional pastoral huts. The results of this project will be useful for archaeology and contribute to the management of cultural heritage in high altitude landscapes
Transient Effects of Snow Cover Duration on Primary Growth and Leaf Traits in a Tundra Shrub
With the recent climate warming, tundra ecotones are facing a progressive acceleration of spring snowpack melting and extension of the growing season, with evident consequences to vegetation. Along with summer temperature, winter precipitation has been recently recognised as a crucial factor for tundra shrub growth and physiology. However, gaps of knowledge still exist on long-living plant responses to different snowpack duration, especially on how intra-specific and year-to-year variability together with multiple functional trait adjustments could influence the long-term responses. To fill this gap, we conducted a 3 years snow manipulation experiment above the Alpine treeline on the typical tundra species Juniperus communis, the conifer with the widest distributional range in the north emisphere. We tested shoot elongation, leaf area, stomatal density, leaf dry weight and leaf non-structural carbohydrate content of plants subjected to anticipated, natural and postponed snowpack duration. Anticipated snowpack melting enhanced new shoot elongation and increased stomatal density. However, plants under prolonged snow cover seemed to compensate for the shorter growing period, likely increasing carbon allocation to growth. In fact, these latter showed larger needles and low starch content at the beginning of the growing season. Variability between treatments slightly decreased over time, suggesting a progressive acclimation of juniper to new conditions. In the context of future warming scenarios, our results support the hypothesis of shrub biomass increase within the tundra biome. Yet, the picture is still far from being complete and further research should focus on transient and fading effects of changing conditions in the long term
Radial Growth of Qilian Juniper on the Northeast Tibetan Plateau and Potential Climate Associations
There is controversy regarding the limiting climatic factor for tree radial growth at the alpine treeline on the northeastern Tibetan Plateau. In this study, we collected 594 increment cores from 331 trees, grouped within four altitude belts spanning the range 3550 to 4020 m.a.s.l. on a single hillside. We have developed four equivalent ring-width chronologies and shown that there are no significant differences in their growth-climate responses during 1956 to 2011 or in their longer-term growth patterns during the period AD 1110â2011. The main climate influence on radial growth is shown to be precipitation variability. Missing ring analysis shows that tree radial growth at the uppermost treeline location is more sensitive to climate variation than that at other elevations, and poor tree radial growth is particularly linked to the occurrence of serious drought events. Hence water limitation, rather than temperature stress, plays the pivotal role in controlling the radial growth of Sabina przewalskii Kom. at the treeline in this region. This finding contradicts any generalisation that tree-ring chronologies from high-elevation treeline environments are mostly indicators of temperature changes
Moisture-driven shift in the climate sensitivity of white spruce xylem anatomical traits is coupled to large-scale oscillation patterns across northern treeline in northwest North America
Tree growth at northern treelines is generally temperature-limited due to cold and short growing seasons. However, temperature-induced drought stress was repeatedly reported for certain regions of the boreal forest in northwestern North America, provoked by a significant increase in temperature and possibly reinforced by a regime shift of the pacific decadal oscillation (PDO). The aim of this study is to better understand physiological growth reactions of white spruce, a dominant species of the North American boreal forest, to PDO regime shifts using quantitative wood anatomy and traditional tree-ring width (TRW) analysis. We investigated white spruce growth at latitudinal treeline across a >1,000\ua0km gradient in northwestern North America. Functionally important xylem anatomical traits (lumen area, cell-wall thickness, cell number) and TRW were correlated with the drought-sensitive standardized precipitation-evapotranspiration index of the growing season. Correlations were computed separately for complete phases of the PDO in the 20th century, representing alternating warm/dry (1925-1946), cool/wet (1947-1976) and again warm/dry (1977-1998) climate regimes. Xylem anatomical traits revealed water-limiting conditions in both warm/dry PDO regimes, while no or spatially contrasting associations were found for the cool/wet regime, indicating a moisture-driven shift in growth-limiting factors between PDO periods. TRW reflected only the last shift of 1976/1977, suggesting different climate thresholds and a higher sensitivity to moisture availability of xylem anatomical traits compared to TRW. This high sensitivity of xylem anatomical traits permits to identify first signs of moisture-driven growth in treeline white spruce at an early stage, suggesting quantitative wood anatomy being a powerful tool to study climate change effects in the northwestern North American treeline ecotone. Projected temperature increase might challenge growth performance of white spruce as a key component of the North American boreal forest biome in the future, when drier conditions are likely to occur with higher frequency and intensity
Complementarity in the adoption of traceability of beef cattle in Brazil.
Complementarity is an interesting approach to explain technology adoption. Taking account the other activities the farm performs in its production strategy can help understanding the decision on the adoption of new agricultural technology. This paper aims to evidence the existence of synergic effect resulting from the joint adoption of feedlot and traceability certification of beef cattle in Brazil. A sample of 84 beef cattle farms provided data to test hypotheses by using an OLS regression model. A measure of performance ? revenue ? is regressed on variables representing both isolated and joint adoption of capital-intensive production system and traceability. The results suggest the existence of synergic effect when joint adoption takes place. Joint adoption is influenced by a set of management practices, such as forward contracts, training of employees and zootechnical performance control, which are shared by both capital-intensive production systems and traceability
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- 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 . 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
New criteria for the molecular identification of cereal grains associated with archaeological artefacts.
The domestication and transmission of cereals is one of the most fundamental components of early farming, but direct evidence of their use in early culinary practices and economies has remained frustratingly elusive. Using analysis of a well-preserved Early Bronze Age wooden container from Switzerland, we propose novel criteria for the identification of cereal residues. Using gas chromatography mass spectrometry (GC-MS), we identified compounds typically associated with plant products, including a series of phenolic lipids (alkylresorcinols) found only at appreciable concentration in wheat and rye bran. The value of these lipids as cereal grain biomarkers were independently corroborated by the presence of macrobotanical remains embedded in the deposit, and wheat and rye endosperm peptides extracted from residue. These findings demonstrate the utility of a lipid-based biomarker for wheat and rye bran and offer a methodological template for future investigations of wider range of archaeological contexts. Alkylresorcinols provide a new tool for residue analysis which can help explore the spread and exploitation of cereal grains, a fundamental component of the advent and spread of farming
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