Lichenometric dating (lichenometry) and the biology of the lichen genus rhizocarpon:challenges and future directions

Lichenometric dating (lichenometry) involves the use of lichen measurements to estimate the age of exposure of various substrata. Because of low radial growth rates and considerable longevity, species of the crustose lichen genus Rhizocarpon have been the most useful in lichenometry. The primary assumption of lichenometry is that colonization, growth and mortality of Rhizocarpon are similar on surfaces of known and unknown age so that the largest thalli present on the respective faces are of comparable age. This review describes the current state of knowledge regarding the biology of Rhizocarpon and considers two main questions: (1) to what extent does existing knowledge support this assumption; and (2) what further biological observations would be useful both to test its validity and to improve the accuracy of lichenometric dates? A review of the Rhizocarpon literature identified gaps in knowledge regarding early development, the growth rate/size curve, mortality, regeneration, competitive effects, colonization, and succession on rock surfaces. The data suggest that these processes may not be comparable on different rock surfaces, especially in regions where growth rates and thallus turnover are high. In addition, several variables could differ between rock surfaces and influence maximum thallus size, including rate and timing of colonization, radial growth rates, environmental differences, thallus fusion, allelopathy, thallus mortality, colonization and competition. Comparative measurements of these variables on surfaces of known and unknown age may help to determine whether the basic assumptions of lichenometry are valid. Ultimately, it may be possible to take these differences into account when interpreting estimated dates

Past and future adaptation pathways

Adaptation pathways are increasingly being used as a foresight tool to help guide the implementation of climate change adaptation and deliberate transformation. This paper applies a pathways lens as a hindsight tool to provide new understanding about past change and adaptation relevant for improving future adaptation pathways approaches. Four case studies of past adaptations to change are examined: Solomon Islands Communities, Canadian forest-dependent communities, a Transylvanian village, and responses to climate adaptation policies in Australia. The results highlight that responses to change in these diverse case studies involve complex transitions that gradually create new conditions and trajectories; manifest as multiple but inter-related pathways of change and response at different social or spatial scales (e.g. different paths for different households or communities); have legacies and continuities across time that affect future pathways of change; are affected by power in complex ways; and can create further change and need for adaptation. Analyses also highlight that when working with prospective adaptation approaches as a response to climate change there is a need to consider: (1) underlying assumptions, values and principles associated with the future; (2) the existence of inter-connected multiple pathways and their implications for reinforcing existing social inequalities; and (3) how understanding past change provides inspiration for new and transformative futures. Overall, the paper concludes that shifts towards analyses for change rather than simply about change, such as adaptation pathways, will require more careful consideration of underlying ontological assumptions about the relationships between past, present and future

Search for leptophobic Z ' bosons decaying into four-lepton final states in proton-proton collisions at root s=8 TeV

Peer reviewe

Search for black holes and other new phenomena in high-multiplicity final states in proton-proton collisions at root s=13 TeV

Peer reviewe

Search for high-mass diphoton resonances in proton-proton collisions at 13 TeV and combination with 8 TeV search

Peer reviewe

Search for heavy resonances decaying into a vector boson and a Higgs boson in final states with charged leptons, neutrinos, and b quarks

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Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV

Peer reviewe

Search for neutral resonances decaying into a Z boson and a pair of b jets or τ leptons

A search is performed for a new resonance decaying into a lighter resonance and a Z boson. Two channels are studied, targeting the decay of the lighter resonance into either a pair of oppositely charged τ leptons or a bb‾ pair. The Z boson is identified via its decays to electrons or muons. The search exploits data collected by the CMS experiment at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.8 fb −1 . No significant deviations are observed from the standard model expectation and limits are set on production cross sections and parameters of two-Higgs-doublet models