A novel stochastic method for reconstructing daily precipitation times-series using tree-ring data from the western Canadian Boreal Forest

Tree ring data provide proxy records of historical hydroclimatic conditions that are widely used for reconstructing precipitation time series. Most previous applications are limited to annual time scales, though information about daily precipitation would enable a range of additional analyses of environmental processes to be investigated and modelled. We used statistical downscaling to simulate stochastic daily precipitation ensembles using dendrochronological data from the western Canadian boreal forest. The simulated precipitation series were generally consistent with observed precipitation data, though reconstructions were poorly constrained during short periods of forest pest outbreaks. The proposed multiple temporal scale precipitation reconstruction can generate annual daily maxima and persistent monthly wet and dry episodes, so that the observed and simulated ensembles have similar precipitation characteristics (i.e. magnitude, peak, and duration)—an improvement on previous modelling studies. We discuss how ecological disturbances may limit reconstructions by inducing non-linear responses in tree growth, and conclude with suggestions of possible applications and further development of downscaling methods for dendrochronological data

Tree rings provide early warning signals of jack pine mortality across a moisture gradient in the southern boreal forest

Recent declines in productivity and tree survival have been widely observed in boreal forests. We used early warning signals (EWS) in tree ring data to anticipate premature mortality in jack pine (Pinus banksiana) - an extensive and dominant species occurring across the moisture-limited southern boreal forest in North America. We sampled tree rings from 113 living and 84 dead trees in three soil moisture regimes (subxeric, submesic, subhygric) in central Saskatchewan, Canada. We reconstructed annual increments of tree basal area to investigate (1) whether we could detect EWS related to mortality of individual trees, and (2) how water availability and tree growth history may explain the mortality warning signs. EWS were evident as punctuated changes in growth patterns prior to transition to an alternative state of reduced growth before dying. This transition was likely triggered by a combination of severe drought and insect outbreak. Higher moisture availability associated with a soil moisture gradient did not appear to reduce tree sensitivity to stress-induced mortality. Our results suggest tree rings offer considerable potential for detecting critical transitions in tree growth, which are linked to premature mortality

Rethinking the social impacts of the arts

The paper presents a critical discussion of the current debate over the social impacts of the arts in the UK. It argues that the accepted understanding of the terms of the debate is rooted in a number of assumptions and beliefs that are rarely questioned. The paper goes on to present the interim findings of a three‐year research project, which aims to rethink the social impact of the arts, with a view to determining how these impacts might be better understood. The desirability of a historical approach is articulated, and a classification of the claims made within the Western intellectual tradition for what the arts “do” to people is presented and discussed

Institutional creativity and pathologies of potential space: The modern university

This paper proposes the applicability of object relations psychoanalytic conceptions of dialogue (Ogden, 1986, 1993) to thinking about relationships and relational structures and their governance in universities. It proposes that: the qualities of dialogic relations in creative institutions are the proper index of creative productivity; that is of, as examples, ’thinking’ (Evans, 2004), ’emotional learning’ (Salzberger-Wittenburg et al., 1983) or ’criticality’ (Barnett, 1997); contemporary institutions’ explicit preoccupation in assuring, monitoring and managing creative ’dialogue’ can, in practice, pervert creative processes and thoughtful symbolic productivity, thus inhibiting students’ development and the quality of ’thinking space’ for teaching and research. In this context the paper examines uncanny and perverse connections between Paulo Freire’s (1972) account of educational empowerment and dialogics (from his Pedagogy of the oppressed) to the consumerist (see, for example, Clarke & Vidler, 2005) rhetoric of student empowerment, as mediated by some strands of managerialism in contemporary higher education. The paper grounds its critique of current models of dialogue, feedback loops, audit and other mechanisms of accountability (Power, 1997; Strathern, 2000), in a close analysis of how creative thinking emerges. The paper discusses the failure to maintain a dialogic space in humanities and social science areas in particular, exploring psychoanalytic conceptions from Donald Winnicott (1971), Milner (1979), Thomas Ogden (1986) and Csikszentmihalyi (1997). Coleridge’s ideas about imagination as the movement of thought between subjective and objective modes are discussed in terms of both intra- and inter-subjective relational modes of ’dialogue’, which are seen as subject to pathology in the pathologically structured psychosocial environment. Current patterns of institutional governance, by micromanaging dialogic spaces, curtail the ’natural’ rhythms and temporalities of imagination by giving an over-emphasis to the moment of outcome, at the expense of holding the necessary vagaries of process in the institutional ’mind’. On the contrary, as this paper argues, creative thinking lies in sporadic emergences at the conjunction of object/(ive) outcome and through (thought) processes

Spinal afferent neurons projecting to the rat lung and pleura express acid sensitive channels

BACKGROUND: The acid sensitive ion channels TRPV1 (transient receptor potential vanilloid receptor-1) and ASIC3 (acid sensing ion channel-3) respond to tissue acidification in the range that occurs during painful conditions such as inflammation and ischemia. Here, we investigated to which extent they are expressed by rat dorsal root ganglion neurons projecting to lung and pleura, respectively. METHODS: The tracer DiI was either injected into the left lung or applied to the costal pleura. Retrogradely labelled dorsal root ganglion neurons were subjected to triple-labelling immunohistochemistry using antisera against TRPV1, ASIC3 and neurofilament 68 (marker for myelinated neurons), and their soma diameter was measured. RESULTS: Whereas 22% of pulmonary spinal afferents contained neither channel-immunoreactivity, at least one is expressed by 97% of pleural afferents. TRPV1(+)/ASIC3(- )neurons with probably slow conduction velocity (small soma, neurofilament 68-negative) were significantly more frequent among pleural (35%) than pulmonary afferents (20%). TRPV1(+)/ASIC3(+ )neurons amounted to 14 and 10% respectively. TRPV1(-)/ASIC3(+ )neurons made up between 44% (lung) and 48% (pleura) of neurons, and half of them presumably conducted in the A-fibre range (larger soma, neurofilament 68-positive). CONCLUSION: Rat pleural and pulmonary spinal afferents express at least two different acid-sensitive channels that make them suitable to monitor tissue acidification. Patterns of co-expression and structural markers define neuronal subgroups that can be inferred to subserve different functions and may initiate specific reflex responses. The higher prevalence of TRPV1(+)/ASIC3(- )neurons among pleural afferents probably reflects the high sensitivity of the parietal pleura to painful stimuli

Acid-evoked Ca2+ signalling in rat sensory neurones: effects of anoxia and aglycaemia

Ischaemia excites sensory neurones (generating pain) and promotes calcitonin gene-related peptide release from nerve endings. Acidosis is thought to play a key role in mediating excitation via the activation of proton-sensitive cation channels. In this study, we investigated the effects of acidosis upon Ca2+ signalling in sensory neurones from rat dorsal root ganglia. Both hypercapnic (pHo 6.8) and metabolic–hypercapnic (pHo 6.2) acidosis caused a biphasic increase in cytosolic calcium concentration ([Ca2+]i). This comprised a brief Ca2+ transient (half-time approximately 30 s) caused by Ca2+ influx followed by a sustained rise in [Ca2+]i due to Ca2+ release from caffeine and cyclopiazonic acid-sensitive internal stores. Acid-evoked Ca2+ influx was unaffected by voltage-gated Ca2+-channel inhibition with nickel and acid sensing ion channel (ASIC) inhibition with amiloride but was blocked by inhibition of transient receptor potential vanilloid receptors (TRPV1) with (E)-3-(4-t-butylphenyl)-N-(2,3-dihydrobenzo[b][1,4] dioxin-6-yl)acrylamide (AMG 9810; 1 μM) and N-(4-tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl) tetrahydropryazine-1(2H)-carbox-amide (BCTC; 1 μM). Combining acidosis with anoxia and aglycaemia increased the amplitude of both phases of Ca2+ elevation and prolonged the Ca2+ transient. The Ca2+ transient evoked by combined acidosis, aglycaemia and anoxia was also substantially blocked by AMG 9810 and BCTC and, to a lesser extent, by amiloride. In summary, the principle mechanisms mediating increase in [Ca2+]i in response to acidosis are a brief Ca2+ influx through TRPV1 followed by sustained Ca2+ release from internal stores. These effects are potentiated by anoxia and aglycaemia, conditions also prevalent in ischaemia. The effects of anoxia and aglycaemia are suggested to be largely due to the inhibition of Ca2+-clearance mechanisms and possible increase in the role of ASICs

Comparison of Tree-Ring and Eddy-Covariance Derived Annual Ecosystem Production Estimates for Jack Pine and Trembling Aspen Forests in Saskatchewan, Canada

Reliable projections of future carbon (C) dynamics are essential to resource management decision making under a changing climate. Additional corroborative data may reduce uncertainty in C flux estimates. Here we use a tree-ring based hybrid biometric modelling approach to estimate annual ecosystem production at jack pine (Pinus banksiana) and aspen (Populus tremuloides and Populus balsamifera) plots co-located with eddy-covariance installations in the boreal forest of Saskatchewan, Canada for a 28 year (1985 to 2012) period. Correspondence between tree-ring and eddy-covariance derived estimates was better for jack pine (14-year overlap, 1999 to 2012) than aspen (16-year overlap, 1997 to 2012), and better for some C fluxes than others. In particular, tree-ring estimates of annual and cumulative net ecosystem production were larger than eddy-covariance derived estimates for the overlapping period. Allometric equations, belowground production, and biomass turnover could neither be confirmed nor ruled out as causes of discrepancy, but a lower stand density and higher carbon use efficiency would together reduce observed differences for aspen. Tree-ring based estimates of biomass increment or net primary production showed good temporal correspondences with both current and previous year eddy-covariance analogues, and net and gross primary production. Similar comparisons for net ecosystem production and heterotrophic respiration had mixed results. This study improves on previous work by comparing independent estimates of the same fluxes quantities and demonstrates the value of tree-ring data for evaluating C flux estimates

Political Playwriting:The Art of Thinking in Public

The article reflects on the nature of the political in theatre, assessing the notion that theatre is the last free public space and evaluating the claims to be political of rival, problematic modes of writing-the theatre of fact or verbatim theatre and the allegorical late plays of Bond, Pinter and Churchill, turning to consider the problematic legacy of Brecht, the avatar of the political. The discussion turns to writers often excluded from the political nomenclature, developing the notion of the centrality of critique and offering an argument for the Naturalist writers as propagators of true 'thinking aloud', thereby suggesting they provide a model for theatre as such. The piece concludes with a discussion of the author's own contribution to the genre in the light of these analyses