Dynamics of leaf water relations components in co-occurring iso- and anisohydric conifer species

Because iso- and anisohydric species differ in stomatal regulation of the rate and magnitude of fluctuations in shoot water potential, they may be expected to show differences in the plasticity of their shoot water relations components, but explicit comparisons of this nature have rarely been made. We subjected excised shoots of co-occurring anisohydric Juniperus monosperma and isohydric Pinus edulis to pressure-volume analysis with and without prior artificial rehydration. In J. monosperma, the shoot water potential at turgor loss (Ψ[subscript TLP]) ranged from −3.4 MPa in artificially rehydrated shoots to −6.6 MPa in shoots with an initial Ψ of −5.5 MPa, whereas in P. edulis mean Ψ[subscript TLP] remained at ∼−3.0 MPa over a range of initial Ψ from −0.1 to −2.3 MPa.The shoot osmotic potential at full turgor and the bulk modulus of elasticity also declined sharply with shoot Ψ in J. monosperma, but not in P. edulis. The contrasting behaviour of J. monosperma and P. edulis reflects differences in their capacity for homeostatic regulation of turgor that may be representative of aniso- and isohydric species in general, and may also be associated with the greater capacity of J. monosperma to withstand severe drought.Keywords: osmotic potential, anisohydry, turgor, isohydry, droughtKeywords: osmotic potential, anisohydry, turgor, isohydry, drough

Expression of functional traits during seedling establishment in two populations of Pinus ponderosa from contrasting climates

First-year tree seedlings represent a particularly vulnerable life stage and successful seedling establishment is crucial for forest regeneration. We investigated the extent to which Pinus ponderosa P. & C. Lawson populations from different climate zones exhibit differential expression of functional traits that may facilitate their establishment. Seeds from two populations from sites with contrasting precipitation and temperature regimes east (PIPOdry) and west (PIPOmesic) of the Oregon Cascade mountains were sown in a common garden experiment and grown under two water availability treatments (control and drought). Aboveground biomass accumulation, vegetative phenology, xylem anatomy, plant hydraulic architecture, foliar stable carbon isotope ratios (δ13C), gas exchange and leaf water relations characteristics were measured. No treatment or population-related differences in leaf water potential were detected. At the end of the first growing season, aboveground biomass was 74 and 44% greater in PIPOmesic in the control and drought treatments, respectively. By early October, 73% of PIPOdry seedlings had formed dormant buds compared with only 15% of PIPOmesic seedlings. Stem theoretical specific conductivity, calculated from tracheid dimensions and packing density, declined from June through September and was nearly twice as high in PIPOmesic during most of the growing season, consistent with measured values of specific conductivity. Intrinsic water-use efficiency based on δ13C values was higher in PIPOdry seedlings for both treatments across all sampling dates. There was a negative relationship between values of δ13C and leaf-specific hydraulic conductivity across populations and treatments, consistent with greater stomatal constraints on gas exchange with declining seedling hydraulic capacity. Integrated growing season assimilation and stomatal conductance estimated from foliar δ13C values and photosynthetic CO2-response curves were 6 and 28% lower, respectively, in PIPOdry seedlings. Leaf water potential at the turgor loss point was 0.33 MPa more negative in PIPOdry, independent of treatment. Overall, PIPOdry seedlings exhibited more conservative behavior, suggesting reduced growth is traded off for increased resistance to drought and extreme temperatures.Keywords: gas exchange, carbon isotope discrimination, phenology, osmotic potential, hydraulic architecture, genetic variatio

Linking nonstructural carbohydrate dynamics to gas exchange and leaf hydraulic behavior in Pinus edulis and Juniperus monosperma

Leaf hydraulics, gas exchange and carbon storage in Pinus edulis and Juniperus monosperma, two tree species on opposite ends of the isohydry–anisohydry spectrum, were analyzed to examine relationships between hydraulic function and carbohydrate dynamics. Leaf hydraulic vulnerability, leaf water potential (Wl), leaf hydraulic conductance (Kleaf), photosynthesis (A), stomatal conductance (gs) and nonstructural carbohydrate (NSC) content were analyzed throughout the growing season. Leaf hydraulic vulnerability was significantly lower in the relatively anisohydric J. monosperma than in the more isohydric P. edulis. In P. edulis, ψ₁ dropped and stayed below 50% loss of leaf hydraulic conductance (P₅₀) early in the day during May, August and around midday in September, leading to sustained reductions in K[subscript leaf]. In J. monosperma, ψ₁ dropped below P₅₀ only during August, resulting in the maintenance of K[subscript leaf] during much of the growing season. Mean A and g[subscript s] during September were significantly lower in P. edulis than in J. monosperma. Foliar total NSC was two to three times greater in J. monosperma than in P. edulis in June, August and September. Consistently lower levels of total NSC in P. edulis suggest that its isohydric strategy pushes it towards the exhaustion of carbon reserves during much of the growing season.Keywords: Juniperus monosperma, Carbon storage, Leaf hydraulics, Pinus edulis, Carbon starvation, Growth limitation, Nonstructural carbohydrate (NSC), Drough

Impacts of dwarf mistletoe on the physiology of host Tsuga heterophylla trees as recorded in tree-ring C and O stable isotopes

See article for Abstract. Keywords: mesophyll conductance, effective path lengt

Playing Games with Tito:Designing Hybrid Museum Experiences for Critical Play

This article brings together two distinct, but related perspectives on playful museum experiences: Critical play and hybrid design. The article explores the challenges involved in combining these two perspectives, through the design of two hybrid museum experiences that aimed to facilitate critical play with/in the collections of the Museum of Yugoslavia and the highly contested heritage they represent. Based on reflections from the design process as well as feedback from test users, we describe a series of challenges: Challenging the norms of visitor behaviour, challenging the role of the artefact, and challenging the curatorial authority. In conclusion, we outline some possible design strategies to address these challenges

Efficient Physical Embedding of Topologically Complex Information Processing Networks in Brains and Computer Circuits

Nervous systems are information processing networks that evolved by natural selection, whereas very large scale integrated (VLSI) computer circuits have evolved by commercially driven technology development. Here we follow historic intuition that all physical information processing systems will share key organizational properties, such as modularity, that generally confer adaptivity of function. It has long been observed that modular VLSI circuits demonstrate an isometric scaling relationship between the number of processing elements and the number of connections, known as Rent's rule, which is related to the dimensionality of the circuit's interconnect topology and its logical capacity. We show that human brain structural networks, and the nervous system of the nematode C. elegans, also obey Rent's rule, and exhibit some degree of hierarchical modularity. We further show that the estimated Rent exponent of human brain networks, derived from MRI data, can explain the allometric scaling relations between gray and white matter volumes across a wide range of mammalian species, again suggesting that these principles of nervous system design are highly conserved. For each of these fractal modular networks, the dimensionality of the interconnect topology was greater than the 2 or 3 Euclidean dimensions of the space in which it was embedded. This relatively high complexity entailed extra cost in physical wiring: although all networks were economically or cost-efficiently wired they did not strictly minimize wiring costs. Artificial and biological information processing systems both may evolve to optimize a trade-off between physical cost and topological complexity, resulting in the emergence of homologous principles of economical, fractal and modular design across many different kinds of nervous and computational networks

Years of life lost and morbidity cases attributable to transportation noise and air pollution : a comparative health risk assessment for Switzerland in 2010

There is growing evidence that chronic exposure to transportation related noise and air pollution affects human health. However, health burden to a country of these two pollutants have been rarely compared.; As an input for external cost quantification, we estimated the cardiorespiratory health burden from transportation related noise and air pollution in Switzerland, incorporating the most recent findings related to the health effects of noise.; Spatially resolved noise and air pollution models for the year 2010 were derived for road, rail and aircraft sources. Average day-evening-night sound level (Lden) and particulate matter (PM10) were selected as indicators, and population-weighted exposures derived by transportation source. Cause-specific exposure-response functions were derived from a meta-analysis for noise and literature review for PM10. Years of life lost (YLL) were calculated using life table methods; population attributable fraction was used for deriving attributable cases for hospitalisations, respiratory illnesses, visits to general practitioners and restricted activity days.; The mean population weighted exposure above a threshold of 48dB(A) was 8.74dB(A), 1.89dB(A) and 0.37dB(A) for road, rail and aircraft noise. Corresponding mean exposure contributions were 4.4, 0.54, 0.12μg/m(3) for PM10. We estimated that in 2010 in Switzerland transportation caused 6000 and 14,000 YLL from noise and air pollution exposure, respectively. While there were a total of 8700 cardiorespiratory hospital days attributed to air pollution exposure, estimated burden due to noise alone amounted to 22,500 hospital days.; YLL due to transportation related pollution in Switzerland is dominated by air pollution from road traffic, whereas consequences for morbidity and indicators of quality of life are dominated by noise. In terms of total external costs the burden of noise equals that of air pollution

Non-structural carbohydrates in woody plants compared among laboratories

Non-structural carbohydrates (NSC) in plant tissue are frequently quantified to make inferences about plant responses to environmental conditions. Laboratories publishing estimates of NSC of woody plants use many different methods to evaluate NSC. We asked whether NSC estimates in the recent literature could be quantitatively compared among studies. We also asked whether any differences among laboratories were related to the extraction and quantification methods used to determine starch and sugar concentrations. These questions were addressed by sending sub-samples collected from five woody plant tissues, which varied in NSC content and chemical composition, to 29 laboratories. Each laboratory analyzed the samples with their laboratory-specific protocols, based on recent publications, to determine concentrations of soluble sugars, starch and their sum, total NSC. Laboratory estimates differed substantially for all samples. For example, estimates for Eucalyptus globulus leaves (EGL) varied from 23 to 116 (mean = 56) mg g⁻¹ for soluble sugars, 6–533 (mean = 94) mg g⁻¹ for starch and 53–649 (mean = 153) mg g⁻¹ for total NSC. Mixed model analysis of variance showed that much of the variability among laboratories was unrelated to the categories we used for extraction and quantification methods (method category R² = 0.05–0.12 for soluble sugars, 0.10–0.33 for starch and 0.01–0.09 for total NSC). For EGL, the difference between the highest and lowest least squares means for categories in the mixed model analysis was 33 mg g⁻¹ for total NSC, compared with the range of laboratory estimates of 596 mg g⁻¹. Laboratories were reasonably consistent in their ranks of estimates among tissues for starch (r = 0.41–0.91), but less so for total NSC (r = 0.45–0.84) and soluble sugars (r = 0.11–0.83). Our results show that NSC estimates for woody plant tissues cannot be compared among laboratories. The relative changes in NSC between treatments measured within a laboratory may be comparable within and between laboratories, especially for starch. To obtain comparable NSC estimates, we suggest that users can either adopt the reference method given in this publication, or report estimates for a portion of samples using the reference method, and report estimates for a standard reference material. Researchers interested in NSC estimates should work to identify and adopt standard methods.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Oxford University Press. The published article can be found at: http://treephys.oxfordjournals.org/Keywords: soluble sugars, starch, particle size, reference method, standardization, non-structural carbohydrate chemical analysis, extraction and quantification consistenc

Solid state growth of piezoelectric single crystals

Solid state single crystal growth (SSCG) is a promising alternative to melt growth methods for obtaining single crystals. SSCG has many benefits including cost effectiveness, producing crystals with no composition gradient and allowing the growth of crystals that are difficult to obtain due to incongruent melting points. This method is based on the abnormal grain growth that occurs naturally when only a small amount of liquid phase is introduced upon sintering. Therefore, as the material does not have to be completely in liquid form the temperature required is reduced. Abnormal grain growth allows a few large grains to grow at a much higher rate, scavenging the matrix grains. This accelerated growth is only stopped when the large grains impinge upon one another. Crystal seeds may be used in the place of abnormal grains and if abnormal grain growth in the matrix is prevented the crystal may grow without impingement for the time allowed. Here, the results of both grain growth and crystal growth experiments using BaTiO3, (Bax,Cax-1)(Tiy,Zry-1 )O3 and Ba(Tix,Zrx-1)O3 are presented. BaTiO3 single crystals have been successfully grown and crystal growth has been observed in (Bax,Cax-1)(Tiy,Zry-1 )O3, Ba(Tix,Zrx-1)O3 and in preliminary experiments using Pb(Tix,Zrx-1)O3