Measuring poverty in Britain as a multi-dimensional concept, 1991 to 2003

While poverty is widely accepted to be an inherently multi-dimensional concept, it has proved very difficult to develop measures that both capture this multi-dimensionality and facilitate comparison of trends over time. Structural equation modelling appears to offer a solution to this conundrum and is used to exploit the British Household Panel Study to create a multi-dimensional measure of poverty. The analysis reveals that the decline in poverty in Britain between 1991 and 2003 was driven by falls in material deprivation, but more especially by reduced financial stress, particularly during the early 1990s. The limitations and potential of the new approach are critically discussed. © 2008 Cambridge University Press

Horses with equine recurrent uveitis have an activated CD4+ T-cell phenotype that can be modulated by mesenchymal stem cells in vitro.

Equine recurrent uveitis (ERU) is an immune-mediated disease causing repeated or persistent inflammatory episodes which can lead to blindness. Currently, there is no cure for horses with this disease. Mesenchymal stem cells (MSCs) are effective at reducing immune cell activation in vitro in many species, making them a potential therapeutic option for ERU. The objectives of this study were to define the lymphocyte phenotype of horses with ERU and to determine how MSCs alter T-cell phenotype in vitro. Whole blood was taken from 7 horses with ERU and 10 healthy horses and peripheral blood mononuclear cells were isolated. The markers CD21, CD3, CD4, and CD8 were used to identify lymphocyte subsets while CD25, CD62L, Foxp3, IFNγ, and IL10 were used to identify T-cell phenotype. Adipose-derived MSCs were expanded, irradiated (to control proliferation), and incubated with CD4+ T-cells from healthy horses, after which lymphocytes were collected and analyzed via flow cytometry. The percentages of T-cells and B-cells in horses with ERU were similar to normal horses. However, CD4+ T-cells from horses with ERU expressed higher amounts of IFNγ indicating a pro-inflammatory Th1 phenotype. When co-incubated with MSCs, activated CD4+ T-cells reduced expression of CD25, CD62L, Foxp3, and IFNγ. MSCs had a lesser ability to decrease activation when cell-cell contact or prostaglandin signaling was blocked. MSCs continue to show promise as a treatment for ERU as they decreased the CD4+ T-cell activation phenotype through a combination of cell-cell contact and prostaglandin signaling

Forest Composition Change and Biophysical Climate Feedbacks Across Boreal North America

Deciduous tree cover is expected to increase in North American boreal forests with climate warming and wildfire. This shift in composition has the potential to generate biophysical cooling via increased land surface albedo. Here we use Landsat-derived maps of continuous tree canopy cover and deciduous fractional composition to assess albedo change over recent decades. We find, on average, a small net decrease in deciduous fraction from 2000 to 2015 across boreal North America and from 1992 to 2015 across Canada, despite extensive fire disturbance that locally increased deciduous vegetation. We further find near-neutral net biophysical change in radiative forcing associated with albedo when aggregated across the domain. Thus, while there have been widespread changes in forest composition over the past several decades, the net changes in composition and associated post-fire radiative forcing have not induced systematic negative feedbacks to climate warming over the spatial and temporal scope of our study

Impacts of Climate and Insect Herbivory on Productivity and Physiology of Trembling Aspen (Populus tremuloides) in Alaskan Boreal Forests

Climate change is impacting forested ecosystems worldwide, particularly in the Northern Hemisphere where warming has increased at a faster rate than the rest of the globe. As climate warms, trembling aspen (Populus tremuloides) is expected to become more successful in northern boreal forests because of its current presence in drier areas of North America. However, large-scale productivity decline of aspen has recently been documented throughout the United States and Canada as a result of drought and insect outbreaks. We used tree ring measurements (basal area increment (BAI) and stable carbon isotopes (δ 13C)) and remote sensing indices of vegetation productivity (NDVI) to study the impact of climate and damage by the aspen epidermal leaf miner (Phyllocnistis populiella) on aspen productivity and physiology in interior Alaska. We found that productivity decreased with greater leaf mining and was not sensitive to growing season (GS) moisture availability. Although productivity decreased during high leaf mining years, it recovered to pre-outbreak levels during years of low insect damage, suggesting a degree of resilience to P. populiella mining. Climate and leaf mining interacted to influence tree ring δ 13C, with greater leaf mining resulting in decreased δ 13C when GS moisture availability was low. We also found that NDVI was negatively associated with leaf mining, and positively correlated with BAI and the δ 13C decrease corresponding to mining. This suggests that NDVI is capturing not only variations in productivity, but also changes in physiology associated with P. populiella. Overall, these findings indicate that the indirect effects of P. populiella mining have a larger impact on aspen productivity and physiology than climate under current conditions, and is essential to consider when assessing growth, physiology and NDVI trends in interior Alaska

Bottom-up drivers of future fire regimes in western boreal North America

Forest characteristics, structure, and dynamics within the North American boreal region are heavily influenced by wildfire intensity, severity, and frequency. Increasing temperatures are likely to result in drier conditions and longer fire seasons, potentially leading to more intense and frequent fires. However, an increase in deciduous forest cover is also predicted across the region, potentially decreasing flammability. In this study, we use an individual tree-based forest model to test bottom-up (i.e. fuels) vs top-down (i.e. climate) controls on fire activity and project future forest and wildfire dynamics. The University of Virginia Forest Model Enhanced is an individual tree-based forest model that has been successfully updated and validated within the North American boreal zone. We updated the model to better characterize fire ignition and behavior in relation to litter and fire weather conditions, allowing for further interactions between vegetation, soils, fire, and climate. Model output following updates showed good agreement with combustion observations at individual sites within boreal Alaska and western Canada. We then applied the updated model at sites within interior Alaska and the Northwest Territories to simulate wildfire and forest response to climate change under moderate (RCP 4.5) and extreme (RCP 8.5) scenarios. Results suggest that changing climate will act to decrease biomass and increase deciduous fraction in many regions of boreal North America. These changes are accompanied by decreases in fire probability and average fire intensity, despite fuel drying, indicating a negative feedback of fuel loading on wildfire. These simulations demonstrate the importance of dynamic fuels and dynamic vegetation in predicting future forest and wildfire conditions. The vegetation and wildfire changes predicted here have implications for large-scale changes in vegetation composition, biomass, and wildfire severity across boreal North America, potentially resulting in further feedbacks to regional and even global climate and carbon cycling

Bottom-Up Drivers of Future Fire Regimes in Western Boreal North America

Forest characteristics, structure, and dynamics within the North American boreal region are heavily influenced by wildfire intensity, severity, and frequency. Increasing temperatures are likely to result in drier conditions and longer fire seasons, potentially leading to more intense and frequent fires. However, an increase in deciduous forest cover is also predicted across the region, potentially decreasing flammability. In this study, we use an individual tree-based forest model to test bottom-up (i.e. fuels) vs top-down (i.e. climate) controls on fire activity and project future forest and wildfire dynamics. The University of Virginia Forest Model Enhanced is an individual tree-based forest model that has been successfully updated and validated within the North American boreal zone. We updated the model to better characterize fire ignition and behavior in relation to litter and fire weather conditions, allowing for further interactions between vegetation, soils, fire, and climate. Model output following updates showed good agreement with combustion observations at individual sites within boreal Alaska and western Canada. We then applied the updated model at sites within interior Alaska and the Northwest Territories to simulate wildfire and forest response to climate change under moderate (RCP 4.5) and extreme (RCP 8.5) scenarios. Results suggest that changing climate will act to decrease biomass and increase deciduous fraction in many regions of boreal North America. These changes are accompanied by decreases in fire probability and average fire intensity, despite fuel drying, indicating a negative feedback of fuel loading on wildfire. These simulations demonstrate the importance of dynamic fuels and dynamic vegetation in predicting future forest and wildfire conditions. The vegetation and wildfire changes predicted here have implications for large-scale changes in vegetation composition, biomass, and wildfire severity across boreal North America, potentially resulting in further feedbacks to regional and even global climate and carbon cycling

Patterns of Ecosystem Structure and Wildfire Carbon Combustion Across Six Ecoregions of the North American Boreal Forest

Increases in fire frequency, extent, and severity are expected to strongly impact the structure and function of boreal forest ecosystems. An important function of the boreal forest is its ability to sequester and store carbon (C). Increasing disturbance from wildfires, emitting large amounts of C to the atmosphere, may create a positive feedback to climate warming. Variation in ecosystem structure and function throughout the boreal forest is important for predicting the effects of climate warming and changing fire regimes on C dynamics. In this study, we compiled data on soil characteristics, stand structure, pre-fire C pools, C loss from fire, and the potential drivers of these C metrics from 527 sites distributed across six ecoregions of North America’s western boreal forests. We assessed structural and functional differences between these fire-prone ecoregions using data from 417 recently burned sites (2004–2015) and estimated ecoregion-specific relationships between soil characteristics and depth from 167 of these sites plus an additional 110 sites (27 burned, 83 unburned). We found that northern boreal ecoregions were generally older, stored and emitted proportionally more belowground than aboveground C, and exhibited lower rates of C accumulation over time than southern ecoregions. We present ecoregion-specific estimates of depth-wise soil characteristics that are important for predicting C combustion from fire. As climate continues to warm and disturbance from wildfires increases, the C dynamics of these fire-prone ecoregions are likely to change with significant implications for the global C cycle and its feedbacks to climate change

Photometry of Magellanic Cloud clusters with the Advanced Camera for Surveys - I. The old LMC clusters NGC 1928, 1939 and Reticulum

(Abridged) We present the results of photometric measurements from images of the LMC globular clusters NGC 1928, 1939 and Reticulum taken with ACS on HST. F555W and F814W exposures result in high accuracy CMDs for these three clusters. This is the first time that CMDs for NGC 1928 and 1939 have been published. All three clusters possess CMDs with features indicating them to be >10 Gyr old, including main sequence turn-offs at V~23 and well populated HBs. We use the CMDs to obtain metallicity and reddening estimates for each cluster. NGC 1939 is a metal poor cluster, with [Fe/H] = -2.10 +/- 0.19, while NGC 1928 is significantly more metal rich, with [Fe/H] = -1.27 +/- 0.14. Reticulum's abundance lies between the two, at [Fe/H] = -1.66 +/- 0.12. All three clusters are moderately reddened with values ranging from E(V-I) = 0.07 +/- 0.02 for Reticulum and E(V-I) = 0.08 +/- 0.02 for NGC 1928, to E(V-I) = 0.16 +/- 0.03 for NGC 1939. We estimate the HB morphology of each cluster. NGC 1928 and 1939 possess HBs consisting almost exclusively of stars to the blue of the instability strip. In contrast, Reticulum has an intermediate HB morphology, with stars across the instability strip. Using a variety of dating techniques we show that these three clusters are coeval with each other and the oldest Galactic and LMC globular clusters, to within ~2 Gyr. The census of known old LMC globular clusters therefore now numbers 15 plus the unique, somewhat younger cluster ESO121-SC03. The NGC 1939 field contains another cluster in the line-of-sight, NGC 1938. A CMD for this object shows it to be less than ~400 Myr old, and it is therefore unlikely to be physically associated with NGC 1939.Comment: 15 pages, 9 figures. Accepted for publication in MNRAS. For a version with full resolution figures visit http://www.ast.cam.ac.uk/~dmackey/acs1.html (recommended

Species compositional differences on different-aged glacial landscapes drive contrasting responses of tundra to nutrient addition

Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Blackwell Publishing for personal use, not for redistribution. The definitive version was published in Journal of Ecology 93 (2005): 770-782, doi:10.1111/j.1365-2745.2005.01006.x.In the northern foothills of the Brooks Range, Alaska, moist non-acidic tundra dominates more recently deglaciated upland landscapes, whereas moist acidic tundra dominates older upland landscapes. In previous studies, experimental fertilization of moist acidic tussock tundra greatly increased the abundance and productivity of the deciduous dwarf shrub Betula nana. However, this species is largely absent from moist non-acidic tundra. These two common upland tundra community types exhibited markedly different responses to fertilization with nitrogen and phosphorus. In moist acidic tundra, cover of deciduous shrubs (primarily B. nana) increased after only 2 years, and by 4 years vascular biomass and above-ground net primary productivity (ANPP) had increased significantly, almost entirely because of Betula. In moist non-acidic tundra, both biomass and ANPP were again significantly greater, but no single species dominated the response to fertilization. Instead, the effect was due to a combination of several small, sometimes statistically non-significant responses by forbs, graminoids and prostrate deciduous shrubs. The different growth form and species' responses suggest that fertilization will cause carbon cycling through plant biomass to diverge in these two tundra ecosystems. Already, production of new stems by apical growth has increased relative to leaf production in acidic tundra, whereas the opposite has occurred in non-acidic tundra. Secondary stem growth has also increased as a component of primary production in acidic tundra, but is unchanged in non-acidic tundra. Thus, fertilization will probably increase carbon sequestration in woody biomass of B. nana in acidic tundra, while increasing carbon turnover (but not storage) of non-woody species in non-acidic tundra. These results indicate that nutrient enrichment can have very different consequences for plant communities that occur on different geological substrates, because of differences in composition, even though they share the same regional species pool. Although the specific edaphic factors that maintain compositional differences in this case are unknown, variation in soil pH and related variability in soil nutrient availability may well play a role.This research was supported by a collaborative grant from the National Science Foundation (OPP-9902695 to S.E.H. and OPP-9902721 to L.G.) and by the Arctic LTER (DEB-9810222)

Spectroscopic and nonlinear optical properties of the four positional isomers of 4α-(4-tert-butylphenoxy) phthalocyanine

The spectroscopic and nonlinear optical properties of the positional isomers of metal free 4α-(4-tert-butylphenoxy) phthalocyanine are presented. Second order nonlinear polarizability (β), imaginary hyperpolarizability (Im(γ)) and imaginary susceptibility (Im[χ(3)]) values were determined for the four positional isomers. The measured β values of the four isomers displayed the following trend, C4h (34.0 × 10−5 m MW−1) > D2h (28.8 × 10−5 m MW−1) > C2v (22.8 × 10−5 m MW−1) > Cs (13.7 × 10−5 m MW−1)