9095 research outputs found
Sort by
Charles Thomas
Get PDFCharles Thomas was a polymath who made a major contribution to our understanding of the archaeology of late Roman and early medieval western and northern Britain and Ireland. He transformed our understanding of the material and other evidence associated with the evolution of Christianity in western and northern Britain, arguing for the continuity of Christianity from the Roman period, rather than subsequent reintroduction from Gaul. His impact on many different aspects of the archaeology and history of his native Cornwall and Scilly was immense, including a significant contribution to our understanding of post-Roman pottery, particularly imports from the Mediterranean, Gaul and Iberia
How do tree species with different successional stages affect soil organic nitrogen transformations?
Get PDFOrganic nitrogen (N) is the most important N component of soil organic matter.However, knowledge on how tree species with different successional stages affect its transformations in soils remains limited. To address this issue, we sampled mineral soils (0−10 cm) in monocultures composed by tree species of different successional stages, including early (black alder and silver birch), early to mid (sycamore and European ash), and late (sweet chestnut, pedunculate oak and European beech), and measured the potential protease activity, the microbial uptake and respiration of 14C-labeled organic N (L-alanine and L-trialanine), and the mineralization of L-alanine N. The activities of alanine aminopeptidase and leucine aminopeptidase (153.8−341.9 and 91.6−147.9 nmol/g/h, respectively), the half-life of the uptake of alanine and trialanine (26.7−39.6 and 60.8−78.6 min, respectively), the half-life of the mineraliztion of alanine and trialanine (1.98−2.45 and 2.98−4.13 h, respectively) by soil microbes were altered by tree species of different successional stages, systematically changing the transformation chain of soil organic N. From trees of early successional stage to that of late, the turnover rates of soil organic N appeared to decrease and the half-life appeared to increase significantly. The (carbon) C:N ratio of soil microbial biomass was positively related to the half-life of 14Clabeled alanine and trialanine mineralization, and was negatively related to the C use efficiency of alanine, suggesting that microbial demand for C could partially drive the assimilation of soil organic N. Our results suggest that the successional stage of tree species play an important role in regulating the soil organic N turnover. An improved understanding of how tree species with different successional stages influence microbial function and soil organic N cycling is beneficial to future afforestation and forest management, alleviating the impacts of global change on the ecosystem
Numerical simulation of thermal stratification in Lake Qiandaohu using an improved WRF-Lake model
Get PDFLake thermal stratification is important for regulating lake environments and ecosystems and is sensitive to climate change and human activity. However, numerical simulation of coupled hydrodynamics and heat transfer processes in deep lakes using one-dimensional lake models remains challenging because of the insufficient representation of key parameters. In this study, Lake Qiandaohu, a deep and warm monomictic reservoir, was used as an example to investigate thermal stratification via an improved parameterization scheme of the Weather Research and Forecast (WRF)-Lake. A comparison with in situ observations demonstrated that the default WRF-Lake model was able to simulate well the seasonal variation of the lake thermal structure. However, the simulations exhibited cold biases in lake surface water temperature (LSWT) throughout the year while generating weaker stratification in summer, thereby leading to an earlier cooling period in autumn. With an improved parameterization (i.e., via determination of initial lake water temperature profiles, light extinction coefficients, eddy diffusion coefficients and surface roughness lengths), the modified WRF-Lake model was able to better simulate LSWT and thermal stratification. Critically, employing realistic initial conditions for lake water temperature is essential for producing realistic hypolimnetic water temperatures. The use of time-dependent light extinction coefficients resulted in a deep thermocline and warm LSWT. Enlarging eddy diffusivity led to stronger mixing in summer and further influenced autumn cooling. The parameterized surface roughness lengths mitigated the excessive turbulent heat loss at the lake surface, improved the model performance in simulating LSWT, and generated a warm mixed layer. This study provides guidance on model parameterization for simulating the thermal structure of deep lakes and advances our understanding of the strength and revolution of lake thermal stratification under seasonal changes
The Impact of Sovereign Credit Ratings on Voters’ Preferences
Get PDFWe investigate the political power of credit rating agencies by building a theoretical model that illustrates how heterogeneous voters change their political preferences after receiving credit signals which infer the quality of their governments. We empirically test this hypothesis using a rich dataset of daily sovereign ratings, outlook and watch signals assigned by S&P, Moody’s and Fitch to EU countries from 2000 to 2017, along with a unique dataset measuring public support for governments. We find that negative rating signals lead to a significant decrease in government support, therefore influencing the electoral prospects of political parties. Both sociotropic and egocentric voters’ preferences are affected by sovereign ratings. Our results are confirmed across a battery of robustness tests and various modelling approaches, including fixed effects and difference in differences models and propensity score matching. Our findings offer wide-ranging implications for policy makers, political parties, governments, and the rating industry
Northern Welsh:Illustrations of the IPA
Get PDFA detailed description of the phonological and phonetic features of the Welsh accent spoken in north Wales
“You don't have to perform for the trees”: The longer-term effects of nature-based interventions on wellbeing
Get PDFThe health and wellbeing benefits of engagement with the natural environment are well documented, but a lack of prospective research means that the sustainability of effects is unknown. Nature-based interventions (NBIs) seek to extend benefits to a wide, socially inclusive range of people. The primary aim of this study was to develop an improved understanding of one such initiative on personal wellbeing over time.The study involved adults recruited from Actif Woods Wales, a pan-Wales woodland activity programme. A questionnaire using validated measures assessed participants at baseline (n = 120), end of course (n = 74) and three months later (n = 57), in terms of mental wellbeing, social trust, self-reported health, self-efficacy, self-esteem and physical activity. A parallel qualitative study sought in-depth appreciation of processes of change with five end of course and four follow up focus groups.Significant positive increases were demonstrated in all psychosocial measures by end of course. These gains held at the follow up stage providing critical evidence of maintained change. Thematic analysis of the qualitative data revealed positive shifts in self-perspective that were reflected in wider lifestyle changes. Participant narratives showed how social processes and nature played an important role in supporting the wellbeing benefits experienced.This mixed methods study addressed identified gaps for research that furthers understanding of how NBIs can support health and wellbeing longer term. Findings point to a need for sustainable funding and support for NBI projects to embed the role that they can play in delivering therapeutic and preventative outcomes
Realizing Gender Diversity on Corporate Boards
Get PDFThis study examines the effectiveness of soft law through scrutinizing national policies for enhancing the proportion of women on corporate boards. While using soft laws, which have less precision and obligation dimensions than conventional laws, is widespread within financial regulation, the relative performance of soft laws is unexplored. To resolve this, we undertake a comparative examination of 14,012 firms from 99 nations, using a three-stage analysis to examine the effect of different policies, their format and influence of institutional factors on female board representation. We report that soft laws are effective for promoting gender equality on corporate boards and the effectiveness of policies is strongly influenced by the enforcement, implementation and compliance dimensions of policy, and institutional factors. Policies are most potent when enforced using a moderate level of sanctions, with a longer compliance period and a diversity target less distant from a firm’s precedent gender diversity level
The Reach Up Parenting Program, Child Development, and Maternal Depression: A Meta-analysis
Get PDFEvidence is needed on effective approaches to build parents' ability to promote child development feasible in low- and middle-income countries. Our objective was to synthesize impact of the Reach Up early childhood parenting program in several low- and middle-income countries and examine moderation by family and implementation characteristics. Systematic search using PubMed and Academic Search Elite/EBSCO Host. Randomized controlled trials of the Reach Up program from 1985 to February 2022 were selected. Data were extracted by 2 independent researchers. Primary outcomes were child cognitive, language, and motor development. Secondary outcomes were home stimulation and maternal depressive symptoms. We synthesized pooled effect sizes using random effect inverse-variance weighting and effect modification by testing pooled subgroup effect estimates using the χ2 test for heterogeneity. Average effect size across 18 studies ranged from 0.49 (95% confidence interval [CI] 0.32 to 0.66) for cognition, 0.38 (CI 0.24 to 0.51) for language, 0.27 (CI 0.13 to 0.40) for motor development, 0.37 (CI 0.21 to 0.54) for home stimulation, and -0.09 (CI -0.19 to 0.01) for maternal depressive symptoms. Impacts were larger in studies targeted to undernourished children, with mean enrollment older than age 12 months and intervention duration 6 to 12 months. Quality of evidence assessed with the Cochrane Assessment of Risk of Bias and GRADE system was moderate. Instruments used to assess child development varied. In moderator analyses, some subgroups included few studies. Reach Up benefits child development and home stimulation and is adaptable across cultures and delivery methods. Child and implementation characteristics modified the effects, with implications for scaling. [Abstract copyright: Copyright © 2023 by the American Academy of Pediatrics.
A global analysis of avian island diversity–area relationships in the Anthropocene
Get PDFResearch on island species–area relationships (ISAR) has expanded to incorporate functional (IFDAR) and phylogenetic (IPDAR) diversity. However, relative to the ISAR, we know little about IFDARs and IPDARs, and lack synthetic global analyses of variation in form of these three categories of island diversity–area relationship (IDAR). Here, we undertake the first comparative evaluation of IDARs at the global scale using 51 avian archipelagic data sets representing true and habitat islands. Using null models, we explore how richness-corrected functional and phylogenetic diversity scale with island area. We also provide the largest global assessment of the impacts of species introductions and extinctions on the IDAR. Results show that increasing richness with area is the primary driver of the (non-richness corrected) IPDAR and IFDAR for many data sets. However, for several archipelagos, richness-corrected functional and phylogenetic diversity changes linearly with island area, suggesting that the dominant community assembly processes shift along the island area gradient. We also find that archipelagos with the steepest ISARs exhibit the biggest differences in slope between IDARs, indicating increased functional and phylogenetic redundancy on larger islands in these archipelagos. In several cases introduced species seem to have ‘re-calibrated’ the IDARs such that they resemble the historic period prior to recent extinctions