Integrating Stand and Soil Properties to Understand Foliar Nutrient Dynamics during Forest Succession Following Slash-and-Burn Agriculture in the Bolivian Amazon

Secondary forests cover large areas of the tropics and play an important role in the global carbon cycle. During secondary forest succession, simultaneous changes occur among stand structural attributes, soil properties, and species composition. Most studies classify tree species into categories based on their regeneration requirements. We use a high-resolution secondary forest chronosequence to assign trees to a continuous gradient in species successional status assigned according to their distribution across the chronosequence. Species successional status, not stand age or differences in stand structure or soil properties, was found to be the best predictor of leaf trait variation. Foliar δ13C had a significant positive relationship with species successional status, indicating changes in foliar physiology related to growth and competitive strategy, but was not correlated with stand age, whereas soil δ13C dynamics were largely constrained by plant species composition. Foliar δ15N had a significant negative correlation with both stand age and species successional status, – most likely resulting from a large initial biomass-burning enrichment in soil 15N and 13C and not closure of the nitrogen cycle. Foliar %C was neither correlated with stand age nor species successional status but was found to display significant phylogenetic signal. Results from this study are relevant to understanding the dynamics of tree species growth and competition during forest succession and highlight possibilities of, and potentially confounding signals affecting, the utility of leaf traits to understand community and species dynamics during secondary forest succession

Velocidade de crescimento da raiz como parâmetro de resistência à seca no algodoeiro

Selection for speed of root growth was done on seedlings for three varieties of cotton (Gossypium hirsutum L.r. latifolium Hutch) both in greenhouse and in laboratory, in order to obtain strains with better drought resistance. Of the three varieties used: Acala del Cerro, Allen 333/57 and SU-0450/8909, the latter presented always a better heritability and genetical gain. After four cycles of recurrent selection the heritability for root growth in this variety was 37% with a genetical gain of 65%. These results were obtained with adult plants and therefore it can be concluded that early selection for speed of root growth in seedlings results in longer roots in grown-up plants.Foi realizado um estudo em condições de casa de vegetação e laboratório, objetivando verificar o efeito da seleção para maior velocidade de crescimento da raiz em algodoeiro (Gossypium hirsutum L.r. latifolium Hutch) e sua aplicação como parâmetro usado pelo melhoramento genético, como critério de seleção de plantas resistentes à seca. Foram usadas as cultivares Acala del Cerro, Allen 333/57 e SU-0450/8909. Esta última variedade apresentou, consistentemente, uma herdabilidade elevada para o caráter selecionado e um grande ganho genético. Na fase adulta e com quatro ciclos de seleção, a cultivar SU-0450/8909 mostra uma herdabilidade de 37% e um ganho genético de 65%. Ficou assim evidenciado que os indivíduos selecionados, mesmo na fase de plântulas para maior velocidade de crescimento do sistema radicular, conservaram uma maior raiz na fase de planta adulta

Perceptions of, and reactions to, environmental heat: a brief note on issues of concern in relation to occupational health

Average temperatures around the world are already increasing, and climate change projections suggest that global mean temperatures will continue to rise. As the effects, and projected effects, of climate change are becoming clearer, it is more apparent that the health effects of heat exposure will need further investigation. The risks associated with heat exposure are especially relevant to understandings of occupational health for people involved in labouring or agricultural work in low-income countries. This review is a partial look at the ways in which issues surrounding heat exposure and occupational health have been treated in some of the available literature. This literature focuses on military-related medical understandings of heat exposure as well as heat exposure in working environments. The ways that these issues have been treated throughout the literature reflect the ways in which technologies of observation are intertwined with social attitudes. The effects of heat on the health of working people, as well as identification of risk groups, will require further research in order to promote prophylactic measures as well as to add to understandings of the actual and potential consequences of climatic change

Reliability of a tool for measuring theory of planned behaviour constructs for use in evaluating research use in policymaking

<p>Abstract</p> <p>Background</p> <p>Although measures of knowledge translation and exchange (KTE) effectiveness based on the theory of planned behavior (TPB) have been used among patients and providers, no measure has been developed for use among health system policymakers and stakeholders. A tool that measures the intention to use research evidence in policymaking could assist researchers in evaluating the effectiveness of KTE strategies that aim to support evidence-informed health system decision-making. Therefore, we developed a 15-item tool to measure four TPB constructs (intention, attitude, subjective norm and perceived control) and assessed its face validity through key informant interviews.</p> <p>Methods</p> <p>We carried out a reliability study to assess the tool's internal consistency and test-retest reliability. Our study sample consisted of 62 policymakers and stakeholders that participated in deliberative dialogues. We assessed internal consistency using Cronbach's alpha and generalizability (G) coefficients, and we assessed test-retest reliability by calculating Pearson correlation coefficients (<it>r</it>) and G coefficients for each construct and the tool overall.</p> <p>Results</p> <p>The internal consistency of items within each construct was good with alpha ranging from 0.68 to alpha = 0.89. G-coefficients were lower for a single administration (G = 0.34 to G = 0.73) than for the average of two administrations (G = 0.79 to G = 0.89). Test-retest reliability coefficients for the constructs ranged from <it>r </it>= 0.26 to <it>r </it>= 0.77 and from G = 0.31 to G = 0.62 for a single administration, and from G = 0.47 to G = 0.86 for the average of two administrations. Test-retest reliability of the tool using G theory was moderate (G = 0.5) when we generalized across a single observation, but became strong (G = 0.9) when we averaged across both administrations.</p> <p>Conclusion</p> <p>This study provides preliminary evidence for the reliability of a tool that can be used to measure TPB constructs in relation to research use in policymaking. Our findings suggest that the tool should be administered on more than one occasion when the intervention promotes an initial 'spike' in enthusiasm for using research evidence (as it seemed to do in this case with deliberative dialogues). The findings from this study will be used to modify the tool and inform further psychometric testing following different KTE interventions.</p

A rapid and sensitive method to detect siRNA-mediated mRNA cleavage in vivo using 5′ RACE and a molecular beacon probe

Specific detection of mRNA cleavage by 5′RACE is the only method to confirm the knockdown of mRNA by RNA interference, but is rarely reported for in vivo studies. We have combined 5′-RNA-linker-mediated RACE (5′-RLM-RACE) with real-time PCR using a molecular beacon to develop a rapid and specific method termed MBRACE, which we have used to detect small-interfering RNA (siRNA)-induced cleavage of ApoB, RRM1 and YBX1 transcripts in vitro, and ApoB in vivo. When RNA from siRNA-transfected cells was used for 5′-RLM-RACE and a cleavage site-specific molecular beacon probe was included in subsequent real-time PCR analysis, the specific mRNA cleavage product was detected. Detection of siRNA-mediated cleavage was also observed when RNA from mouse liver following administration of ApoB-specific siRNA was analysed, even in cases where ApoB knockdown measured by real-time PCR was <10%. With its sensitivity and specificity, this variation on the 5′RACE method should prove a useful tool to detect mRNA cleavage and corroborate knockdown studies following siRNA use in vivo

An analysis of the utilisation of chemoprophylaxis against Pneumocystis jirovecii pneumonia in patients with malignancy receiving corticosteroid therapy at a cancer hospital

Pneumocystis jirovecii pneumonia (PCP) is associated with high mortality in immunocompromised patients without human immunodeficiency virus infection. However, chemoprophylaxis is highly effective. In patients with solid tumours or haematologic malignancy, several risk factors for developing PCP have been identified, predominantly corticosteroid therapy. The aims of this study were to identify the potentially preventable cases of PCP in patients receiving corticosteroid therapy at a tertiary care cancer centre and to estimate the frequency of utilisation of chemoprophylaxis in these patients. Two retrospective reviews were performed. Over a 10-year period, 14 cases of PCP were identified: no cases were attributable to failed chemoprophylaxis, drug allergy or intolerance. During a 6-month period, 73 patients received high-dose corticosteroid therapy (⩾25 mg prednisolone or ⩾4 mg dexamethasone daily) for ⩾4 weeks. Of these, 22 (30%) had haematologic malignancy, and 51 (70%) had solid tumours. Fewer patients with solid tumours received prophylaxis compared to patients with haematologic malignancy (3.9 vs 63.6%, P<0.0001). Guidelines for PCP chemoprophylaxis in patients with haematologic malignancy or solid tumours who receive corticosteroid therapy are proposed. Successful primary prevention of PCP in this population will require a multifaceted approach targeting the suboptimal prescribing patterns for chemoprophylaxis