100 research outputs found
Trace anomaly of the conformal gauge field
The proposed by Bastianelli and van Nieuwenhuizen new method of calculations
of trace anomalies is applied in the conformal gauge field case. The result is
then reproduced by the heat equation method. An error in previous calculation
is corrected. It is pointed out that the introducing gauge symmetries into a
given system by a field-enlarging transformation can result in unexpected
quantum effects even for trivial configurations.Comment: 9 pages, LaTeX file, BI-TP 93/3
Effect of forest structure and management on the functional diversity and composition of understorey plant communities
Questions
Do forest structural parameters related to stand heterogeneity enhance functional diversity (FD) of understorey plant communities? Do FD and functional composition of understorey plant communities vary between high-forest (HF) and old coppices-with-standard (oldCWS) management types? Are HF stands characterized by a higher FD than oldCWS?
Location
Submediterranean beech forests of Montagne della Duchessa Reserve (central Italy).
Methods
We sampled 57 (20 m × 20 m) forest plots, 29 oldCWS and 28 HF stands, where we recorded plant species cover abundance. We used Leaf–Height–Seed and clonal traits, and run multiple separate linear models to quantify the effect of forest structural parameters and management types on FD and functional composition of understorey plant communities.
Results
We found that increasing lying deadwood enhanced FD of specific leaf area (SLA) through micro-environmental heterogeneity of soil fertility regardless of management type. We also found that increased horizontal stratification filtered the range of plant sizes, probably through light reduction. HF management enhanced FD of SLA and clonal traits through micro-environmental heterogeneity, while reducing the FD of plant size and seed mass. HF tended to select plant communities characterized by high resource acquisition strategies but lower persistence between ramets, possibly as an effect of more mature forest conditions.
Conclusion
Our study suggests that understorey plant community diversity and composition change in response to forest structure and management. Combining Leaf–Height–Seed with clonal traits offers a promising framework for understanding and predicting plant response to management practices
Effects of a dominant species on the functional diversity of coexisting species in temperate deciduous understorey
The herb layer plays a significant role in maintaining forest functions, and its community composition is determined by various abiotic factors and biotic interactions. This study attempted to investigate the interspecific plant–plant biotic interactions using a functional traits approach. Specifically, the effects of a dominant species coverage on the functional diversity of coexisting species in the temperate forest understory were studied. Species coverage and soil moisture data were collected using a 1 m2 quadrat couplet (2 × 1 m2) from six sites alongside a 20 m linear transect encompassing a cover gradient of Allium ursinum in southwest Hungary. Major plant functional dimensions i.e., aboveground, and clonal functional traits were considered. Linear and nonlinear mixed models to quantify the effects of biotic interaction on the functional diversity of every single trait and multiple traits were employed. Both aboveground traits and clonal traits of persistent clonal growth organs responded positively to the A. ursinum L., cover gradient. The coexistence of understory species in the presence of a monodominant species seems to be mainly influenced by aboveground traits as compared to the clonal traits suggesting, a role of niche differentiation. The consistent impact of A. ursinum coverage on coexisting species dynamics highlights a need for similar in-depth studies in various forest settings
Association of osteoarthritis risk factors with knee and hip pain in a population-based sample of 29-59 year olds in Denmark: a cross-sectional analysis.
BACKGROUND: This study aimed to a) describe the prevalence of knee and hip osteoarthritis risk factors in a population of 29-59 year old individuals, b) estimate the association between persistent knee/hip pain and osteoarthritis risk factors, and c) describe the prevalence of osteoarthritis risk factors, including specific biomechanical risk factors, in individuals with prolonged persistent knee or hip pain. METHODS: Participants completed the "Early Detection and Prevention" pilot study questionnaire, including items on presence of knee/hip pain within the last month and osteoarthritis risk factors. Individuals reporting knee/hip problems completed a second questionnaire, including items about most problematic joint and specific biomechanical osteoarthritis risk factors. After describing the prevalence of persistent knee/hip pain and osteoarthritis risk factors among respondents stratified for sex and age, logistic regression was used to estimate the strength of associations between osteoarthritis risk factors and presence of knee/hip pain. The prevalence of prolonged persistent pain (i.e. knee/hip pain reported at both questionnaires) and osteoarthritis risk factors among respondents with prolonged persistent knee and hip pain, were described. RESULTS: Two thousand six hundred sixty-one respondents completed the first survey. The one-month prevalence of persistent knee/hip pain was 27%. Previous knee/hip injury was associated with persistent knee/hip pain for both sexes in all age groups, while a family history of osteoarthritis was associated with persistent knee/hip pain in all age groups except for 29-39 year old men. A higher BMI was associated with persistent knee/hip pain in 40-59 year old women, and 50-59 year old men. Eight hundred sixty seven respondents completed the second questionnaire. Knee/hip injuries and surgeries were more common in individuals with prolonged persistent knee than hip pain. CONCLUSIONS: Knee/hip pain within the last month was frequent among individuals aged 29-59 years. Multiple known osteoarthritis risk factors were associated with presence of knee/hip pain. Joint injury and previous surgery were more common in individuals with knee than hip pain. The results support the notion that joint injury and overweight during early adulthood are signs of a trajectory towards symptomatic osteoarthritis later in life and may help earlier identification of groups at high risk of future symptomatic osteoarthritis. TRIAL REGISTRATION: ClinicalTrials.gov ( NCT02797392 ). Registered April 29,2016
Functional response of an invasive tall grass (Brachypodium genuense) to environmental variability in sub-Mediterranean climate
We found that in more productive conditions (deeper soil, medium/high pH values, northfacing
slopes, and “conservative” land forms) populations of B. genuense showed higher
SLA, plant height and cover values. This underlies a fast-growing strategy based on high
resource acquisition/use rate, as well as higher competitive ability for above-ground
resources (e.g. light). The opposite trend emerged for unproductive/dry conditions (southfacing
slopes, shallow soils, lower pH values). Under these constraints, SLA, plant height
and cover value decreased underlying a slow-growing strategy with high conservation and
low acquisition rate of resource. In addition, we found that very high nitrogen amount might
have a detrimental effect on B. genuense individuals decreasing the SLA values, thus
requiring the plant to change the growth strategy
Predictors of recruitment and retention in randomized controlled trials of behavioural smoking cessation interventions: a systematic review and meta-regression analysis
AIM: To investigate predictors of participant eligibility, recruitment, and retention in behavioural randomised controlled trials (RCTs) for smoking cessation. METHOD: Systematic review and pre-specified meta-regression analysis of behavioural RCTs for smoking cessation including adult (≥18 years old) smokers. The pre-specified predictors were identified through a literature review and experts' consultation and included participant, trial and intervention characteristics and recruitment and retention strategies. Measurements included eligibility rates (proportion of people eligible for the trials), recruitment rates, retention rates, and differential retention rates. RESULTS: 172 RCTs with 89,639 participants. Eligibility [median 57.6%; IQR 34.7-83.7], recruitment [median 66.4%; IQR 42.7-85.2] and retention rates [median 80.5%; IQR 42.7-85.2] varied considerably across studies. For eligibility rates, the recruitment strategy appeared not to be associated with eligibility rates. For recruitment rates, use of indirect recruitment strategies (e.g., public announcements) [OR 0.30, 95% CI 0.11-0.82] and self-help interventions [OR 0.14, 95% CI 0.03-0.67] were associated with lower recruitment rates. For retention rates, higher retention was seen if the sample had ongoing physical health condition/s [OR 1.66, 95% CI 1.04-2.63] whereas lower retention was seen amongst primarily female samples [OR 0.83, 95% CI 0.71-0.98] and those motivated to quit smoking [OR 0.74, 95% CI 0.55-0.99], when indirect recruitment methods were used [OR 0.60, 95% CI 0.38-0.97], and at longer follow-up assessments [OR 0.83, 95% CI 0.79-0.87]. For differential retention, higher retention in the intervention group occurred when the intervention but not comparator group received financial incentives for smoking cessation [OR 1.35, 95% CI: 1.02-1.77]. CONCLUSIONS: In randomised controlled trials of behavioural smoking cessation interventions, recruitment and retention rates appear to be higher for smoking cessation interventions that include a person-to-person rather than at-a-distance contact; male participants, smokers with chronic conditions, smokers not initially motivated to quit and shorter follow-up assessments seems to be associated with improved retention; financial incentive interventions improve retention in groups receiving them relative to comparison groups
Involvement of Noradrenergic Neurotransmission in the Stress- but not Cocaine-Induced Reinstatement of Extinguished Cocaine-Induced Conditioned Place Preference in Mice: Role for β-2 Adrenergic Receptors
The responsiveness of central noradrenergic systems to stressors and cocaine poses norepinephrine as a potential common mechanism through which drug re-exposure and stressful stimuli promote relapse. This study investigated the role of noradrenergic systems in the reinstatement of extinguished cocaine-induced conditioned place preference by cocaine and stress in male C57BL/6 mice. Cocaine- (15 mg/kg, i.p.) induced conditioned place preference was extinguished by repeated exposure to the apparatus in the absence of drug and reestablished by a cocaine challenge (15 mg/kg), exposure to a stressor (6-min forced swim (FS); 20–25°C water), or administration of the α-2 adrenergic receptor (AR) antagonists yohimbine (2 mg/kg, i.p.) or BRL44408 (5, 10 mg/kg, i.p.). To investigate the role of ARs, mice were administered the nonselective β-AR antagonist, propranolol (5, 10 mg/kg, i.p.), the α-1 AR antagonist, prazosin (1, 2 mg/kg, i.p.), or the α-2 AR agonist, clonidine (0.03, 0.3 mg/kg, i.p.) before reinstatement testing. Clonidine, prazosin, and propranolol failed to block cocaine-induced reinstatement. The low (0.03 mg/kg) but not high (0.3 mg/kg) clonidine dose fully blocked FS-induced reinstatement but not reinstatement by yohimbine. Propranolol, but not prazosin, blocked reinstatement by both yohimbine and FS, suggesting the involvement of β-ARs. The β-2 AR antagonist ICI-118551 (1 mg/kg, i.p.), but not the β-1 AR antagonist betaxolol (10 mg/kg, i.p.), also blocked FS-induced reinstatement. These findings suggest that stress-induced reinstatement requires noradrenergic signaling through β-2 ARs and that cocaine-induced reinstatement does not require AR activation, even though stimulation of central noradrenergic neurotransmission is sufficient to reinstate
Predictors of recruitment and retention in randomized controlled trials of behavioural smoking cessation interventions: a systematic review and meta-regression analysis
Aim: To investigate predictors of participant eligibility, recruitment and retention in behavioural randomized controlled trials (RCTs) for smoking cessation. Method: Systematic review and pre-specified meta-regression analysis of behavioural RCTs for smoking cessation including adult (≥ 18-year-old) smokers. The pre-specified predictors were identified through a literature review and experts’ consultation and included participant, trial and intervention characteristics and recruitment and retention strategies. Outcome measures included eligibility rates (proportion of people eligible for the trials), recruitment rates, retention rates and differential retention rates. Results: A total of 172 RCTs with 89 639 participants. Eligibility [median 57.6%; interquartile range (IQR) = 34.7–83.7], recruitment (median 66.4%; IQR = 42.7–85.2) and retention rates (median 80.5%; IQR = 68.5–89.5) varied considerably across studies. For eligibility rates, the recruitment strategy appeared not to be associated with eligibility rates. For recruitment rates, use of indirect recruitment strategies (e.g. public announcements) [odds ratio (OR) = 0.30, 95% confidence interval (CI) = 0.11–0.82] and self-help interventions (OR = 0.14, 95% CI = 0.03–0.67) were associated with lower recruitment rates. For retention rates, higher retention was seen if the sample had ongoing physical health condition/s (OR = 1.66, 95% CI = 1.04–2.63), whereas lower retention was seen amongst primarily female samples (OR = 0.83, 95% CI = 0.71–0.98) and those motivated to quit smoking (OR = 0.74, 95% CI = 0.55–0.99) when indirect recruitment methods were used (OR = 0.60, 95% CI = 0.38–0.97) and at longer follow-up assessments (OR = 0.83, 95% CI = 0.79–0.87). For differential retention, higher retention in the intervention group occurred when the intervention but not comparator group received financial incentives for smoking cessation (OR = 1.35, 95% CI = 1.02–1.77). Conclusions: In randomized controlled trials of behavioural smoking cessation interventions, recruitment and retention rates appear to be higher for smoking cessation interventions that include a person-to-person rather than at-a-distance contact; male participants, smokers with chronic conditions, smokers not initially motivated to quit and shorter follow-up assessments seems to be associated with improved retention; financial incentive interventions improve retention in groups receiving them relative to comparison groups
Tailoring CONSORT-SPI to improve the reporting of smoking cessation intervention trials: An expert consensus study
Background and Aims: Inadequate reporting of smoking cessation intervention trials is common and leads to significant challenges for researchers. The aim of this study was to tailor CONSORT (Consolidated Standards of Reporting Trials)-SPI (Social and Psychological Interventions) guidelines to improve reporting of trials of behavioural interventions to promote smoking cessation. Method: Informed by missing data from the IC-SMOKE (Intervention and Comparison group support provided in SMOKing cEssation) systematic review project, this study used a multi-stage Delphi process to examine which items could be added or modified to improve the reporting of smoking cessation trials. The first stage involved an on-line survey of 17 international experts in smoking cessation and trial methodology voting on the importance of items for inclusion in the updated guidelines. This was followed by a face-to-face expert consensus meeting attended by 15 of these experts, where the final inclusion and exclusion of new items and modifications were agreed upon. A nine-point Likert scale was used to establish consensus, with suggested modifications requiring agreement of 75% or more. Disagreements in the first stage were presented again at the second stage for discussion and a second round of voting. Only items which reached the threshold for agreement were included. Results: The experts agreed on the inclusion of 10 new items and the specification of 12 existing items. This included modifications that could apply to trials more widely (e.g. the rationale for the comparator), but also modifications that were very specific to smoking cessation trials (e.g. the reporting of smoking cessation outcomes). Conclusions: A Delphi study has developed a modified CONSORT-SPI guideline (CONSORT-SPI-SMOKE) to improve the reporting of trials of behavioural interventions to promote smoking cessation
Can we identify response markers to antihypertensive drugs? First results from the Ideal Trial
Current antihypertensive strategies do not take into account that individual characteristics may influence the magnitude of blood pressure (BP) reduction. Guidelines promote trial-and-error approaches with many different drugs. We conducted the Identification of the Determinants of the Efficacy of Arterial blood pressure Lowering drugs (IDEAL) Trial to identify factors associated with BP responses to perindopril and indapamide. IDEAL was a cross-over, double-blind, placebo-controlled trial, involving four 4-week periods: indapamide, perindopril and two placebo. Eligible patients were untreated, hypertensive and aged 25-70 years. The main outcome was systolic BP (SBP) response to drugs. The 112 participants with good compliance had a mean age of 52. One in every three participants was a woman. In middle-aged women, the SBP reduction from drugs was -11.5 mm Hg (indapamide) and -8.3 mm Hg (perindopril). In men, the response was significantly smaller: -4.8 mm Hg (indapamide) and -4.3 (perindopril) (P for sex differences 0.001 and 0.015, respectively). SBP response to perindopril decreased by 2 mm Hg every 10 years of age in both sexes (P=0.01). The response to indapamide increased by 3 mm Hg every 10 years of age gradient in women (P=0.02). Age and sex were important determinants of BP response for antihypertensive drugs in the IDEAL population. This should be taken into account when choosing drugs a priori.Journal of Human Hypertension advance online publication, 17 April 2014; doi:10.1038/jhh.2014.29
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