Allometry and photosynthetic capacity of poplar (Populus deltoides) along a metal contamination gradient in an urban brownfield

The value of urban green space has become an increasingly controversial issue. In particular, development of novel vegetative assemblages on vacant lands may have many formerly unrecognized benefits. However, questions remain regarding the functional impairment of these assemblages due to degraded soils. We investigated the effects of elevated concentrations of soil metals on allometry and photosynthetic capacity of naturally colonized poplars (Populus deltoides Michx.) growing at Liberty State Park, New Jersey. We found that allometries of harvested trees did not differ significantly between the low metal load (LML) and high metal load (HML) sites suggesting that metal contamination did not negatively affect carbon allocation patterns of the target species. Likewise, photosynthetic parameters did not differ significantly between the LML and HML sites, suggesting that soil metal contamination did not negatively affect photosynthetic capacity. However, trees from the LML site were significantly younger for a given size than trees from the HML site. Trees from the medium metal load site (MML) differed significantly in allometry and photosynthetic parameters from the other two sites suggesting other edaphic and ecological factors are a stronger driver for carbon allocation patterns and photosynthetic capacity in these trees. Taken together, this research suggests that sapling establishment and growth may be impaired by heavy metals and that trees in HML sites may incur more maintenance costs than trees in LML sites. However, given enough time, poplars can provide considerable rehabilitation of urban brownfields, particularly those that exhibit soil metal contamination.     

Introduction: Leading Lesbians Fight Disease and Disability

This thematic issue of the Journal of Lesbian Studies focuses on the ways in which lesbian leaders have dealt with disease and disability. In the articles that follow, eight prominent lesbians describe what it means to cope with serious illness and medical treatment in the context of lesbian identity and community. This introduction provides an overview of some of the themes that arose in the various articles, focusing on lesbian support systems as well as best medical practices.     

Long-Term Tetracycline Use in the Treatment of Acne Vulgaris—The Role of Routine Laboratory Monitoring

Abstract

The medical directors of 125 college health services were surveyed to determine the frequency and extent of routine laboratory monitoring of patients with acne treated with low-dose oral tetracycline. Thirty-seven percent of the practitioners in 89 health services treating acne routinely order screening tests. Thirty-five percent obtain blood counts, 24% obtain liver function tests, and 21% order both types of tests. Sixty-three percent of health service practitioners ordered no routine laboratory testing. A literature review revealed that the reported renal, hepatic, and hematopoietic side effects of tetracycline occurred in patients on high-dose intravenous therapy, in critically ill or hospitalized patients, in patients with initial renal insufficiency, or in older patients. Although idiosyncratiac reactions have occurred, no significant side effects found by routine monitoring have been reported with low-dose oral tetracycline in healthy patients. A more cost-effective approach to the use of the laboratory in tetracycline therapy of acne would be to obtain laboratory tests only on high-risk patients or on those patients who develop symptoms.     

Managing the external financing constraints of social enterprises: A systematic review of a diversified research landscape

Social enterprises, located between non-profit organisations and for-profit firms, often struggle to acquire external funding. An increasing amount of research on the external financing of social enterprises stems from a fragmented body of the literature anchored in a variety of subject areas (e.g. entrepreneurship, public sector management, general management and strategy). We systematically review 204 academic articles published between 1998 and 2021 to bridge the knowledge gaps in these subject areas by: (1) mapping the field of the external financing of social enterprises at the individual, organisational and institutional levels; (2) synthesising the findings to develop an overarching framework; and (3) discussing theoretically sound future research avenues. We find that research at the individual level focuses primarily on investors’ perspective of the ideal characteristics of a social entrepreneur. Research at the organisational level often addresses the dual logics of social enterprises and their impact on the successful financing of these businesses and the role of investor–investee collaboration. Research at the institutional level can be clustered into cultural, economic, political and legal factors. Overall, we stress the need for research that adopts an overarching view by considering all three levels of analysis simultaneously and using organisational and economic theories.     

Progression-free survival in oncological clinical studies: Assessment time bias and methods for its correction

Progression-free survival (PFS) is a frequently used endpoint in oncological clinical studies. In case of PFS, potential events are progression and death. Progressions are usually observed delayed as they can be diagnosed not before the next study visit. For this reason potential bias of treatment effect estimates for progression-free survival is a concern. In randomized trials and for relative treatment effects measures like hazard ratios, bias-correcting methods are not necessarily required or have been proposed before. However, less is known on cross-trial comparisons of absolute outcome measures like median survival times. This paper proposes a new method for correcting the assessment time bias of progression-free survival estimates to allow a fair cross-trial comparison of median PFS. Using median PFS for example, the presented method approximates the unknown posterior distribution by a Bayesian approach based on simulations. It is shown that the proposed method leads to a substantial reduction of bias as compared to estimates derived from maximum likelihood or Kaplan–Meier estimates. Bias could be reduced by more than 90% over a broad range of considered situations differing in assessment times and underlying distributions. By coverage probabilities of at least 94% based on the credibility interval of the posterior distribution the resulting parameters hold common confidence levels. In summary, the proposed approach is shown to be useful for a cross-trial comparison of median PFS.     

Assessing goodness-of-fit for evaluation of dose-proportionality

For the clinical development of a new drug, the determination of dose-proportionality is an essential part of the pharmacokinetic evaluations, which may provide early indications of non-linear pharmacokinetics and may help to identify sub-populations with divergent clearances. Prior to making any conclusions regarding dose-proportionality, the goodness-of-fit of the model must be assessed to evaluate the model performance. We propose the use of simulation-based visual predictive checks to improve the validity of dose-proportionality conclusions for complex designs. We provide an illustrative example and include a table to facilitate review by regulatory authorities.     

Contraceptive use at first intercourse among Jewish women in Israel, 1962–1988

Using data from the 1987–1988 Study of Fertility and Family Formation,this study examines the family planning practices of Jewish Israeli womenwho first had intercourse between 1962 and 1988. The overwhelming majorityof women reported using no contraception at first intercourse, and among those who did practice birth control approximately half relied on modern techniques. While the likelihood that Israeli women used contraception at first sex changed little between 1962 and 1988, there has been a marked shift towards the adoption of efficient methods of birth control. Moreover, factors which promote female empowerment, including education and military service, have been positively associated with contraceptive use at first intercourse. Among those women who practiced contraception at first intercourse, those from Africa and Asia have been especially likely to make use of inefficient methods such as withdrawal.