Small-sample asymptotic distributions of M-estimators of location

Asymptotic formulae for the distribution of M-estimators, i.e. maximum likelihood type estimators, of location, including the arithmetic mean, are derived which numerical studies show to give relative errors for densities and tail areas of the order of magnitude of 1% down to sample sizes 3 and 4 even in the extreme tails. The paper is the continuation of earlier work by the second author and is also closely related to Daniels's work on the saddlepoint approximation. The method consists in expanding the derivative of the logarithm of the unstandardized density of the estimator in powers of 1/n at each point, using recentring by means of conjugate distributions. This method yields a unified point of view for the comparison of other asymptotic methods, namely saddlepoint method, Edgeworth expansion and large deviations approach, which are also compared numericall

Strong Response of an Invasive Plant Species (Centaurea solstitialis L.) to Global Environmental Changes.

Global environmental changes are altering interactions among plant species, sometimes favoring invasive species. Here, we examine how a suite of five environmental factors, singly and in combination, can affect the success of a highly invasive plant. We introduced Centaurea solstitialis L. (yellow starthistle), which is considered by many to be California’s most troublesome wildland weed, to grassland plots in the San Francisco Bay Area. These plots experienced ambient or elevated levels of warming, atmospheric CO2, precipitation, and nitrate deposition, and an accidental fire in the previous year created an additional treatment. Centaurea grew more than six times larger in response to elevated CO2, and, outside of the burned area, grew more than three times larger in response to nitrate deposition. In contrast, resident plants in the community responded less strongly (or did not respond) to these treatments. Interactive effects among treatments were rarely significant. Results from a parallel mesocosm experiment, while less dramatic, supported the pattern of results observed in the field. Taken together, our results suggest that ongoing environmental changes may dramatically increase Centaurea’s prevalence in western North America

Allogeneic morphogenetic protein vs. recombinant human bone morphogenetic protein-2 in lumbar interbody fusion procedures: a radiographic and economic analysis

BACKGROUND: Since the introduction of rhBMP-2 (Infuse®) in 2002, surgeons have had an alternative substitute to autograft and its related donor site morbidity. Recently, the prevalence of reported adverse events and complications related to the use of rhBMP-2 has raised many ethical and legal concerns for surgeons. Additionally, the cost and decreasing reimbursement landscape of rhBMP-2 use have required identification of a viable alternative. Osteo allogeneic morphogenetic protein (OsteoAMP®) is a commercially available allograft-derived growth factor rich in osteoinductive, angiogenic, and mitogenic proteins. This study compares the radiographic fusion outcomes between rhBMP-2 and OsteoAMP allogeneic morphogenetic protein in lumbar interbody fusion spine procedures. METHODS: Three hundred twenty-one (321) patients from three centers underwent a transforaminal lumbar interbody fusion (TLIF) or lateral lumbar interbody fusion (LLIF) procedure and were assessed by an independent radiologist for fusion and radiographically evident complications. The independent radiologist was blinded to the intervention, product, and surgeon information. Two hundred and twenty-six (226) patients received OsteoAMP with autologous local bone, while ninety-five (95) patients received Infuse with autologous local bone. Patients underwent radiographs (x-ray and/or CT) at standard postoperative follow-up intervals of approximately 1, 3, 6, 12, and 18 months. Fusion was defined as radiographic evidence of bridging across endplates, or bridging from endplates to interspace disc plugs. Osteobiologic surgical supply costs were also analyzed to ascertain cost differences between OsteoAMP and rhBMP-2. RESULTS: OsteoAMP produced higher rates of fusion at 6, 12, and 18 months (p ≤ 0.01). The time required for OsteoAMP to achieve fusion was approximately 40% less than rhBMP-2 with approximately 70% fewer complications. Osteobiologic supply costs were 80.5% lower for OsteoAMP patients (73.7% lower per level) than for rhBMP-2. CONCLUSIONS: Results of this study indicate that OsteoAMP is a viable alternative to rhBMP-2 both clinically and economically when used in TLIF and LLIF spine procedures

Primary Production of the Biosphere: Integrating Terrestrial and Oceanic Components

Integrating conceptually similar models of the growth of marine and terrestrial primary producers yielded an estimated global net primary production (NPP) of 104.9 petagrams of carbon per year, with roughly equal contributions from land and oceans. Approaches based on satellite indices of absorbed solar ra-diation indicate marked heterogeneity in NPP for both land and oceans, re-flecting the influence of physical and ecological processes. The spatial and temporal distributions of ocean NPP are consistent with primary limitation by light, nutrients, and temperature. On land, water limitation imposes additional constraints. On land and ocean, progressive changes in NPP can result in altered carbon storage, although contrasts in mechanisms of carbon storage and rates of organic matter turnover result in a range of relations between carbon storage and changes in NPP. Biological processes on land and in the oceans strongly affect the global carbon cycle on all time scales (1–4). In both component

The IPCC AR5 guidance note on consistent treatment of uncertainties: A common approach across the working groups

Evaluation and communication of the relative degree of certainty in assessment findings are key cross-cutting issues for the three Working Groups of the Intergovernmental Panel on Climate Change. A goal for the Fifth Assessment Report, which is currently under development, is the application of a common framework with associated calibrated uncertainty language that can be used to characterize findings of the assessment process. A guidance note for authors of the Fifth Assessment Report has been developed that describes this common approach and language, building upon the guidance employed in past Assessment Reports. Here, we introduce the main features of this guidance note, with a focus on how it has been designed for use by author teams. We also provide perspectives on considerations and challenges relevant to the application of this guidance in the contribution of each Working Group to the Fifth Assessment Report. Despite the wide spectrum of disciplines encompassed by the three Working Groups, we expect that the framework of the new uncertainties guidance will enable consistent communication of the degree of certainty in their policy-relevant assessment findings

Access to and quality of sexual and reproductive health services in Britain during the early stages of the COVID-19 pandemic: a qualitative interview study of patient experiences

INTRODUCTION: Access to quality sexual and reproductive health (SRH) services remains imperative even during a pandemic. Our objective was to understand experiences of delayed or unsuccessful access to SRH services in Britain during the early stages of the COVID-19 pandemic. METHODS: In October and November 2020 we conducted semi-structured telephone interviews with 14 women and six men reporting an unmet need for SRH services in the Natsal-COVID survey, a large-scale quasi-representative web-panel survey of sexual health and behaviour during COVID-19 (n=6654). We purposively sampled eligible participants using sociodemographic quotas. Inductive thematic analysis was used to explore service access and quality and to identify lessons for future SRH service delivery. RESULTS: Twenty participants discussed experiences spanning 10 SRH services including contraception and antenatal/maternity care. Participants reported hesitancy and self-censorship of need. Accessing telemedicine and 'socially-distanced' services required tenacity. Challenges included navigating changing information and procedures; perceptions of gatekeepers as obstructing access; and inflexible appointment systems. Concerns about reconfigured services included reduced privacy; decreased quality of interactions with professionals; reduced informal support; and fewer preventive SRH practices. However, some participants also described more streamlined services and staff efforts to compensate for disruptions. Many viewed positively the ongoing blending of telemedicine with in-person care. CONCLUSION: The COVID-19 pandemic impacted access and quality of SRH services. Participants' accounts revealed self-censorship of need, difficulty navigating shifting service configurations and perceived quality reductions. Telemedicine offers potential if intelligently combined with in-person care. We offer initial evidence-based recommendations for promoting an equitable restoration and future adaption of services

Access to and quality of sexual and reproductive health services in Britain during the early stages of the COVID-19 pandemic: a qualitative interview study of patient experiences

INTRODUCTION: Access to quality sexual and reproductive health (SRH) services remains imperative even during a pandemic. Our objective was to understand experiences of delayed or unsuccessful access to SRH services in Britain during the early stages of the COVID-19 pandemic. METHODS: In October and November 2020 we conducted semi-structured telephone interviews with 14 women and six men reporting an unmet need for SRH services in the Natsal-COVID survey, a large-scale quasi-representative web-panel survey of sexual health and behaviour during COVID-19 (n=6654). We purposively sampled eligible participants using sociodemographic quotas. Inductive thematic analysis was used to explore service access and quality and to identify lessons for future SRH service delivery. RESULTS: Twenty participants discussed experiences spanning 10 SRH services including contraception and antenatal/maternity care. Participants reported hesitancy and self-censorship of need. Accessing telemedicine and 'socially-distanced' services required tenacity. Challenges included navigating changing information and procedures; perceptions of gatekeepers as obstructing access; and inflexible appointment systems. Concerns about reconfigured services included reduced privacy; decreased quality of interactions with professionals; reduced informal support; and fewer preventive SRH practices. However, some participants also described more streamlined services and staff efforts to compensate for disruptions. Many viewed positively the ongoing blending of telemedicine with in-person care. CONCLUSION: The COVID-19 pandemic impacted access and quality of SRH services. Participants' accounts revealed self-censorship of need, difficulty navigating shifting service configurations and perceived quality reductions. Telemedicine offers potential if intelligently combined with in-person care. We offer initial evidence-based recommendations for promoting an equitable restoration and future adaption of services