Search for: All records

Winters in northeastern North America have warmed faster than summers, with impacts on ecosystems and society. Global climate models (GCMs) indicate that winters will continue to warm and lose snow in the future, but uncertainty remains regarding the magnitude of warming. Here, we project future trends in winter indicators under lower and higher climate-warming scenarios based on emission levels across northeastern North America at a fine spatial scale (1/16°) relevant to climate-related decision making. Under both climate scenarios, winters continue to warm with coincident increases in days above freezing, decreases in days with snow cover, and fewer nights below freezing. Deep snowpacks become increasingly short-lived, decreasing from a historical baseline of 2 months of subnivium habitat to <1 month under the warmer, higher-emissions climate scenario. Warmer winter temperatures allow invasive pests such as Adelges tsugae (Hemlock Woolly Adelgid) and Dendroctonus frontalis (Southern Pine Beetle) to expand their range northward due to reduced overwinter mortality. The higher elevations remain more resilient to winter warming compared to more southerly and coastal regions. Decreases in natural snowpack and warmer temperatures point toward a need for adaptation and mitigation in the multi-million-dollar winter-recreation and forest-management economies. 

Abstract Integration of native bone into orthopedic devices is a key factor in long‐term implant success. The material‐tissue interface is generally accepted to consist of a hydroxyapatite layer so bioactive materials that can spontaneously generate this hydroxyapatite layer after implantation may improve patient outcomes. Per the ISO 22317:2014 standard, “Implants for surgery – In vitro evaluation for apatite‐forming ability of implant materials,” bioactivity performance statements can be assessed by soaking the material in simulated body fluid (SBF) and evaluating the surface for the formation of a hydroxyapatite layer; however, variations in test methods may alter hydroxyapatite formation and result in false‐positive assessments. The goal of this study was to identify the effect of SBF formulation on bioactivity assessment. Bioglass® (45S5 and S53P4) and non‐bioactive Ti‐6Al‐4V were exposed to SBF formulations varying in calcium ion and phosphate concentrations as well as supporting ion concentrations. Scanning electron microscopy and X‐ray powder diffraction evaluation of the resulting hydroxyapatite layers revealed that SBF enriched with double or quadruple the calcium and phosphate ion concentrations increased hydroxyapatite crystal size and quantity compared to the standard formulation and can induce hydroxyapatite crystallization on surfaces traditionally considered non‐bioactive. Altering concentrations of other ions, for example, bicarbonate, changed hydroxyapatite induction time, quantity, and morphology. For studies evaluating the apatite‐forming ability of a material to support bioactivity performance statements, test method parameters must be adequately described and controlled. It is unclear if apatite formation after exposure to any of the SBF formulations is representative of an in vivo biological response. The ISO 23317 standard test method should be further developed to provide additional guidance on apatite characterization and interpretation of the results.