Temporal dynamics of soil fungi in a pyrodiverse dry-sclerophyll forest.

Fire is a major evolutionary and ecological driver that shapes biodiversity in forests. While above-ground community responses to fire have been well-documented, those below-ground are much less understood. However, below-ground communities, including fungi, play key roles in forests and facilitate the recovery of other organisms after fire. Here, we used internal transcribed spacer (ITS) meta-barcoding data from forests with three different times since fire [short (3 years), medium (13-19 years) and long (>26 years)] to characterize the temporal responses of soil fungal communities across functional groups, ectomycorrhizal exploration strategies and inter-guild associations. Our findings indicate that fire effects on fungal communities are strongest in the short to medium term, with clear distinctions between communities in forests with a short time (3 years) since fire, a medium time (13-19 years) and a long time (>26 years) since fire. Ectomycorrhizal fungi were disproportionately impacted by fire relative to saprotrophs, but the direction of the response varied depending on morphological structures and exploration strategies. For instance, short-distance ectomycorrhizal fungi increased with recent fire, while medium-distance (fringe) ectomycorrhizal fungi decreased. Further, we detected strong, negative inter-guild associations between ectomycorrhizal and saprotrophic fungi but only at medium and long times since fire. Given the functional significance of fungi, the temporal changes in fungal composition, inter-guild associations and functional groups after fire demonstrated in our study may have functional implications that require adaptive management to curtail.

Forest restoration in a time of fire: perspectives from tall, wet eucalypt forests subject to stand-replacing wildfires.

Wildfires have the potential to add considerably to the already significant challenge of achieving effective forest restoration in the UN Decade on Ecosystem Restoration. While fire can sometimes promote forest restoration (e.g. by creating otherwise rare, early successional habitats), it can thwart it in others (e.g. by depleting key patch types and stand structures). Here we outline key considerations in facilitating restoration of some tall wet temperate forest ecosystems and some boreal forest ecosystems where the typical fire regime is rare high-severity stand-replacing fire. Some of these ecosystems are experiencing altered fire regimes such as increased fire extent, severity and/or frequency. Achieving good restoration outcomes in such ecosystems demands understanding fire regimes and their impacts on vegetation and other elements of biodiversity and then selecting ecosystem-appropriate management interventions. Potential actions range from doing nothing (as the ecosystem already maintains full post-fire regenerative capacity) to interventions prior to a conflagration like prescribed burning to limit the risks of high-severity fire, excluding activities that impair post-fire recovery (e.g. post-fire logging), and artificial seeding where natural regeneration fails. The most ecologically effective actions will be ecosystem-specific and context-specific and informed by knowledge of the ecosystem in question (such as plant life-history attributes) and inter-relationships with attributes like vegetation condition at the time it is burnt (e.g. young versus old forest). This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.

Assessment of Structural Competency in Baccalaureate Nursing Students: A Descriptive Study.

ABSTRACT: Structural competency describes the ability to recognize structural factors that affect health disparities, such as inequity and stigma. These structural factors can alter a patient's symptoms and risk for certain diseases. The purpose of this study was to describe baccalaureate nursing students' attributions of the effects of structural factors on health. Participants in this study attributed structural factors as being relevant to adverse health outcomes. Findings demonstrated differences in attribution of structural factors by academic level. Given the shifting demographics in the United States and gaps in health care access, further research is needed on the development of structural competence in nursing students.

Disturbance alters the forest soil microbiome.

Billions of microorganisms perform critical below-ground functions in all terrestrial ecosystems. While largely invisible to the naked eye, they support all higher lifeforms, form symbiotic relationships with ~90% of terrestrial plant species, stabilize soils, and facilitate biogeochemical cycles. Global increases in the frequency of disturbances are driving major changes in the structure and function of forests. However, despite their functional significance, the disturbance responses of forest microbial communities are poorly understood. Here, we explore the influence of disturbance on the soil microbiome (archaea, fungi and bacteria) of some of the world's tallest and most carbon-dense forests, the Mountain Ash forests of south-eastern Australia. From 80 sites, we identified 23,277 and 19,056 microbial operational taxonomic units from the 0-10 cm and 20-30 cm depths of soil respectively. From this extensive data set, we found the diversity and composition of these often cryptic communities has been altered by human and natural disturbance events. For instance, the diversity of ectomycorrhizal fungi declined with clearcut logging, the diversity of archaea declined with salvage logging, and bacterial diversity and overall microbial diversity declined with the number of fires. Moreover, we identified key associations between edaphic (soil properties), environmental (slope, elevation) and spatial variables and the composition of all microbial communities. Specifically, we found that soil pH, manganese, magnesium, phosphorus, iron and nitrate were associated with the composition of all microbial communities. In a period of widespread degradation of global forest ecosystems, our findings provide an important and timely insight into the disturbance responses of soil microbial communities, which may influence key ecological functions.

Temporal patterns of forest seedling emergence across different disturbance histories.

Forest ecosystems experience a myriad of natural and anthropogenic disturbances that shape ecological communities. Seedling emergence is a critical, preliminary stage in the recovery of forests post​ disturbance and is triggered by a series of abiotic and biotic changes. However, the long-term influence of different disturbance histories on patterns of seedling emergence is poorly understood.Here, we address this research gap by using an 11-year dataset gathered between 2009 and 2020 to quantify the influence of different histories of natural (wildfire) and anthropogenic (clearcut and postfire salvage logging) disturbances on emerging seedlings in early-successional Mountain Ash forests in southeastern Australia. We also describe patterns of seedling emergence across older successional forests varying in stand age (stands that regenerated in <1900s, 1939, 1970-90, and 2007-11).Seedling emergence was highest in the first three years post disturbance. Stand age and disturbance history significantly influenced the composition and abundance of plant seedlings. Specifically, in salvage-logged forests, plant seedlings were the most different from similarly aged forests with other disturbance histories. For instance, relative to clearcut and unlogged, burnt forests of the same age, salvage logging had the lowest overall richness, the lowest counts of Acacia seedlings, and an absence of common species including Acacia obliquinervia, Acacia frigescens, Cassinia arcuealta, Olearia argophylla, Pimelea axiflora, Polyscias sambucifolia, and Prosanthera melissifolia over the survey period. Synthesis: Our findings provide important new insights into the influence of different disturbance histories on regenerating forests and can help predict plant community responses to future disturbances, which may influence forest recovery under altered disturbance regimes.

Direct and indirect disturbance impacts in forests.

Human and natural disturbances are key drivers of change in forest ecosystems. Yet, the direct and indirect mechanisms which underpin these changes remain poorly understood at the ecosystem level. Here, using structural equation modelling across a 150+ year chronosequence, we disentangle the direct and indirect effects of major disturbances in a temperate forest ecosystem. We show that wildfires, logging and post-fire (salvage) logging can affect plant and microbial communities and abiotic soil properties both directly and indirectly through plant-soil-microbial interactions. We quantified 68 direct and indirect disturbance effects across these components, with the majority resulting in ecosystem-wide adverse effects. Indirect disturbance effects accounted for 43% of total disturbance effects, with some amplifying or partially mitigating direct disturbance effects. Overall, human disturbances were associated with more negative effects than natural disturbances. Our analyses provide novel insights into the multifaceted dynamics of forest disturbances and the mechanisms which underpin their relative impacts.

Logging and fire regimes alter plant communities.

Disturbances are key drivers of plant community composition, structure, and function. Plant functional traits, including life forms and reproductive strategies are critical to the resilience and resistance of plant communities in the event of disturbance. Climate change and increasing anthropogenic disturbance are altering natural disturbance regimes globally. When these regimes shift beyond the adaptive resilience of plant functional traits, local populations and ecosystem functions can become compromised. We tested the influence of multiple disturbances, of varying intensity and frequency, on the composition and abundance of vascular plant communities and their respective functional traits (life forms and reproductive strategies) in the wet sclerophyll, Mountain Ash Eucalyptus regnans forests of southeastern Australia. Specifically, we quantified the effect of the type and number of disturbances (including fires, clearcut logging, and salvage logging) on plant community composition. We found that clearcut and salvage logging and the number of fires significantly influenced plant community composition and functional traits. Specifically, multiple fires resulted in lower populations of species that depend on on-site seeding for persistence. This includes the common tree species Eucalyptus regnans, Pomaderris aspera, and Acacia dealbata. In contrast, clearcut and salvage logged sites supported abundant on-site seeder species. However, species that depend on resprouting by surviving individuals, such as common and keystone "tree ferns" Dicksonia antarctica and Cyathea australis, declined significantly. Our data have important implications for understanding the relationship between altered disturbance regimes and plant communities and the respective effects on ecosystem function. In a period of rapid global environmental change, with disturbances predicted to increase and intensify, it is critical to address the impact of altered disturbance regimes on biodiversity.

Generation of axially modulated plasma waveguides using a spatial light modulator.

We demonstrate the generation of axially modulated plasma waveguides using spatially patterned high-energy laser pulses. A spatial light modulator (SLM) imposes transverse phase front modulations on a low-energy (10 mJ) laser pulse which is interferometrically combined with a high-energy (130-450 mJ) pulse, sculpting its intensity profile. This enables dynamic and programmable shaping of the laser profile limited only by the resolution of the SLM and the intensity ratio of the two pulses. The plasma density profile formed by focusing the patterned pulse with an axicon lens is likewise dynamic and programmable. Centimeter-scale, axially modulated plasmas of varying shape and periodicity are demonstrated.

Shock formation in supersonic cluster jets and its effect on axially modulated laser-produced plasma waveguides.

We examine the generation of axially modulated plasmas produced from cluster jets whose supersonic flow is intersected by thin wires. Such plasmas have application to modulated plasma waveguides. By appropriately limiting shock waves from the wires, plasma axial modulation periods can be as small as 70 µm, with plasma structures as narrow as 45 µm. The effect of shocks is eliminated with increased cluster size accompanied by a reduced monomer component of the flow.

Dual-gated bilayer graphene hot-electron bolometer.

Graphene is an attractive material for use in optical detectors because it absorbs light from mid-infrared to ultraviolet wavelengths with nearly equal strength. Graphene is particularly well suited for bolometers-devices that detect temperature-induced changes in electrical conductivity caused by the absorption of light-because its small electron heat capacity and weak electron-phonon coupling lead to large light-induced changes in electron temperature. Here, we demonstrate a hot-electron bolometer made of bilayer graphene that is dual-gated to create a tunable bandgap and electron-temperature-dependent conductivity. The bolometer exhibits a noise-equivalent power (33 fW Hz(-1/2) at 5 K) that is several times lower, and intrinsic speed (>1 GHz at 10 K) three to five orders of magnitude higher than commercial silicon bolometers and superconducting transition-edge sensors at similar temperatures.

Physical and chemical characterization of the surface layers formed on dentin following treatment with a fluoridated toothpaste containing NovaMin.

OBJECTIVE: To characterize in vitro the formation and robustness of a layer formed on dentin following treatment with a fluoridated toothpaste containing calcium sodium phosphosilicate (NovaMin) using modem imaging and analysis techniques. METHODS: Calcium sodium phosphosilicate (CSPS)-containing toothpaste was brushed on to etched dentin specimens twice daily for up to five days. In between applications the samples were stored in artificial saliva. Additionally, certain samples underwent a chemical challenge in the form of a dietary acid, whereby samples were exposed to a cola or grapefruit juice beverage for five minutes on day 4 of the five-day study. The ability of the CSPS-containing formulation to occlude tubules was assessed visually by scanning electron microscope (SEM) imaging and compared to a water control. In a second experiment, the mechanical resistance of the layer was assessed using profilometry after controlled brushing for 200 brush strokes with a wet medium-bristled toothbrush. To visualize the layer and characterize the tubule occlusion, longitudinal cross-sections were prepared using a focused ion beam scanning electron microscope (FIB SEM), and analysis performed by energy dispersive x-ray spectroscopy (EDS) and electron diffraction. Owing to the complexity of the mixed material deposited after application of the toothpaste, material from inside a dentin tubule was selectively removed after five days of treatment, and the morphologically different materials imaged and analyzed by electron diffraction in the transmission electron microscope (TEM). RESULTS: SEM inspection showed significant coverage of the dentin samples after application of CSPS toothpaste for all five days, in contrast to the water control where the majority of tubules remained open after all five days. Exposure of the NovaMin-treated samples to common dietary acids did not lead to re-exposure of the tubules. Profilometry measurements demonstrated an intact layer covering the dentin surface after one and five days. EDS analysis and electron diffraction indicated the layer and the material plugging the tubule to be a calcium phosphate material with a crystallographic structure similar to hydroxyapatite. CONCLUSION: CSPS contained in toothpaste formulations adhered to exposed dentin surfaces. The layer formed was resistant to acid and mechanical challenges. Characterization of this layer indicated it was hydroxyapatite-like in nature.

The natural course of preneoplastic lesions in bronchial epithelium.

PURPOSE: To study the natural history of preneoplastic lesions in the bronchial mucosa of the individuals at risk. PATIENTS AND METHODS: White light and autofluorescence bronchoscopy examinations have been done in 52 individuals harboring 134 preneoplastic lesions (WHO criteria). End points were the development of carcinoma in situ (CIS) or squamous cell cancer (SCC) or the highest category of dysplasia up until March 1, 2003 for the remaining preneoplastic lesions. RESULTS: Distribution and outcome of preneoplastic lesions have been found to be unrelated to various risk factors such as smoking history, past history of cancer, or chronic obstructive pulmonary disease. Nonstepwise changes of preneoplastic lesions are seen. Regression rate has been 54%. Progression to CIS/SCC has been 13.4% (18 of 134) and was for severe dysplasia, significantly higher (P < 0.003) than preneoplastic lesions showing lower-grade dysplasia (squamous metaplasia, mild and moderate dysplasia). Time to progression was not significantly different. However, when analyzed per individual, no significant difference of progression rate between individuals with or without severe dysplasia was seen (39% versus 26%; P = 0.36). CONCLUSIONS: The 54% regression rate of all preneoplastic lesions, 26% to 39% progression rate to CIS/SCC of individuals with lower-grade dysplasia or severe dysplasia with no significant difference in progression rate and time to progression combined with nonstepwise histologic changes unrelated to the initial histologic grading indicate that one cannot differentiate the potentially more malignant preneoplastic lesions among the many preneoplastic lesions present in the bronchial mucosa. The initial WHO classification of any preneoplastic lesion cannot be reliably used for accurate risk assessment of field carcinogenesis.

HPV testing can reduce the number of follow-up visits in women treated for cervical intraepithelial neoplasia grade 3.

OBJECTIVE: We evaluated high-risk human papillomavirus (HPV) testing by Hybrid Capture II (HC II) in addition to cytology to predict recurrent/residual cervical intraepithelial neoplasia (CIN) 2/3 and cervical cancer in women treated for CIN 3. METHODS: Follow-up study of 108 women with histologically confirmed CIN 3. RESULTS: Pretreatment, in 96% (104/108) of the smears high-risk HPV DNA was present. Posttreatment, 71% (77/108) of the women had normal cytology and negative HC II test and none developed recurrent/residual disease during a median follow-up of 28.8 months with a range of 2.4-64.8 months. One of the 12% (13/108) of women with normal cytology and positive HC II test was diagnosed with cervical adenocarcinoma. One of the 7% (8/108) of women with abnormal cytology (borderline dyskaryosis or worse) and negative HC II test was diagnosed with CIN 2. Three of the 9% (10/108) of women with abnormal cytology and a positive HC II test were diagnosed with CIN 2/3. These results show an increased risk for recurrent/residual CIN 2/3 and cervical carcinoma when at least one posttreatment test is positive. The highest relative risk (72.9, 95% CI 25-210) was present in women with both tests positive. CONCLUSIONS: HPV testing with Hybrid Capture II in conjunction with cytology can be used as a tool to select women with an increased risk for recurrent/residual CIN 2/3 and cervical cancer. The standard policy in The Netherlands is cytology at 6, 12, and 24 months posttreatment. However, for women with both normal cytology and negative HC II test at 6 months the chance to develop recurrent/residual CIN 2/3 and cervical carcinoma is so low that retesting at 12 months can be omitted.