407 research outputs found

    Controls on spatial and temporal variability in nitrous oxide fluxes across a tropical rainforest ecosystem in the Luquillo experimental forest, Puerto Rico

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    Nitrous oxide (N2O) is a trace gas that contributes to the greenhouse effect and participates in the reactions that destroy stratospheric ozone. Soil microbial processes are significant producers of this trace gas, particularly in tropical areas, which are considered major sources in the global N2O budget. Nitrous oxide fluxes to the atmosphere are variable in space and time. In this study, spatial and temporal variability in surface N2O fluxes were assessed as well as the major environmental controls on N2O production for a tropical rainforest watershed in northeastern Puerto Rico. A static chamber technique was used to assess surface fluxes and soil air probes were installed at different depths to determine soil concentrations of N2O, methane (CH4), and oxygen (O2). Suction lysimeters were installed to sample soil water for the concentrations of the major regulators of the production of N2O, specifically, nitrate (NO3-), dissolved organic carbon (DOC), and ammonium (NH4+). Water table heights were monitored manually over the course of the study. Patterns in surface N2O flux across three topographic sequences were stable through time. The three sequences had similar flux rates in aerobic, slope environments and the streambank, however, they differed in anaerobic, riparian environments. The greatest fluxes in two of the sites and lowest fluxes in the third site occurred at the junction between the slope and the riparian zone. In one of the sites, the slope-riparian break was where soil water NO3-- and DOC concentrations decreased precipitously. Soil N2O concentrations were greatest in probes that had intermediate O2 concentrations. Over the course of storm events, there were no drastic changes in N2 O fluxes or the concentrations of the controllers of its production in the break between the slope and the riparian zone. Redox status is helpful in predicting where N2O fluxes will occur on the landscape, with sites that are intermediate in O2 status having the highest N 2O fluxes. Soil surface fluxes are not predictable based on soil concentrations of N2O, so physical effects on gas transport must be important in this rainforest ecosystem. Short-term temporal variability is not important for the slope-riparian break, but may be in other topographic positions

    ‘Welcome to #GabFam’: Far-right virtual community on Gab.

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    With large social media platforms coming under increasing pressure to deplatform far-right users, the Alternative Technology movement (Alt-Tech) emerged as a new digital support infrastructure for the far right. We conduct a qualitative analysis of the prominent Alt-Tech platform Gab, a social networking service primarily modelled on Twitter, to assess the far-right virtual community on the platform. We find Gab’s technological affordances – including its lack of content moderation, culture of anonymity, microblogging architecture and funding model – have fostered an ideologically eclectic far-right community united by fears of persecution at the hands of ‘Big Tech’. We argue that this points to the emergence of a novel techno-social victimology as an axis of far-right virtual community, wherein shared experiences or fears of being deplatformed facilitate a coalescing of assorted far-right tendencies online

    Effects of a Long Chain n-3 Polyunsaturated Fatty Acid-rich Multi-ingredient Nutrition Supplement on Body Composition and Physical Function in Older Adults with Low Skeletal Muscle Mass.

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    Six months of supplementation with a multi-ingredient nutrition supplement was investigated in older adults with low skeletal muscle mass given the recently purported benefits of such approaches. Community-dwelling older adults (age, 74.9 ± 3.6 y; M/F, 18/19) participated in a double-blind, placebo-controlled, randomized trial involving daily consumption of either fruit juice placebo (PLA) or supplement (SUPP) in the form of a 200-mL carton of a juice-based emulsion of long chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) (3000 mg as 1500 mg docosahexaenoic acid and 1500 mg eicosapentaenoic acid), whey protein isolate (8 g), vitamin D3 (400 IU), and resveratrol (150 mg). Body composition, physical function, and circulating markers of metabolic health were assessed at baseline (PRE), and after 3 (MID) and 6 (POST) months of supplementation. Lean body mass (LBM) was unchanged in either group, but fat mass increased in SUPP by 1.41 (0.75, 2.07) kg at POST (+6.4%

    The dependence of theoretical synthetic spectra on α-enhancement in young, binary stellar populations

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    The enhancement of α elements such as oxygen is an important phase in the chemical evolution of the early Universe, with nebular material becoming enriched in these elements sooner than iron. Here, we present models which incorporate stellar spectra with α-enhanced compositions, focusing on the impact on the integrated light of young stellar populations, including those with large binary star fractions using the Binary Populations and Spectral Synthesis (BPASS) framework, while using Solar-scaled stellar evolution models. We find that broad spectrum outputs such as production of ionizing flux, the ultraviolet spectral slope and optical colours are only weakly affected by a change i

    Epidemiological, clinical and genetic aspects of adult onset isolated focal dystonia in Ireland

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    Background: Adult onset idiopathic isolated focal dystonia presents with a number of phenotypes. Reported prevalence rates vary considerably; well-characterized cohorts are important to our understanding of this disorder. Aim: To perform a nationwide epidemiological study of adult onset idiopathic isolated focal dystonia in the Republic of Ireland. Methods: Patients with adult onset idiopathic isolated focal dystonia were recruited from multiple sources. Diagnosis was based on assessment by a neurologist with an expertise in movement disorders. When consent was obtained, a number of clinical features including family history were assessed. Results: On the prevalence date there were 592 individuals in Ireland with adult onset idiopathic isolated focal dystonia, a point prevalence of 17.8 per 100 000 (95% confidence interval 16.4-19.2). Phenotype numbers were cervical dystonia 410 (69.2%), blepharospasm 102 (17.2%), focal hand dystonia 39 (6.6%), spasmodic dysphonia 18 (3.0%), musician\u27s dystonia 17 (2.9%) and oromandibular dystonia six (1.0%). Sixty-two (16.5%) of 375 consenting index cases had a relative with clinically confirmed adult onset idiopathic isolated focal dystonia (18 multiplex and 24 duplex families). Marked variations in the proportions of patients with tremor, segmental spread, sensory tricks, pain and psychiatric symptoms by phenotype were documented. Conclusions: The prevalence of adult onset idiopathic isolated focal dystonia in Ireland is higher than that recorded in many similar service-based epidemiological studies but is still likely to be an underestimate. The low proportion of individuals with blepharospasm may reflect reduced environmental exposure to sunlight in Ireland. This study will serve as a resource for international comparative studies of environmental and genetic factors in the pathogenesis of the disorder

    Comparative metagenomic, phylogenetic and physiological analyses of soil microbial communities across nitrogen gradients

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    Terrestrial ecosystems are receiving elevated inputs of nitrogen (N) from anthropogenic sources and understanding how these increases in N availability affect soil microbial communities is critical for predicting the associated effects on belowground ecosystems. We used a suite of approaches to analyze the structure and functional characteristics of soil microbial communities from replicated plots in two long-term N fertilization experiments located in contrasting systems. Pyrosequencing-based analyses of 16S rRNA genes revealed no significant effects of N fertilization on bacterial diversity, but significant effects on community composition at both sites; copiotrophic taxa (including members of the Proteobacteria and Bacteroidetes phyla) typically increased in relative abundance in the high N plots, with oligotrophic taxa (mainly Acidobacteria) exhibiting the opposite pattern. Consistent with the phylogenetic shifts under N fertilization, shotgun metagenomic sequencing revealed increases in the relative abundances of genes associated with DNA/RNA replication, electron transport and protein metabolism, increases that could be resolved even with the shallow shotgun metagenomic sequencing conducted here (average of 75 000 reads per sample). We also observed shifts in the catabolic capabilities of the communities across the N gradients that were significantly correlated with the phylogenetic and metagenomic responses, indicating possible linkages between the structure and functioning of soil microbial communities. Overall, our results suggest that N fertilization may, directly or indirectly, induce a shift in the predominant microbial life-history strategies, favoring a more active, copiotrophic microbial community, a pattern that parallels the often observed replacement of K-selected with r-selected plant species with elevated N
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