On the Complementarity of Higgs and Radion Searches at LHC

Models with 3-branes in extra dimensions typically imply the existence of a radion, phi that can mix with the Higgs, h, thereby modifying the Higgs properties and the prospects for its detectability at the LHC. The presence of the phi will extend the scope of the LHC searches. Detection of both the phi and the h might be possible. In this paper, we study the complementarity of the observation of gg -> h, with h -> gamma gamma or h -> ZZ -> 4 leptons, and gg -> phi -> ZZ -> 4 leptons at the LHC in the context of the Randall-Sundrum model. The potential for determining the nature of the detected scalar(s) at the LHC and at an e+e- linear collider is discussed, both separately and in combination.Comment: 11 pages, 5 figure

Warming, drought, and disturbances lead to shifts in functional composition: a millennial‐scale analysis for Amazonian and Andean sites

Tropical forests are changing in composition and productivity, probably in response to changes in climate and disturbances. The responses to these multiple environmental drivers, and the mechanisms underlying the changes, remain largely unknown. Here, we use a functional trait approach on timescales of 10,000 years to assess how climate and disturbances influence the community-mean adult height, leaf area, seed mass, and wood density for eight lowland and highland forest landscapes. To do so, we combine data of eight fossil pollen records with functional traits and proxies for climate (temperature, precipitation, and El Niño frequency) and disturbances (fire and general disturbances). We found that temperature and disturbances were the most important drivers of changes in functional composition. Increased water availability (high precipitation and low El Niño frequency) generally led to more acquisitive trait composition (large leaves and soft wood). In lowland forests, warmer climates decreased community-mean height probably because of increased water stress, whereas in highland forests warmer climates increased height probably because of upslope migration of taller species. Disturbance increased the abundance of acquisitive, disturbance-adapted taxa with small seeds for quick colonization of disturbed sites, large leaves for light capture, and soft wood to attain fast height growth. Fire had weak effects on lowland forests but led to more stress-adapted taxa that are tall with fast life cycles and small seeds that can quickly colonize burned sites. Site-specific analyses were largely in line with cross-site analyses, except for varying site-level effects of El Niño frequency and fire activity, possibly because regional patterns in El Niño are not a good predictor of local changes, and charcoal abundances do not reflect fire intensity or severity. With future global changes, tropical Amazonian and Andean forests may transition toward shorter, drought- and disturbance-adapted forests in the lowlands but taller forests in the highlands

Multiple Polymorphisms Affect Expression and Function of the Neuropeptide S Receptor (NPSR1)

Peer reviewe

Evidence confirms an anthropic origin of Amazonian Dark Earths.

Arising from: Silva et al. Nature Communications https://doi.org/10.1038/s41467-020-20184-2 (2021

The collapse of megafaunal populations in southeastern Brazil

Whether humans or climate change caused the extinction of megafaunal populations is actively debated. Caves in the Lagoa Santa provide mixed assemblages of megafauna and human remains; however, it remains uncertain the extent to which humans and megafauna interacted or overlapped temporally. Here we present the first paleoecological record from lowland South America that tracks the decline of megafauna and its ecological implications. We provide a data set for pollen, charcoal, and Sporormiella, from two lakes in southeastern Brazil that span the last 23,000 yr. The data showed reduced abundances of Sporormiella and an inferred megafaunal population decline that began 18,000 yr ago, with the functional extinction occurring between 12,000 and 11,500 yr ago. Population declines coincided with wet events. The age of the final megafaunal decline is within the range of the first human occupation of the region. Our data are consistent with climate causing the population collapse, with humans preventing population recovery and inducing extinction. We did not observe some of the ecological repercussions documented at other sites and attributed to the megafaunal extinction. Habitat-specific ecological consequences of the extinction add to the heterogeneity of late Pleistocene and early Holocene landscapes

Data from: Scarce fire activity in the north and north-western Amazonian forests during the last 10,000 years

Data related to:William D. Gosling, S. Yoshi Maezumi, Britte M. Heijink, Majoi N. Nascimento, Marco F. Raczka, Masha T. van der Sande, Mark B. Bush, Crystal N.H. McMichaelScarce fire activity in the north and north-western Amazonian forests during the last 10,000 yearsPlant Ecology & DiversityDOI: https://doi.org/10.1080/17550874.2021.200804

Quantifying local-scale changes in Amazonian forest cover using phytoliths

The ecosystem services and immense biodiversity of Amazon rainforests are threatened by deforestation and forest degradation. A key goal of modern archaeology and paleoecology in Amazonia is to establish the extent and duration of past forest disturbance by humans. Fossil phytoliths are an established proxy to identify the duration of disturbance in lake sedimentary and soil archives. What is not known, is the spatial scale of such forest disturbances when identified by phytoliths. Here we use phytolith assemblages to detect local-scale forest openings, provide an estimate of extent, and consider long-term forest recovery. We use modern phytolith assemblages of 50 Amazonian lakes to i) assess how phytolith assemblages vary across forest cover at 5 spatial scales (100 m, 200 m, 500 m, 1 km, 2 km), ii) model which phytolith morphotypes can accurately predict forest cover at 5 spatial scales, and iii) compare phytoliths with pollen to quantify their relative ability to detect forest cover changes. DCA results show phytolith assemblages could be used to differentiate low, intermediate, and high forest cover values, but not to distinguish between biogeographical gradients across Amazonia. Beta regression models show Poaceae phytoliths can accurately predict forest cover within 200 m of Amazonian lakes. This modern calibration dataset can be used to make quantitative reconstructions of forest cover changes in Amazonia, to generate novel insights into long-term forest recovery. Combining phytoliths and pollen provides a unique opportunity to make qualitative and quantitative reconstructions of past vegetation changes, to better understand how human activities, environmental and climatic changes have shaped modern Amazonian forests

Data from: Warming, drought and disturbances lead to shifts in functional composition: a millennial-scale analysis for Amazonian and Andean sites

The data were used to evaluate long-term (~10,000 y) changes in the functional composition of tree communities in Amazonian and Andean forests, and how these changes are explained by climate change, droughts, and disturbances. The dataset contains community-weighted means (CWM) over time of four traits: wood density, seed mass, leaf area and adult tree height. Traits were weighted by taxon abundances derived from fossil pollen records. The dataset also contains data on climate (d18O), temperature, droughts (El Niño frequency), fire disturbance (from charcoal abundance), and other general disturbances (from Cecropia abundance)