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Climate drives shifts in grass reproductive phenology across the western USA
The capacity of grass species to alter their reproductive timing across space and through time can indicate their ability to cope with environmental variability and help predict their future performance under climate change.
We determined the long-term (1895–2013) relationship between flowering times of grass species and climate in space and time using herbarium records across ecoregions of the western USA.
There was widespread concordance of C3 grasses accelerating flowering time and general delays for C4 grasses with increasing mean annual temperature, with the largest changes for annuals and individuals occurring in more northerly, wetter ecoregions. Flowering time was delayed for most grass species with increasing mean annual precipitation across space, while phenology–precipitation relationships through time were more mixed.
Our results suggest that the phenology of most grass species has the capacity to respond to increases in temperature and altered precipitation expected with climate change, but weak relationships for some species in time suggest that climate tracking via migration or adaptation may be required. Divergence in phenological responses among grass functional types, species, and ecoregions suggests that climate change will have unequal effects across the western USA.
Journal Article
A microfluidic platform integrating functional vascularized organoids-on-chip
The development of vascular networks in microfluidic chips is crucial for the long-term culture of three-dimensional cell aggregates such as spheroids, organoids, tumoroids, or tissue explants. Despite rapid advancement in microvascular network systems and organoid technologies, vascularizing organoids-on-chips remains a challenge in tissue engineering. Most existing microfluidic devices poorly reflect the complexity of in vivo flows and require complex technical set-ups. Considering these constraints, we develop a platform to establish and monitor the formation of endothelial networks around mesenchymal and pancreatic islet spheroids, as well as blood vessel organoids generated from pluripotent stem cells, cultured for up to 30 days on-chip. We show that these networks establish functional connections with the endothelium-rich spheroids and vascular organoids, as they successfully provide intravascular perfusion to these structures. We find that organoid growth, maturation, and function are enhanced when cultured on-chip using our vascularization method. This microphysiological system represents a viable organ-on-chip model to vascularize diverse biological 3D tissues and sets the stage to establish organoid perfusions using advanced microfluidics.
Vascularization remains a significant challenge in organoid technology. Here, the authors develop a microfluidic platform that enhances organoid growth, function and maturation, by establishing functional perfusable vascular networks.
Journal Article
Contamination levels and human health risk assessment of toxic heavy metals in street dust in an industrial city in Northwest China
This study investigated the content, distribution, and contamination levels of toxic metals (Cd, Cr, Cu, Pb, and Zn) in street dust in Lanzhou, an industrial city in Northwest China. Meanwhile, the risk these metals posed to the urban ecosystem and human health was also evaluated using the potential ecological risk index and human exposure model. Results showed that concentrations of these metals in the dust are higher than the background value of local soil, with Cu having the highest levels. The districts of Anning and Xigu had the most extreme levels of contamination, while Chengguan and Qilihe districts were lightly contaminated, which can be partly attributed to human activities and traffic densities. In comparison with the concentrations of selected metals in other cities, the concentrations of heavy metals in Lanzhou were generally at moderate or low levels. Heavy metal concentration increased with decreasing dust particle size. The pollution indices of Cr, Cd, Cu, Pb, and Zn were in the range of 0.289–2.09, 0.332–2.15, 1.38–6.21, 0.358–2.59, and 0.560–1.83 with a mean of 1.37, 1.49, 3.18, 1.48, and 0.897, respectively. The geo-accumulation index (Igeo) suggested that Zn in street dust was of geologic origin, while Cd, Cr, Pb, and Cu were significantly impacted by anthropogenic sources. The comprehensive pollution index showed that urban dust poses a high potential ecological risk in Lanzhou. Non-carcinogenic and carcinogenic effects due to exposure to urban street dust were assessed for both children and adults. For non-carcinogenic effects, ingestion appeared to be the main route of exposure to dust particles and thus posed a higher health risk to both children and adults for all metals, followed by dermal contact. Hazard index values for all studied metals were lower than the safe level of 1, and Cr exhibited the highest risk value (0.249) for children, suggesting that the overall risk from exposure to multiple metals in dust is low. The carcinogenic risk for Cd and Cr was all below the acceptable level (< 10−6).
Journal Article
A network community structure similarity index for weighted networks
Identification of communities in complex systems is an essential part of network analysis. Accordingly, measuring similarities between communities is a fundamental part of analysing community structure in different, yet related, networks. Commonly used methods for quantifying network community similarity fail to consider the effects of edge weights. Existing methods remain limited when the two networks being compared have different numbers of nodes. In this study, we address these issues by proposing a novel network community structure similarity index (NCSSI) based on the edit distance concept. NCSSI is proposed as a similarity index for comparing network communities. The NCSSI incorporates both community labels and edge weights. The NCSSI can also be employed to assess the similarity between two communities with varying numbers of nodes. We test the proposed method using simulated data and case-study analysis of New York Yellow Taxi flows and compare the results with that of other commonly used methods (i.e., mutual information and the Jaccard index). Our results highlight how NCSSI effectively captures the impact of both label and edge weight changes and their impacts on community structure, which are not captured in existing approaches. In conclusion, NCSSI offers a new approach that incorporates both label and weight variations for community similarity measurement in complex networks.
Journal Article
Defining crime : a critique of the concept and its implication
\"Defining Crime explores the limitations of the legal definition of crime, how that politically based definition has shaped criminological research, and why criminologists must redefine crime to include scientific objectivity. Lynch, Stretesky, and Long argue that a scientific definition of crime must be detached from criminal law and the variation the political construction imposes. The authors propose an alternative definition of crime, explore its limitations, and how it can reshape criminological research. \"-- Provided by publisher.
Book
Sea-level rise due to polar ice-sheet mass loss during past warm periods
We know that the sea level will rise as climate warms. Nevertheless, accurate projections of how much sea-level rise will occur are difficult to make based solely on modern observations. Determining how ice sheets and sea level have varied in past warm periods can help us better understand how sensitive ice sheets are to higher temperatures. Dutton et al. review recent interdisciplinary progress in understanding this issue, based on data from four different warm intervals over the past 3 million years. Their synthesis provides a clear picture of the progress we have made and the hurdles that still exist. Science , this issue 10.1126/science.aaa4019 Reconstructing past magnitudes, rates, and sources of sea-level rise can help project what our warmer future may hold. Interdisciplinary studies of geologic archives have ushered in a new era of deciphering magnitudes, rates, and sources of sea-level rise from polar ice-sheet loss during past warm periods. Accounting for glacial isostatic processes helps to reconcile spatial variability in peak sea level during marine isotope stages 5e and 11, when the global mean reached 6 to 9 meters and 6 to 13 meters higher than present, respectively. Dynamic topography introduces large uncertainties on longer time scales, precluding robust sea-level estimates for intervals such as the Pliocene. Present climate is warming to a level associated with significant polar ice-sheet loss in the past. Here, we outline advances and challenges involved in constraining ice-sheet sensitivity to climate change with use of paleo–sea level records.
Journal Article