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1.
PLoS Biol ; 14(1): e1002357, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26785119

RESUMEN

Extinction rates in the Anthropocene are three orders of magnitude higher than background and disproportionately occur in the tropics, home of half the world's species. Despite global efforts to combat tropical species extinctions, lack of high-quality, objective information on tropical biodiversity has hampered quantitative evaluation of conservation strategies. In particular, the scarcity of population-level monitoring in tropical forests has stymied assessment of biodiversity outcomes, such as the status and trends of animal populations in protected areas. Here, we evaluate occupancy trends for 511 populations of terrestrial mammals and birds, representing 244 species from 15 tropical forest protected areas on three continents. For the first time to our knowledge, we use annual surveys from tropical forests worldwide that employ a standardized camera trapping protocol, and we compute data analytics that correct for imperfect detection. We found that occupancy declined in 22%, increased in 17%, and exhibited no change in 22% of populations during the last 3-8 years, while 39% of populations were detected too infrequently to assess occupancy changes. Despite extensive variability in occupancy trends, these 15 tropical protected areas have not exhibited systematic declines in biodiversity (i.e., occupancy, richness, or evenness) at the community level. Our results differ from reports of widespread biodiversity declines based on aggregated secondary data and expert opinion and suggest less extreme deterioration in tropical forest protected areas. We simultaneously fill an important conservation data gap and demonstrate the value of large-scale monitoring infrastructure and powerful analytics, which can be scaled to incorporate additional sites, ecosystems, and monitoring methods. In an era of catastrophic biodiversity loss, robust indicators produced from standardized monitoring infrastructure are critical to accurately assess population outcomes and identify conservation strategies that can avert biodiversity collapse.


Asunto(s)
Biodiversidad , Aves , Conservación de los Recursos Naturales , Bosques , Mamíferos , Animales , Ecología/métodos , Clima Tropical
2.
Glob Chang Biol ; 23(9): 3934-3955, 2017 09.
Artículo en Inglés | MEDLINE | ID: mdl-28145063

RESUMEN

Novel climates - emerging conditions with no analog in the observational record - are an open problem in ecological modeling. Detecting extrapolation into novel conditions is a critical step in evaluating bioclimatic projections of how species and ecosystems will respond to climate change. However, biologically informed novelty detection methods remain elusive for many modeling algorithms. To assist with bioclimatic model design and evaluation, we present a first-approximation assessment of general novelty based on a simple and consistent characterization of climate. We build on the seminal global analysis of Williams et al. (2007 PNAS, 104, 5738) by assessing of end-of-21st-century novelty for North America at high spatial resolution and by refining their standardized Euclidean distance into an intuitive Mahalanobian metric called sigma dissimilarity. Like this previous study, we found extensive novelty in end-of-21st-century projections for the warm southern margin of the continent as well as the western Arctic. In addition, we detected localized novelty in lower topographic positions at all latitudes: By the end of the 21st century, novel climates are projected to emerge at low elevations in 80% and 99% of ecoregions in the RCP4.5 and RCP8.5 emissions scenarios, respectively. Novel climates are limited to 7% of the continent's area in RCP4.5, but are much more extensive in RCP8.5 (40% of area). These three risk factors for novel climates - regional susceptibility, topographic position, and the magnitude of projected climate change - represent a priori evaluation criteria for the credibility of bioclimatic projections. Our findings indicate that novel climates can emerge in any landscape. Interpreting climatic novelty in the context of nonlinear biological responses to climate is an important challenge for future research.


Asunto(s)
Cambio Climático , Ecosistema , Cadena Alimentaria , Predicción , América del Norte
3.
Ecol Lett ; 19(6): 710-22, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27111656

RESUMEN

Global change has made it important to understand the factors that shape species' distributions. Central to this area of research is the question of whether species' range limits primarily reflect the distribution of suitable habitat (i.e. niche limits) or arise as a result of dispersal limitation. Over-the-edge transplant experiments and ecological niche models are commonly used to address this question, yet few studies have taken advantage of a combined approach for inferring the causes of range limits. Here, we synthesise results from existing transplant experiments with new information on the predicted suitability of sites based on niche models. We found that individual performance and habitat suitability independently decline beyond range limits across multiple species. Furthermore, inferences from transplant experiments and niche models were generally concordant within species, with 31 out of 40 cases fully supporting the hypothesis that range limits are niche limits. These results suggest that range limits are often niche limits and that the factors constraining species' ranges operate at scales detectable by both transplant experiments and niche models. In light of these findings, we outline an integrative framework for addressing the causes of range limits in individual species.


Asunto(s)
Distribución Animal , Ecosistema , Modelos Biológicos , Dispersión de las Plantas , Animales , Modelos Lineales
4.
ACS Appl Mater Interfaces ; 16(25): 32587-32598, 2024 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-38771585

RESUMEN

Passive heat management is crucial in space, especially for extended missions involving protection from sunlight. Thermal coatings with desirable optical properties can drastically reduce the power consumed by active cooling systems, thereby reserving more resources for other critical systems onboard. Specifically, materials with wavelength-dependent reflectance and emittance are desirable for managing incident sunlight and self-cooling by thermal emission. This study demonstrates the use of polymer nanofibers, specifically poly(tetrafluoroethylene) (PTFE), for passive temperature control in space applications. This study describes the electrospinning fabrication process to create nanofibers and how process parameters can be varied to control the fiber geometry. We combine poly(tetrafluoroethylene) (PTFE) and poly(ethylene oxide) (PEO) polymers to fabricate highly reflective thermal control materials by electrospinning. To understand the role of material and fiber geometry, we measure spectral reflectance, absorptance, and transmittance using spectrophotometers interfaced with integrating spheres. We control the materials' fiber geometry and solar reflectance by modifying the solution properties, flow rate, rotating collector speed, and fabrication time. With 220-1560 µm thick electrospun nanofiber materials, we demonstrate an average solar reflectance of 94.73-99.75%, with values approaching 99.9% for thicker samples, which is among the highest for space applications. Meanwhile, a thermal emittance of 81.4% was observed at 300 K for a 3360 µm thick sample. The durability of these samples was also tested under ultraviolet light and atomic oxygen. Compared to the state-of-the-art materials, the electrospun PTFE-PEO fibers present a new paradigm for passive thermal management in space applications.

5.
Sci Data ; 8(1): 307, 2021 11 26.
Artículo en Inglés | MEDLINE | ID: mdl-34836980

RESUMEN

High-resolution climatic data are essential to many questions and applications in environmental research and ecology. Here we develop and implement a new semi-mechanistic downscaling approach for daily precipitation estimate that incorporates high resolution (30 arcsec, ≈1 km) satellite-derived cloud frequency. The downscaling algorithm incorporates orographic predictors such as wind fields, valley exposition, and boundary layer height, with a subsequent bias correction. We apply the method to the ERA5 precipitation archive and MODIS monthly cloud cover frequency to develop a daily gridded precipitation time series in 1 km resolution for the years 2003 onward. Comparison of the predictions with existing gridded products and station data from the Global Historical Climate Network indicates an improvement in the spatio-temporal performance of the downscaled data in predicting precipitation. Regional scrutiny of the cloud cover correction from the continental United States further indicates that CHELSA-EarthEnv performs well in comparison to other precipitation products. The CHELSA-EarthEnv daily precipitation product improves the temporal accuracy compared with a large improvement in the spatial accuracy especially in complex terrain.

6.
Crit Rev Biomed Eng ; 49(2): 1-8, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34936312

RESUMEN

Airway management has undergone dramatic transformation since the development of videolaryngoscopy (VL). VL improves glottic views when compared to direct laryngoscopy (DL). The image obtained is from a camera at the tip of the curved blade, and the view is not direct line of sight. Placement of the endotracheal tube (ETT) may therefore require the ETT to be manipulated in multiple planes to match the curvature of the VL blade. This placement of the ETT "around the corner" may be difficult without additional airway aids. The aim of this retrospective observational study was to determine whether endotracheal placement during VL in patients with a difficult airway required the use of an additional airway aid (bougie or fiberoptic scope). Difficult airway was defined as a Cormack and Lehane (C&L) grade 3 or 4 view obtained using DL prior to VL use. Data from 165 patients was included in the study. Simple ETT placement without an additional airway device was achieved in only 20.6% of cases (n = 34). The remaining 131 patients required a bougie or fiberscope to assist intubation. ETT placement was not possible with the bougie in 33 patients. These 33 patients were successfully intubated using a fiberscope-assisted VL (FAV) technique. VL improved C&L grade 3 views by at least one grade in 99.1% of cases, and grade 4 view to a grade 1 or 2 in 96.3% of cases. VL improves glottic view in patients with a difficult airway; but in nearly 80% of patients, a bougie or fiberscope is required to properly place the ETT. Practitioners should be aware that improved glottic views with VL may not translate into simple ETT placement, and additional airway aids need to be readily available.


Asunto(s)
Laringoscopios , Laringoscopía , Humanos , Intubación Intratraqueal
7.
Evol Appl ; 13(1): 116-131, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31892947

RESUMEN

We evaluate genomic data, relative to phenotypic and climatic data, as a basis for assisted gene flow and genetic conservation. Using a seedling common garden trial of 281 lodgepole pine (Pinus contorta) populations from across western Canada, we compare genomic data to phenotypic and climatic data to assess their effectiveness in characterizing the climatic drivers and spatial scale of local adaptation in this species. We find that phenotype-associated loci are equivalent or slightly superior to climate data for describing local adaptation in seedling traits, but that climate data are superior to genomic data that have not been selected for phenotypic associations. We also find agreement between the climate variables associated with genomic variation and with 20-year heights from a long-term provenance trial, suggesting that genomic data may be a viable option for identifying climatic drivers of local adaptation where phenotypic data are unavailable. Genetic clines associated with the experimental traits occur at broad spatial scales, suggesting that standing variation of adaptive alleles for this and similar species does not require management at scales finer than those indicated by phenotypic data. This study demonstrates that genomic data are most useful when paired with phenotypic data, but can also fill some of the traditional roles of phenotypic data in management of species for which phenotypic trials are not feasible.

8.
Nat Commun ; 9(1): 783, 2018 02 22.
Artículo en Inglés | MEDLINE | ID: mdl-29472566

RESUMEN

Climate change can drive local climates outside the range of their historical year-to-year variability, straining the adaptive capacity of ecological and human communities. We demonstrate that dependencies between climate variables can produce larger and earlier departures from natural variability than is detectable in individual variables. Using the example of summer temperature (Tx) and precipitation (Pr), we show that this departure intensification effect occurs when the bivariate climate change trajectory is misaligned with the dominant mode of joint historical variability. Departure intensification is evident in all six CMIP5 models that we examined: 23% (9-34%) of the global land area of each model exhibits a pronounced increase in 2σ anomalies in the Tx-Pr regime relative to Tx or Pr alone. Observational data suggest that summer Tx-Pr correlations in distinct regions on all continents are sufficient to produce departure intensification. Precipitation can be an important driver of multivariate climate change signals relative to natural variability, despite typically having a much weaker univariate signal than temperature.

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