255 research outputs found
The Role of Antarctica in Biogeographical Reconstruction: A Point of View
Premise of research. The opening of the Drake Passage in the Miocene (disconnecting Antarctica and South America and resulting in the establishment of the Circumpolar Current preventing warm waters from the north to reach the polar continent) has led to the formation of the ice sheets and the retreat of the temperate to tropical vegetation that had covered Antarctica for millions of years. With only two current native vascular plant species, Antarctica has been virtually ignored in biogeographical reconstructions and, when considered, only a posteriori invoked as a route of dispersal to reconcile inferred disjunct biogeographical patterns.
Methodology. Here, we provide a brief overview of the rich fossil record of Antarctica, further confirming that many plant families were once present on this continent and that the age of a family is mostly not correlated with its presence or absence on the continent. Such evidence indicates a need to develop a paleogeographical model incorporating Antarctica that can be applied to constrain ancestral area reconstructions.Wepropose such a model and investigate its effects on biogeographical scenarios using the cosmopolitan plant family Myrtaceae (a family with a rich fossil record in Antarctica) as a case study.
Pivotal results. Based on this evidence and previous studies that have shown the importance of Antarctica in the biogeography and evolution of plant lineages, we argue that this region should routinely be included as a predefined area in biogeographical analyses.
Conclusions. A possible paleogeographical model including Antarctica is proposed. It is subdivided into five time slices and spans the last 160 Myr. We expect that the formal inclusion of Antarctica in ancestral area reconstructions (using an evidence-based biogeographical model) will open further discussions and research programs assessing the importance of this area in shaping the current temperate and tropical floras and increase the precision of resulting biogeographical patterns
Water-soluble polymers: emerging contaminants detected, separated and quantified by a novel Gpc/Maldi-Tof method
Water-soluble polymers (WSPs) are additives used as thickeners, stabilisers and flocculants in industry and in household products, including personal care products. Given their widespread use, it is likely WSPs enter the environment, particularly through wastewaters. This is of concern as there is little ecotoxicological research on their fate and behaviour once in the environment, which means their risk to aquatic life is not understood. The lack of suitable analytical techniques to detect, characterise and quantify WSPs hinders research on the potential impact of these polymers. A novel method has been developed that identifies polymers within a sample and separates them using gel-permeation chromatography (GPC). This is coupled with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS), to quantify the polymer fractions using molecular weight information. This process has been carried out on a range of aqueous media. Polyethylene glycol (PEG) ingredients were successfully separated from non-polymeric material in a commercial shaving gel personal care product (PCP), before being quantified at 1.62âŻwt%. This method was applied to a spiked wastewater influent sample to demonstrate the extraction and separation of PEG from organic constituents such as dissolved organic matter (DOM). This highlighted the additional challenges of analysing WSPs in the environment, as factors such as sorption and biodegradation affected the total recovery of PEG, with an extraction efficiency of 53%. Overall, this method was applied for the extraction of PEG from a PCP with accurate quantification, before a proof-of-concept extraction from wastewater demonstrated the difficulties associated with WSP analysis in environmental samples. This method provides opportunities to use tandem GPC/MALDI-TOF MS to quantify WSPs in a broad array of environmental samples. Additional studies could include its application to wastewater or freshwater monitoring
The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. VII. Ophiuchus Observed with MIPS
We present maps of 14.4 deg^2 of the Ophiuchus dark clouds observed by the Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS). These high-quality maps depict both numerous point sources and extended dust emission within the star-forming and nonâstar-forming portions of these clouds. Using PSF-fitting photometry, we detect 5779 sources at 24 ÎŒm and 81 sources at 70 ÎŒm at the 10 Ï level of significance. Three hundred twenty-three candidate young stellar objects (YSOs) were identified according to their positions on the MIPS/2MASS K versus color-magnitude diagrams, as compared to 24 ÎŒm detections in the SWIRE extragalactic survey. We find that more than half of the YSO candidates, and almost all those with protostellar Class I spectral energy distributions, are confined to the known cluster and aggregates
Theory of Star Formation
We review current understanding of star formation, outlining an overall
theoretical framework and the observations that motivate it. A conception of
star formation has emerged in which turbulence plays a dual role, both creating
overdensities to initiate gravitational contraction or collapse, and countering
the effects of gravity in these overdense regions. The key dynamical processes
involved in star formation -- turbulence, magnetic fields, and self-gravity --
are highly nonlinear and multidimensional. Physical arguments are used to
identify and explain the features and scalings involved in star formation, and
results from numerical simulations are used to quantify these effects. We
divide star formation into large-scale and small-scale regimes and review each
in turn. Large scales range from galaxies to giant molecular clouds (GMCs) and
their substructures. Important problems include how GMCs form and evolve, what
determines the star formation rate (SFR), and what determines the initial mass
function (IMF). Small scales range from dense cores to the protostellar systems
they beget. We discuss formation of both low- and high-mass stars, including
ongoing accretion. The development of winds and outflows is increasingly well
understood, as are the mechanisms governing angular momentum transport in
disks. Although outstanding questions remain, the framework is now in place to
build a comprehensive theory of star formation that will be tested by the next
generation of telescopes.Comment: 120 pages, to appear in ARAA. No changes from v1 text; permission
statement adde
Botanical Monography in the Anthropocene
Unprecedented changes in the Earth's biota are prompting urgent efforts to describe and conserve plant diversity. For centuries, botanical monographs â comprehensive systematic treatments of a family or genus â have been the gold standard for disseminating scientific information to accelerate research. The lack of a monograph compounds the risk that undiscovered species become extinct before they can be studied and conserved. Progress towards estimating the Tree of Life and digital information resources now bring even the most ambitious monographs within reach. Here, we recommend best practices to complete monographs urgently, especially for tropical plant groups under imminent threat or with expected socioeconomic benefits. We also highlight the renewed relevance and potential impact of monographies for the understanding, sustainable use, and conservation of biodiversity.Fil: Grace, Olwen M.. Royal Botanic Gardens, Kew; Reino UnidoFil: PĂ©rez-Escobar, Oscar A.. Royal Botanic Gardens, Kew; Reino UnidoFil: Lucas, Eve J.. Royal Botanic Gardens, Kew; Reino UnidoFil: Vorontsova, Maria S.. Royal Botanic Gardens, Kew; Reino UnidoFil: Lewis, Gwilym P.. Royal Botanic Gardens, Kew; Reino UnidoFil: Walker, Barnaby E.. Royal Botanic Gardens, Kew; Reino UnidoFil: Lohmann, LĂșcia G.. Universidade de Sao Paulo; BrasilFil: Knapp, Sandra. Natural History Museum; Reino UnidoFil: Wilkie, Peter. Royal Botanic Gardens; Reino UnidoFil: Sarkinen, Tiina. Royal Botanic Gardens; Reino UnidoFil: Darbyshire, Iain. Royal Botanic Gardens; Reino UnidoFil: Lughadha, Eimear Nic. Royal Botanic Gardens; Reino UnidoFil: Monro, Alexandre. Royal Botanic Gardens; Reino UnidoFil: Woudstra, Yannick. Universidad de Copenhagen; Dinamarca. Royal Botanic Gardens; Reino UnidoFil: Demissew, Sebsebe. Addis Ababa University; EtiopĂaFil: Muasya, A. Muthama. University Of Cape Town; SudĂĄfricaFil: DĂaz, Sandra Myrna. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto Multidisciplinario de BiologĂa Vegetal. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas FĂsicas y Naturales. Instituto Multidisciplinario de BiologĂa Vegetal; ArgentinaFil: Baker, William J.. Royal Botanic Gardens, Kew; Reino UnidoFil: Antonelli, Alexandre. University of Oxford; Reino Unido. University Goteborg; Sueci
Strategies to reduce waiting times in outpatient rehabilitation services for adults with physical disabilities : a systematic literature review
Objective: Identifying effective strategies to reduce waiting times is a crucial issue in many areas of health services. Long waiting times for rehabilitation services have been associated with numerous adverse effects in people with disabilities. The main objective of this study was to conduct a systematic literature review to assess the effectiveness of service redesign strategies to reduce waiting times in outpatient rehabilitation services for adults with physical disabilities.
Methods: We conducted a systematic review, searching three databases (MEDLINE, CINAHL and EMBASE) from their inception until May 2021. We identified studies with comparative data evaluating the effect of rehabilitation services redesign strategies on reducing waiting times. The Mixed Methods Appraisal Tool was used to assess the methodological quality of the studies. A narrative synthesis was conducted.
Results: Nineteen articles including various settings and populations met the selection criteria. They covered physiotherapy (n = 11), occupational therapy (n = 2), prosthetics (n = 1), exercise physiology (n = 1) and multidisciplinary (n = 4) services. The methodological quality varied (n = 10 high quality, n = 6 medium, n = 3 low); common flaws being missing information on the pre-redesign setting and characteristics of the populations. Seven articles assessed access processes or referral management strategies (e.g. self-referral), four focused on extending/modifying the roles of service providers (e.g. to triage) and eight changed the model of care delivery (e.g. mode of intervention). The different redesign strategies had positive effects on waiting times in outpatient rehabilitation services.
Conclusions: This review highlights the positive effects of many service redesign strategies. These findings suggest that there are several effective strategies to choose from to reduce waiting times and help better respond to the needs of persons experiencing physical disabilities
The Simons Observatory Large Aperture Telescope Receiver
The Simons Observatory (SO) Large Aperture Telescope Receiver (LATR) will be
coupled to the Large Aperture Telescope located at an elevation of 5,200 m on
Cerro Toco in Chile. The resulting instrument will produce arcminute-resolution
millimeter-wave maps of half the sky with unprecedented precision. The LATR is
the largest cryogenic millimeter-wave camera built to date with a diameter of
2.4 m and a length of 2.6 m. It cools 1200 kg of material to 4 K and 200 kg to
100 mk, the operating temperature of the bolometric detectors with bands
centered around 27, 39, 93, 145, 225, and 280 GHz. Ultimately, the LATR will
accommodate 13 40 cm diameter optics tubes, each with three detector wafers and
a total of 62,000 detectors. The LATR design must simultaneously maintain the
optical alignment of the system, control stray light, provide cryogenic
isolation, limit thermal gradients, and minimize the time to cool the system
from room temperature to 100 mK. The interplay between these competing factors
poses unique challenges. We discuss the trade studies involved with the design,
the final optimization, the construction, and ultimate performance of the
system
Genomic insights into rapid speciation within the worldâs largest tree genus Syzygium
Species radiations, despite immense phenotypic variation, can be difficult to resolve phylogenetically when genetic change poorly matches the rapidity of diversification. Genomic potential furnished by palaeopolyploidy, and relative roles for adaptation, random drift and hybridisation in the apportionment of genetic variation, remain poorly understood factors. Here, we study these aspects in a model radiation, Syzygium, the most species-rich tree genus worldwide. Genomes of 182 distinct species and 58 unidentified taxa are compared against a chromosome-level reference genome of the sea apple, Syzygium grande. We show that while Syzygium shares an ancient genome doubling event with other Myrtales, little evidence exists for recent polyploidy events. Phylogenomics confirms that Syzygium originated in Australia-New Guinea and diversified in multiple migrations, eastward to the Pacific and westward to India and Africa, in bursts of speciation visible as poorly resolved branches on phylogenies. Furthermore, some sublineages demonstrate genomic clines that recapitulate cladogenetic events, suggesting that stepwise geographic speciation, a neutral process, has been important in Syzygium diversification
Large Scale Searches for Brown Dwarfs and Free-Floating Planets
Searches of large scale surveys have resulted in the discovery of over 1000
brown dwarfs in the Solar neighbourhood. In this chapter we review the progress
in finding brown dwarfs in large datasets, highlighting the key science goals,
and summarising the surveys that have contributed most significantly to the
current sample.Comment: Accepted to appear in the Handbook of Exoplanets (Springer); Editors:
Hans J. Deeg & Juan Antonio Belmont
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