4,006 research outputs found
Genome-wide analyses of the Bemisia tabaci species complex reveal contrasting patterns of admixture and complex demographic histories.
Once considered a single species, the whitefly, Bemisia tabaci, is a complex of numerous morphologically indistinguishable species. Within the last three decades, two of its members (MED and MEAM1) have become some of the world's most damaging agricultural pests invading countries across Europe, Africa, Asia and the Americas and affecting a vast range of agriculturally important food and fiber crops through both feeding-related damage and the transmission of numerous plant viruses. For some time now, researchers have relied on a single mitochondrial gene and/or a handful of nuclear markers to study this species complex. Here, we move beyond this by using 38,041 genome-wide Single Nucleotide Polymorphisms, and show that the two invasive members of the complex are closely related species with signatures of introgression with a third species (IO). Gene flow patterns were traced between contemporary invasive populations within MED and MEAM1 species and these were best explained by recent international trade. These findings have profound implications for delineating the B. tabaci species status and will impact quarantine measures and future management strategies of this global pest
Ground-based aerosol characterization during the South American Biomass Burning Analysis (SAMBBA) field experiment
This paper investigates the physical and chemical
characteristics of aerosols at ground level at a site
heavily impacted by biomass burning. The site is located
near Porto Velho, Rondônia, in the southwestern part of the
Brazilian Amazon rainforest, and was selected for the deployment
of a large suite of instruments, among them an
Aerosol Chemical Speciation Monitor. Our measurements
were made during the South American Biomass Burning
Analysis (SAMBBA) field experiment, which consisted of
a combination of aircraft and ground-based measurements
over Brazil, aimed to investigate the impacts of biomass
burning emissions on climate, air quality, and numerical
weather prediction over South America. The campaign took
place during the dry season and the transition to the wet season
in September/October 2012.
During most of the campaign, the site was impacted by
regional biomass burning pollution (average CO mixing ratio
of 0.6 ppm), occasionally superimposed by intense (up
to 2 ppm of CO), freshly emitted biomass burning plumes.
Aerosol number concentrations ranged from ∼ 1000 cm−3
to
peaks of up to 35 000 cm−3
(during biomass burning (BB)
events, corresponding to an average submicron mass mean
concentrations of 13.7 µg m−3
and peak concentrations close
to 100 µg m−3
. Organic aerosol strongly dominated the submicron
non-refractory composition, with an average concentration
of 11.4 µg m−3
. The inorganic species, NH4, SO4,
NO3, and Cl, were observed, on average, at concentrations
of 0.44, 0.34, 0.19, and 0.01 µg m−3
, respectively. Equivalent
black carbon (BCe) ranged from 0.2 to 5.5 µg m−3
,
with an average concentration of 1.3 µg m−3
. During BB
peaks, organics accounted for over 90 % of total mass (submicron
non-refractory plus BCe), among the highest values
described in the literature.
We examined the ageing of biomass burning organic
aerosol (BBOA) using the changes in the H : C and O : C
ratios, and found that throughout most of the aerosol processing
(O : C ∼= 0.25 to O : C ∼= 0.6), no remarkable change
is observed in the H : C ratio (∼ 1.35). Such a result contrasts
strongly with previous observations of chemical ageing
of both urban and Amazonian biogenic aerosols. At higher
levels of processing (O : C > 0.6), the H : C ratio changes
with a H : C/O : C slope of −0.5, possibly due to the development
of a combination of BB (H : C/O : C slope =
0) and biogenic (H : C/O : C slope = −1) organic aerosol
(OA). An analysis of the 1OA/1CO mass ratios yields
very little enhancement in the OA loading with atmospheric
processing, consistent with previous observations. These
results indicate that negligible secondary organic aerosol
(SOA) formation occurs throughout the observed BB plume
Published by Copernicus Publications on behalf of the European Geosciences Union.
12070 J. Brito et al.: Ground-based aerosol characterization during SAMBBA
processing, or that SOA formation is almost entirely balanced
by OA volatilization.
Positive matrix factorization (PMF) of the organic aerosol
spectra resulted in three factors: fresh BBOA, aged BBOA,
and low-volatility oxygenated organic aerosol (LV-OOA).
Analysis of the diurnal patterns and correlation with external
markers indicates that during the first part of the campaign,
OA concentrations are impacted by local fire plumes
with some chemical processing occurring in the near-surface
layer. During the second part of the campaign, long-range
transport of BB plumes above the surface layer, as well as
potential SOAs formed aloft, dominates OA concentrations
at our ground-based sampling site.
This manuscript describes the first ground-based deployment
of the aerosol mass spectrometry at a site heavily impacted
by biomass burning in the Amazon region, allowing
a deeper understanding of aerosol life cycle in this important
ecosystem.This work was supported by the Foundation
for Research Support of the State of São Paulo (FAPESP,
projects 2012/14437-9 and 2013/05014-0), CNPq project 475735-
2012-9, INCT Amazonia, and Natural Environment Research
Council (NERC) project NE/J010073/1. We thank A. Ribeiro,
A. L. Loureiro, F. Morais, F. Jorge, and S. Morais for technical and
logistics support. We thank the National Institute of Meteorology
for providing valuable meteorological data. We gratefully acknowledge
S. Hacon, J. Silva, and W. Bastos for support in the successful
operation of the sampling site
The Unreasonable Effectiveness of Texture Transfer for Single Image Super-resolution
While implicit generative models such as GANs have shown impressive results
in high quality image reconstruction and manipulation using a combination of
various losses, we consider a simpler approach leading to surprisingly strong
results. We show that texture loss alone allows the generation of perceptually
high quality images. We provide a better understanding of texture constraining
mechanism and develop a novel semantically guided texture constraining method
for further improvement. Using a recently developed perceptual metric employing
"deep features" and termed LPIPS, the method obtains state-of-the-art results.
Moreover, we show that a texture representation of those deep features better
capture the perceptual quality of an image than the original deep features.
Using texture information, off-the-shelf deep classification networks (without
training) perform as well as the best performing (tuned and calibrated) LPIPS
metrics. The code is publicly available.Comment: 19 pages, 14 figure
Alien Registration- Parent, Joseph B. (Van Buren, Aroostook County)
https://digitalmaine.com/alien_docs/32354/thumbnail.jp
Near-field emission profiling of Rainforest and Cerrado fires in Brazil during SAMBBA 2012
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Atmospheric Chemistry and Physics (ACP).We profile trace gas and particulate emissions from near-field airborne measurements of discrete smoke plumes in Brazil during the 2012 biomass burning season. The South American Biomass Burning Analysis (SAMBBA) Project conducted during September and October 2012 sampled across two distinct fire regimes prevalent in the Amazon Basin. Combined measurements from a Compact Time Of Flight Aerosol Mass Spectrometer (C-ToF-AMS) and a Single Particle Soot Photometer (SP2) are reported for the first time in a tropical biomass burning environment. Emissions from a mostly-smouldering rainforest wildfire in Rondonia state and numerous smaller flaming Cerrado fires in Tocantins state are presented. While the Cerrado fires appear to be representative of typical fire conditions in the existing literature, the rainforest wildfire likely represents a more extreme example of biomass burning with a bias towards mostly-smouldering emissions. We determined fire integrated modified combustion efficiencies, emission ratios and emission factors for trace gas and particulate components for these two fire types, alongside aerosol microphysical properties. Seven times more black carbon was emitted from the Cerrado fires per unit of fuel combustion (EFBC of 0.13 ± 0.04 g kg−1) compared to the rainforest fire (EFBC of 0.019 ± 0.006 g kg−1) and more than six times the amount of organic aerosol was emitted from the rainforest fire per unit of fuel combustion (EFOC of 5.00 ± 1.58 g kg−1) compared to the Cerrado fires (EFOC of 0.82 ± 0.26 g kg−1).
Particulate phase species emitted from the fires sampled are generally lower than those reported in previous studies and in emission inventories, which is likely a combination of differences in fire combustion efficiency and fuel content, along with different measurement techniques. Previous modelling studies focussed on the biomass burning season in tropical South America have required significant scaling of emissions to reproduce in-situ and satellite aerosol concentrations over the region. Our results do not indicate that emission factors used in inventories are biased low, which could be one potential cause of the reported underestimates in modelling studies. This study supplements and updates trace gas and particulate emission factors for fire type specific biomass burning in Brazil for use in weather and climate models. The study illustrates that initial fire conditions can result in substantial differences in terms of their emitted chemical components, which can potentially perturb the Earth system.We would like to acknowledge the substantial efforts of the whole SAMBBA team before, during and after the project.
Airborne data was obtained using the BAe-146-301 Atmospheric Research Aircraft (ARA) flown by Directflight Ltd and managed by the
Facility for Airborne Atmospheric Measurements (FAAM), which is a joint entity of the Natural Environment Research Council (NERC) and the Met Office. Active fire data was produced by the University of Maryland and acquired from the online Fire Information for Resource
Management System (FIRMS; https://earthdata.nasa.gov/data/near-real-time-data/firms/abouts; specific product: MCD14ML). E.
Darbyshire was supported by NERC studentship NE/J500057/1 and NE/K500859/1. This work was supported by the NERC SAMBBA
project NE/J010073/1
Near-field emission profiling of tropical forest and Cerrado fires in Brazil during SAMBBA 2012
This is the final version. Available from European Geosciences Union (EGU) / Copernicus Publications via the DOI in this record. Data availability: All raw time series data used to derive the emission ratios and factors from the FAAM research aircraft are publicly available from the Centre for Environmental Data Analysis website (http://www.ceda.ac.uk/, last access: 12 March 2018). Direct links to the flight data records are given in the reference list (Facility for Airborne Atmospheric Measurements, Natural Environment Research Council, and Met Office, 2014a, b).We profile trace gas and particulate emissions from near-field airborne measurements of discrete smoke plumes in Brazil during the 2012 biomass burning season. The South American Biomass Burning Analysis (SAMBBA) Project conducted during September and October 2012 sampled across two distinct fire regimes prevalent in the Amazon Basin. Combined measurements from a Compact Time-of-Flight Aerosol Mass Spectrometer (C-ToF-AMS) and a Single Particle Soot Photometer (SP2) are reported for the first time in a tropical biomass burning environment. Emissions from a mostly smouldering tropical forest wildfire in Rondônia state and numerous smaller flaming Cerrado fires in Tocantins state are presented. While the Cerrado fires appear to be representative of typical fire conditions in the existing literature, the tropical forest wildfire likely represents a more extreme example of biomass burning with a bias towards mostly smouldering emissions. We determined fire-integrated modified combustion efficiencies, emission ratios and emission factors for trace gas and particulate components for these two fire types, alongside aerosol microphysical properties. Seven times more black carbon was emitted from the Cerrado fires per unit of fuel combustion (EFBC of 0.13±0.04ĝ€†gĝ€†kg-1) compared to the tropical forest fire (EFBC of 0.019±0.006gĝ€†kg-1), and more than 6 times the amount of organic aerosol was emitted from the tropical forest fire per unit of fuel combustion (EFOM of 8.00±2.53gĝ€†kg-1, EFOC of 5.00±1.58gĝ€†kg-1) compared to the Cerrado fires (EFOM of 1.31±0.42gĝ€†kg-1, EFOC of 0.82±0.26gĝ€†kg-1). Particulate-phase species emitted from the fires sampled are generally lower than those reported in previous studies and in emission inventories, which is likely a combination of differences in fire combustion efficiency and fuel mixture, along with different measurement techniques. Previous modelling studies focussed on the biomass burning season in tropical South America have required significant scaling up of emissions to reproduce in situ and satellite aerosol concentrations over the region. Our results do not indicate that emission factors used in inventories are biased low, which could be one potential cause of the reported underestimates in modelling studies. This study supplements and updates trace gas and particulate emission factors for fire-type-specific biomass burning in Brazil for use in weather and climate models. The study illustrates that initial fire conditions can result in substantial differences in terms of their emitted chemical components, which can potentially perturb the Earth system.NERCMet Offic
Agency, qualia and life: connecting mind and body biologically
Many believe that a suitably programmed computer could act for its own goals and experience feelings. I challenge this view and argue that agency, mental causation and qualia are all founded in the unique, homeostatic nature of living matter. The theory was formulated for coherence with the concept of an agent, neuroscientific data and laws of physics. By this method, I infer that a successful action is homeostatic for its agent and can be caused by a feeling - which does not motivate as a force, but as a control signal. From brain research and the locality principle of physics, I surmise that qualia are a fundamental, biological form of energy generated in specialized neurons. Subjectivity is explained as thermodynamically necessary on the supposition that, by converting action potentials to feelings, the neural cells avert damage from the electrochemical pulses. In exchange for this entropic benefit, phenomenal energy is spent as and where it is produced - which precludes the objective observation of qualia
The ATR Inhibitor AZD6738 Synergizes with Gemcitabine In Vitro and In Vivo to Induce Pancreatic Ductal Adenocarcinoma Regression.
Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest cancers, and overall survival rates have barely improved over the past five decades. The antimetabolite gemcitabine remains part of the standard of care but shows very limited antitumor efficacy. Ataxia telangiectasia and Rad3-related protein (ATR), the apical kinase of the intra-S-phase DNA damage response, plays a central role in safeguarding cells from replication stress and can therefore limit the efficacy of antimetabolite drug therapies. We investigated the ability of the ATR inhibitor, AZD6738, to prevent the gemcitabine-induced intra-S-phase checkpoint activation and evaluated the antitumor potential of this combination in vitro and in vivo In PDAC cell lines, AZD6738 inhibited gemcitabine-induced Chk1 activation, prevented cell-cycle arrest, and restrained RRM2 accumulation, leading to the strong induction of replication stress markers only with the combination. Moreover, synergistic growth inhibition was identified in a panel of 5 mouse and 7 human PDAC cell lines using both Bliss Independence and Loewe models. In clonogenic assays, the combination abrogated survival at concentrations for which single agents had minor effects. In vivo, AZD6738 in combination with gemcitabine was well tolerated and induced tumor regression in a subcutaneous allograft model of a KrasG12D; Trp53R172H; Pdx-Cre (KPC) mouse cancer cell line, significantly extending survival. Remarkably, the combination also induced regression of a subgroup of KPC autochthonous tumors, which generally do not respond well to conventional chemotherapy. Altogether, our data suggest that AZD6738 in combination with gemcitabine merits evaluation in a clinical trial in patients with PDAC. Mol Cancer Ther; 17(8); 1670-82. ©2018 AACR
The activity of signal crayfish (Pacifastacus leniusculus) in relation to thermal and hydraulic dynamics of an alluvial stream, UK
Signal crayfish (Pacifastacus leniusculus) are an invasive species of global significance because of their detrimental impacts on freshwater environments and native organisms. The movement of signal crayfish was continuously monitored for 150-days through a 20-m reach of an alluvial stream in the UK. Passive integrated transponder-tags were attached to crayfish, allowing their location to be monitored relative to 16 antennae which were buried beneath the river bed. The activity of crayfish was related to water depth and temperature, which were continuously monitored within the instrumented reach. Crayfish were highly nocturnal, with less than 6% of movements recorded during daylight hours. Activity declined from September and was minimal in November when water temperature was low and flow depth was high. However, relations between environmental parameters and crayfish activity had poor explanatory power which may partly reflect biological processes not accounted for in this study. Water depth and temperature had a limiting relationship with crayfish activity, quantified using quantile regression. The results extend existing data on signal crayfish nocturnalism and demonstrate that, although signal crayfish can tolerate a range of flows, activity becomes limited as water temperature declines seasonally and when water depth remains high in autumn and winter months
Simultaneous disruption of two DNA polymerases, Polη and Polζ, in Avian DT40 cells unmasks the role of Polη in cellular response to various DNA lesions
Replicative DNA polymerases are frequently stalled by DNA lesions. The resulting replication blockage is released by homologous recombination (HR) and translesion DNA synthesis (TLS). TLS employs specialized TLS polymerases to bypass DNA lesions. We provide striking in vivo evidence of the cooperation between DNA polymerase η, which is mutated in the variant form of the cancer predisposition disorder xeroderma pigmentosum (XP-V), and DNA polymerase ζ by generating POLη−/−/POLζ−/− cells from the chicken DT40 cell line. POLζ−/− cells are hypersensitive to a very wide range of DNA damaging agents, whereas XP-V cells exhibit moderate sensitivity to ultraviolet light (UV) only in the presence of caffeine treatment and exhibit no significant sensitivity to any other damaging agents. It is therefore widely believed that Polη plays a very specific role in cellular tolerance to UV-induced DNA damage. The evidence we present challenges this assumption. The phenotypic analysis of POLη−/−/POLζ−/− cells shows that, unexpectedly, the loss of Polη significantly rescued all mutant phenotypes of POLζ−/− cells and results in the restoration of the DNA damage tolerance by a backup pathway including HR. Taken together, Polη contributes to a much wide range of TLS events than had been predicted by the phenotype of XP-V cells
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