Environmental pollutants from the Scott and Shackleton expeditions during the ‘Heroic Age’ of Antarctic exploration

Early explorers to Antarctica built wooden huts and brought huge quantities of supplies and equipment to support their geographical and scientific studies for several years. When the expeditions ended and relief ships arrived, a rapid exodus frequently allowed only essential items to be taken north. The huts and thousands of items were left behind. Fuel depots with unused containers of petroleum products, asbestos materials, and diverse chemicals were also left at the huts. This investigation found high concentrations of polyaromatic hydrocarbons in soils under and around the historic fuel depots, including anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, fluorene, and pyrene, as well as benzo[a]anthracene, benzo[a]pyrene, and fluoranthene, which are recognized carcinogens. Asbestos materials within the huts have been identified and extensive amounts of fragmented asbestos were found littering the ground around the Cape Evans hut. These materials are continually abraded and fragmented as tourists walk over them and the coarse scoria breaks and grinds down the materials. A chemical spill, within the Cape Evans hut, apparently from caustic substances from one of the scientific experiments, has caused an unusual deterioration and defibration on affected woods. Although these areas are important historic sites protected by international treaties, the hazardous waste materials left by the early explorers should be removed and remedial action taken to restore the site to as pristine a condition as possible. Recommendations are discussed for international efforts to study and clean up these areas, where the earliest environmental pollution in Antarctica was produced

Screening fungi isolated from historic Discovery Hut on Ross Island, Antarctica for cellulose degradation

To survive in Antarctica, early explorers of Antarctica's Heroic Age erected wooden buildings and brought in large quantities of supplies. The introduction of wood and other organic materials may have provided new nutrient sources for fungi that were indigenous to Antarctica or were brought in with the materials. From 30 samples taken from Discovery Hut, 156 filamentous fungi were isolated on selective media. Of these, 108 were screened for hydrolytic activity on carboxymethyl cellulose, of which 29 demonstrated activities. Endo-1, 4-β-glucanase activity was confirmed in the extracellular supernatant from seven isolates when grown at 4°C, and also when they were grown at 15°C. Cladosporium oxysporum and Geomyces sp. were shown to grow on a variety of synthetic cellulose substrates and to use cellulose as a nutrient source at temperate and cold temperatures. The research findings from the present study demonstrate that Antarctic filamentous fungi isolated from a variety of substrates (wood, straw, and food stuffs) are capable of cellulose degradation and can grow well at low temperatures

The possible disappearance of a massive star in the low metallicity galaxy PHL 293B

We investigate a suspected very massive star in one of the most metal-poor dwarf galaxies, PHL~293B. Excitingly, we find the sudden disappearance of the stellar signatures from our 2019 spectra, in particular the broad H lines with P~Cygni profiles that have been associated with a massive luminous blue variable (LBV) star. Such features are absent from our spectra obtained in 2019 with the ESPRESSO and X-shooter instruments of the ESO's VLT. We compute radiative transfer models using CMFGEN that fit the observed spectrum of the LBV and are consistent with ground-based and archival Hubble Space Telescope photometry. Our models show that during 2001--2011 the LBV had a luminosity $L_* = 2.5-3.5 \times 10^6 ~L_{\odot}$, a mass-loss rate $\dot{M} = 0.005-0.020 ~M_{\odot}$~yr$^{-1}$, a wind velocity of 1000~km~s$^{-1}$, and effective and stellar temperatures of $T_\mathrm{eff} = 6000-6800$~K and $T_\mathrm{*}=9500-15000$~K. These stellar properties indicate an eruptive state. We consider two main hypotheses for the absence of the broad emission components from the spectra obtained since 2011. One possibility is that we are seeing the end of an LBV eruption of a surviving star, with a mild drop in luminosity, a shift to hotter effective temperatures, and some dust obscuration. Alternatively, the LBV could have collapsed to a massive black hole without the production of a bright supernova.Comment: 8, pages, 7 figures, MNRAS accepted ; see also the ESO press release at: https://www.eso.org/public/news/eso2010

Massive black holes regulated by luminous blue variable mass loss and magnetic fields

We investigate the effects of mass loss during the main-sequence (MS) and post-MS phases of massive star evolution on black hole (BH) birth masses. We compute solar metallicity Geneva stellar evolution models of an 85 $M_{\odot}$ star with mass-loss rate ($\dot{M}$) prescriptions for MS and post-MS phases and analyze under which conditions such models could lead to very massive BHs. Based on the observational constraints for $\dot{M}$ of luminous stars, we discuss two possible scenarios that could produce massive BHs at high metallicity. First, if a massive BH progenitor evolves from the observed population of massive MS stars known as WNh stars, we show that its average post-MS mass-loss rate has to be less than $1\,\times10^{-5}\,M_{\odot}$/yr. However, this is lower than the typical observed mass-loss rates of luminous blue variables (LBV). Second, a massive BH progenitor could evolve from a yet undetected population of $80-85$ $M_{\odot}$ stars with strong surface magnetic fields, which could quench mass loss during the evolution. In this case, the average mass-loss rate during the post-MS LBV phase has to be less than $5\,\times10^{-5}\,M_{\odot}$/yr to produce 70 $M_{\odot}$ BHs. We suggest that LBVs that explode as SNe have large envelopes and small cores that could be prone to explosion, possibly evolving from binary interaction (either mergers or mass gainers that do not fully mix). Conversely, LBVs that directly collapse to BHs could have evolve from massive single stars or binary-star mergers that fully mix, possessing large cores that would favor BH formation.Comment: Accepted in Ap

Misogynoir: Challenges in Detecting Intersectional Hate

"Misogynoir" is a term that refers to the anti-Black forms of misogyny that Black women experience. To explore how current automated hate speech detection approaches perform in detecting this type of hate, we evaluated the performance of two state-of-the-art detection tools, HateSonar and Google's Perspective API, on a balanced dataset of 300 tweets, half of which are examples of misogynoir and half of which are examples of supporting Black women and an imbalanced dataset of 3138 tweets of which 162 tweets are examples of misogynoir and 2976 tweets are examples of allyship tweets. We aim to determine if these tools flag these messages under any of their classifications of hateful speech (e.g. "hate speech'', "offensive language", "toxicity'' etc.). Close analysis of the classifications and errors shows that current hate speech detection tools are ineffective in detecting misogynoir. They lack sensitivity to context, which is an essential component for misogynoir detection. We found that tweets likely to be classified as hate speech explicitly reference racism or sexism or use profane or aggressive words. Subtle tweets without references to these topics are more challenging to classify. We find that the lack of sensitivity to context may make such tools not only ineffective but potentially harmful to Black women

Clinical Validation of a Sensitive Test for Saliva Collected in Healthcare and Community Settings with Pooling Utility for Severe Acute Respiratory Syndrome Coronavirus 2 Mass Surveillance

The clinical performance of saliva compared with nasopharyngeal swabs (NPSs) has shown conflicting results in healthcare and community settings. In the present study, a total of 429 matched NPS and saliva sample pairs, collected in either healthcare or community setting, were evaluated. Phase-1 (protocol U) tested 240 matched NPS and saliva sample pairs; phase 2 (SalivaAll protocol) tested 189 matched NPS and saliva sample pairs, with an additional sample homogenization step before RNA extraction. A total of 85 saliva samples were evaluated with both protocols. In phase-1, 28.3% (68/240) samples tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from saliva, NPS, or both. The detection rate from saliva was lower compared with that from NPS samples (50.0% versus 89.7%). In phase-2, 50.2% (95/189) samples tested positive for SARS-CoV-2 from saliva, NPS, or both. The detection rate from saliva was higher compared with that from NPS samples (97.8% versus 78.9%). Of the 85 saliva samples evaluated with both protocols, the detection rate was 100% for samples tested with SalivaAll, and 36.7% with protocol U. The limit of detection with SalivaAll protocol was 20 to 60 copies/mL. The pooled testing approach demonstrated a 95% positive and 100% negative percentage agreement. This protocol for saliva samples results in higher sensitivity compared with NPS samples and breaks the barrier to using pooled saliva for SARS-CoV-2 testing

TNF-Induced Target Cell Killing by CTL Activated through Cross-Presentation

SummaryViruses can escape cytotoxic T cell (CTL) immunity by avoiding presentation of viral components via endogenous MHC class I antigen presentation in infected cells. Cross-priming of viral antigens circumvents such immune escape by allowing noninfected dendritic cells to activate virus-specific CTLs, but they remain ineffective against infected cells in which immune escape is functional. Here, we show that cross-presentation of antigen released from adenovirus-infected hepatocytes by liver sinusoidal endothelial cells stimulated cross-primed effector CTLs to release tumor necrosis factor (TNF), which killed virus-infected hepatocytes through caspase activation. TNF receptor signaling specifically eliminated infected hepatocytes that showed impaired anti-apoptotic defense. Thus, CTL immune surveillance against infection relies on two similarly important but distinct effector functions that are both MHC restricted, requiring either direct antigen recognition on target cells and canonical CTL effector function or cross-presentation and a noncanonical effector function mediated by TNF

Heavy d-electron quasiparticle interference and real-space electronic structure of Sr₃Ru₂O₇

As well as providing subatomic-scale real-space images of metals, the scanning tunnelling microscope also reveals momentum–space information. Now it is possible to use this technique to image a heavy-electron liquid and obtain information on orbital structures. The intriguing idea that strongly interacting electrons can generate spatially inhomogeneous electronic liquid-crystalline phases is over a decade old, but these systems still represent an unexplored frontier of condensed-matter physics. One reason is that visualization of the many-body quantum states generated by the strong interactions, and of the resulting electronic phases, has not been achieved. Soft condensed-matter physics was transformed by microscopies that enabled imaging of real-space structures and patterns. A candidate technique for obtaining equivalent data in the purely electronic systems is spectroscopic imaging scanning tunnelling microscopy (SI-STM). The core challenge is to detect the tenuous but ‘heavy’ momentum (k)-space components of the many-body electronic state simultaneously with its real-space constituents. Sr₃Ru₂O₇ provides a particularly exciting opportunity to address these issues. It possesses a very strongly renormalized ‘heavy’ d-electron Fermi liquid and exhibits a field-induced transition to an electronic liquid-crystalline phase. Finally, as a layered compound, it can be cleaved to present an excellent surface for SI-STM.Instituto de Física de Líquidos y Sistemas Biológico

Transcriptome analysis of Pseudomonas aeruginosa PAO1 grown at both body and elevated temperatures

YesFunctional genomics research can give us valuable insights into bacterial gene function. RNA Sequencing (RNA-seq) can generate information on transcript abundance in bacteria following abiotic stress treatments. In this study, we used the RNA-seq technique to study the transcriptomes of the opportunistic nosocomial pathogen Pseudomonas aeruginosa PAO1 following heat shock. Samples were grown at both the human body temperature (37 C) and an arbitrarily-selected temperature of 46 C. In this work using RNA-seq, we identified 133 genes that are differentially expressed at 46 C compared to the human body temperature. Our work identifies some key P. aeruginosa PAO1 genes whose products have importance in both environmental adaptation as well as in vivo infection in febrile hosts. More importantly, our transcriptomic results show that many genes are only expressed when subjected to heat shock. Because the RNA-seq can generate high throughput gene expression profiles, our work reveals many unanticipated genes with further work to be done exploring such genes products.University of Malaya High Impact Research (HIR) UM-MOHE HIR Grants (UM.C/625/1/HIR/MOHE/CHAN/14/1, No. H-50001-A000027; UM.C/625/1/HIR/MOHE/CHAN/01, No. A000001-50001); PPP Grant (PG081-2015B

Using GFP as a biomarker to visualize the process of bacterial infection in black carp (Mylopharyngodon piceus)

As one of the most critical pathogens, Aeromonas hydrophila (AH) can cause motile aeromonad septicemia (MAS) in freshwater fish. In recent decades, a myriad of studies had been done for bacterial infect fish. However, the mechanism of bacterial infects fish especially freshwater fish was scanty. This study was conducted for investigating the invasion pathway of A. hydrophila in vivo of black carp. We have performed A. hydrophila 4332 transformed with a plasmid encoding the green fluorescent protein (pGFPuv) (AH4332GFPuv) in black carp. The AH4332GFPuv had similar growth properties and virulence as the wild-type strains under the simulated natural condition. In this study, black carp were divided into five groups: IM (challenged via immersion), IBD (increased stocking density), SAW (skin artificially wounded by scalpel), MR (mucus removed from the body surface), and C0 (control group). The number of AH4332GFPuv in gill, liver, spleen, intestine, mid kidney, head kidney, muscle, eye, brain, heart, and blood were examined after 72 h post-infection from all groups. Significantly high bacterial numbers were observed in the gills and intestine. The number of bacteria was significantly higher in IBD group than IM group. In conclusion, the gill, intestines, and injured skin are likely to be the primary infection routes.info:eu-repo/semantics/publishedVersio