Hot Rocks: Constraining the Thermal Conditions of the Mistastin Lake Impact Melt Deposits Using Zircon Grain Microstructures

The production of superheated melt during hypervelocity impact events has been proposed to be a common occurrence on terrestrial planetary bodies. Recent direct evidence of superheated impact melt temperatures exceeding \u3e2370°C from the Kamestastin (Mistastin Lake) impact structure, Canada, was based on a single impact glass sample. Such high superheated melt temperatures have strong implications for the evolution of crustal material, the thermal history of impact cratering events, and the rheology of impact melt. However, although widely predicted in previous studies, with the exception of the Mistastin Lake impact glass, there is little direct evidence for superheated temperatures in multiple settings across an impact structure. Therefore, an outstanding question is how heterogeneous are superheated conditions across a single impact structure. In this work, we analyze the crystallographic orientations and microstructures of zircon grains and the precursor parent phases of baddeleyite crystals, from four different samples representing the entire melt-bearing stratigraphy at Mistastin: an impact glass, a vesicular clast-poor impact melt rock, a clast-rich impact melt rock, and a glass-bearing impact breccia. Using electron microprobe analysis followed by electron backscatter diffraction, we discovered that four zircon grains with vermicular coronae of baddeleyite crystals from the impact glass contain evidence for a cubic zirconia precursor, indicative of temperature conditions \u3e2370°C. We also report evidence of superheating up to 1673°C in the glass-bearing impact breccia. In addition, we also report the first occurrence at Mistastin of the high-pressure zircon polymorph reidite and former reidite in granular neoblastic (FRIGN) zircon in grains from the glass-bearing impact breccia, implying minimum peak shocks from 30–40 GPa. The identification of superheating from two localities at Mistastin demonstrates (1) that superheating is not restricted solely to rapidly cooled impact melt rock samples and is therefore more distributed across impact structures, and (2) we can investigate the P-T evolution pathways of impact melt from different impact settings, providing a clearer picture of the thermal conditions and history of the impact structure

New Caledonian crows learn the functional properties of novel tool types.

New Caledonian crows were presented with Bird and Emery's (2009a) Aesop's fable paradigm, which requires stones to be dropped into a water-filled tube to bring floating food within reach. The crows did not spontaneously use stones as tools, but quickly learned to do so, and to choose objects and materials with functional properties. Some crows discarded both inefficient and non-functional objects before observing their effects on the water level. Interestingly, the crows did not learn to discriminate between functional and non-functional objects and materials when there was an arbitrary, rather than causal, link between object and reward. This finding suggests that the crows' performances were not based on associative learning alone. That is, learning was not guided solely by the covariation rate between stimuli and outcomes or the conditioned reinforcement properties acquired by functional objects. Our results, therefore, show that New Caledonian crows can process causal information not only when it is linked to sticks and stick-like tools but also when it concerns the functional properties of novel types of tool

Tuberculosis incidence correlates with sunshine : an ecological 28-year time series study

Birmingham is the largest UK city after London, and central Birmingham has an annual tuberculosis incidence of 80 per 100,000. We examined seasonality and sunlight as drivers of tuberculosis incidence. Hours of sunshine are seasonal, sunshine exposure is necessary for the production of vitamin D by the body and vitamin D plays a role in the host response to tuberculosis. Methods: We performed an ecological study that examined tuberculosis incidence in Birmingham from Dec 1981 to Nov 2009, using publicly-available data from statutory tuberculosis notifications, and related this to the seasons and hours of sunshine (UK Meteorological Office data) using unmeasured component models. Results: There were 9,739 tuberculosis cases over the study period. There was strong evidence for seasonality, with notifications being 24.1% higher in summer than winter (p<0.001). Winter dips in sunshine correlated with peaks in tuberculosis incidence six months later (4.7% increase in incidence for each 100 hours decrease in sunshine, p<0.001). Discussion and Conclusion: A potential mechanism for these associations includes decreased vitamin D levels with consequent impaired host defence arising from reduced sunshine exposure in winter. This is the longest time series of any published study and our use of statutory notifications means this data is essentially complete. We cannot, however, exclude the possibility that another factor closely correlated with the seasons, other than sunshine, is responsible. Furthermore, exposure to sunlight depends not only on total hours of sunshine but also on multiple individual factors. Our results should therefore be considered hypothesis-generating. Confirmation of a potential causal relationship between winter vitamin D deficiency and summer peaks in tuberculosis incidence would require a randomized-controlled trial of the effect of vitamin D supplementation on future tuberculosis incidence

Denoising the Denoisers: an independent evaluation of microbiome sequence error-correction approaches

High-depth sequencing of universal marker genes such as the 16S rRNA gene is a common strategy to profile microbial communities. Traditionally, sequence reads are clustered into operational taxonomic units (OTUs) at a defined identity threshold to avoid sequencing errors generating spurious taxonomic units. However, there have been numerous bioinformatic packages recently released that attempt to correct sequencing errors to determine real biological sequences at single nucleotide resolution by generating amplicon sequence variants (ASVs). As more researchers begin to use high resolution ASVs, there is a need for an in-depth and unbiased comparison of these novel “denoising” pipelines. In this study, we conduct a thorough comparison of three of the most widely-used denoising packages (DADA2, UNOISE3, and Deblur) as well as an open-reference 97% OTU clustering pipeline on mock, soil, and host-associated communities. We found from the mock community analyses that although they produced similar microbial compositions based on relative abundance, the approaches identified vastly different numbers of ASVs that significantly impact alpha diversity metrics. Our analysis on real datasets using recommended settings for each denoising pipeline also showed that the three packages were consistent in their per-sample compositions, resulting in only minor differences based on weighted UniFrac and Bray–Curtis dissimilarity. DADA2 tended to find more ASVs than the other two denoising pipelines when analyzing both the real soil data and two other host-associated datasets, suggesting that it could be better at finding rare organisms, but at the expense of possible false positives. The open-reference OTU clustering approach identified considerably more OTUs in comparison to the number of ASVs from the denoising pipelines in all datasets tested. The three denoising approaches were significantly different in their run times, with UNOISE3 running greater than 1,200 and 15 times faster than DADA2 and Deblur, respectively. Our findings indicate that, although all pipelines result in similar general community structure, the number of ASVs/OTUs and resulting alpha-diversity metrics varies considerably and should be considered when attempting to identify rare organisms from possible background noise

Detection of Helicobacter pylori Microevolution and Multiple Infection from Gastric Biopsies by Housekeeping Gene Amplicon Sequencing

Despite the great efforts devoted to research on Helicobacter pylori, the prevalence of single-strain infection or H. pylori mixed infection and its implications in the mode of transmission of this bacterium are still controversial. In this study, we explored the usefulness of housekeeping gene amplicon sequencing in the detection of H. pylori microevolution and multiple infections. DNA was extracted from five gastric biopsies from four patients infected with distinct histopathological diagnoses. PCR amplification of six H. pylori-specific housekeeping genes was then assessed on each sample. Optimal results were obtained for the cgt and luxS genes, which were selected for amplicon sequencing. A total of 11,833 cgt and 403 luxS amplicon sequences were obtained, 2042 and 112 of which were unique sequences, respectively. All cgt and luxS sequences were clustered at 97% to 9 and 13 operational taxonomic units (OTUs), respectively. For each sample from a different patient, a single OTU comprised the majority of sequences in both genes, but more than one OTU was detected in all samples. These results suggest that multiple infections with a predominant strain together with other minority strains are the main way by which H. pylori colonizes the human stomach

Nox2 contributes to age-related oxidative damage to neurons and the cerebral vasculature

Oxidative stress plays an important role in aging-related neurodegeneration. This study used littermates of WT and Nox2-knockout (Nox2KO) mice plus endothelial cell-specific human Nox2 overexpression-transgenic (HuNox2Tg) mice to investigate Nox2-derived ROS in brain aging. Compared with young WT mice (3-4 months), aging WT mice (20-22 months) had obvious metabolic disorders and loss of locomotor activity. Aging WT brains had high levels of angiotensin II (Ang II) and ROS production; activation of ERK1/2, p53, and γH2AX; and losses of capillaries and neurons. However, these abnormalities were markedly reduced in aging Nox2KO brains. HuNox2Tg brains at middle age (11-12 months) already had high levels of ROS production and activation of stress signaling pathways similar to those found in aging WT brains. The mechanism of Ang II-induced endothelial Nox2 activation in capillary damage was examined using primary brain microvascular endothelial cells. The clinical significance of Nox2-derived ROS in aging-related loss of cerebral capillaries and neurons was investigated using postmortem midbrain tissues of young (25-38 years) and elderly (61-85 years) adults. In conclusion, Nox2 activation is an important mechanism in aging-related cerebral capillary rarefaction and reduced brain function, with the possibility of a key role for endothelial cells

EXIT-chart aided hybrid multiuser detector design for frequency-domain-spread chip-interleaved MC-CDMA

With the advent of EXtrinsic Information Transfer (EXIT) charts, we are capable of analyzing, predicting and visually comparing the convergence behaviours of different turbo Multi-User Detectector (MUD)s. The different MUDs have diverse EXIT characteristics and hence their superposition allows us to create a combined EXIT curve, which closely matches that of the channel decoder. Hence a near-capacity operation is facilitated by combining the benifits of different MUDs and therefore to create a superior MUD. Thus in this contribution, we propose a novel hybrid MUD combining scheme, which combines the advantages of a high performance and low complexity in form of an advanced hybrid MUD solution. The transmitted bits are unknown at the receiver, hence it is not feasible to directly evaluate the mutual information gain of the iterative MUD in consecutive iterations, hence we propose a realistic algorithm for estimating this mutual information gain, which is then used for activating the most appropriate constituent MUD as and when it is necessary. The constituent MUDs are the Matched Filter (MF) based Soft Interference Cancellation (SoIC) and the optimum Bayesian MUDs, which are invoked in the scenario of Frequency-Domain-Spread Chip-Interleaved (FDSCI) Multiple Carrier Code Division Multiple Access (MC-CDMA). The resultant hybrid MUD is capable of outperforming both the MF-SoIC and Bayesian turbo MUDs in the terms of the attainable complexity and Bit-Error-Rate (BER) performance

Outpatient Treatment with AZD7442 (Tixagevimab/Cilgavimab) Prevented COVID-19 Hospitalizations over 6 Months and Reduced Symptom Progression in the TACKLE Randomized Trial

INTRODUCTION: We assessed effects of AZD7442 (tixagevimab/cilgavimab) on deaths from any cause or hospitalizations due to coronavirus disease 2019 (COVID-19) and symptom severity and longer-term safety in the TACKLE adult outpatient treatment study. METHODS: Participants received 600 mg AZD7442 (n = 452) or placebo (n = 451) ≤ 7 days of COVID-19 symptom onset. RESULTS: Death from any cause or hospitalization for COVID-19 complications or sequelae through day 169 (key secondary endpoint) occurred in 20/399 (5.0%) participants receiving AZD7442 versus 40/407 (9.8%) receiving placebo [relative risk reduction (RRR) 49.1%; 95% confidence interval (CI) 14.5, 69.7; p = 0.009] or 50.7% (95% CI 17.5, 70.5; p = 0.006) after excluding participants unblinded before day 169 for consideration of vaccination). AZD7442 reduced progression of COVID-19 symptoms versus placebo through to day 29 (RRR 12.5%; 95% CI 0.5, 23.0) and improved most symptoms within 1-2 weeks. Over median safety follow-up of 170 days, adverse events occurred in 174 (38.5%) and 196 (43.5%) participants receiving AZD7442 or placebo, respectively. Cardiac serious adverse events occurred in two (0.4%) and three (0.7%) participants receiving AZD7442 or placebo, respectively. CONCLUSIONS: AZD7442 was well tolerated and reduced hospitalization and mortality through 6 months, and symptom burden through 29 days, in outpatients with mild-to-moderate COVID-19. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov, NCT04723394. ( https://beta. CLINICALTRIALS: gov/study/NCT04723394 )