Heavy-metal hot subdwarfs (sdB and sdO) represent a small group of stars with unusually high concentrations of trans-iron elements in their atmospheres, having abundances ~ 10000 times solar. One ...example is LS IV-14\(^{\circ}\) 116, where a number of heavy-metal absorption lines of Sr II, Y III and Zr IV have been observed in the optical band 4000 - 5000 A. We use a fully relativistic Dirac atomic R-Matrix (DARC) to calculate photoionization cross sections of Sr\(^{0}\), Y\(^{+}\) and Zr\(^{2+}\) from their ground state to the twentieth excited level. We use the cross sections and the oscillator strengths to simulate the spectrum of a hot subdwarf. We obtain complete sets of photoionization cross sections for the three ions under study. We use these data to calculate the opacity of the stellar atmospheres of hot subdwarf stars, and show that for overabundances observed in some heavy-metal subdwarves, photo-excitation from zirconium, in particular, does contribute some back warming in the model.
Here we report a prospective life-cycle net energy assessment of a hypothetical large-scale photoelectrochemical (PEC) hydrogen production facility with energy output equivalent to 1 GW continuous ...annual average (1 GW HHV = 610 metric tons of H 2 per day). We determine essential mass and energy flows based on fundamental principles, and use heuristic methods to conduct a preliminary engineering design of the facility. We then develop and apply a parametric model describing system-wide energy flows associated with the production, utilization, and decommissioning of the facility. Based on these flows, we calculate and interpret life-cycle net energy metrics for the facility. We find that under base-case conditions the energy payback time is 8.1 years, the energy return on energy invested (EROEI) is 1.7, and the life-cycle primary energy balance over the 40 years projected service life of the facility is +500 PJ. The most important model parameters affecting the net energy metrics are the solar-to-hydrogen (STH) conversion efficiency and the life span of the PEC cells; parameters associated with the balance of systems (BOS), including construction and operation of the liquid and gas handling infrastructure, play a much smaller role.
The number of tree species on Earth Cazzolla Gatti, Roberto; Reich, Peter B; Gamarra, Javier G P ...
Proceedings of the National Academy of Sciences - PNAS,
02/2022, Letnik:
119, Številka:
6
Journal Article, Web Resource
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One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species ...concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness.
The stimulator of interferon genes (STING) protein bridges sensors of cytosolic DNA and the inflammatory pathway mediated by interferon-β. Activating mutations in the
STING
gene cause a vascular and ...pulmonary syndrome.
Studies involving children with monogenic autoinflammatory disease have provided insights into the regulation of key proinflammatory cytokine pathways and their role in causing systemic and organ-specific inflammation.
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We studied six patients who presented in early infancy with systemic inflammation and violaceous, scaling lesions of fingers, toes, nose, cheeks, and ears that progressed to acral necrosis in most of the patients and did not respond to therapy. A mixed histologic pattern was observed, consisting of a prominent dermal inflammatory infiltrate with features of leukocytoclastic vasculitis and microthrombotic angiopathy of small dermal vessels. Three of the patients had severe interstitial lung . . .
IMPORTANCE: Tests that predict outcomes for patients with acute myeloid leukemia (AML) are imprecise, especially for those with intermediate risk AML. OBJECTIVES: To determine whether genomic ...approaches can provide novel prognostic information for adult patients with de novo AML. DESIGN, SETTING, AND PARTICIPANTS: Whole-genome or exome sequencing was performed on samples obtained at disease presentation from 71 patients with AML (mean age, 50.8 years) treated with standard induction chemotherapy at a single site starting in March 2002, with follow-up through January 2015. In addition, deep digital sequencing was performed on paired diagnosis and remission samples from 50 patients (including 32 with intermediate-risk AML), approximately 30 days after successful induction therapy. Twenty-five of the 50 were from the cohort of 71 patients, and 25 were new, additional cases. EXPOSURES: Whole-genome or exome sequencing and targeted deep sequencing. Risk of identification based on genetic data. MAIN OUTCOMES AND MEASURES: Mutation patterns (including clearance of leukemia-associated variants after chemotherapy) and their association with event-free survival and overall survival. RESULTS: Analysis of comprehensive genomic data from the 71 patients did not improve outcome assessment over current standard-of-care metrics. In an analysis of 50 patients with both presentation and documented remission samples, 24 (48%) had persistent leukemia-associated mutations in at least 5% of bone marrow cells at remission. The 24 with persistent mutations had significantly reduced event-free survival vs the 26 who cleared all mutations (median 95% CI: 6.0 months 95% CI, 3.7-9.6 for persistent mutations vs 17.9 months 95% CI, 11.3-40.4 for cleared mutations, log-rank P < .001; hazard ratio HR, 3.67 95% CI, 1.93-7.11, P < .001) and reduced overall survival (median 95% CI: 10.5 months 95% CI, 7.5-22.2 for persistent mutations vs 42.2 months 95% CI, 20.6-not estimable for cleared mutations, log-rank P = .003; HR, 2.86 95% CI, 1.39-5.88, P = .004). Among the 32 patients with intermediate cytogenetic risk, the 14 patients with persistent mutations had reduced event-free survival compared with the 18 patients who cleared all mutations (median 95% CI: 8.8 months 95% CI, 3.7-14.6 for persistent mutations vs 25.6 months 95% CI, 11.4-not estimable for cleared mutations, log-rank P = .003; HR, 3.32 95% CI, 1.44-7.67, P = .005) and reduced overall survival (median 95% CI: 19.3 months 95% CI, 7.5-42.3 for persistent mutations vs 46.8 months 95% CI, 22.6-not estimable for cleared mutations, log-rank P = .02; HR, 2.88 95% CI, 1.11-7.45, P = .03). CONCLUSIONS AND RELEVANCE: The detection of persistent leukemia-associated mutations in at least 5% of bone marrow cells in day 30 remission samples was associated with a significantly increased risk of relapse, and reduced overall survival. These data suggest that this genomic approach may improve risk stratification for patients with AML.
Energetic thin films with high mass loadings of nanosized components have been recently fabricated using electrospray deposition. These films are composed of aluminum nanoparticles (nAl) ...homogeneously dispersed in an energetic fluoropolymer binder, poly(vinylidene fluoride) (PVDF). The nascent oxide shell of the nAl has been previously shown to undergo a preignition reaction (PIR) with fluoropolymers such as polytetrafluoroethylene (PTFE). This work examines the PIR between alumina and PVDF to further explain the reaction mechanism of the Al/PVDF system. Temperature jump (T-jump) ignition experiments in air, argon, and vacuum environments showed that the nAl is fluorinated by gas phase species due to a decrease in reactivity in a vacuum. Thermogravimetric analysis coupled with differential scanning calorimetry (TGA/DSC) was used to confirm the occurrence of a PIR, and gas phase products during the PIR and fluorination of nAl were investigated with temperature jump time-of-flight mass spectrometry (T-jump TOFMS). Results show a direct correlation between the amount of alumina in the PVDF film and the relative signal intensity of hydrogen fluoride release (HF). Although the PIR between alumina and PVDF plays an important role in the Al/PVDF reaction mechanism, burn speeds of Al/PVDF films containing additional pure alumina particles showed no burn speed enhancement.
BACKGROUND:Although cardiac procedures are commonly used to treat cardiovascular disease, they are costly. Administrative data sources could be used to track cardiac procedures, but sources of such ...data have not been validated against clinical registries.
OBJECTIVES:To examine accuracy of cardiac procedure coding in administrative databases versus a prospective clinical registry.
SAMPLE:We examined a total of 182,018 common cardiac procedures including percutaneous coronary intervention (PCI), coronary artery bypass graft (CABG) surgery, valve surgery, and cardiac catheterization procedures during fiscal years 2005 and 2006 across 18 cardiac centers in Ontario, Canada.
RESEARCH DESIGN:Accuracy of codes in the Canadian Institute for Health Information (CIHI) administrative databases were compared with the clinical registry of the Cardiac Care Network.
RESULTS:Comparing 17,511 CIHI and 17,404 registry procedures for CABG surgery, the positive predictive value (PPV) of CIHI-coded CABG surgery was 97%. In 6229 CIHI-coded and 5885 registry-coded valve surgery procedures, the PPV of the administrative data source was 96%. Comparing 38,527 PCI procedures in CIHI to 38,601 in the registry, the PPV of CIHI was 94%. Among 119,751 CIHI-coded and 111,725 registry-coded cardiac catheterization procedures, the PPV of administrative data was 94%. When the procedure date window was expanded from the same day to ±1 days, the PPV was 96% (PCI) and exceeded 98% (CABG surgery), 97% (valve surgery), and 95% (cardiac catheterization).
CONCLUSIONS:Using a clinical registry as the gold standard, the coding accuracy of common cardiac procedures in the CIHI administrative database was high.
Fluorinated organic compounds are frequently used across the chemical and life sciences. Although a large, structurally diverse pool of alkyl fluorides is nowadays available, synthetic applications ...trail behind the widely accepted utility of other halides. We envisioned that C(sp
)-C(sp
) cross-coupling reactions of alkyl fluorides with fluorophilic organozinc compounds should be possible through a heterolytic mechanism that involves short-lived ion pairs and uses the stability of the Zn-F bond as the thermodynamic driving force. This would be mechanistically different from previously reported radical reactions and overcome long-standing limitations of organometallic cross-coupling methodology, including competing β-hydride elimination, homodimerization and hydrodefluorination. Here, we show a practical C
-F bond functionalization method that expands the currently restricted synthetic space of unactivated primary, secondary and tertiary C(sp
)-F bonds but also uses benzylic, propargylic and acyl fluorides. Many functional groups and sterically demanding substrates are tolerated, which allows practical carbon-carbon bond formation and late-stage functionalization.
Pulsation in faint blue stars Byrne, Conor M; Jeffery, C Simon
Monthly notices of the Royal Astronomical Society,
02/2020, Letnik:
492, Številka:
1
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ABSTRACT
Following the discovery of blue large-amplitude pulsators (BLAPs) by the OGLE survey, additional hot, high-amplitude pulsating stars have been discovered by the Zwicky Transient Facility. It ...has been proposed that all of these objects are low-mass pre-white dwarfs and that their pulsations are driven by the opacity of iron-group elements. With this expanded population of pulsating objects, it was decided to compute a sequence of post-common-envelope stellar models using the mesa stellar evolution code and to examine the pulsation properties of low-mass pre-white dwarfs using non-adiabatic analysis with the gyre stellar oscillation code. By including the effects of atomic diffusion and radiative levitation, it is shown that a large region of instability exists from effective temperatures of 30 000 K up to temperatures of at least 50 000 K and at a wide range of surface gravities. This encompasses both groups of pulsator observed so far, and confirms that the driving mechanism is through iron group element opacity. We make some conservative estimates about the range of periods, masses, temperatures, and gravities in which further such pulsators might be observed.
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