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Budgets of turbulent kinetic energy (TKE) and turbulent potential energy (TPE) at different scales $\ell$ in sheared, stably stratified turbulence are analysed using a filtering approach. Competing effects in the flow are considered, along with the physical mechanisms governing the energy fluxes between scales, and the budgets are used to analyse data from direct numerical simulation at buoyancy Reynolds number $Re_b=O(100)$. The mean TKE exceeds the TPE by an order of magnitude at the large scales, with the difference reducing as $\ell$ is decreased. At larger scales, buoyancy is never observed to be positive, with buoyancy always converting TKE to TPE. As $\ell$ is decreased, the probability of locally convecting regions increases, though it remains small at scales down to the Ozmidov scale. The TKE and TPE fluxes between scales are both downscale on average, and their instantaneous values are correlated positively, but not strongly so, and this occurs due to the different physical mechanisms that govern these fluxes. Moreover, the contributions to these fluxes arising from the sub-grid fields are shown to be significant, in addition to the filtered scale contributions associated with the processes of strain self-amplification, vortex stretching and density gradient amplification. Probability density functions (PDFs) of the $Q,R$ invariants of the filtered velocity gradient are considered and show that as $\ell$ increases, the sheared-drop shape of the PDF becomes less pronounced and the PDF becomes more symmetric about $R=0$.
The two-dimensional acoustic wave equation for inviscid compressible boundary layer flows, i.e. the Pridmore-Brown equation with an exponential velocity profile for homentropic flows, is studied for the reflection and over-reflection of acoustic waves based on the exact solution in terms of the confluent Heun function. The reflection coefficient $R$, which is the ratio of the amplitude of the reflected to that of the incoming acoustic wave, is determined as a function of the streamwise wavenumber $\alpha$, the Mach number $M$ and the incident angle $\phi$ of the acoustic waves. Over-reflection refers to $R>1$, i.e. the reflected wave has a larger amplitude than the incident wave. We prove that, in the supersonic context, energy is always transferred from the base flow to the reflected wave, i.e. $R<1$ does not exist. Meanwhile, this fact is intimately linked to the critical layer. We show that the presence of the critical layer leads to an optimal energy exchange from the base flow into the acoustic wave, i.e. the critical layer ensures $R>1$. In our analysis, we observe a special phenomenon, resonant over-reflection, which is proven to be closely related to resonant frequencies $\omega _r$ of unstable modes of the temporal stability of the base flow. At resonant frequencies of the first unstable mode, the over-reflection coefficient exhibits an unusual peak in an extremely narrow frequency interval. The maximum values of these peaks are largely synchronized with the variation of the growth rate $\omega _i$ of the unstable modes. In addition, resonant over-reflection appears also at resonant frequencies of other higher unstable modes, but their peaks of the over-reflection coefficient are always smaller than that induced by the first unstable mode.
Increasing interest in three-dimensional nanostructures adds impetus to electron microscopy techniques capable of imaging at or below the nanoscale in three dimensions. We present a reconstruction algorithm that takes as input a focal series of four-dimensional scanning transmission electron microscopy (4D-STEM) data. We apply the approach to a lead iridate, Pb$_2$Ir$_2$O$_7$, and yttrium-stabilized zirconia, Y$_{0.095}$Zr$_{0.905}$O$_2$, heterostructure from data acquired with the specimen in a single plan-view orientation, with the epitaxial layers stacked along the beam direction. We demonstrate that Pb–Ir atomic columns are visible in the uppermost layers of the reconstructed volume. We compare this approach to the alternative techniques of depth sectioning using differential phase contrast scanning transmission electron microscopy (DPC-STEM) and multislice ptychographic reconstruction.
The enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR) links the folate cycle that produces one-carbon units with the methionine cycle that converts these into S-adenosylmethionine (SAM), the universal methyl donor for almost all methyltransferases. Previously, MTHFR has been shown to be regulated by phosphorylation, which suppresses its activity. SAM levels have been shown to increase substantially soon after initiation of meiotic maturation of the mouse germinal vesicle (GV) stage oocyte and then decrease back to their original low level in mature second meiotic metaphase (MII) eggs. As MTHFR controls the entry of one-carbon units into the methionine cycle, it is a candidate regulator of the SAM levels in oocytes and eggs. Mthfr transcripts are expressed in mouse oocytes and preimplantation embryos and MTHFR protein is present at each stage. In mature MII eggs, the apparent molecular weight of MTHFR was increased compared with GV oocytes, which we hypothesized was due to increased phosphorylation. The increase in apparent molecular weight was reversed by treatment with lambda protein phosphatase (LPP), indicating that MTHFR is phosphorylated in MII eggs. In contrast, LPP had no effect on MTHFR from GV oocytes, 2-cell embryos, or blastocysts. MTHFR was progressively phosphorylated after initiation of meiotic maturation, reaching maximal levels in MII eggs before decreasing again after egg activation. As phosphorylation suppresses MTHFR activity, it is predicted that MTHFR becomes inactive during meiotic maturation and is minimally active in MII eggs, which is consistent with the reported changes in SAM levels during mouse oocyte maturation.
Background: Proteogenomics, the integration of proteomics and RNASeq expands the discovery landscape for candidate expressed gene networks to obtain novel insights into host response in post-infectious hydrocephalus (PIH). We examined the cerebrospinal fluid (CSF) of infants with PIH, and case controlled against age-matched infants with non-postinfectious hydrocephalus (NPIH) to probe the molecular mechanisms of PIH, leveraging molecular identification of bacterial and viral pathogens. Methods: Ventricular CSF samples of 100 infants ≤ 3 months of age with PIH (n=64) and NPIH (n=36) were analyzed with proteomics and RNASeq. 16S rRNA/DNA sequencing and virome capture identified Paenibacillus spp. and cytomegalovirus as dominant pathogenetic bacteria implicated in our PIH cohort. Proteogenomics assessed differential expression, gene set enrichment and activated gene pathways. Results: Of 616 proteins and 11,114 genes, there was enrichment for the immune system, cell-cell junction signaling and response to oxidative stress. Proteogenomics yielded 33 functionally and genetically associated gene sets related to neutrophil activation, platelet activation, and cytokines (interleukins and interferon) signaling. Conclusions: We identified PIH patients with severe disease at time of hydrocephalus surgery, to have differential expression of proteins/genes involved in neuroinflammation, ependymal barrier integrity and reaction to oxidative stress. Further studies are needed to examine those proteins/genes as biomarkers for PIH.
To evaluate prevalence and risk factors of posttraumatic stress disorder (PTSD) and depression among directly exposed (DE) and indirectly or nonexposed (INE) populations in Sri Lanka 8 y after the Indian Ocean Tsunami in 2004.
Methods:
Population-based structured survey study was conducted among Sri Lankan adults living in 5 coastal districts, Hamboantha, Matara, Galle, Kalutara, and Colombo in 2012-2013. A total of 430 individuals, 325 in DE, 105 in INE, participated in the survey. DE and INE groups were compared for demographics and outcomes. Bivariate and multiple logistic regressions with backward selection were used to identify risk factors for partial PTSD and depression.
Results:
The prevalence of PTSD, partial PTSD and depression were 2.8%, 10.5%, and 18.8% in DE group, respectively. In multivariable analyses tsunami exposure, female gender, subjective physical health before the tsunami, previous trauma, and depression were significantly associated with partial PTSD. Female gender, high frequency of religious activity, previous trauma, social support, and PTSD were significantly associated with depression.
Conclusions:
The psychological impacts of the tsunami did wane over time, but still present at lower rate even in 8 y. It is important to address these lingering sequelae and expand access to at risk individuals.
As part of a project to implement antimicrobial dashboards at select facilities, we assessed physician attitudes and knowledge regarding antibiotic prescribing.
Design:
An online survey explored attitudes toward antimicrobial use and assessed respondents’ management of four clinical scenarios: cellulitis, community-acquired pneumonia, non–catheter-associated asymptomatic bacteriuria, and catheter-associated asymptomatic bacteriuria.
Setting:
This study was conducted across 16 Veterans’ Affairs (VA) medical centers in 2017.
Participants:
Physicians working in inpatient settings specializing in infectious diseases (ID), hospital medicine, and non-ID/hospitalist internal medicine.
Methods:
Scenario responses were scored by assigning +1 for answers most consistent with guidelines, 0 for less guideline-concordant but acceptable answers and −1 for guideline-discordant answers. Scores were normalized to 100% guideline concordant to 100% guideline discordant across all questions within a scenario, and mean scores were calculated across respondents by specialty. Differences in mean score per scenario were tested using analysis of variance (ANOVA).
Results:
Overall, 139 physicians completed the survey (19 ID physicians, 62 hospitalists, and 58 other internists). Attitudes were similar across the 3 groups. We detected a significant difference in cellulitis scenario scores (concordance: ID physicians, 76%; hospitalists, 58%; other internists, 52%; P = .0087). Scores were numerically but not significantly different across groups for community-acquired pneumonia (concordance: ID physicians, 75%; hospitalists, 60%; other internists, 56%; P = .0914), for non–catheter-associated asymptomatic bacteriuria (concordance: ID physicians, 65%; hospitalists, 55%; other internists, 40%; P = .322), and for catheter-associated asymptomatic bacteriuria (concordance: ID physicians, 27% concordant; hospitalists, 8% discordant; other internists 13% discordant; P = .12).
Conclusions:
Significant differences in performance regarding management of cellulitis and low overall performance regarding asymptomatic bacteriuria point to these conditions as being potentially high-yield targets for stewardship interventions.
The surge in critically ill patients has pressured hospitals to expand their intensive care unit capacities and critical care staff. This was difficult given the country’s shortage of intensivists. This paper describes the implementation of a multidisciplinary central line placement team and its impact in reducing the vascular access workload of ICU physicians during the height of the COVID-19 pandemic.
Methods:
Vascular surgeons, interventionalists, and anesthesiologists, were redeployed to the ICU Access team to place central and arterial lines. Nurses with expertise in vascular access were recruited to the team to streamline consultation and assist with line placement.
Results:
While 51 central and arterial lines were placed per 100 ICU patients in 2019, there were 87 central and arterial lines placed per 100 COVID-19 ICU patients in the sole month of April, 2020. The ICU Access Team placed 107 of the 226 vascular access devices in April 2020, reducing the procedure-related workload of ICU treating teams by 46%.
Conclusions:
The ICU Access Team was able to complete a large proportion of vascular access insertions without reported complications. Given another mass casualty event, this ICU Access Team could be reassembled to rapidly meet the increased vascular access needs of patients.
Ediacaran cap dolostone atop Marinoan glacial deposits contains complex sedimentary structures with extremely negative δ13Ccarb values in close association with oscillations in palaeoclimatic and oceanographic proxy records. However, the precise geological, geochronological and geochemical context of the cap dolostone is not clarified, which hampers us from correctly interpreting the extremely negative δ13Ccarb values and their causal relationships with the Snowball Earth hypothesis. In this study, we conducted detailed in situ geochronological and geochemical analyses on the calcite within the cap dolostone from the Ediacaran Doushantuo Formation in South China in order to define its formation and relationship to the Snowball Earth hypothesis. Petrographic observations show that formation of dolomite pre-dates precipitation of calcite and pyrite, which pre-dates quartz cementation in the basal cap carbonate. Calcite cement within the cap dolostone yielded a U–Pb age of 636.5 ± 7.4/17.8 Ma (2σ, MSWD = 1.6, n = 36/40), which is within uncertainty of a published dolomite U–Pb age of 632 ± 17 Ma (recalculated as 629.3 ± 16.7/22.9 Ma). These age constraints negate the possibility that the calcite cement was formed by late Ediacaran or Cambrian hydrothermal activity. The rare earth element distribution patterns suggest a dominant seawater origin overprinted by subsequent early Ediacaran hydrothermal activity. The combined age, petrographic and geochemical data suggest oxidization of methane clathrates in response to complicated interplay between eustasy and isostatic rebound and hydrothermal fluids.
Magnetohydrodynamic (MHD) simulations of the solar corona have become more popular with the increased availability of computational power. Modern computational plasma codes, relying upon computational fluid dynamics (CFD) methods, allow the coronal features to be resolved using solar surface magnetograms as inputs. These computations are carried out in a full three-dimensional domain and, thus, selection of the correct mesh configuration is essential to save computational resources and enable/speed up convergence. In addition, it has been observed that for MHD simulations close to the hydrostatic equilibrium, spurious numerical artefacts might appear in the solution following the mesh structure, which makes the selection of the grid also a concern for accuracy. The purpose of this paper is to discuss and trade off two main mesh topologies when applied to global solar corona simulations using the unstructured ideal MHD solver from the COOLFluiD platform. The first topology is based on the geodesic polyhedron and the second on $UV$ mapping. Focus is placed on aspects such as mesh adaptability, resolution distribution, resulting spurious numerical fluxes and convergence performance. For this purpose, first a rotating dipole case is investigated, followed by two simulations using real magnetograms from the solar minima (1995) and solar maxima (1999). It is concluded that the most appropriate mesh topology for the simulation depends on several factors, such as the accuracy requirements, the presence of features near the polar regions and/or strong features in the flow field in general. If convergence is of concern and the simulation contains strong dynamics, then grids which are based on the geodesic polyhedron are recommended compared with more conventionally used $UV$-mapped meshes.
We performed severe acute respiratory coronavirus virus 2 (SARS-CoV-2) antinucleocapsid IgG testing on 5,557 healthcare providers and found a seroprevalence of 3.9%. African Americans were more likely to test positive than Whites, and HCWs with household exposure and those working on COVID-19 cohorting units were more likely to test positive than their peers.
This paper proposes an online entry trajectory planning based on predictor corrector algorithm that satisfies terminal constraints, path constraints and geographic constraints for lifting-body entry vehicles. The vehicle is considered as a 3DOF point mass. A piecewise linear bank profile in the altitude-versus-velocity (H-V) plane is used to project the longitudinal trajectory and a heading angle corridor-based bank angle reversal logic is designed to satisfy the geographic constraints simultaneously. The algorithm in longitudinal plane solves the problem of the mismatch between terminal range and height and the algorithm in lateral plane satisfies the no-fly zone constraint. Simulation results with the CAV-H model show that the proposed algorithm can generate entry trajectories satisfying multiple constraints and has certain robustness.
Older adults with exceptional memory function, designated “SuperAgers,” include individuals over age 80, with episodic memory at least as good as individuals ages 50s–60s. The Northwestern University SuperAging cohort is defined by performance on an established test of verbal memory. The purpose of this study was to determine if superior verbal memory extends to nonverbal memory in SuperAgers by examining differences in the National Institutes of Health Toolbox® (NIHTB) between older adults with exceptional memory and those with average-for-age cognition.
Method:
SuperAgers (n = 46) and cognitively average-for-age older adults (n = 31) completed a comprehensive neuropsychological battery and the NIHTB Cognition module. Multiple linear regressions were used to examine differences on subtests between groups.
Results:
There was a significant effect of group on the Picture Sequence Memory score, (p = .007), such that SuperAgers had higher scores than cognitively average-for-age older adults. There were no other group effects across other non-episodic memory NIHTB Cognition measures.
Conclusions:
Findings from this study demonstrated stronger performance on the memory measure of the NIHTB in SuperAgers compared to cognitively average-for-age older adults demonstrating superior memory in not only verbal but also nonverbal episodic memory in this group. Additionally, this study adds to the literature validating the NIHTB in older adults, particularly in a novel population of adults over age 80 with exceptional memory.
Subthreshold depression could be a significant precursor to and a risk factor for major depression. However, reliable estimates of the prevalence and its contribution to developing major depression under different terminologies depicting subthreshold depression have to be established.
Methods
By searching PubMed and Web of Science using predefined inclusion criteria, we included 1 129 969 individuals from 113 studies conducted. The prevalence estimates were calculated using the random effect model. The incidence risk ratio (IRR) was estimated by measuring the ratio of individuals with subthreshold depression who developed major depression compared to that of non-depressed individuals from 19 studies (88, 882 individuals).
Results
No significant difference in the prevalence among the different terminologies depicting subthreshold depression (Q = 1.96, p = 0.5801) was found. By pooling the prevalence estimates of subthreshold depression in 113 studies, we obtained a summary prevalence of 11.02% [95% confidence interval (CI) 9.78–12.33%]. The youth group had the highest prevalence (14.17%, 95% CI 8.82–20.55%), followed by the elderly group (12.95%, 95% CI 11.41-14.58%) and the adult group (8.92%, 95% CI 7.51–10.45%). Further analysis of 19 studies' incidence rates showed individuals with subthreshold depression had an increased risk of developing major depression (IRR = 2.95, 95% CI 2.33–3.73), and the term minor depression showed the highest IRR compared with other terms (IRR = 3.97, 95% CI 3.17–4.96).
Conclusions
Depression could be a spectrum disorder, with subthreshold depression being a significant precursor to and a risk factor for major depression. Proactive management of subthreshold depression could be effective for managing the increasing prevalence of major depression.
Cutaneous leishmaniasis (CL) is a spectrum of clinical manifestations characterized by severe skin ulcerations that leads to social stigma. There are limited treatment options for CL, and the available drugs are becoming less efficacious due to drug resistance. More efficacious and safer antileishmanial drugs are needed. In this study, the biological effect of seven synthetically accessible nitroaromatic compounds was evaluated in vitro against amastigotes of Leishmania amazonensis, followed by in vivo evaluation using mouse models of CL. Two compounds (6 and 7) were active against amastigotes in vitro [half-maximal effective concentration (EC50): 4.57 ± 0.08 and 9.19 ± 0.68 μm, respectively], with selectivity indexes >50, and the other compounds were not selective. In vivo, compounds 6 and 7 (10 mg kg−1, twice a day for 14 days) failed to reduce skin lesion sizes and parasite loads determined by light microscopy of lesion imprints and quantitative polymerase chain reaction. Nevertheless, the in vitro leishmanicidal efficacy sustained their use as templates for nitroimidazole-based antileishmanial drug discovery programmes focusing on analogues with more suitable properties.
To persist (without immigration) in habitats with unpredictable environmental conditions, annuals must produce seeds each year or have a seed bank. Thus, we predicted that compared to perennials, annuals have a wider germination temperature range (GTR, the difference in temperature between the week with the highest and the week with the lowest germination during the natural germination season). We determined the GTR via germination phenology data for 350 herbaceous species in 59 families from the eastern USA: summer annuals (SA), 63; winter annuals (WA), 83; monocarpic perennials (MP), 28; and polycarpic perennials (PP), 176. There was no significant phylogenetic signal for the GTR. The width of the GTR during the first spring germination season was 9.6, 8.7 and 8.8°C for MP, PP and SA, respectively, and during the first autumn germination season 12.8, 11.8 and 12.4°C for MP, PP and WA, respectively. Annuals did not have a wider GTR than perennials in either the spring or the autumn germination season. Our data suggest that selection for early germination in either spring or autumn has resulted in only small differences in the GTR. We predict that global warming will have little or no effect on reshaping the germination phenology of herbaceous species of temperate eastern North America.