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In this cohort of Escherichia coli and Klebsiella spp hospital-onset bacteremia, isolated fluoroquinolone resistance had a larger relative impact on mortality than other phenotypic resistance patterns. This finding may support stewardship efforts targeting unnecessary fluoroquinolone use and increased attention from infection prevention and control departments.
Following publication, errors were discovered in the y-axis labels of the electron and hole concentration plots in the following figure panels: figure 4c, figure 4d, figure 5c, figure 5d, figure 6c, figure 6d, figure 8c and figure 8d. The error does not affect the description, analysis or conclusions. The correct representation of the figure panels are shown here.
Eta Carinae is the most massive active binary within 10,000 light-years. While famous for the largest non-terminal stellar explosion ever recorded, observations reveal a supermassive (∼120 M⊙) binary consisting of an LBV and either a WR or extreme O star in a very eccentric orbit (e=0.9) with a 5.54-year period. Dramatic changes across multiple wavelengths are routinely observed as the stars move about in their highly elliptical orbits, especially around periastron when the hot (∼40 kK) companion star delves deep into the denser and much cooler (∼15 kK) extended wind photosphere of the LBV primary. Many of these changes are due to a dynamic wind-wind collision region (WWCR) that forms between the stars, plus expanding radiation-illuminated fossil WWCRs formed one, two, and three 5.54-year orbital cycles ago. These fossil WWCRs have been spatially and spectrally resolved by the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) at multiple epochs, resulting in data cubes that spatially map Eta Carinae’s innermost WWCRs and follow temporal changes in several forbidden emission lines (e.g. [Fe iii] 4659 Å, [Fe ii] 4815 Å) across the 5.54-year cycle. We present initial results of 3D time-dependent hydrodynamical and radiative-transfer simulations of the Eta Carinae binary and its WWCRs with the goal of producing synthetic data cubes of forbidden emission lines for comparison to the available HST/STIS observations. Comparison of the theoretical models to the observations reveals important details about the binary’s orbital motion, photoionization properties, and recent (5–15year) mass loss history. Such an analysis also provides a baseline for following future changes in Eta Carinae, essential for understanding the late-stage evolution of a nearby supernova progenitor. Our modeling methods can also be adapted to a number of other colliding wind binary systems (e.g. WR 140) that are scheduled to be studied with future observatories (e.g. the James Webb Space Telescope).
The stellar winds of hot stars have an important impact on both stellar and galactic evolution, yet their structure and internal processes are not fully understood in detail. One of the best nearby laboratories for studying such massive stellar winds is the O4I(n)fp star ζ Pup. After briefly discussing existing X-ray observations from Chandra and XMM, we present a simulation of X-ray emission line profile measurements for the upcoming 840 kilosecond Chandra HETGS observation. This simulation indicates that the increased S/N of this new observation will allow several major steps forward in the understanding of massive stellar winds. By measuring X-ray emission line strengths and profiles, we should be able to differentiate between various stellar wind models and map the entire wind structure in temperature and density. This legacy X-ray spectrum of ζ Pup will be a useful benchmark for future X-ray missions.
Background: EMBRACE (NCT02462759) Part 1 is a randomized, double-blind, sham-procedure controlled study assessing safety/tolerability of intrathecal nusinersen (12-mg equivalent dose) in symptomatic infants/children with SMA who were not eligible to participate in ENDEAR or CHERISH. Methods: Eligible participants had onset of SMA symptoms at ≤6 months with 3 SMN2 copies; onset at ≤6 months, age >7 months and 2 copies; or onset at >6 months, age ≤18 months, and 2/3 copies. Safety/tolerability was the primary endpoint. Exploratory endpoints included Hammersmith Infant Neurological Examination Section 2 (HINE-2) motor milestone attainment, change in ventilator use, and growth. Results: EMBRACE Part 1 was terminated early based on positive results from ENDEAR. Safety/tolerability was similar to previous trials. More nusinersen-treated (11/14;79%) vs. sham–treated individuals (2/7;29%) were HINE-2 motor milestone responders. Between Day 183 and 302, mean (SD) hours of ventilator use changed by +1.236 (3.712) hours in nusinersen-treated (n=12) and +2.123 (3.023) hours in sham–treated individuals (n=7). Similar increases in weight and body length were observed in nusinersen-treated and sham–treated individuals by Day 183. Conclusions: In EMBRACE Part 1, nusinersen demonstrated a favorable benefit-risk profile. These results add to the aggregated efficacy, safety/tolerability data of nusinersen in SMA.
Increasing evidence suggests that the presence of mobile ions in perovskite solar cells (PSCs) can cause a current–voltage curve hysteresis. Steady state and transient current–voltage characteristics of a planar metal halide CH3NH3PbI3 PSC are analysed with a drift-diffusion model that accounts for both charge transport and ion vacancy motion. The high ion vacancy density within the perovskite layer gives rise to narrow Debye layers (typical width ~2 nm), adjacent to the interfaces with the transport layers, over which large drops in the electric potential occur and in which significant charge is stored. Large disparities between (I) the width of the Debye layers and that of the perovskite layer (~600 nm) and (II) the ion vacancy density and the charge carrier densities motivate an asymptotic approach to solving the model, while the stiffness of the equations renders standard solution methods unreliable. We derive a simplified surface polarisation model in which the slow ion dynamics are replaced by interfacial (non-linear) capacitances at the perovskite interfaces. Favourable comparison is made between the results of the asymptotic approach and numerical solutions for a realistic cell over a wide range of operating conditions of practical interest.
Research has shown both production and health benefits for the use of chicory (Cichorium intybus) within ruminant diets. Despite this, little was known about the effects of this forage, containing differing fatty acid profiles and secondary plant compounds compared with ryegrass, on beef stability, fatty acid composition or sensory properties. An experiment was conducted to investigate whether the inclusion of chicory in the diet of grazing beef steers would alter these three properties in the M. Longissimus muscle when compared with beef steers grazing perennial ryegrass (Lolium perenne). Triplicate 2 ha plots were established with a chicory (cv. Puna II)/perennial ryegrass mix or a perennial ryegrass control. A core group of 36 Belgian Blue – cross steers were used within a 2-year beef finishing experiment (n=6/replicate plot). In the 2nd grazing year, steers were slaughtered as they reached a target fat class of 3. Muscle pH was checked 2 and 48 h post-slaughter. A section of the hindloin joint containing the M. Longissimus lumborum muscle was removed and a 20 mm-thick steak was cut and muscle samples were taken for analysis of vitamin E and fatty acid analysis. The remaining section of the loin was vacuum packed in modified atmosphere packs and subjected to simulated retail display. A section of the conditioned loin was used for sensory analysis. Data on pH, vitamin E concentration and colour stability in a simulated retail display showed there were no effects of including chicory in the diet of grazing beef steers on meat stability. There were also no differences found in the fatty acid composition or the overall eating quality of the steaks from the two treatments. In conclusion, there were no substantive effects of including chicory in the swards of grazing beef cattle on meat stability, fatty acid composition or sensory properties of the M. Longissimus muscle when compared with beef steers grazing ryegrass-only swards.
There are an estimated 1.5 million internally displaced persons (IDPs) in Ukraine because of the armed conflict in the east of the country. The aim of this paper is to examine utilisation patterns of mental health and psychosocial support (MHPSS) care among IDPs in Ukraine.
A cross-sectional survey design was used. Data were collected from 2203 adult IDPs throughout Ukraine between March and May 2016. Data on mental health care utilisation were collected, along with outcomes including post-traumatic stress disorder (PTSD), depression and anxiety. Descriptive and multivariate regression analyses were used.
PTSD prevalence was 32%, depression prevalence was 22%, and anxiety prevalence was 17%. Among those that likely required care (screened positive with one of the three disorders, and also self-reporting a problem) there was a large treatment gap, with 74% of respondents who likely required MHPSS care over the past 12 months not receiving it. For the 26% (N = 180) that had sought care, the most common sources of services/support were pharmacies, family or district doctor/paramedic (feldsher), neurologist at a polyclinic, internist/neurologist at a general hospital, psychologists visiting communities, and non-governmental organisations/volunteer mental health/psychosocial centres. Of the 180 respondents who did seek care, 163 could recall whether they had to pay for their care. Of these 163 respondents, 72 (44%) recalled paying for the care they received despite government care officially being free in Ukraine. The average costs they paid for care was US$107 over the previous 12 months. All 180 respondents reported having to pay for medicines and the average costs for medicines was US$109 over the previous 12 months. Among the 74% had not sought care despite likely needing it; the principal reasons for not seeking care were: thought that they would get better by using their own medications, could not afford to pay for health services or medications, no awareness of where to receive help, poor understanding by health care providers, poor quality of services, and stigma/embarrassment. The findings from multivariate regression analysis show the significant influence of a poor household economic situation on not accessing care.
The study highlights a high burden of mental disorders and large MHPSS treatment gap among IDPs in Ukraine. The findings support the need for a scaled-up, comprehensive and trauma-informed response to provision of MHPSS care of IDPs in Ukraine alongside broader health system strengthening.
Recent studies have improved our understanding of nearshore marine ecosystems surrounding Ascension Island (central Atlantic Ocean), but little is known about Ascension's benthic environment beyond its shallow coastal waters. Here, we report the first detailed physical and biological examination of the seabed surrounding Ascension Island at 100–1000 m depth. Multibeam swath data were used to map fine scale bathymetry and derive seabed slope and rugosity indices for the entire area. Water temperature and salinity profiles were obtained from five Conductivity, Temperature, Depth (CTD) deployments, revealing a spatially consistent thermocline at 80 m depth. A camera lander (Shelf Underwater Camera System; SUCS) provided nearly 400 images from 21 sites (100 m transects) at depths of 110–1020 m, showing high variability in the structure of benthic habitats and biological communities. These surveys revealed a total of 95 faunal morphotypes (mean richness >14 per site), complemented by 213 voucher specimens constituting 60 morphotypes collected from seven targeted Agassiz trawl (AGT) deployments. While total faunal density (maximum >300 m−2 at 480 m depth) increased with rugosity, characteristic shifts in multivariate assemblage structure were driven by depth and substratum type. Shallow assemblages (~100 m) were dominated by black coral (Antipatharia sp.) on rocky substrata, cup corals (Caryophyllia sp.) and sea urchins (Cidaris sp.) were abundant on fine sediment at intermediate depths (250–500 m), and shrimps (Nematocarcinus spp.) were common at greater depths (>500 m). Other ubiquitous taxa included serpulid and sabellid polychaetes and brittle stars (Ophiocantha sp.). Cold-water corals (Lophelia cf. pertusa), indicative of Vulnerable Marine Ecosystems (VMEs) and representing substantial benthic carbon accumulation, occurred in particularly dense aggregations at <350 m but were encountered as deep as 1020 m. In addition to enhancing marine biodiversity records at this locality, this study provides critical baseline data to support the future management of Ascension's marine environment.
Eta Carinae is one of the most massive observable binaries. Yet determination of its orbital and physical parameters is hampered by obscuring winds. However the effects of the strong, colliding winds changes with phase due to the high orbital eccentricity. We wanted to improve measures of the orbital parameters and to determine the mechanisms that produce the relatively brief, phase-locked minimum as detected throughout the electromagnetic spectrum. We conducted intense monitoring of the He ii λ4686 line in η Carinae for 10 months in the year 2014, gathering ~300 high S/N spectra with ground- and space-based telescopes. We also used published spectra at the FOS4 SE polar region of the Homunculus, which views the minimum from a different direction. We used a model in which the He ii λ4686 emission is produced by two mechanisms: a) one linked to the intensity of the wind-wind collision which occurs along the whole orbit and is proportional to the inverse square of the separation between the companion stars; and b) the other produced by the ‘bore hole’ effect which occurs at phases across the periastron passage. The opacity (computed from 3D SPH simulations) as convolved with the emission reproduces the behavior of equivalent widths both for direct and reflected light. Our main results are: a) a demonstration that the He ii λ4686 light curve is exquisitely repeatable from cycle to cycle, contrary to previous claims for large changes; b) an accurate determination of the longitude of periastron, indicating that the secondary star is ‘behind’ the primary at periastron, a dispute extended over the past decade; c) a determination of the time of periastron passage, at ~4 days after the onset of the deep light curve minimum; and d) show that the minimum is simultaneous for observers at different lines of sight, indicating that it is not caused by an eclipse of the secondary star, but rather by the immersion of the wind-wind collision interior to the inner wind of the primary.
As already mentioned in earlier chapters, the eikonal approximation can become invalid in local regions of the plasma. The most common problems are caustics (see Chapter 5), tunneling, and mode conversion. Both tunneling and mode conversion are processes where one incoming ray splits into two outgoing rays, a transmitted ray and a converted ray. The matched asymptotic methods are therefore more complicated than for caustics. Tunneling concerns only one eigenvalue of the N × N dispersion matrix, while mode conversion entails two. It follows that tunneling involves only one polarization, while mode conversion is associated with a pair. Therefore, tunneling can be reduced by Galerkin projection locally to a scalar formulation, while mode conversion is inherently a vector problem. An important point we should emphasize is the following: For caustics, it is always possible to find a local representation where the eikonal approximation is valid. In contrast, in tunneling and mode conversion regions, there is no representation in which the eikonal approximation is valid. It is only when we consider points far from the conversion region that we recover eikonal behavior. This leads to two important questions:
If the eikonal approximation is not valid within the conversion region, why persist in using ray tracing there?
Although the eikonal approximation is valid for the incoming wave field (by assumption), what justifies the assumption that the transmitted and converted wave fields become eikonal once more?
One of the major goals of this book is to develop the reader's geometrical intuition as it applies to the study of waves in plasmas, while at the same time developing useful methods for quantitative analysis. The great advantage of a geometrical approach is that it brings our visual intuition into play. We can sometimes develop a deeper physical understanding by drawing simple pictures. That deeper intuition can then guide us to new analytical approaches, or help us see the way through a complicated calculation. In the end, of course, we must be able to calculate solutions of wave equations, so in this chapter we provide a brief overview of methods for visualizing solutions and we provide some examples of field construction.
The outline of the chapter is as follows: We begin by summarizing why it is so challenging to visualize eikonal solutions in phase spaces of dimension higher than two. We first introduce the Poincaré surface of section, which is a commonly used tool for the study of higher-dimensional dynamical systems. While straightforward to understand and easy to use, the surface of section does not provide a global view of the Lagrange surface of rays, so it still leaves something to be desired. We then present some novel ideas for global visualization in two spatial dimensions (four-dimensional ray phase space) and consider two examples. The first example concerns electromagnetic waves in two spatial dimensions propagating from a vacuum into a dense plasma with a cutoff.
This is the central chapter of the book. We emphasize that in this chapter we introduce the eikonal approximation without discussing the accuracy of the approximation, or how to deal with situations where it breaks down (for example, at caustics or in mode conversion regions). Those are matters for later chapters. The great advantage of eikonal methods is that they reduce the solution of systems of PDEs, or systems of integrodifferential equations, to the solution of a family of ODEs. This often results in a substantial increase in computational speed in applications. In addition, the ray trajectories themselves often provide useful physical insight. The outline of topics follows.
Eikonal theory for multicomponent wave equations is first developed in x-space where we derive the eikonal equation for the phase and the action conservation law (in the form of a nonlinear PDE). It should be noted that the dispersion function that arises from the variational principle is one of the eigenvalues of the dispersion matrix, restricted to its zero locus in phase space. The polarization is its associated eigenvector. We discuss the fact that the interpretation of these results and the method of solution of the eikonal and action transport equations are most natural when viewed in ray phase space.
We then discuss how to relate the x-space and phase space viewpoints, the key ideas being lifts and projections. The notion of a Lagrange manifold arises naturally in this context as a lifting of a local region of x-space into phase space. Singularities that appear under projection are related to caustics, which are dealt with in Chapter 5.