The dynamics of plasma electrons in the focus of a petawatt laser beam are studied via measurements of their x-ray synchrotron radiation. With increasing laser intensity, a forward directed beam of x ...rays extending to 50 keV is observed. The measured x rays are well described in the synchrotron asymptotic limit of electrons oscillating in a plasma channel. The critical energy of the measured synchrotron spectrum is found to scale as the Maxwellian temperature of the simultaneously measured electron spectra. At low laser intensity transverse oscillations are negligible as the electrons are predominantly accelerated axially by the laser generated wakefield. At high laser intensity, electrons are directly accelerated by the laser and enter a highly radiative regime with up to 5% of their energy converted into x rays.
Single-shot absorption measurements have been performed using the multi-keV x rays generated by a laser-wakefield accelerator. A 200 TW laser was used to drive a laser-wakefield accelerator in a mode ...which produced broadband electron beams with a maximum energy above 1 GeV and a broad divergence of ≈15 mrad FWHM. Betatron oscillations of these electrons generated 1.2±0.2×10^{6} photons/eV in the 5 keV region, with a signal-to-noise ratio of approximately 300∶1. This was sufficient to allow high-resolution x-ray absorption near-edge structure measurements at the K edge of a titanium sample in a single shot. We demonstrate that this source is capable of single-shot, simultaneous measurements of both the electron and ion distributions in matter heated to eV temperatures by comparison with density functional theory simulations. The unique combination of a high-flux, large bandwidth, few femtosecond duration x-ray pulse synchronized to a high-power laser will enable key advances in the study of ultrafast energetic processes such as electron-ion equilibration.
Susceptibility testing is an important tool in the clinical setting; its utility is based on the availability of categorical endpoints, breakpoints (BPs), or epidemiological cutoff values ...(ECVs/ECOFFs). CLSI and EUCAST have developed antifungal susceptibility testing, BPs, and ECVs for some fungal species. Although the concentration gradient strip bioMérieux Etest is useful for routine testing in the clinical laboratory, ECVs are not available for all agent/species; the lack of clinical data precludes development of BPs. We reevaluated and consolidated Etest data points from three previous studies and included new data. We defined ECOFFinder Etest ECVs for three sets of species-agent combinations: fluconazole, posaconazole, and voriconazole and 9
spp.; amphotericin B and 3 nonprevalent
spp.; and caspofungin and 4 Aspergillus spp. The total of Etest MICs from 23 laboratories (Europe, the Americas, and South Africa) included (antifungal agent dependent): 17,242 Candida albicans, 244 C. dubliniensis, 5,129 C. glabrata species complex (SC), 275 C. guilliermondii (Meyerozyma guilliermondii), 1,133 C. krusei (
), 933 C. kefyr (Kluyveromyces marxianus), 519 C. lusitaniae (Clavispora lusitaniae), 2,947 C. parapsilosis SC, 2,214 C. tropicalis, 3,212 Aspergillus fumigatus, 232 A. flavus, 181 A. niger, and 267 A. terreus SC isolates. Triazole MICs for 66 confirmed non-wild-type (non-WT)
isolates were available (
point mutations). Distributions fulfilling CLSI ECV criteria were pooled, and ECOFFinder Etest ECVs were established for triazoles (9
spp.), amphotericin B (3 less-prevalent
spp.), and caspofungin (4 Aspergillus spp.). Etest fluconazole ECVs could be good detectors of
non-WT isolates (59/61 non-WT, 4 of 6 species).
We describe the first demonstration of plasma mirrors made using freely suspended, ultra-thin films formed dynamically and in-situ. We also present novel particle-in-cell simulations that for the ...first time incorporate multiphoton ionization and dielectric models that are necessary for describing plasma mirrors. Dielectric plasma mirrors are a crucial component for high intensity laser applications such as ion acceleration and solid target high harmonic generation because they greatly improve pulse contrast. We use the liquid crystal 8CB and introduce an innovative dynamic film formation device that can tune the film thickness so that it acts as its own antireflection coating. Films can be formed at a prolonged, high repetition rate without the need for subsequent realignment. High intensity reflectance above 75% and low-field reflectance below 0.2% are demonstrated, as well as initial ion acceleration experimental results that demonstrate increased ion energy and yield on shots cleaned with these plasma mirrors.
To determine the Etest-based epidemiological cut-off values (ECVs) for antifungal agents against the most frequent yeast and Aspergillus fumigatus species isolated in 12 French hospitals.
For each ...antifungal agent, the Etest MICs in yeast and A. fumigatus isolates from 12 French laboratories were retrospectively collected from 2004 to 2018. The ECVs were then calculated using the iterative statistical method with a 97.5% cut-off.
Forty-eight Etest ECVs were determined for amphotericin B, caspofungin, micafungin, anidulafungin, fluconazole, voriconazole, posaconazole and itraconazole, after pooling and analysing the MICs of 9654 Candida albicans, 2939 Candida glabrata SC, 1458 Candida parapsilosis SC, 1148 Candida tropicalis, 575 Candida krusei, 518 Candida kefyr, 241 Candida lusitaniae, 131 Candida guilliermondii and 1526 Aspergillus fumigatus species complex isolates. These ECVs were 100% concordant (identical or within one two-fold dilution) with the previously reported Etest-based ECVs (when available), and they were concordant in 76.1% of cases with the Clinical and Laboratory Standards Institute ECVs and in 81.6% of cases with the European Committee on Antimicrobial Susceptibility Testing ECVs.
On the basis of these and other previous results, we recommend the determination of method-dependent ECVs. Etest ECVs should not be used instead of breakpoints, but may be useful to identify non-wild-type isolates with potential resistance to antifungal agents, and to indicate that an isolate may not respond as expected to the standard treatment.
Hydrodynamic optically-field-ionized (HOFI) plasma channels up to 100 mm long are investigated. Optical guiding is demonstrated of laser pulses with a peak input intensity of6×1017Wcm−2through 100 mm ...long plasma channels with on-axis densities measured interferometrically to be as low asne0=(1.0±0.3)×1017cm−3. Guiding is also observed at lower axial densities, which are inferred from magneto-hydrodynamic simulations to be approximately7×1016cm−3. Measurements of the power attenuation lengths of the channels are shown to be in good agreement with those calculated from the measured transverse electron density profiles. To our knowledge, the plasma channels investigated in this work are the longest, and have the lowest on-axis density, of any free-standing waveguide demonstrated to guide laser pulses with intensities above>1017Wcm−2.
section
is a species complex currently comprised of 14 cryptic species whose prevalence in clinical samples as well as antifungal susceptibility are poorly known. The aims of this study were to ...investigate
clinical isolates at the species level and to perform antifungal susceptibility analyses by reference and commercial methods. Eighty-two clinical
isolates were collected from 8 French university hospitals. Molecular identification was performed by sequencing parts of beta-tubulin and calmodulin genes. MICs or minimum effective concentrations (MECs) were determined for 8 antifungal drugs using both EUCAST broth microdilution (BMD) methods and concentration gradient strips (CGS). Among the 79
isolates,
(
= 61),
(
= 13),
(
= 3), and
(
= 2) were identified. All strains had MICs of ≥1 mg/liter for amphotericin B, except for two isolates (both
) that had MICs of 0.25 mg/liter. Four
isolates were resistant to at least one azole drug, including one with pan-azole resistance, yet no mutation in the
gene was found. All strains had low MECs for the three echinocandins. The essential agreements (EAs) between BMD and CGS were >90%, except for those of amphotericin B (79.7%) and itraconazole (73.4%). Isolates belonging to the
section
identified in clinical samples show wider species diversity beyond the known
Azole resistance inside the section
is uncommon and is not related to CYP51A mutations here. Finally, CGS is an interesting alternative for routine antifungal susceptibility testing.
Summary
This article concerns validation and verification (V&V) of the open source OpenFOAM incompressible flow solver that is widely used in both research and industry for the simulation of ...turbulent flows. Its numerical discretization scheme relies on classical finite volumes that are second order in space on regular grids. The solver is benchmarked using a challenging test case for which direct numerical simulation (DNS) reference data exist. The geometrical configuration of this flow is very simple, yet the behavior of the flow is 3D, complex, and unsteady, requiring an accurate flow solver to capture the associated physics. The physical problem addressed here requires huge computational grids. Computations are thus carried using parallel domain decomposition methods on a fairly large number of cores. The validation study performed here is particularly severe as it consists in comparing OpenFOAM results with DNS data obtained using high‐order codes. As simulations of turbulent flows require great computational resources, results concerning strong and weak scalability of the OpenFOAM flow solver are also presented. The performances of the code are assessed on two different HPC infrastructures. The experiences carried here show that OpenFOAM scales fairly up to 1000 cores on a Tier‐1cluster. The influences of the processor hardware and network topology are also highlighted. This study also provides profiling diagnostics thanks to the Integrated Performance Monitor (IPM).
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