1,006 research outputs found
Performance of a multianalyte \u27rule-out\u27 assay in pregnant individuals with suspected preeclampsia
BACKGROUND: The ability to diagnose preeclampsia clinically is suboptimal. Our objective was to validate a novel multianalyte assay and characterize its performance, when intended for use as an aid to rule-out preeclampsia.
METHODS: Prospective, multicenter cohort study of pregnant individuals presenting between 28
RESULTS: One thousand thirty-six pregnant individuals were enrolled in the study cohort with an incidence of preeclampsia of 30.3% (27.6%-33.2%). The time to develop preeclampsia was shorter for those with an at-risk compared with negative assay result (log-rank
CONCLUSIONS: We confirmed that a novel multianalyte assay was associated with the time to develop preeclampsia and has a moderate sensitivity and negative likelihood ratio but high negative predictive value when assessed as an aid to rule out preeclampsia within 7 days of enrollment.
REGISTRATION: The study was registered on Clinicaltrials.gov (Identifier NCT02780414)
Formation de poudres carbonées dans un plasma de haute fréquence produit à très basse pression dans des mélanges acétylène-argon
Dusty plasmas are plasmas that contain solid particles of nano- or micrometer size. They are widespread in the cosmic environment and act as precursors in the formation of planets and stars. Such plasmas are also used in laboratories for the synthesis of nanocomposites, which have wide technological and medical applications. While a large scientific effort has been invested in the study and control of such plasmas, the initial growth mechanism of powders (i.e. before they reach several tens of nanometers) remains poorly known.
This work contributes primarily to expand the fundamental knowledge in the field of dusty plasmas. Our goal is to understand the physical chemistry of high-frequency plasmas magnetically confined in chemically reactive gases. In addition, we aim by examining the kinetics of the precursors in the plasma to understand the mechanisms of nanoparticle formation in the volume and to control their characteristics in a magnetically confined low pressure Ar/C2H2 plasma. This contribution has a direct impact on science and plasma applications. Among the applications related directly to this research, we mention the synthesis of carbon-based nanocomposites for their integration in solar cells and biomaterials.
By examining the plasma characteristics (plasma temperature and density, cation and anion density) and correlating them to those of the dust particles, we found that the magnetic field changes the process of the formation of these particles in the discharge at very low pressure. Specifically, it stimulates the nucleation of carbon nanoparticles through several channels, i.e. through the anions and cations.
These nanoparticles include two different phases, an amorphous carbon layer and a porous core formed of grains aggregate. These grains are formed of graphite nanocrystals coated with an amorphous layer. Moreover, the radius of the dust particles increases with the magnetic field, which is related to the enhancement of their residence time in the plasma volume.Les plasmas poudreux sont des plasmas qui contiennent des particules solides de taille nano- ou même micrométrique. Ils sont répandus dans l'environnement cosmique et jouent le rôle de précurseurs dans la formation des planètes et des étoiles. Ce type de plasma est également utilisé dans les laboratoires pour la synthèse des nanocomposites possédant de vastes applications dans le monde technologique et médical. Tandis qu’un grand effort scientifique a été investi dans l’étude et le contrôle de ce type de plasmas, les mécanismes initiaux de formation des poudres (i.e. avant qu’elles atteignent quelques dizaines de nanomètres) demeurent très peu connus. On sait toutefois que des réactions physico-chimiques sont à l’origine de précurseurs des poudres qui déclenchent la nucléation.
Ce travail contribue en premier lieu à accroître les connaissances fondamentales dans le domaine des plasmas poudreux en général. Il s’agit en particulier de comprendre la physico-chimie des plasmas de haute fréquence de très basse pression soumis à un confinement magnétique dans des gaz chimiquement réactifs. Plus spécifiquement, l’objectif de ce travail est d’examiner la cinétique des précurseurs produits dans le plasma afin de comprendre les mécanismes de formation de nanoparticules en volume et le contrôle de leurs caractéristiques dans des mélanges d’Ar/C2H2 de très basse pression confinés magnétiquement. Cet apport a des retombées directes en science et applications des plasmas. Parmi les applications directement visées par cette recherche, notons la synthèse de nanomatériaux composites à base de carbone pour leur intégration dans les cellules solaires et les biomatériaux.
En examinant les caractéristiques du plasma (température et densité du plasma, densité des cations et des anions) et en les corrélant à celles des particules de poudre, on constate que le champ magnétique modifie le processus de la formation des particules poudreuses dans la décharge à très basse pression. Plus précisément, il favorise la nucléation des nanoparticules de carbone à travers plusieurs voies impliquant les anions et les cations. Ces nanoparticules comprennent deux phases différentes, une couche de carbone amorphe et un noyau poreux formé d'un agrégat de grains eux-mêmes constitués de nanocristaux de graphite revêtus d'une couche amorphe. On constate que le rayon moyen des particules de poudre augmente avec le champ magnétique, ce qui est lié à l’amélioration de leur temps de résidence dans le volume du plasma
Nonlinear Transport through Quantum Dots Studied by the Time-Dependent DMRG
Recent developments on studies of transport through quantum dots obtained by
applying the time-dependent density matrix renormalization group method are
summarized. Some new aspects of Kondo physics which appear in nonequilibrium
steady states are discussed both for the single dot case and for the serially
coupled double-quantum-dot case.Comment: 8 pages, 15 figure
The infinite-range quantum random Heisenberg magnet
We study with exact diagonalization techniques the Heisenberg model for a
system of SU(2) spins with S=1/2 and random infinite-range exchange
interactions. We calculate the critical temperature T_g for the spin-glass to
paramagnetic transition. We obtain T_g ~ 0.13, in good agreement with previous
quantum Monte Carlo and analytical estimates. We provide a detailed picture for
the different kind of excitations which intervene in the dynamical response
chi''(w,T) at T=0 and analyze their evolution as T increases. We also calculate
the specific heat Cv(T). We find that it displays a smooth maximum at TM ~
0.25, in good qualitative agreement with experiments. We argue that the fact
that TM>Tg is due to a quantum disorder effect.Comment: 17 pages, 14 figure
Impact of timely obstetric simulation on vaginal breech delivery management
Background: The management of breech presentations represents a significant challenge in obstetrics, necessitating advanced skills for optimal clinical outcomes. Simulation-based training has emerged as a promising approach to enhance the proficiency of healthcare professionals in assisted vaginal breech deliveries, potentially improving neonatal outcomes.
Methods: This research study was conducted at Rafic Hariri University Hospital, Beirut, to evaluate the impact of simulation-based training on the management of breech presentations. Using Robson’s classification, a comparative analysis was performed on the outcomes of breech deliveries before and after the implementation of this training. The focus was primarily on assisted vaginal deliveries within the R6 (all nulliparous women with a single breech baby, cesarean section) and R7 (all multiparous women with a single breech baby, cesarean section) groups.
Results: Post-training, there was a notable increase in the rate of assisted vaginal deliveries in the R6 category, indicating the effectiveness of the simulation-based training. However, the rate of assisted vaginal deliveries within the R7 group showed no significant change. Additionally, the positive impact of the training demonstrated a time-sensitive decline, underscoring the necessity for ongoing practice and reinforcement of skills.
Conclusions: Simulation-based training offers substantial benefits in managing breech presentations, particularly evident in the increased rate of assisted vaginal deliveries among nulliparous women (R6). However, the absence of change in the multiparous women (R7) group and the time-sensitive reduction in training effectiveness highlight the critical need for continuous skill development and reinforcement
Deeply Virtual Compton Scattering Cross Section at High Bjorken \u3csub\u3eB\u3c/sub\u3e
We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable B. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of B, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs
Intrauterine device is embraced by the placenta
The intrauterine device (IUD) is a contraceptive method which are tiny, T-shaped plastic, that is placed within the uterus and left there, is used all throughout the world with more than 99% effectiveness rate. Pregnancy with a levonorgestrel-releasing intrauterine system (LNG-IUS) in situ is very rare. Intracavitary pregnancy with an IUD can lead to a higher risk of infection and preterm birth. We described a case of a live birth with an IUD inserted into the placenta. A 27-year-old Syrian woman in G4P3 with a history of healthy vaginal deliveries arrived in our delivery room at 39+3 weeks gestation complaining of labor pain A vaginal examination revealed bulging membranes and a fully dilated cervix. She delivered a live baby boy, weighing 3100 g and being sent to the nursery with an APGAR score of 9 to 10. When the placenta was examined, a white foreign object that was embedded there was discovered to be an intrauterine device. Although intrauterine pregnancy is a potential problem that must be taken into account, ectopic pregnancy is a reasonably common complication of intrauterine contraceptive devices. Although several studies have shown that term pregnancies with excellent prognoses can occur after the removal of intrauterine devices, close monitoring is necessary to detect misplaced copper-T and prevent undesired births
Iris-Wasm: robust and modular verification of WebAssembly programs
WebAssembly makes it possible to run C/C++ applications on the web with near-native performance. A WebAssembly program is expressed as a collection of higher-order ML-like modules, which are composed together through a system of explicit imports and exports using a host language, enabling a form of higher- order modular programming. We present Iris-Wasm, a mechanized higher-order separation logic building on a specification of Wasm 1.0 mechanized in Coq and the Iris framework. Using Iris-Wasm, we are able to specify and verify individual modules separately, and then compose them modularly in a simple host language featuring the core operations of the WebAssembly JavaScript Interface. Building on Iris-Wasm, we develop a logical relation that enforces robust safety: unknown, adversarial code can only affect other modules through the functions that they explicitly export. Together, the program logic and the logical relation allow us to formally verify functional correctness of WebAssembly programs, even when they invoke and are invoked by unknown code, thereby demonstrating that WebAssembly enforces strong isolation between modules
NVX-CoV2373-induced T- and B-cellular immunity in immunosuppressed people with multiple sclerosis that failed to respond to mRNA and viral vector SARS-CoV-2 vaccines
Importance: Immunological response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is important, especially in people with multiple sclerosis (pwMS) on immunosuppressive therapies.
Objective: This study aims to determine whether adjuvanted protein-based vaccine NVX-CoV2373 is able to induce an immune response to SARS-CoV-2 in pwMS with inadequate responses to prior triple mRNA/viral vector vaccination.
Design, setting, and participants: We conducted a single-center, prospective longitudinal cohort study at the MS Center in Dresden, Germany. In total, 65 participants were included in the study in accordance with the following eligibility criteria: age > 18 years, immunomodulatory treatment, and insufficient T-cellular and humoral response to prior vaccination with at least two doses of SARS-CoV-2 mRNA (BNT162b2, mRNA-1273) or viral vector vaccines (AZD1222, Ad26.COV2.S).
Interventions: Intramuscular vaccination with two doses of NVX-CoV2373 at baseline and 3 weeks of follow-up.
Main outcomes and measures: The development of SARS-CoV-2-specific antibodies and T-cell responses was evaluated.
Results: For the final analysis, data from 47 patients on stable treatment with sphingosine-1-phosphate receptor (S1PR) modulators and 17 on ocrelizumab were available. The tolerability of the NVX-CoV2373 vaccination was overall good and comparable to the one reported for the general population. After the second NVX-CoV2373 vaccination, 59% of S1PR-modulated patients developed antispike IgG antibodies above the predefined cutoff of 200 binding antibody units (BAU)/ml (mean, 1,204.37 [95% CI, 693.15, 2,092.65] BAU/ml), whereas no clinically significant T-cell response was found. In the subgroup of the patients on ocrelizumab treatment, 23.5% developed antispike IgG > 200 BAU/ml (mean, 116.3 [95% CI, 47.04, 287.51] BAU/ml) and 53% showed positive spike-specific T-cellular responses (IFN-gamma release to antigen 1: mean, 0.2 [95% CI, 0.11, 0.31] IU/ml; antigen 2: mean, 0.24 [95% CI, 0.14, 0.37]) after the second vaccination.
Conclusions: Vaccination with two doses of NVX-CoV2373 was able to elicit a SARS-CoV-2-specific immune response in pwMS lacking adequate immune responses to previous mRNA/viral vector vaccination. For patients receiving S1PR modulators, an increase in anti-SARS-CoV-2 IgG antibodies was detected after NVX-CoV2373 vaccination, whereas in ocrelizumab-treated patients, the increase of antiviral T-cell responses was more pronounced. Our data may impact clinical decision-making by influencing the preference for NVX-CoV2373 vaccination in pwMS receiving treatment with S1PR modulation or anti-CD20 treatment
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