5,055 research outputs found
Capturing Vacuum Fluctuations and Photon Correlations in Cavity Quantum Electrodynamics with Multi-Trajectory Ehrenfest Dynamics
We describe vacuum fluctuations and photon-field correlations in interacting
quantum mechanical light-matter systems, by generalizing the application of
mixed quantum-classical dynamics techniques. We employ the multi-trajectory
implementation of Ehrenfest mean field theory, traditionally developed for
electron-nuclear problems, to simulate the spontaneous emission of radiation in
a model quantum electrodynamical cavity-bound atomic system. We investigate the
performance of this approach in capturing the dynamics of spontaneous emission
from the perspective of both the atomic system and the cavity photon field,
through a detailed comparison with exact benchmark quantum mechanical
observables and correlation functions. By properly accounting for the quantum
statistics of the vacuum field, while using mixed quantum-classical (mean
field) trajectories to describe the evolution, we identify a surprisingly
accurate and promising route towards describing quantum effects in realistic
correlated light-matter systems
Nuclear Mixing Meters for Classical Novae
Classical novae are caused by mass transfer episodes from a main sequence
star onto a white dwarf via Roche lobe overflow. This material forms an
accretion disk around the white dwarf. Ultimately, a fraction of this material
spirals in and piles up on the white dwarf surface under electron-degenerate
conditions. The subsequently occurring thermonuclear runaway reaches hundreds
of megakelvin and explosively ejects matter into the interstellar medium. The
exact peak temperature strongly depends on the underlying white dwarf mass, the
accreted mass and metallicity, and the initial white dwarf luminosity.
Observations of elemental abundance enrichments in these classical nova events
imply that the ejected matter consists not only of processed solar material
from the main sequence partner but also of material from the outer layers of
the underlying white dwarf. This indicates that white dwarf and accreted matter
mix prior to the thermonuclear runaway. The processes by which this mixing
occurs require further investigation to be understood. In this work, we analyze
elemental abundances ejected from hydrodynamic nova models in search of
elemental abundance ratios that are useful indicators of the total amount of
mixing. We identify the abundance ratios CNO/H, Ne/H, Mg/H, Al/H, and
Si/H as useful mixing meters in ONe novae. The impact of thermonuclear reaction
rate uncertainties on the mixing meters is investigated using Monte Carlo
post-processing network calculations with temperature-density evolutions of all
mass zones computed by the hydrodynamic models. We find that the current
uncertainties in the P(,)S rate influence the Si/H
abundance ratio, but overall the mixing meters found here are robust against
nuclear physics uncertainties. A comparison of our results with observations of
ONe novae provides strong constraints for classical nova models
Clinical review: Update of avian influenza A infections in humans
Influenza A viruses have a wide host range for infection, from wild waterfowl to poultry to humans. Recently, the cross-species transmission of avian influenza A, particularly subtype H5N1, has highlighted the importance of the non-human subtypes and their incidence in the human population has increased over the past decade. During cross-species transmission, human disease can range from the asymptomatic to mild conjunctivitis to fulminant pneumonia and death. With these cases, however, the risk for genetic change and development of a novel virus increases, heightening the need for public health and hospital measures. This review discusses the epidemiology, host range, human disease, outcome, treatment, and prevention of cross-transmission of avian influenza A into humans
PERBANDINGAN KATEGORI KEJAHATAN EKONOMI SECARA GLOBAL DAN INDONESIA
Penelitian ini bertujuan untuk menganalisis perbedaan kategori fraud yang terjadi secara global dan diakui di Indonesia. Studi ini didasarkan pada data yang dikumpulkan oleh badan-badan atau organisasi pemberantasan fraud, seperti PricewaterhouseCoopers (PwC), Association of Certified Fraud Examiners (ACFE) yang merupakan data hasil survei dari tahun 2016 sampai 2022. Hasil penelitian ini menunjukkan penyalahgunaan aset mendominasi kategori fraud di awal pandemi, namun kemudian menurun setelah pandemi dan digantikan oleh customer fraud dan cybercrime. Begitu juga kasus penipuan di Indonesia, baik sebelum maupun sesudah pandemi, kasus penipuan masih didominasi oleh korupsi
Referencing Sources of Molecular Spectroscopic Data in the Era of Data Science: Application to the HITRAN and AMBDAS Databases
The application described has been designed to create bibliographic entries
in large databases with diverse sources automatically, which reduces both the
frequency of mistakes and the workload for the administrators. This new system
uniquely identifies each reference from its digital object identifier (DOI) and
retrieves the corresponding bibliographic information from any of several
online services, including the SAO/NASA Astrophysics Data Systems (ADS) and
CrossRef APIs. Once parsed into a relational database, the software is able to
produce bibliographies in any of several formats, including HTML and BibTeX,
for use on websites or printed articles. The application is provided
free-of-charge for general use by any scientific database. The power of this
application is demonstrated when used to populate reference data for the HITRAN
and AMBDAS databases as test cases. HITRAN contains data that is provided by
researchers and collaborators throughout the spectroscopic community. These
contributors are accredited for their contributions through the bibliography
produced alongside the data returned by an online search in HITRAN. Prior to
the work presented here, HITRAN and AMBDAS created these bibliographies
manually, which is a tedious, time-consuming and error-prone process. The
complete code for the new referencing system can be found at
\url{https://github.com/hitranonline/refs}.Comment: 11 pages, 5 figures, already published online at
https://doi.org/10.3390/atoms802001
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