275 research outputs found
Stability investigations of isotropic and anisotropic exponential inflation in the Starobinsky-Bel-Robinson gravity
In this paper, we would like to examine whether a novel
Starobinsky-Bel-Robinson gravity model admits stable exponential inflationary
solutions with or without spatial anisotropies. As a result, we are able to
derive an exact de Sitter inflationary to this Starobinsky-Bel-Robinson model.
Furthermore, we observe that an exact Bianchi type I inflationary solution does
not exist in the Starobinsky-Bel-Robinson model. However, we find that a
modified Starobinsky-Bel-Robinson model, in which the sign of coefficient of
term is flipped from positive to negative, can admit the corresponding
Bianchi type I inflationary solution. Unfortunately, stability analysis using
the dynamical system approach indicates that both of these inflationary
solutions turn out to be unstable. Interestingly, we show that a stable de
Sitter inflationary solution can be obtained in the modified
Starobinsky-Bel-Robinson gravity.Comment: 26 pages, 2 figures. V2 with the abstract revised to improve its
clarity, some relevant references added, and some typos fixed. All main
calculations and conclusions remain unchanged. Comments are welcom
Hierarchical Control of Grid-Connected Hydrogen Electrolyzer Providing Grid Services
This paper presents the operation modes and control architecture of the
grid-connected hydrogen electrolyzer systems for the provision of frequency and
voltage supports. The analysis is focused on the primary and secondary loops in
the hierarchical control scheme. At the power converter inner control loop, the
voltage- and current-control modes are analyzed. At the primary level, the
droop and opposite droop control strategies to provide voltage and frequency
support are described. Coordination between primary control and secondary,
tertiary reserves is discussed. The case studies and real-time simulation
results are provided using Typhoon HIL to back the theoretical investigation
Anisotropic power-law inflation for models of non-canonical scalar fields non-minimally coupled to a two-form field
In this paper, we investigate the validity of the so-called cosmic no-hair
conjecture in the framework of anisotropic inflation models of non-canonical
scalar fields non-minimally coupled to a two-form field. In particular, we
focus on two typical {\it k}-inflation and Dirac-Born-Infeld inflation models,
in which we find a set of exact anisotropic power-law inflationary solutions.
Interestingly, these solutions are shown to be stable and attractive during an
inflationary phase using the dynamical system analysis. The obtained results
indicate that the non-minimal coupling between the scalar and two-form fields
acts as a non-trivial source of generating stable spatial anisotropies during
the inflationary phase and therefore violates the prediction of the cosmic
no-hair conjecture, even when the scalar field is of non-canonical forms.Comment: 16 pages, 6 figures. Comments are welcom
1-D Convolutional Graph Convolutional Networks for Fault Detection in Distributed Energy Systems
This paper presents a 1-D convolutional graph neural network for fault
detection in microgrids. The combination of 1-D convolutional neural networks
(1D-CNN) and graph convolutional networks (GCN) helps extract both
spatial-temporal correlations from the voltage measurements in microgrids. The
fault detection scheme includes fault event detection, fault type and phase
classification, and fault location. There are five neural network model
training to handle these tasks. Transfer learning and fine-tuning are applied
to reduce training efforts. The combined recurrent graph convolutional neural
networks (1D-CGCN) is compared with the traditional ANN structure on the
Potsdam 13-bus microgrid dataset. The achievable accuracy of 99.27%, 98.1%,
98.75%, and 95.6% for fault detection, fault type classification, fault phase
identification, and fault location respectively.Comment: arXiv admin note: text overlap with arXiv:2210.1517
A case of hepatic cyst-induced internal jugular venous thrombosis
• Echocardiography can demonstrate hepatic cyst–induced right atrial compression. • Hepatic cyst–induced blood flow stasis can cause internal jugular venous thrombus. • Laparoscopic deroofing of hepatic cysts is a safe and effective treatment
CONTAMINATION BY ARSENIC AND LEAD IN RESIDENTS FROM VIETNAM
Joint Research on Environmental Science and Technology for the Eart
The CIPAZ study protocol: an open label randomised controlled trial of azithromycin versus ciprofloxacin for the treatment of children hospitalised with dysentery in Ho Chi Minh City, Vietnam
Background: Diarrhoeal disease remains a common cause of illness and death in children <5 years of age. Faecal-oral infection by Shigella spp. causing bacillary dysentery is a leading cause of moderate-to-severe diarrhoea, particularly in low and middle-income countries. In Southeast Asia, S. sonnei predominates and infections are frequently resistant to first-line treatment with the fluoroquinolone, ciprofloxacin. While resistance to all antimicrobials is increasing, there may be theoretical and clinical benefits to prioritizing treatment of bacillary dysentery with the azalide, azithromycin. In this study we aim to measure the efficacy of treatment with azithromycin compared with ciprofloxacin, the current standard of care, for the treatment of children with bacillary dysentery.
Methods and analysis: We will perform a multicentre, open-label, randomized controlled trial of two therapeutic options for the antimicrobial treatment of children hospitalised with dysentery. Children (6–60 months of age) presenting with symptoms and signs of dysentery at Children’s Hospital 2 in Ho Chi Minh City will be randomised (1:1) to treatment with either oral ciprofloxacin (15mg/kg/twice daily for 3 days, standard-of-care) or oral azithromycin (10mg/kg/daily for 3 days). The primary endpoint will be the proportion of treatment failure (defined by clinical and microbiological parameters) by day 28 (+3 days) and will be compared between study arms by logistic regression modelling using treatment allocation as the main variable.
Ethics and dissemination: The study protocol (version 1.2 dated 27th December 2018) has been approved by the Oxford Tropical Research Ethics Committee (47–18) and the ethical review boards of Children's Hospital 2 (1341/NĐ2-CĐT). The study has also been approved by the Vietnamese Ministry of Health (5044/QĐ-BYT).
Trial registration: Clinicaltrials.gov: NCT03854929 (February 26th 2019)
Effectiveness of cervical pessary compared to cervical cerclage with or without vaginal progesterone for the prevention of preterm birth in women with twin pregnancies and a short cervix : Study protocol for a two-by-two factorial randomised clinical trial
Peer reviewedPublisher PD
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