29 research outputs found
A wavelet-based approach to the analysis and modelling of financial time series exhibiting strong long-range dependence: the case of Southeast Europe
<div><p>This paper demonstrates the utilization of wavelet-based tools for the analysis and prediction of financial time series exhibiting strong long-range dependence (LRD). Commonly emerging markets' stock returns are characterized by LRD. Therefore, we track the LRD evolvement for the return series of six Southeast European stock indices through the application of a wavelet-based semi-parametric method. We further engage the á trous wavelet transform in order to extract deeper knowledge on the returns term structure and utilize it for prediction purposes. In particular, a multiscale autoregressive (MAR) model is fitted and its out-of-sample forecast performance is benchmarked to that of ARMA. Additionally, a data-driven MAR feature selection procedure is outlined. We find that the wavelet-based method captures adequately LRD dynamics both in calm as well as in turmoil periods detecting the presence of transitional changes. At the same time, the MAR model handles with the complicated autocorrelation structure implied by the LRD in a parsimonious way achieving better performance.</p></div
Enhanced Activated Carbon Cathode Performance for Microbial Fuel Cell by Blending Carbon Black
Activated
carbon (AC) is a useful and environmentally sustainable catalyst for
oxygen reduction in air-cathode microbial fuel cells (MFCs), but there
is great interest in improving its performance and longevity. To enhance
the performance of AC cathodes, carbon black (CB) was added into AC
at CB:AC ratios of 0, 2, 5, 10, and 15 wt % to increase electrical
conductivity and facilitate electron transfer. AC cathodes were then
evaluated in both MFCs and electrochemical cells and compared to reactors
with cathodes made with Pt. Maximum power densities of MFCs were increased
by 9–16% with CB compared to the plain AC in the first week.
The optimal CB:AC ratio was 10% based on both MFC polarization tests
and three electrode electrochemical tests. The maximum power density
of the 10% CB cathode was initially 1560 ± 40 mW/m<sup>2</sup> and decreased by only 7% after 5 months of operation compared to
a 61% decrease for the control (Pt catalyst, 570 ± 30 mW/m<sup>2</sup> after 5 months). The catalytic activities of Pt and AC (plain
or with 10% CB) were further examined in rotating disk electrode (RDE)
tests that minimized mass transfer limitations. The RDE tests showed
that the limiting current of the AC with 10% CB was improved by up
to 21% primarily due to a decrease in charge transfer resistance (25%).
These results show that blending CB in AC is a simple and effective
strategy to enhance AC cathode performance in MFCs and that further
improvement in performance could be obtained by reducing mass transfer
limitations
Transmembrane NADH Oxidation with Tetracyanoquinodimethane
The design of efficient schemes for
nicotinamide adenine dinucleotide
(NAD) regeneration is essential for the development of enzymatic biotechnological
processes in order to sustain continuous production. In line with
our motivation for the encapsulation of redox cascades in liposomes
to serve as microbioreactors, we developed a straightforward strategy
for the interfacial oxidation of entrapped NADH by ferricyanide as
an external electron acceptor. Instead of the commonly applied enzymatic
regeneration methods, we employed a hydrophobic redox shuttle embedded
in the liposome bilayer. Tetracyanoquinodimethane
(TCNQ) mediated electron transfer across the membrane and thus allowed
us to shortcut and emulate part of the electron transfer chain functionality
without the involvement of membrane proteins. To describe the experimental
system, we developed a mathematical model which allowed for the determination
of rate constants and exhibited handy predictive utility
Table_1_Resurgence of respiratory syncytial virus with dominance of RSV-B during the 2022–2023 season.doc
BackgroundRespiratory syncytial virus (RSV) is a common cause of upper and lower respiratory tract infections. This study aimed to explore the prevalence of respiratory syncytial virus (RSV) and other respiratory viruses in Bulgaria, characterize the genetic diversity of RSV strains, and perform amino acid sequence analyses of RSV surface and internal proteins.MethodsClinical and epidemiological data and nasopharyngeal swabs were prospectively collected from patients with acute respiratory infections between October 2020 and May 2023. Real-time PCR for 13 respiratory viruses, whole-genome sequencing, phylogenetic, and amino acid analyses were performed.ResultsThis study included three epidemic seasons (2020–2021, 2021–2022, and 2022–2023) from week 40 of the previous year to week 20 of the following year. Of the 3,047 patients examined, 1,813 (59.5%) tested positive for at least one viral respiratory pathogen. RSV was the second most detected virus (10.9%) after SARS-CoV-2 (22%). Coinfections between RSV and other respiratory viruses were detected in 68 cases, including 14 with SARS-CoV-2. After two seasons of low circulation, RSV activity increased significantly during the 2022–2023 season. The detection rates of RSV were 3.2, 6.6, and 13.7% in the first, second, and third seasons, respectively. RSV was the most common virus found in children under 5 years old with bronchiolitis (40%) and pneumonia (24.5%). RSV-B drove the 2022–2023 epidemic. Phylogenetic analysis indicated that the sequenced RSV-B strains belonged to the GB5.0.5a and GB5.0.6a genotypes. Amino acid substitutions in the surface and internal proteins, including the F protein antigenic sites were identified compared to the BA prototype strain.ConclusionThis study revealed a strong resurgence of RSV in the autumn of 2022 after the lifting of anti-COVID-19 measures, the leading role of RSV as a causative agent of serious respiratory illnesses in early childhood, and relatively low genetic diversity in circulating RSV strains.</p
Table_2_Resurgence of respiratory syncytial virus with dominance of RSV-B during the 2022–2023 season.docx
BackgroundRespiratory syncytial virus (RSV) is a common cause of upper and lower respiratory tract infections. This study aimed to explore the prevalence of respiratory syncytial virus (RSV) and other respiratory viruses in Bulgaria, characterize the genetic diversity of RSV strains, and perform amino acid sequence analyses of RSV surface and internal proteins.MethodsClinical and epidemiological data and nasopharyngeal swabs were prospectively collected from patients with acute respiratory infections between October 2020 and May 2023. Real-time PCR for 13 respiratory viruses, whole-genome sequencing, phylogenetic, and amino acid analyses were performed.ResultsThis study included three epidemic seasons (2020–2021, 2021–2022, and 2022–2023) from week 40 of the previous year to week 20 of the following year. Of the 3,047 patients examined, 1,813 (59.5%) tested positive for at least one viral respiratory pathogen. RSV was the second most detected virus (10.9%) after SARS-CoV-2 (22%). Coinfections between RSV and other respiratory viruses were detected in 68 cases, including 14 with SARS-CoV-2. After two seasons of low circulation, RSV activity increased significantly during the 2022–2023 season. The detection rates of RSV were 3.2, 6.6, and 13.7% in the first, second, and third seasons, respectively. RSV was the most common virus found in children under 5 years old with bronchiolitis (40%) and pneumonia (24.5%). RSV-B drove the 2022–2023 epidemic. Phylogenetic analysis indicated that the sequenced RSV-B strains belonged to the GB5.0.5a and GB5.0.6a genotypes. Amino acid substitutions in the surface and internal proteins, including the F protein antigenic sites were identified compared to the BA prototype strain.ConclusionThis study revealed a strong resurgence of RSV in the autumn of 2022 after the lifting of anti-COVID-19 measures, the leading role of RSV as a causative agent of serious respiratory illnesses in early childhood, and relatively low genetic diversity in circulating RSV strains.</p
CNVs identified in the each clinical group.
<p>CNVs: median (range; sum); Kruskal-Wallis test.</p
Manhattan plots of standard chi-squared significance values for the 3 genome-wide association studies.
<p>Manhattan plots for (A) comparison 1, (B) comparison 2, and (C) comparison 3; (D) Mixed effects-model analysis of comparison 3.</p
Top 5 CNV regions identified using logistic regression for the association of <i>R. equi</i> with either the binary variable presence or absence of a CNV identified in the region (Presence columns) or the log<sub>2</sub> ratio of intensity values of the CNVs (Intensity columns).
<p>CNVR identification numbers are provided in Supplementary <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098710#pone-0098710-t001" target="_blank">Table 1</a>.</p
Joint analysis of <i>TRPM2</i> SNP UKUL3936.
<p>*Median (range) reported for frequency of allele A, along with the proportion of A alleles among all alleles represented for each group. Joint analysis includes genotypes derived from SNP array and PCR genotyping.</p
Schematic diagram representing the distribution of the total population into the 3 subgroups (<i>R. equi</i> pneumonia foals [clinical], subclinical foals, and unaffected foals), and by genome-wide association studies versus PCR genotyping for TRPM2 SNP.
<p>The 3 comparisons among groups are also summarized.</p