543 research outputs found
The Effects of Financial Crises on the Current Account Balance
This study investigates the effects of banking crises on the current account, using a panel data set of eighty countries over the 1980-2001 period. I adopt a dynamic regression approach and derive impulse response functions that estimate the detailed dynamic responses of the Current-Account-Balance-to-GDP ratio to a banking crisis. I find that banking crises produce current account effects that are substantial and vary over time, which suggests that, by omitting the dynamics, the cross-sectional regressions of most of the literature can be misleading. In particular, my estimates suggest that a banking crisis is followed by an improvement of the current account balance that is sizable and statistically significant. This effect is shown to be temporary, however, lasting for a few years before it dies out in the long run. These results are robust to a number of different specifications. This study also discusses a few interesting extensions related to currency crises and twin crises
Regime Switching Models in Stock Market Returns and the Economic Cycle
This dissertation is the summary of my research in the field of regime switching effects on the US equity market and US economy. We used regime switching models on market index and factors to capture financial market condition changes. We then tested the relationship changes between different assets, and constructed a portfolio rebalance method that uses the market regime information. Also, we applied regime switching models to US GDP and GDP components, to find ways to interpret and predict the US business cycle, especially recessions
Multifunctional Nanoplatform for Single NIR Laser-Regulated Efficient PDT/PTT/Chemotherapy
The combination of phototherapy and chemotherapy with
superior
advantages is a promising strategy for cancer therapy. However, combination
therapy is generally regulated by two different wavelengths of light
or other stimuli, which results in complex operations and inevitable
systemic side effects, even affecting therapeutic efficacy. Herein,
we design a signal NIR light-regulated nanoplatform via the self-assembly
process of reactive oxygen species (ROS)-sensitive prodrug (DTD),
human serum albumin (HSA), and IR780 for combined photothermal/photodynamic
therapy and chemotherapy. Upon 808 nm laser irradiation, IR780 in
nanoparticles generates abundant ROS and a significant photothermal
effect to achieve photothermal/photodynamic therapy. Meanwhile, the
generating ROS further cleans up the thioketal link to release DOX
for chemotherapy. Hence, signal NIR light can effectively control
the process of combination therapy. In vivo and in vitro experiment results demonstrate that the multifunctional
nanoparticles exhibit excellent antitumor efficacy via the combination
of phototherapy and chemotherapy controlled by a signal NIR laser.
Overall, the signal NIR light-regulated nanoparticles with combination
therapy performance provide a versatile platform for enhancing antitumor
efficacy
Evaluation of the Visual Analog Score (VAS) to Assess Acute Mountain Sickness (AMS) in a Hypobaric Chamber
<div><p>Objective</p><p>The visual analog score (VAS) is widely used in clinical medicine to evaluate the severity of subjective symptoms. There is substantial literature on the application of the VAS in medicine, especially in measuring pain, nausea, fatigue, and sleep quality. Hypobaric chambers are utilized to test and exercise the anaerobic endurance of athletes. To this end, we evaluated the degree of AMS using the visual analog scale (VAS) in a hypobaric chamber in which the equivalent altitude was increased from 300 to 3500 m.</p><p>Methods</p><p>We observed 32 healthy young men in the hypobaric chamber (Guizhou, China) and increased the altitude from 300 to 3500 m. During the five hours of testing, we measured the resting blood oxygen saturation (SaO<sub>2</sub>) and heart rate (HR). Using the VAS, we recorded the subjects' ratings of their AMS symptom intensity that occurred throughout the phase of increasing altitude at 300 m, 1500 m, 2000 m, 2500 m, 3000 m, and 3500 m.</p><p>Results</p><p>During the phase of increasing altitude in the hypobaric chamber, the patients' SaO<sub>2</sub> was 96.8±0.8% at 300 m and 87.5±4.1% at 3500 m (P<0.05) and their HR was 79.0±8.0 beats/minute at 300 m and 79.3±11.3 beats/minute at 3500 m. The incidence of symptoms significantly increased from 21.9% at an altitude of 1000 m to 65.6% at an altitude of 3500 m (P<0.05). The composite VAS score, which rated the occurrence of four symptoms (headache, dizziness, fatigue, and gastrointestinal discomfort), was significantly correlated with elevation (P<0.01).</p><p>Conclusion</p><p>Based on the experimental data, the VAS can be used as an auxiliary diagnostic method of Lake Louise score to evaluate AMS and can show the changing severity of symptoms during the process of increased elevation in a hypobaric chamber; it also reflects a significant correlation with altitude.</p></div
The Diagnostic Value of the FIB-4 Index for Staging Hepatitis B-Related Fibrosis: A Meta-Analysis
<div><p>Background</p><p>Liver fibrosis stage is an important factor in determining prognosis and need for treatment in patients infected with hepatitis B virus (HBV). Liver biopsies are typically used to assess liver fibrosis; however, noninvasive alternatives such as the FIB-4 index have also been developed.</p><p>Aims</p><p>To quantify the accuracy of the FIB-4 index in the diagnosis of HBV related fibrosis and cirrhosis.</p><p>Methods</p><p>A meta-analysis of studies comparing the diagnostic accuracy of the FIB-4 index vs. liver biopsy in HBV-infected patients was performed using studies retrieved from the following databases: PubMed, Ovid, EMBASE, the Cochrane Library, the Chinese National Knowledge Infrastructure and the Chinese Biology Medicine disc. A hierarchical summary receiver operating curves model and bivariate model were used to produce summary receiver operating characteristic curves and pooled estimates of sensitivity and specificity. The heterogeneity was explored with meta-regression analysis. Publication bias was detected using Egger’s test and the trim and fill method.</p><p>Results</p><p>12 studies (<i>N</i> = 1,908) and 10 studies (<i>N</i> = 2,105) were included in the meta-analysis for significant fibrosis and cirrhosis, respectively. For significant fibrosis, the area under the hierarchical summary receiver operating curve (AUHSROC) was 0.78 (95% CI = 0.74–0.81). The recommended cutoff value was between 1.45 and 1.62, and the AUHSROC, summary sensitivity and specificity were 0.78 (95% CI = 0.74–0.81), 0.65 (95% CI = 0.56–0.73) and 0.77 (95% CI = 0.7–0.83), respectively. For cirrhosis, the AUHSROC was 0.89 (95% CI = 0.85–0.91). The recommended cutoff value was between 2.9 and 3.6, and the AUHSROC, summary sensitivity and specificity were 0.96 (95% CI = 0.92–1.00), 0.42 (95% CI = 0.36–0.48) and 0.96 (95% CI = 0.95–0.97), respectively. No publication bias was detected.</p><p>Conclusions</p><p>The FIB-4 index is valuable for detecting significant fibrosis and cirrhosis in HBV-infected patients, but has suboptimal accuracy in excluding fibrosis and cirrhosis.</p></div
Impact of the Crystal Structure of Silica Nanoparticles on Rhodamine 6G Adsorption: A Molecular Dynamics Study
Understanding the
mechanism of adsorption of Rhodamine 6G (R6G)
to various crystal structures of silica nanoparticles (SNPs) is important
to elucidate the impact of dye size when measuring the size of the
dye–SNP complex via the time-resolved fluorescence anisotropy
method. In this work, molecular dynamics (MD) simulations were used
to get an insight into the R6G adsorption process, which cannot be
observed using experimental methods. It was found that at low pH,
α-Cristobalite structured SNPs have a strong affinity to R6G;
however, at high pH, more surface silanol groups undergo ionization
when compared with α-Quartz, preventing the adsorption. Therefore,
α-Quartz structured SNPs are more suitable for R6G adsorption
at high pH than the α-Cristobalite ones. Furthermore, it was
found that stable adsorption can occur only when the R6G xanthene
core is oriented flat with respect to the SNP surface, indicating
that the dye size does not contribute significantly to the measured
size of the dye–SNP complex. The requirement of correct dipole
moment orientation indicates that only one R6G molecule can adsorb
on any sized SNP, and the R6G layer formation on SNP is not possible.
Moreover, the dimerization process of R6G and its competition with
the adsorption has been explored. It has been shown that the highest
stable R6G aggregate is a dimer, and in this form, R6G does not adsorb
to SNPs. Finally, using steered molecular dynamics (SMD) with constant-velocity
pulling, the binding energies of R6G dimers and R6G complexes with
both α-Quartz and α-Cristobalite SNPs of 40 Å diameter
were estimated. These confirm that R6G adsorption is most stable on
40 Å α-Quartz at pH 7, although dimerization is equally
possible
Impact of the Crystal Structure of Silica Nanoparticles on Rhodamine 6G Adsorption: A Molecular Dynamics Study
Understanding the
mechanism of adsorption of Rhodamine 6G (R6G)
to various crystal structures of silica nanoparticles (SNPs) is important
to elucidate the impact of dye size when measuring the size of the
dye–SNP complex via the time-resolved fluorescence anisotropy
method. In this work, molecular dynamics (MD) simulations were used
to get an insight into the R6G adsorption process, which cannot be
observed using experimental methods. It was found that at low pH,
α-Cristobalite structured SNPs have a strong affinity to R6G;
however, at high pH, more surface silanol groups undergo ionization
when compared with α-Quartz, preventing the adsorption. Therefore,
α-Quartz structured SNPs are more suitable for R6G adsorption
at high pH than the α-Cristobalite ones. Furthermore, it was
found that stable adsorption can occur only when the R6G xanthene
core is oriented flat with respect to the SNP surface, indicating
that the dye size does not contribute significantly to the measured
size of the dye–SNP complex. The requirement of correct dipole
moment orientation indicates that only one R6G molecule can adsorb
on any sized SNP, and the R6G layer formation on SNP is not possible.
Moreover, the dimerization process of R6G and its competition with
the adsorption has been explored. It has been shown that the highest
stable R6G aggregate is a dimer, and in this form, R6G does not adsorb
to SNPs. Finally, using steered molecular dynamics (SMD) with constant-velocity
pulling, the binding energies of R6G dimers and R6G complexes with
both α-Quartz and α-Cristobalite SNPs of 40 Å diameter
were estimated. These confirm that R6G adsorption is most stable on
40 Å α-Quartz at pH 7, although dimerization is equally
possible
Impact of the Crystal Structure of Silica Nanoparticles on Rhodamine 6G Adsorption: A Molecular Dynamics Study
Understanding the
mechanism of adsorption of Rhodamine 6G (R6G)
to various crystal structures of silica nanoparticles (SNPs) is important
to elucidate the impact of dye size when measuring the size of the
dye–SNP complex via the time-resolved fluorescence anisotropy
method. In this work, molecular dynamics (MD) simulations were used
to get an insight into the R6G adsorption process, which cannot be
observed using experimental methods. It was found that at low pH,
α-Cristobalite structured SNPs have a strong affinity to R6G;
however, at high pH, more surface silanol groups undergo ionization
when compared with α-Quartz, preventing the adsorption. Therefore,
α-Quartz structured SNPs are more suitable for R6G adsorption
at high pH than the α-Cristobalite ones. Furthermore, it was
found that stable adsorption can occur only when the R6G xanthene
core is oriented flat with respect to the SNP surface, indicating
that the dye size does not contribute significantly to the measured
size of the dye–SNP complex. The requirement of correct dipole
moment orientation indicates that only one R6G molecule can adsorb
on any sized SNP, and the R6G layer formation on SNP is not possible.
Moreover, the dimerization process of R6G and its competition with
the adsorption has been explored. It has been shown that the highest
stable R6G aggregate is a dimer, and in this form, R6G does not adsorb
to SNPs. Finally, using steered molecular dynamics (SMD) with constant-velocity
pulling, the binding energies of R6G dimers and R6G complexes with
both α-Quartz and α-Cristobalite SNPs of 40 Å diameter
were estimated. These confirm that R6G adsorption is most stable on
40 Å α-Quartz at pH 7, although dimerization is equally
possible
Joint Network Reconstruction and Community Detection from Rich but Noisy Data
Most empirical studies of complex networks return rich but noisy data, as they measure the network structure repeatedly but with substantial errors due to indirect measurements. In this article, we propose a novel framework, called the group-based binary mixture (GBM) modeling approach, to simultaneously conduct network reconstruction and community detection from such rich but noisy data. A generalized expectation-maximization (EM) algorithm is developed for computing the maximum likelihood estimates, and an information criterion is introduced to consistently select the number of communities. The strong consistency properties of the network reconstruction and community detection are established under some assumption on the Kullback-Leibler (KL) divergence, and in particular, we do not impose assumptions on the true network structure. It is shown that joint reconstruction with community detection has a synergistic effect, whereby actually detecting communities can improve the accuracy of the reconstruction. Finally, we illustrate the performance of the approach with numerical simulations and two real examples. Supplementary materials for this article are available online.</p
Graph showing the HR during the ascent and descent phases.
<p>The change in HR during the ascent and descent phases had no significant relationship with altitude changes (P>0.05).</p
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