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Qualitative analysis for a delayed epidemic model with latent and breaking-out over the Internet
No full textAbstract
We generalize a delayed computer virus model, known as the SLBQRS model in a computer network, by introducing the time delay due to the period that the antivirus software uses to clean viruses in the breaking out computers and the quarantined computers. By choosing the delay as the parameter, we prove the existence of a Hopf bifurcation as the delay crosses a\ua0critical value. Moreover, we study properties of the Hopf bifurcation by applying the center manifold theorem and the normal form theory. Finally, we carry out numerical simulations to support the obtained theoretical conclusions
Stationary solutions and spatial-temporal dynamics of a shadow system of LV competition models
No full textAbstract
The concern of the paper is nonconstant positive solutions of a class of Lotka-Volterra competition systems over 1D domains. We prove the existence of a positive monotonous solution to the shadow system for each small diffusion rate
\u3f5
>
0
. Our theoretical results provide a foundation for further theoretical analysis on the shadow system and give insights on how diffusion and advection rates affect the pattern formation in the advective Lotka-Volterra competition systems. The second part of this paper includes numerical simulations of the nontrivial patterns to the shadow system and its original model. It is demonstrated that nontrivial patterns can develop from small perturbations of the homogeneous solution. Our numerics suggest that this system admits very interesting and complicated spatial-temporal dynamics even over 1D domains
Chebyshev reproducing kernel method: application to two-point boundary value problems
No full textAbstract
In this paper, a new implementation of the reproducing kernel method is proposed in order to obtain the accurate numerical solution of two-point boundary value problems with Dirichlet boundary conditions. Based on reproducing kernel theory, reproducing kernel functions with polynomial form will be constructed in the reproducing kernel spaces spanned by the Chebyshev basis polynomials. Convergence analysis and an error estimation for the present method in
L
w
2
space is also discussed. The numerical solutions obtained by this method are compared with the exact solutions. The results reveal that the proposed method is quite efficient and accurate
Absolute stability of time-varying delay Lurie indirect control systems with unbounded coefficients
No full textAbstract
This paper investigates the absolute stability problem of time-varying delay Lurie indirect control systems with variable coefficients. A positive-definite Lyapunov-Krasovskii functional is constructed. Some novel sufficient conditions for absolute stability of Lurie systems with single nonlinearity are obtained by estimating the negative upper bound on its total time derivative. Furthermore, the results are generalised to multiple nonlinearities. The derived criteria are especially suitable for time-varying delay Lurie indirect control systems with unbounded coefficients. The effectiveness of the proposed results is illustrated using simulation examples
Complications with peripherally inserted central catheters (PICCs) used in hospitalized patients and outpatients: a prospective cohort study
No full textAbstract
Background
Peripherally Inserted Central Catheters (PICCs) are widely used for hospitalized patients and among outpatients. Despite many advantages, PICC-related complications can occur such as infection, thrombosis or mechanical complications.
We aimed to evaluate rates and nature of PICC-related complications from insertion to removal and analyze risk factors of complications at baseline and during healthcare.
Methods
We performed a prospective cohort study looking at PICC-related complication rates in the inpatient and outpatient settings of 163 patients over a 7-month period. Pertinent patient demographics as well as catheter-related factors were collected. The data were analyzed to identify catheter-related complications using univariate and multivariate analysis.
Results
One hundred ninety-two PICCs were monitored for a total of 5218 PICC-days (3337 PICC-days for inpatients, 1881 PICC-days for outpatients). The overall complication rate was 30.2% (11.1 per 1000 PICC-days) with a mean time to onset of 16.1\ua0days. Complications included occlusion (8.9%), accidental withdrawal (8.9%), infections (6.3%) including 9 local infections (4.7%) and 3 bloodstream infections (1.6%), venous thrombosis (1.6%) and hematoma (1%). Complication rate was higher in the hospitalization setting (36.1%; 14.38 per 1000 PICC-days) than in the outpatient setting (19.4%; 3.19 per 1000 PICC-days). Multivariate logistic regression analysis showed that the occurrence of occlusion was significantly associated with an age\u2009>\u200965\ua0years (OR\u2009=\u20094.19; 95% CI [1.1\u201315.81]) and the presence of a pre-occlusive event the week before PICC removal (OR\u2009=\u200976.35; 95% CI [9.36\u2013622.97]).
Conclusions
PICCs appear safe in the inpatient and outpatient settings with low rates of infectious or thrombotic complications. Occlusion and accidental withdrawal were the most common complications, with age >\ua065 and catheter pre-occlusive event associated with an increased likelihood of catheter occlusion
Propagation of pathological \u3b1-synuclein in marmoset brain
No full textAbstract
\u3b1-Synuclein is a defining, key component of Lewy bodies and Lewy neurites in Parkinson\u2019s disease (PD) and dementia with Lewy bodies (DLB), as well as glial cytoplasmic inclusions in multiple system atrophy (MSA). The distribution and spreading of these pathologies are closely correlated with disease progression. Recent studies have revealed that intracerebral injection of synthetic \u3b1-synuclein fibrils or pathological \u3b1-synuclein prepared from DLB or MSA brains into wild-type or transgenic animal brains induced prion-like propagation of phosphorylated \u3b1-synuclein pathology. The common marmoset is a very small primate that is expected to be a useful model of human diseases. Here, we show that intracerebral injection of synthetic \u3b1-synuclein fibrils into adult wild-type marmoset brains (caudate nucleus and/or putamen) resulted in spreading of abundant \u3b1-synuclein pathologies, which were positive for various antibodies to \u3b1-synuclein, including phospho Ser129-specific antibody, anti-ubiquitin and anti-p62 antibodies, at three months after injection. Remarkably, robust Lewy body-like inclusions were formed in tyrosine hydroxylase (TH)-positive neurons in these marmosets, strongly suggesting the retrograde spreading of abnormal \u3b1-synuclein from striatum to substantia nigra. Moreover, a significant decrease in the numbers of TH-positive neurons was observed in the injection-side of the brain, where \u3b1-synuclein inclusions were deposited. Furthermore, most of the \u3b1-synuclein inclusions were positive for 1-fluoro-2,5-bis (3-carboxy-4-hydroxystyryl) benzene (FSB) and thioflavin-S, which are dyes widely used to visualize the presence of amyloid. Thus, injection of synthetic \u3b1-synuclein fibrils into brains of non-transgenic primates induced PD-like \u3b1-synuclein pathologies within only 3\ua0months after injection. Finally, we provide evidence indicating that neurons with abnormal \u3b1-synuclein inclusions may be cleared by microglial cells. This is the first marmoset model for \u3b1-synuclein propagation. It should be helpful in studies to elucidate mechanisms of disease progression and in development and evaluation of disease-modifying drugs for \u3b1-synucleinopathies
Imagining the body in tantric contemplative practice
No full textAbstract
This paper addresses imagination, focusing on two words, bh\u101vana and vikalpa , both frequently translated as "imagination," and addresses the connections imagination has with the body, specifically within the context of contemplative practices. Drawing primarily from the 10th and 11th century philosophical school of the Pratyabhij\uf1\u101 of Abhinavagupta and Utpaladeva, this paper proposes a more complex understanding of imagination as consisting of different forms, some connected with the body, others not. This paper suggests that the medieval Indian understanding of imagination as linked to the body allows this term for imagination to side-step much of our current philosophical difficulty within contemporary coginitive science regarding the mind-body problem
Sensitivity of ionosonde detection of atmospheric disturbances induced by seismic Rayleigh waves at different latitudes
No full textAbstract
Ionospheric disturbance was observed in ionograms at Kazan, Russia
(
55
.
85
\u2218
N
,
48
.
81
\u2218
E
)
, associated with the M8.8 Chile earthquake in 2010
(
35
.
91
\u2218
S
,
72
.
73
\u2218
W
)
. The disturbance was caused by infrasound waves that were launched by seismic Rayleigh waves propagating over 15,000\ua0km along Earth\u2019s surface from the epicenter. This distance was extremely large compared with the detection limit of similar ionospheric disturbances that were previously studied at lower latitudes over Japan. The observations suggest that the sensitivity of ionograms to coseismic atmospheric disturbances in the infrasound range differs at different locations on the globe. A notable difference in the geophysical condition between the Russian and Japanese ionosonde sites is the magnetic inclination (dip angle), which affects the ionosphere\u2013atmosphere dynamical coupling and radio propagation of vertical incidence ionosonde sounding. Numerical simulations of atmospheric\u2013ionospheric perturbation were conducted, and ionograms were synthesized from the disturbed electron density profiles for different magnetic dip angles. The results showed that ionosonde sounding at Kazan was sensitive to the atmospheric disturbances induced by seismic Rayleigh waves compared with that at Japanese sites by a factor of
\u223c
3.
Graphical Abstrac
For robust big data analyses: a collection of 150 important pro-metastatic genes
No full textAbstract
Metastasis is the greatest contributor to cancer-related death. In the era of precision medicine, it is essential to predict and to prevent the spread of cancer cells to significantly improve patient survival. Thanks to the application of a variety of high-throughput technologies, accumulating big data enables researchers and clinicians to identify aggressive tumors as well as patients with a high risk of cancer metastasis. However, there have been few large-scale gene collection studies to enable metastasis-related analyses. In the last several years, emerging efforts have identified pro-metastatic genes in a variety of cancers, providing us the ability to generate a pro-metastatic gene cluster for big data analyses. We carefully selected 285 genes with in vivo evidence of promoting metastasis reported in the literature. These genes have been investigated in different tumor types. We used two datasets downloaded from The Cancer Genome Atlas database, specifically, datasets of clear cell renal cell carcinoma and hepatocellular carcinoma, for validation tests, and excluded any genes for which elevated expression level correlated with longer overall survival in any of the datasets. Ultimately, 150 pro-metastatic genes remained in our analyses. We believe this collection of pro-metastatic genes will be helpful for big data analyses, and eventually will accelerate anti-metastasis research and clinical intervention
GSAR: Bioconductor package for Gene Set analysis in R
No full textAbstract
Background
Gene set analysis (in a form of functionally related genes or pathways) has become the method of choice for analyzing omics data in general and gene expression data in particular. There are many statistical methods that either summarize gene-level statistics for a gene set or apply a multivariate statistic that accounts for intergene correlations. Most available methods detect complex departures from the null hypothesis but lack the ability to identify the specific alternative hypothesis that rejects the null.
Results
GSAR (Gene Set Analysis in R) is an open-source R/Bioconductor software package for gene set analysis (GSA). It implements self-contained multivariate non-parametric statistical methods testing a complex null hypothesis against specific alternatives, such as differences in mean (shift), variance (scale), or net correlation structure. The package also provides a graphical visualization tool, based on the union of two minimum spanning trees, for correlation networks to examine the change in the correlation structures of a gene set between two conditions and highlight influential genes (hubs).
Conclusions
Package GSAR provides a set of multivariate non-parametric statistical methods that test a complex null hypothesis against specific alternatives. The methods in package GSAR are applicable to any type of omics data that can be represented in a matrix format. The package, with detailed instructions and examples, is freely available under the GPL (>\u2009=\u20092) license from the Bioconductor web site