Modelling and Analysis of Bacteria Dependent Infectious Diseases with Variable Contact Rates

In this research,we proposed a non-linear SIS model to study the effect of variable interaction rates and non-emigrating population of the human habitat on the spread of bacteria-infected diseases.It assumed that the growth of bacteria is logistic with an intrinsic growth rate is a linear function of infectives.In this model,we assume that contact rates between susceptibles and infectives as well as between susceptibles and bacteria depend on the density of the non-emigrating population and the total population of the habitat.The stability theory has been analyzed to analyzed to study the crucial role played by bacteria in the increased spread of an infectious disease.It is shown that as the density of non-emigrating population increases,the spread of an infectious disease increases.It is shown further that as the emigration increases,the spread of the disease decreases in both the cases of contact mentioned above rates,but this spread increases as these contact rates increase.It suggested that the control of bacteria in the human habitat is very useful to decrease the spread of an infectious disease.These results are confirmed by numerical simulation.

The Dynamics of Vector-Host Feeding Contact Rate with Saturation: A Case of Malaria in Western Kenya

In this study, we develop an expression for a saturated mosquito feeding rate in an SIS malaria model to determine its effect on infection and transmission dynamics of malaria in the highlands of Western Kenya. The basic reproduction number is established as a sharp threshold that determines whether the disease dies out or persists in the population. Precisely, if , the disease-free equilibrium is globally asymptotically stable and the disease always dies out and if , there exists a unique endemic equilibrium which is globally stable and the disease persists. The contribution of the saturated contact rate to the basic reproduction number and the level of the endemic equilibrium are also analyzed.

SIR model with time-varying contact rate

The contact rate is defined as the average number of contacts adequate for disease transmission by an individual per unit time and it is usually assumed to be constant in time.However,in reality,the contact rate is not always constant throughout the year due to different factors such as population behavior,environmental factors and many others.In the case of serious diseases with a high level of infection,the population tends to reduce their contacts in the hope of reducing the risk of infection.Therofore,it is more realistic to consider it to be a function of time.In particular,the study of models with contact rates decreasing in time is well worth exploring.In this paper,an SIR model with a time-varying contact rate is considered.A new form of a contact rate that decreases in time from its initial value till it reaches a certain level and then remains constant is proposed.The proposed form includes two important parameters,which represent how far and how fast the contact rate is reduced.These two parameters are found to play important roles in disease dynamics.The existence and local stability of the equilibria of the model are analyzed.Results on the global stability of disease-free equilibrium and transcritical bifurcation are proved.Numerical simulations are presented to illustrate the theoretical results and to demonstrate the effect of the model parameters related to the behavior of the contact rate on the model dynamics.Finally,comparisons between the constant,variable contact rate and variable contact rate with delay in response cases are presented.

RATE OF INTRAMOLECULAR CONTACT FORMATION IN PROTEINS

In this paper, we estimate the rate of contact formation between two residues in the interior of the proteins using the Szabo, Schulten, and Schulten formula with the probability distribution P（r） based on 375 proteins from PDB （Protein Data Bank）. The probability distribution for residue pair in proteins is different from the Gaussian distribution, especially for short distance between two residues in proteins. The rate of contact formation in the interior of protein is discussed as a function of distance n （=｜j -i｜） between two residues, and it decreases monotonically with n and follows the scaling relationship of k ∝ n^-γ with γ= 1.43 for the contact radius a = 0.40 nm and γ=1.05 for a = 0.50 nm. The diffusion coefficient for the relative diffusion of two residues in the interior of proteins is estimated as D = 6.4 × 10^-6 cm^2/s, which is close to the result that is found for monomer diffusion.

CONVERGENCE RATE OF SOLUTIONS TO STRONG CONTACT DISCONTINUITY FOR THE ONE-DIMENSIONAL COMPRESSIBLE RADIATION HYDRODYNAMICS MODEL

This paper is concerned with a singular limit for the one-dimensional compress- ible radiation hydrodynamics model. The singular limit we consider corresponds to the physical problem of letting the Bouguer number infinite while keeping the Boltzmann number constant. In the case when the corresponding Euler system admits a contact discontinuity wave, Wang and Xie （2011） [12] recently verified this singular limit and proved that the solution of the compressible radiation hydrodynamics model converges to the strong contact 1 discontinuity wave in the L∞-norm away from the discontinuity line at a rate of ε1/4, as the reciprocal of the Bouguer number tends to zero. In this paper, Wang and Xie＇s convergence rate is improved to ε7/8 by introducing a new a priori assumption and some refined energy estimates. Moreover, it is shown that the radiation flux q tends to zero in the L∞-norm away from the discontinuity line, at a convergence rate as the reciprocal of the Bouguer number tends to zero.

Non-Contact Method of Heart Rate Measurement Based on Facial Tracking

Image photoplethysmography can realize low-cost and easy-to-operate non-contact heart rate detection from the facial video, and effectively overcome the limitations of traditional contact method in daily vital sign monitoring. However, it is hard to obtain more accurate heart rate detection values under the conditions of subject’s facial movement, weak ambient light intensity and long detection distance, etc. In this article, a non-contact heart rate detection method based on face tracking is proposed, which can effectively improve the accuracy of non-contact heart rate detection method in practical application. The corner tracker algorithm is used to track the human face to reduce the motion artifact caused by the movement of the subject’s face and enhance the use value of the signal. And the maximum ratio combining algorithm is used to weight the pixel space pulse wave signal in the facial region of interest to improve the pulse wave extraction accuracy. We analyzed the facial images collected under different experimental distances and action states. This proposed method significantly reduces the error rate compared with the independent component analysis method. After theoretical analysis and experimental verification, this method effectively reduces the error rate under different experimental variables and has good consistency with the heart rate value collected by the medical physiological vest. This method will help to improve the accuracy of non-contact heart rate detection in complex environments.

RATE OF INTRA-MOLECULAR CONTACT FORMATION IN SHORT TWO-DIMENSIONAL COMPACT POLYMERS CHAINS

It is important to know the rate of intra-molecular contact formation in proteins in order to understand how proteins fold clearly. Here we investigate the rate of intra-molecular contact formation in short two-dimensional compact polymer chains by calculating the probability distribution p（r） of end-to-end distance r using the enumeration calculation method and HP model on two-dimensional square lattice. The probability distribution of end-to-end distance p（r） of short two-dimensional compact polymers chains may consist of two parts, i.e. p（r） = p1（r） ＋ p2（r）, where p1（r） and p2（r） are different for small r. The rate of contact formation decreases monotonically with the number of bonds N, and the rate approximately conforms to the scaling relation of k（N）∝ N^-α. Here the value of α increases with the contact radius a and it also depends on the percentage of H （hydrophobic） residues in the sequences of compact chains and the energy parameters of ^εНН、 ^εНН and ^εpp. Some comparisons of theoretical predictions with experimental results are also made. This investigation may help us to understand the protein folding.

Study on drying rate in contact drying with flexible screen

The moisture contents (MC) of popular veneers were tested in Composition Board Laboratory of Northeast Forestry University by contact drying with flexible screen. The influence factors considered included temperature, initial moisture contents (IMC), and veneer thickness. Veneer-drying laws under different hot press conditions were analyzed. The results showed that the drying rate increased with temperature rising. 160°C was considered to be more efficient than 140°C and 180°C because excessive high temperature has no significant contribution to drying rate. IMC had significant effect on drying rate. The veneer with high IMC had a higher drying rate at above fiber saturation point (FSP) and a lower drying rate at below FSP, compared to the veneer with low IMC. Average drying rate also varied with thickness in power law.

Influencing Factors and Mortality Prediction of Covid-19 Contact Infection Rate in China

Taking the COVID-19 data from 2020-1-23 to 3-21 days released by the China Health Protection Committee as the sample,the hospital remaining rate,mortality rate and cure rate are selected as covariates,and the contact infection rate is used as response variable to establish a high precision ADL model,results of return substitution show that the predicted value of contact infection rate almost coincides with the sample value,and shows three stages of change characteristics.After March 1,2020,the overall trend is downward,stable below 12%.Main influencing factors of contact infection rate are analyzed quantitatively.Based on this,the ARIMA(1,2,2)model is established to analyze and predict the mortality change trend.The results showed that the domestic COVID-19 mortality rate is stable near 4%after 2020-3-27.

Influence of Metal Oxides on the Arc Erosion Behaviour of Silver Metal Oxides Electrical Contact Materials

In the present work investigations have been made to see the role of metal oxides on the performance of the silver metal oxides electrical contact materials. Silver metal oxide materials of three different compositions Ag-10CdO, Ag-7.6SnO2-2.3ln2O3 and Ag-10ZnO were prepared by internal oxidation process under identical processing conditions. These materials were tested for electrical conductivity, hardness, and erosion loss. Performing an accelerated test on the actual contactor assessed the electrical performance, involving erosion loss and temperature rise of the processed materials. The arc-eroded surface was characterized under scanning electron microscope. The study of the eroded surfaces of contacts indicates that the thermal stability of metal oxides depends on nature of silver-metal oxide interface and their mode of erosion. An attempt is made to correlate the surface features of the eroded contacts with the thermal stability of metal oxides.

Analysis of Energetic Species Caused by Contact Glow Discharge Electrolysis in Aqueous Solution

Contact glow discharge electrolysis is a non-Faradaic electrochemical process with an abnormal relationship between the current and voltage. Hydroxyl radicals, hydrogen radicals and hydrogen peroxide can be produced under the glow discharge, which are often used to degrade organic contaminants in aqueous solution. In this study, with 4-nitrophenol taken as an example of contaminants and tert-butanol as a scavenger of hydroxyl radicals, the role of energetic species in degrading organic compounds was examined in detail. Moreover, the effects of the applied voltage, solution conductivity and pH on the formation of three energetic species were also observed. The formation rate constants of the three energetic species were calculated based on the experimental data.

Social integration: How is it related to self-rated health?

Social integration has well-established health benefits among older adults in observational studies. However, interventions designed to increase social integration have not improved health suggesting important knowledge gaps on how social integration influences health outcomes. This study developed a new measure of social integration, daily social contact, capturing the interpersonal nature of social integration and mobility of individuals, and providing a direct assessment of individuals’ real-time access to companionship and social support. The data used is the 2006-2007 American Time Use Survey (ATUS), which surveyed 25,191 individuals aged 15 years and older (n = 4378 aged 65 years and older). Generalized ordinal logistic regression analyses revealed positive, but non-parallel relationships between daily social contacts and the ordinal categories of self-rated health among older adults. This study may be used to identify populations that experience social exclusion, such that future research can determine more precisely how to intervene to improve health outcomes.

Folding rate prediction using complex network analysis for proteins with two- and three-state folding kinetics

It is a challenging task to investigate the different in- fluence of long-range and short-range interactions on two-state and three-state folding kinetics of protein. The networks of the 30 two-state proteins and 15 three-state proteins were constructed by complex networks analysis at three length scales: Protein Contact Networks, Long-range Interaction Networks and Short-range Interaction Networks. To uncover the relationship between structural properties and folding kinetics of the proteins, the correlations of protein network parameters with protein folding rate and topology parameters contact order were analyzed. The results show that Protein Contact Networks and Short-range Interaction Networks (for both two-state and three-state proteins) exhibit the “small-world” property and Long-range Interaction networks indicate “scale-free” behavior. Our results further indicate that all Protein Contact Networks and Short- range Interaction networks are assortative type. While some of Long-range Interaction Networks are of assortative type, the others are of disassortative type. For two-state proteins, the clustering coefficients of Short-range Interaction Networks show prominent correlation with folding rate and contact order. The assortativity coefficients of Short-range Interaction Networks also show remarkable correlation with folding rate and contact order. Similar correlations exist in Protein Contact Networks of three-state proteins. For two-state proteins, the correlation between contact order and folding rate is determined by the numbers of local contacts. Short- range interactions play a key role in determining the connecting trend among amino acids and they impact the folding rate of two-state proteins directly. For three-state proteins, the folding rate is determined by short-range and long-range interactions among residues together.

一类具有非线性出生率和饱和恢复率的随机SEIR传染病模型的动力学行为

研究了一类具有非线性出生率和非线性接触率的随机SEIR传染病模型的绝灭性、持久性与平稳分布问题。同时利用计算机数值模拟验证了所得结论。本文所得结果改进了相关文献的结论。

纺织品表面抗湿性测试方法的分析及相关性探讨

阐述了纺织品表面抗湿性的测试标准、方法及技术指标,分析了不同测试方法的结果差异以及相关性。结果表明:测试方法应根据使用情况进行选择,沾水等级与滚动角(水)、接触角(正十二烷)显著相关,与接触角(水)无显著相关。

时滞戒毒模型的稳定性和Hopf分岔

研究了一类具有双线性接触率的时滞SLHMTQ戒毒模型.以吸毒者毒瘾复发的时滞为分岔参数,利用特征值法探究了模型的局部渐近稳定性和局部Hopf分岔存在性,推导出模型产生局部Hopf分岔的时滞临界值,并利用中心流形定理讨论了分岔周期解的性质.

CONTACT PROCESS ON HEXAGONAL LATTICE

In this article, we discuss several properties of the basic contact process on hexagonal lattice H, showing that it behaves quite similar to the process on d-dimensional lattice Zd in many aspects. Firstly, we construct a coupling between the contact process on hexagonal lattice and the oriented percolation, and prove an equivalent finite space-time condition for the survival of the process. Secondly, we show the complete convergence theorem and the polynomial growth hold for the contact process on hexagonal lattice. Finally, we prove exponential bounds in the supercritical case and exponential decay rates in the subcritical case of the process.

基于视频信号的非接触式心率和血氧饱和度检测方法综述

心率和血氧饱和度是反映人体健康状况极其重要的生理指标.近年来,基于成像式光电容积描记技术(imaging photoplethysmography,IPPG)的非接触式心率和血氧饱和度检测方法因为其方便快捷且受约束较少等优点开始逐步成为研究热点.主要工作如下:首先,介绍了非接触式检测方法的背景和研究意义;其次,从目标区域检测和感兴趣区域(region of interest,ROI)选取两个方面总结并点明其研究现状以及未来改进方向;再次,从传统方法、信号处理结合深度学习方法以及端到端方法3个方面对心率和血氧饱和度检测方法进行了总结,并梳理了深度学习方法所使用的数据集以及在各个数据集中所展现的检测效果;最后,指出该领域所存在的亟待解决的问题以及未来的研究方向.

水侵气藏型储气库全周期高效建设微观模拟实验

借助微观可视化模型与微流控技术,开展了水侵气藏型储气库初期建库阶段注气驱水及循环储采阶段采气底水上侵、储气排驱水体的模拟实验,分析气液界面稳定机制、气液渗流与赋存规律,探索储气库全周期高效运行的优化调控方式。研究表明:储气库初期建库阶段应调控注气速度,充分发挥重力作用保证气液界面宏观稳定运移,大幅度提高气体的波及能力,为储气库后续循环储采阶段提供更大的储气孔隙空间。储气库循环储采阶段,恒定的储采气速度导致孔隙空间利用率低,逐渐提高储采气速度,从“小吞小吐”逐渐过渡到“大吞大吐”,可以持续打破孔喉内流体的平衡受力状态,扩大储气孔隙空间与流动通道,有利于储气库扩容增效和调峰保供。

2019—2022年上海市静安区学校结核病密接筛查及学校卫生教师结核病知识知晓情况调查

目的:了解上海市静安区学校结核病防控工作现状,为完善学生结核病防治策略提供理论依据。方法:通过静安区学校肺结核登记本,汇总2019—2022年学校或家庭地址位于静安区的学生肺结核患者及结核病密切接触者的相关信息,分析学校结核病流行特征、密切接触者结核感染率等;对静安区托幼机构、小学、初中、高中及中专的学校卫生教师开展问卷调查,了解其对学校结核病相关知识的知晓程度。结果:2019—2022年静安区共发生学校结核病54例,其中,托幼机构、小学、初中、高中学生共17例,大学生25例,托幼机构、小学、初中教职员工12例;主要为因症就诊,共40例。2019—2022年静安区共筛查学校结核病患者密切接触者735人,其中,接受结核感染筛查679人,发现结核潜伏感染阳性63人,潜伏感染阳性率为9.28%(63/679)。其中,托幼机构儿童、学生感染阳性率为7.44%(43/578),教职员工感染阳性率为19.80%(20/101)。符合预防性服药标准且应服药者服药率为13.64%(6/44)。接受调查的202名卫生教师对学校结核病核心信息总知晓率为65.10%,对结核感染核心信息总知晓率为53.34%。结论:静安区学生结核病患者主动发现比例、潜伏感染阳性者预防性服药比例以及学校卫生教师结核病信息知晓率均较低,学校结核病防治相关工作仍需加强。