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Global stability of a delayed SIR epidemic model with density dependent birth and death rates

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不良现象的英语作文

不良现象的英语作文

In contemporary society,various negative phenomena have emerged,posing significant challenges to social harmony and individual wellbeing.Writing an essay on this topic allows us to delve into the root causes,impacts,and potential solutions for these issues.IntroductionBegin your essay by introducing the concept of social ills and their prevalence in modern society.You may want to mention that despite technological advancements and economic growth,certain undesirable behaviors persist.Body Paragraph1:Types of Negative PhenomenaDiscuss the different types of negative phenomena that are prevalent.This could include: Environmental pollution due to industrialization and consumerism. Cyberbullying and the misuse of social media.Corruption in politics and business.Discrimination based on race,gender,or social status.The rise of materialism and the decline of moral values.Body Paragraph2:Causes of Negative PhenomenaExplore the underlying reasons for these issues.Consider factors such as:Lack of education and awareness.Economic disparities and social inequality.The influence of peer pressure and societal norms.Inadequate legal frameworks and enforcement.Body Paragraph3:Impacts of Negative PhenomenaDescribe the consequences of these negative phenomena on individuals and society as a whole.This may include:Mental health issues such as stress and anxiety.Erosion of trust in institutions and fellow citizens.Environmental degradation and loss of biodiversity.Increased crime rates and social unrest.Body Paragraph4:Solutions and PreventionPropose solutions to mitigate or eliminate these negative phenomena.Suggest strategies such as:Implementing and enforcing stricter laws against corruption and discrimination. Promoting education and awareness campaigns to combat ignorance and prejudice. Encouraging corporate social responsibility and sustainable practices.Fostering a culture of empathy,respect,and community engagement.ConclusionConclude your essay by summarizing the main points and reiterating the importance of addressing these negative phenomena.Emphasize the collective responsibility of society to work towards a more harmonious and just world.Sample EssayIn the fabric of our modern society,a tapestry of negative phenomena has woven itself into the daily lives of individuals,often overshadowing the progress we have made.From environmental degradation to social injustices,these issues demand our attention and action.Types of Negative PhenomenaThe spectrum of negative phenomena is vast,encompassing everything from the pollution that chokes our air and water to the cyberbullying that poisons the digital realm. The corruption that taints political and business dealings undermines trust,while discrimination festers,dividing communities and perpetuating inequality.Causes of Negative PhenomenaThe roots of these issues are multifaceted,stemming from a lack of education that leaves individuals vulnerable to misinformation,to economic disparities that breed resentment and desperation.Peer pressure and societal norms can also compel individuals to act against their better judgment,leading to a cycle of negative behavior that is difficult to break.Impacts of Negative PhenomenaThe repercussions of these issues are farreaching,affecting not only the physical and mental health of individuals but also the very fabric of society.The erosion of trust in institutions,the rise in crime,and the environmental damage wrought by unchecked industrialization are but a few of the consequences we face.Solutions and PreventionTo combat these negative phenomena,a multipronged approach is necessary.Stricter laws and their enforcement can deter corruption and cation and awareness campaigns can arm individuals with the knowledge to make informed decisions and resist harmful influences.Encouraging sustainable practices and corporate social responsibility can help mitigate environmental damage.Ultimately,fostering a culture of empathy and respect is key to building a more harmonious society.In conclusion,the negative phenomena that plague our society are complex and deeply entrenched,but they are not insurmountable.By recognizing the interconnectedness of our actions and their consequences,we can work collectively towards a future that is free from these social ills.。

管 轶廿载研究 成就国际权威

管 轶廿载研究 成就国际权威

29管轶：廿载研究 成就国际权威文/冯海波率先分离鉴定出SARS 冠状病毒，率先揭示出2009年新甲型H1N1流感病毒的起源和进化途径，首先完成了用实验动物对其传播性及致病性进行研究的报道，为评估H7N9病毒的大流感特性提供了科学参考依据……20多年来，他不忘初心，带领团队从事流感和其他新发传染性疾病研究，多次协助政府追击传染病毒并有效阻止病毒大规模爆发，为中国及周边地区新发传染病的研究和控制作出了卓越的贡献。

他就是当今禽流感病毒国际权威之一——管轶教授。

[编者按]管轶，现任香港大学终身教授、明德讲座教授、汕头大学兼聘教授，世界卫生组织（WHO）流感专家组顾问、WHO 高致病性禽流感参比实验室联席主任、新发传染性疾病国家重点实验室主任、汕头大学医学院国际感染与免疫研究所感染部主任、香港大学流感研究中心主任、汕头大学.香港大学联合病毒学研究所所长、教育部病毒学与新发病国际合作联合实验室主任、英国皇家医学院公共卫生院杰出外籍院士，研究成果多次在Nature、Science、The Lancet、NewEngland Journal of Medicine、PNAS 等国际顶级学术刊物上发表。

管轶Copyright©博看网 . All Rights Reserved.专题榜样的力量——2019年广东“最美科技工作者”事迹纪实最美科技工作者儿科医生走上病毒研究之路管轶1978年参加高考，被江西医学院（现南昌大学医学院）临床医学系录取，1983年以优异成绩毕业并留校任教。

1983—1986年间，他任江西医学院附属医院儿科讲师及住院医生。

1986年他又考上北京协和医科大学首都儿科研究所，攻读儿科硕士学位，在协和学习期间，他开始接触基础医学研究及各种小儿临床呼吸道疾病。

1989年研究生毕业后，管轶入职汕头大学医学院第一附属医院，任儿科主治医生。

1993年年初，30岁的管轶放弃临床医生的优厚待遇，赴香港大学医学院攻读微生物学博士研究生，从头起学微生物和病毒学的基础科学研究，这是他这一生中最大的转折点。

具有时变时滞的Lurie系统绝对稳定性的时滞相关条件

具有时变时滞的Lurie系统绝对稳定性的时滞相关条件
Vol.31, No.3
ACTA AUTOMATICA SINICA
May, 2005
Delay-dependent Conditions for Absolute Stability of Lurie Control Systems with Time-varying Delay1)
HE Yong WU Min
m
V (x t ) = x T (t )P x (t ) + 2
j =1
σj
t
λj
0
fj (σj )dσj +
t−d(t)
xT (s)Qx(s)ds +
0 −τ
t t+ θ
˙ T (s )Z x ˙ (s)dsdθ (5) x
where P > 0, Q 0, Z > 0, Λ = diag(λ1 , λ2 , · · · , λm ) 0 are to be determined. Calculating the derivative of V (xt ) along the solutions of system (1) yields d V (x t ) dt 2[xT (t)P + f T (σ )ΛC T ] · [Ax(t) + B x(t − d(t)) + Df (σ )]+ xT (t)Qx(t) − (1 − µ)xT (t − d(t))Qx(t − d(t)) −
t t−d(t)
˙ T (s )Z x ˙ (s)ds+ x
(6)
τ [Ax(t) + B x(t − d(t)) + Df (σ )]T Z [Ax(t) + B x(t − d(t)) + Df (σ )] Using the Leibniz-Newton formula, for any matrices N1 , N2 ∈ Rn×n , N3 ∈ Rm×n , 2[xT (t)N1 + xT (t − d(t))N2 + f T (σ )N3 ] · [x(t) − x(t − d(t)) − X11 T On the other hand, for any semi-positive definite matrix X = X12 T X13 holds according to (2). z T (t)(τ X )z (t) − where z (t) = [xT (t) xT (t − d(t)) d V (x t ) dt

GISSI HF中文原文翻译

GISSI HF中文原文翻译

GISSF-HF试验：一项随机、双盲、安慰剂对照试验探究n-3多不饱和脂肪酸对于治疗慢性心衰患者的疗效GISSF-HF研究员*概要背景众多流行病学和实验研究表明，n-3多不饱和脂肪酸（n-3 PUFA）治疗包括心律失常在内的动脉粥样硬化心血管疾病的效果良好。

为验证n-3 PUFA是否能降低该类疾病的发病率和死亡率，我们在众多因任何原因而出现心衰症候的人群中展开了一项调查研究。

方法在意大利的326家心脏病学中心和31所内科医学中心，我们进行了一项随机、双盲、安慰剂对照试验。

该试验不考虑引起心衰的原因和左心室射血分数等因素，将纽约心脏协会（NYHA）心功能II~IV级的患者用一台隐蔽的、由计算机控制的电话随机系统分组，患者随机每日服用1g n-3 PUFA （n=3494）或安慰剂（n=3481），并在随后3.9年中位随访期内（四分位距为3.0~4.5）接受随访观察。

试验的主要终点为总生存期（首次用药到因任何原因死亡的时间），和总生存期或因心血管疾病入院的时间。

采用意向治疗分析。

此项研究已在临床试验网（网址为：）登记注册，编号为NCT00336336。

研究发现我们对所有随机选取的患者进行分析，其中n-3 PUFA组和安慰剂组中分别有955名（27%）和1014名（29%）患者因任何原因出现死亡（校正后的风险比[HR]为0.91，[95.5% CI 0.833–0.998]，P=0.041）。

两组中分别还有1981名（57%）和2053名（59%）患者因心血管疾病死亡或入院（校正后的HR为0.92，[99% CI 0.849–0.999]，P=0.009）。

按绝对值计算，56名患者需要接受中位随访期为3.9年的治疗才能预防一例死亡，或是44名患者需要接受中位随访期为3.9年的治疗才能预防一例如心血管疾病导致的死亡或入院。

两组中出现的主要不良反应均为肠胃功能紊乱，这一比例在n-3 PUFA 组中为3%（96人），而安慰剂组也为3%（92人）。

SIRT1的调节及其在感染性疾病中的作用

SIRT1的调节及其在感染性疾病中的作用

SIRT1的调节及其在感染性疾病中的作用①周云张沛欣（空军军医大学第二附属医院传染科，西安710038）中图分类号R512.63文献标志码A文章编号1000-484X（2021）08-1008-04［摘要］沉默信息调节因子2相关酶1（sirtuin1，SIRT1）是一种NAD+依赖的组蛋白去乙酰化酶，参与多种生物学进程，如细胞分化、衰老、凋亡和能量代谢等。

SIRT1受到多种蛋白及miRNA的调节，对多种免疫性疾病、肿瘤性疾病及感染性疾病具有显著影响。

本文主要对SIRT1的调控及其在感染性疾病中的作用机制进行综述。

［关键词］SIRT1；感染；miRNARegulations of SIRT1and its mechanisms in infectious diseasesZHOU Yun，ZHANG Pei-Xin.The Second Affiliated Hospital of Air Force Medical University，Xi′an710038，China ［Abstract］Sirtuin1（SIRT1），a NAD+dependent histone deacetylase，is involved in various biological processes，such as cell differentiation，aging，apoptosis and energy metabolism.SIRT1is regulated by a variety of proteins and miRNAs，and has a signifi‑cant impact on a variety of immune diseases，neoplastic diseases and infectious diseases.This paper mainly reviews the regulations of SIRT1and its mechanisms in infectious diseases.［Key words］SIRT1；Infection；miRNASIRT1属于沉默信息调节因子（silent informa‑tion regulator2，SIR2）家族，是NAD+依赖的脱乙酰基酶，它由组蛋白和非组蛋白构成。

A delayed SIR epidemic model with general incidence rate

A delayed SIR epidemic model with general incidence rate
2000 Mathematics Subject Classification. 34D23, 37B25, 00A71. Key words and phrases. SIR epidemic model; general incidence rate; time delay; global asymptotic stability; Lyapunov functional. ∗Corresponding author. Email: k.hattaf@yahoo.fr.
dSห้องสมุดไป่ตู้dt
= Λ − µS(t) − f (S(t), I(t))I(t),
dI = f (S(t − τ ), I(t − τ ))I(t − τ )e−µτ − (µ + d + r)I(t). dt
(1.2)
Let C = C([−τ, 0], IR2) be the Banach space of continuous functions mapping the interval [−τ, 0] into IR2 with the topology of uniform convergence. By the funda-
f (0, I) = 0, f or all I ≥ 0,
∂f ∂S
(S,
I
)
>
0,
f or all S > 0 and I ≥ 0,
∂f ∂I
(S,
I
)
≤
0
,
f or all S ≥ 0 and I ≥ 0.
(H1) (H2) (H3)
The first two equations in system (1.1) do not depend on the third equation, and therefore this equation can be omitted without loss of generality. System (1.1) can be rewritten as

光照灵敏度英文

光照灵敏度英文English:Photoperiod sensitivity, also known as photoperiodism, refers to the way in which an organism responds to changes in day length. Different species exhibit varying levels of sensitivity to changes in day length, with some being classified as long-day plants, short-day plants, or day-neutral plants. Long-day plants require longer periods of daylight to initiate flowering, while short-day plants require shorter periods of daylight. Day-neutral plants, on the other hand, are not affected by changes in day length. The sensitivity to changes in day length is controlled by specific genes that regulate the production of flowering hormones. In addition to plants, many animals also exhibit photoperiod sensitivity, which can influence their behavior and physiological processes. Overall, photoperiod sensitivity plays a crucial role in determining the life cycle and reproductive success of various organisms in different environments.Translated content:光期敏感性，也被称为光期效应，指的是生物对白昼长度变化作出反应的方式。

periodical__shandyy__shan2010__1014pdf__101475

脊柱术后并发急性硬脊膜外血肿的诊治进展张景生。

张国庆（青岛大学医学院附属医院，山东青岛２６６００３）关键词：硬脊膜外血肿；脊柱手术中图分类号：Ｒ６８１．５文献标志码：Ａ文章编号：１００２－２６６Ｘ（２０１０）１４－０１１５－０２脊柱术后急性硬脊膜外血肿的发生率为０．１％一３．０％【Ｉ－３］。

本病病情进展迅速，处理不当极易造成脊髓功能不可逆损伤。

脊髓功能恢复情况与脊髓受压程度和受压时间有关，受压程度越重，时间越长，脊髓功能恢复情况越差。

因此及早确诊、尽快减压至关重要。

现将脊柱术后急性硬脊膜外血肿的发生机制及其诊治进展情况综述如下。

１脊柱术后并发硬脊膜外血肿发生原因及机理１．１原因多节段脊柱手术、术前服用抗凝药物以及术前有出血倾向都是术后发生硬脊膜外血肿的高危因素，术中出血量的多少与术后硬脊膜外血肿形成无关【４Ｊ。

多节段脊柱手术损伤椎管内静脉丛可导致大量隐性出血，产生硬脊膜外血肿¨】。

Ａｗａｄ等晡３认为患者年龄＞６０岁，术前应用非瑙体类抗炎药（ＮＳＡＩＯｓ），有凝血障碍性疾病者，多节段脊柱手术以及术中大量出血是脊柱术后并发硬脊膜外血肿的诱发因索。

１．２机理脊柱术后并发急性硬脊膜外血肿的形成机制有以下几点：①静脉出血：椎后静脉及硬脊膜外静脉位于疏松的脂肪组织内，脊柱手术尤其多节段脊柱手术可以破坏椎管内静脉丛，导致大量隐性出血形成血肿口】。

②动脉出血：术中止血不彻底致小动脉持续出血，短时间内形成血肿，压迫脊髓。

③引流不畅：引流管受压、扭曲、管内血块堵塞等导致引流不畅，创口内渗血排出受阻，形成血肿。

２脊柱术后并发硬脊膜外血肿临床表现及诊断２．１发生部位脊柱术后硬脊膜外血肿大都发生在原手术部位哺Ｊ。

硬脊膜外血肿最易发生在胸椎术后，因为胸椎管内的静脉丛最为丰富，加之胸椎管最狭窄，易受损伤出现血肿㈤。

２．２临床表现首先表现为刀口剧烈疼痛，随后出现新的脊髓压迫症状，表现为运动、感觉功能减弱甚至丧失。

相应的神经功能障碍的表现取决于脊髓受压部位。

裴攀-翻译中文

第6章光源和放大器在光纤系统，光纤光源产生的光束携带的信息。

激光二极管和发光二极管是两种最常见的来源。

他们的微小尺寸与小直径的光纤兼容，其坚固的结构和低功耗要求与现代的固态电子兼容。

在以下几个GHz的工作系统，大部分（或数Gb /秒），信息贴到光束通过调节输入电流源。

外部调制（在第4、10章讨论）被认为是当这些率超标。

我们二极管LED和激光研究，包括操作方法，转移特性和调制。

我们计划以获得其他好的或理念的差异的两个来源，什么情况下调用。

当纤维损失导致信号功率低于要求的水平，光放大器都需要增强信号到有效的水平。

通过他们的使用，光纤链路可以延长。

因为光源和光放大器，如此多的共同点，他们都是在这一章处理。

1.发光二极管一个发光二极管[1，2]是一个PN结的半导体发光时正向偏置。

图6.1显示的连接器件、电路符号，能量块和二极管关联。

能带理论提供了对一个）简单的解释半导体发射器（和探测器）。

允许能带通过的是工作组，其显示的宽度能在图中，相隔一禁止区域（带隙）。

在上层能带称为导带，电子不一定要到移动单个原子都是免费的。

洞中有一个正电荷。

它们存在于原子电子的地点已经从一个中立带走，留下的电荷原子与净正。

自由电子与空穴重新结合可以，返回的中性原子状态。

能量被释放时，发生这种情况。

一个n -型半导体拥有自由电子数，如图图英寸6.1。

p型半导体有孔数自由。

当一种P型和一种N型材料费米能级（WF）的P和N的材料一致，并外加电压上作用时，产生的能垒如显示的数字所示。

重参杂材料，这种情况提供许多电子传到和过程中需要排放的孔。

在图中，电子能量增加垂直向上，能增加洞垂直向下。

因此，在N地区的自由电子没有足够的能量去穿越阻碍而移动到P区。

同样，空穴缺乏足够的能量克服障碍而移动进入n区。

当没有外加电压时，由于两种材料不同的费米能级产生的的能量阻碍，就不能自由移动。

外加电压通过升高的N端势能，降低一侧的P端势能，从而是阻碍减小。

如果供电电压（电子伏特）与能级（工作组）相同，自由电子和自由空穴就有足够的能量移动到交界区，如底部的数字显示，当一个自由电子在交界区遇到了一个空穴，电子可以下降到价带，并与空穴重组。

学术英语之社科 Unit 1 Section B 翻译

New Airport Landing Fees Delayed机场降落收费新政策延期1the government has delayed by at last a month a plan to reduce congestion at the nation's airports following stiff resistance from airlines.受到航空公司的强烈反对，政府关于减轻国家机场的拥堵的计划，至少推迟了一个月。

2.A new federal policy allowing airports to charge higher landing fees during peak periods, and for other reasons, aims to reduce delays by encouraging airlines to spread their flights more evenly throughout the day .The policy which also encourages congested airports to include in landing fees the cost of expansion projects,had been scheduled to take effect in March,following a 45-day comment period.一项新的联邦政策允许机场在高峰期收取更高的降落费用，或因其它原因，旨在鼓励航空公司在一天内更均匀地安排航班起落以减少延误。

该政策还鼓励拥挤的机场将机场扩建项目的成本纳入到机场降落收费中。

此项政策原计划三月份生效，并设置了45天的征询意见期。

3.But airline trade groups, which oppose the plan,requested a 30-day extension of the comment period. Their request has been granted, a Transportation Department spokesman said Thursday.但是反对这项方案的航空公司贸易团体，要求将征询意见期延长30天。

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Keywords: SIR epidemic model; Time delay; Global asymptotic stability
1. Introduction
In modeling the spread of infectious disease through the population, it is assumed that the total population size is constant in classical models. More recent studies consider a epidemic model with density dependence to describe disease transmission in variable population size (see [3,6,8] etc.). Takeuchi et al. [10,11] studied the SIR infectious disease model in which an infectious disease is transmitted by a vector after an incubation time. Their model assumes that the birth rate and the death rate are all constant, so the dynamics of the total population is very simple. In order to investigate disease dynamics for the model with more demographic effects, it should be assumed that birth and death rates are density dependent. Moreover, in order to make the model more realistic, we incorporate the incubation time during which the infectious agents develop in the vector. Thus we consider an epidemic model with time delay.
where a is a convex combination constant and r = b − d > 0 is the intrinsic growth rate and K > 0 is the carrying capacity of the population. The first term in (1) has a density dependent per capita birth rate coefficient b − arN /K and the second term has a density dependent per capita death rate coefficient d + (1 − a)rN /K. For 0 < a < 1 the birth rate decreases and the death rate increases to its carrying capacity K; these are consistent with the limited resources associated with density-dependence. The birth rate is density independent when a = 0 and the death rate is density independent when a = 1.
S∗ = K , R0
I ∗ = (d + (1 − a)r)(R0 − 1)K ,
R∗ = d + (1 − a)r I ∗.
R0 is called the basic reproduction number. In the next section we analyze the stability of the endemic equilibrium E+ and give a global stability criterion in
The initial condition of (2) is given by
S( ) =
1( ), I ( ) =
2( ), R( ) =
3( ), (−h
0)
(3)
w
3)T ∈ C. C denotes the Banach space C([−h, 0], R3) of continuous functions mapping the interval [−h, 0] into R3.
S(t) +
b − a rN (t) K
N (t),
I˙(t) =
S (t )I N (t
(t −
− h) h)
−
d + (1 − a) rN (t) K
I (t) − I (t),
R˙(t) = I (t) − d + (1 − a) rN (t) R(t),
(2)
K
where , b, , d and r are positive constants. is the effective per capita contact rate constant of infective individuals and is the recovery rate of the infectives. The model (2) assumes that the all newborns are susceptibles.
System (2) always has the disease free equilibrium E0 = (K, 0, 0). Furthermore, if
R0 ≡ d + (1 − a)r +
= b − ar +
> 1,
(4)
then system (2) also has the unique endemic equilibrium E∗ = (S∗, I ∗, R∗), where
Naoki Yoshida, Tadayuki Hara∗
Department of Mathematical Sciences, Osaka Prefecture University, Sakai 599-8531, Japan Received 28 June 2004; received in revised form 26 October 2005
can infect a susceptible human. Then, our model becomes a system of differential equations with time delay
S˙(t) = −
S(t)I (t − h) − N (t − h)
d + (1 − a) rN (t) K
We assume that the force of infection is proportional to I (t − h)/N (t − h) where the nonnegative constant h is a time delay during which the infectious agents develop in the vector and it is only after the time that the infected vector
It is our purpose to analyze a SIR epidemic model with the incubation time and density dependent birth and death rates. The host population is divided into susceptible, infective and recovered individual whose numbers are denoted by S, I and R. The number of the total population is denoted by N (=S + I + R). As in the paper [4], we assume that the dynamics of the total population are governed by the following logistic equation:
Journal of Computational and Applied Mathematics 201 (2007) 339 – 347
/locate/cam
Global stability of a delayed SIR epidemic model with density dependent birth and death rates
N˙ = b − a rN N − d + (1 − a) rN N ,
(1)
K
K
∗ Corresponding author. Tel.: +81 722 54 9358; fax: +81 722 59 3340. E-mail address: hara@ms.osakafu-u.ac.jp (T. Hara).
case R0 > 1. We give a summary of our results in Section 3.
2. Main result
Throughout of this paper, we focus on the dynamics of the solutions of (2) in the following restricted region: