取整对Logistic种群模型动态的影响

不考虑环境嗓音,Logistic取整模型的种群动态是非混沌的,只会出现稳态和周期;在1＜r＜3和0＜r＜1区间,取整模型较原始模型能较快收敛到定态或者灭绝;增大K不能消除取整效应;取整模型周期长度受初值、K值和r值的影响;取整是混沌控制的一条新途径,它可能是自然种群中很少能检测到混沌的重要原因之一．     

New Policies,New Technologies: Modelling the Potential for Improved Smear Microscopy Services in Malawi

Background

To quantify the likely impact of recent WHO policy recommendations regarding smear microscopy and the introduction of appropriate low-cost fluorescence microscopy on a) case detection and b) laboratory workload.

Methodology/Principal Findings

An audit of the laboratory register in an urban hospital, Lilongwe, Malawi, and the application of a simple modelling framework. The adoption of the new definition of a smear-positive case could directly increase case detection by up to 28%. Examining Ziehl-Neelsen (ZN) sputum smears for up to 10 minutes before declaring them negative has previously been shown to increase case detection (over and above that gained by the adoption of the new case definition) by 70% compared with examination times in routine practice. Three times the number of staff would be required to adequately examine the current workload of smears using ZN microscopy. Through implementing new policy recommendations and LED-based fluorescence microscopy the current laboratory staff complement could investigate the same number of patients, examining auramine-stained smears to an extent that is equivalent to a 10 minutes ZN smear examination.

Conclusions/Significance

Combined implementation of the new WHO recommendations on smear microscopy and LED-based fluorescence microscopy could result in substantial increases in smear positive case-detection using existing human resources and minimal additional equipment.     

Multiple Model Approach: Exploring the Limits of Comparative Modeling

One of the biggest problems in modeling distantly related proteins is the quality of the target-template alignment. This problem often results in low quality models that do not utilize all the information available in the template structure. The divergence of alignments at a low sequence identity level, which is a hindrance in most modeling attempts, is used here as a basis for a new technique of Multiple Model Approach (MMA). Alternative alignments prepared here using different mutation matrices and gap penalties, combined with automated model building, are used to create a set of models that explore a range of possible conformations for the target protein. Models are evaluated using different techniques to identify the best model. In the set of examples studied here, the correct target structure is known, which allows the evaluation of various alignment and evaluation strategies. For a randomly selected group of distantly homologous protein pairs representing all structural classes and various fold types, it is shown that a threading score based on simplified statistical potentials of mean force can identify the best models and, consequently, the most reliable alignment. In cases where the difference between target and template structures is significant, the threading score shows clearly that all models are wrong, therefore disqualifying the template.     

Effects of Infection on Honey Bee Population Dynamics: A Model

We propose a model that combines the dynamics of the spread of disease within a bee colony with the underlying demographic dynamics of the colony to determine the ultimate fate of the colony under different scenarios. The model suggests that key factors in the survival or collapse of a honey bee colony in the face of an infection are the rate of transmission of the infection and the disease-induced death rate. An increase in the disease-induced death rate, which can be thought of as an increase in the severity of the disease, may actually help the colony overcome the disease and survive through winter. By contrast, an increase in the transmission rate, which means that bees are being infected at an earlier age, has a drastic deleterious effect. Another important finding relates to the timing of infection in relation to the onset of winter, indicating that in a time interval of approximately 20 days before the onset of winter the colony is most affected by the onset of infection. The results suggest further that the age of recruitment of hive bees to foraging duties is a good early marker for the survival or collapse of a honey bee colony in the face of infection, which is consistent with experimental evidence but the model provides insight into the underlying mechanisms. The most important result of the study is a clear distinction between an exposure of the honey bee colony to an environmental hazard such as pesticides or insecticides, or an exposure to an infectious disease. The results indicate unequivocally that in the scenarios that we have examined, and perhaps more generally, an infectious disease is far more hazardous to the survival of a bee colony than an environmental hazard that causes an equal death rate in foraging bees.     

Modeling the Potential Distribution of Bacillus anthracis under Multiple Climate Change Scenarios for Kazakhstan

Anthrax, caused by the bacterium Bacillus anthracis, is a zoonotic disease that persists throughout much of the world in livestock, wildlife, and secondarily infects humans. This is true across much of Central Asia, and particularly the Steppe region, including Kazakhstan. This study employed the Genetic Algorithm for Rule-set Prediction (GARP) to model the current and future geographic distribution of Bacillus anthracis in Kazakhstan based on the A2 and B2 IPCC SRES climate change scenarios using a 5-variable data set at 55 km² and 8 km² and a 6-variable BioClim data set at 8 km². Future models suggest large areas predicted under current conditions may be reduced by 2050 with the A2 model predicting ∼14–16% loss across the three spatial resolutions. There was greater variability in the B2 models across scenarios predicting ∼15% loss at 55 km², ∼34% loss at 8 km², and ∼30% loss with the BioClim variables. Only very small areas of habitat expansion into new areas were predicted by either A2 or B2 in any models. Greater areas of habitat loss are predicted in the southern regions of Kazakhstan by A2 and B2 models, while moderate habitat loss is also predicted in the northern regions by either B2 model at 8 km². Anthrax disease control relies mainly on livestock vaccination and proper carcass disposal, both of which require adequate surveillance. In many situations, including that of Kazakhstan, vaccine resources are limited, and understanding the geographic distribution of the organism, in tandem with current data on livestock population dynamics, can aid in properly allocating doses. While speculative, contemplating future changes in livestock distributions and B. anthracis spore promoting environments can be useful for establishing future surveillance priorities. This study may also have broader applications to global public health surveillance relating to other diseases in addition to B. anthracis.     

家兔新型动脉粥样硬化狭窄模型的建立及其动态观察

目的　为血管成形术后再狭窄的研究提供非球囊扩张和动脉造影的简单易行的新型动脉粥样硬化斑块狭窄动物模型。方法　选择日本大耳白兔 18只 (含正常组 6只 ) ,用电刺激血栓形成仪刺激颈总动脉并在术后高脂饲料喂养 6周 ,模型分别于术后 3天、1周、3周、6周处死颈总动脉取材 ,常规病理切片行HE、弹力V G染色 ,光学显微镜观察病理变化。结果　术后 1周内动脉有血栓形成 ,内皮剥脱和部分内弹力板断裂 ,内皮细胞增生 ,中膜局部平滑肌细胞有少量水肿、消失 ,外膜有中性粒细胞浸润 ;术后 3周以上则内膜明显增生 ,内膜下脂质沉积 ,中膜平滑肌细胞核有轻度减少 ,纤维组织及基质增生 ,以损伤部位更明显 ,外膜刺激部位有轻度增厚。术后 6周 6只动物颈总动脉均形成管腔狭窄。结论　用电刺激加高脂饲料喂养的方法可成功建立动脉粥样硬化狭窄的动物模型 ;该模型的病理表现与人类动脉粥样硬化的病理过程相似 ,且避免了二次球囊造模法形成的血管盲端     

A Stable Lyophilized Reagent for Use in a Potential Reference Assay for Quantitation of Anti-D in Immunoglobulin Products

Quality control of anti-D immunoglobulins intended for in vivo clinical use requires in vitro assay of potency. A lyophilized biotinylated monoclonal anti-D (biotinylated Brad-5; 99/698) has been evaluated for its suitability to serve as a working reagent in a competitive enzyme-linked immunoassay (EIA) for anti-D quantitation. The reagent demonstrated acceptable stability in accelerated degradation tests and following reconstitution. Twelve international laboratories obtained comparable potencies for each of nine anti-D samples using 99/698 in a standardized assay procedure using erythrocytes fixed to microtitre plates. We also describe the use of trehalose for stabilization of dried erythrocyte-coated microtitre plates.     

Tobacco Industry Manipulation of Tobacco Excise and Tobacco Advertising Policies in the Czech Republic: An Analysis of Tobacco Industry Documents

Background

The Czech Republic has one of the poorest tobacco control records in Europe. This paper examines transnational tobacco companies'' (TTCs'') efforts to influence policy there, paying particular attention to excise policies, as high taxes are one of the most effective means of reducing tobacco consumption, and tax structures are an important aspect of TTC competitiveness.

Methods and Findings

TTC documents dating from 1989 to 2004/5 were retrieved from the Legacy Tobacco Documents Library website, analysed using a socio-historical approach, and triangulated with key informant interviews and secondary data. The documents demonstrate significant industry influence over tobacco control policy. Philip Morris (PM) ignored, overturned, and weakened various attempts to restrict tobacco advertising, promoting voluntary approaches as an alternative to binding legislation. PM and British American Tobacco (BAT) lobbied separately on tobacco tax structures, each seeking to implement the structure that benefitted its own brand portfolio over that of its competitors, and enjoying success in turn. On excise levels, the different companies took a far more collaborative approach, seeking to keep tobacco taxes low and specifically to prevent any large tax increases. Collective lobbying, using a variety of arguments, was successful in delaying the tax increases required via European Union accession. Contrary to industry arguments, data show that cigarettes became more affordable post-accession and that TTCs have taken advantage of low excise duties by raising prices. Interview data suggest that TTCs enjoy high-level political support and continue to actively attempt to influence policy.

Conclusion

There is clear evidence of past and ongoing TTC influence over tobacco advertising and excise policy. We conclude that this helps explain the country''s weak tobacco control record. The findings suggest there is significant scope for tobacco tax increases in the Czech Republic and that large (rather than small, incremental) increases are most effective in reducing smoking. Please see later in the article for the Editors'' Summary     

A New Method for Nonlinear Dynamic Analysis of the Multi-kinetics Neural Mass Model

ObjectiveThe aim was to use a new method to analyze the nonlinear dynamic characteristics of the multi-kinetics neural mass model. We hope that this new method can be as an auxiliary judgment tool for the diagnosis of brain diseases and the identification of brain activity states.MethodsWe apply the Lorenz plot to analyze the nonlinear dynamic characteristics of electroencephalogram (EEG) signals from the multi-kinetics neural mass models. The standard deviations in two orthogonal directions of the Lorenz plot are further used to quantify the nonlinear dynamic characteristics of EEG signals.ResultsThe results show that the normalized signal frequency power spectrum may not be able to distinguish normal EEG signals and epileptiform spikes, but the Lorenz plot can distinguish the normal EEG signals and epileptiform spikes effectively. For EEG signals with multi-rhythms, the Lorenz plot of all the simulated signals are oval, but the value of SD1/SD2 increases monotonically when the multi-rhythm EEG signals change from low frequency to high frequency.ConclusionThe Lorenz plot of EEG signals with different rhythms presents different distribution. It is an effective nonlinear analysis method for EEG signals.     

Future Impact of Various Interventions on the Burden of COPD in Canada: A Dynamic Population Model

Background

Chronic obstructive pulmonary disease (COPD) is a growing economic burden worldwide. Smoking cessation is thought to be the single most effective way of reducing the economic burden of COPD. The impact of other strategies such as interventions that predict risk of disease, reduce progression of disease, or reduce exacerbations has not been systematically studied.

Objectives

We estimated the economic and clinical burden of COPD over the next 25 years in Canada and the impact of three potential interventions (screening test for predisposition to COPD, new drugs to avoid progression into more severe disease stages, and predictive test for exacerbations) on COPD burden.

Methods

Using a dynamic simulation model, we projected the total burden of COPD (cost, morbidity, and mortality) from 2011 to 2035 using the population of Canada as a case study. The model stratified population based on sex, age, smoking status, respiratory symptoms, and their COPD stage. The cost and quality adjusted life years (QALYs) associated with each intervention were estimated.

Results

The model indicates that annual societal cost of COPD is $4.52 billion (B) Canadian dollars in 2011 and will reach $3.61B ($7.33B undiscounted) per year in 2035. Over the next 25 years, COPD will be responsible for approximately $101.4B in societal costs ($147.5B undiscounted) and 12.9 million QALYs lost (19.0 million undiscounted). Our results suggested that the best strategy to reduce the financial burden of COPD is by reducing exacerbations. Smoking cessation, while it is the cornerstone of COPD prevention, has only a modest effect in attenuating the financial burden of COPD over the next 25 years in Western countries such as Canada.

Conclusion

Our data suggest that any intervention that can reduce the number of exacerbations has a substantial impact on morbidity and costs of COPD and should be considered in conjunction with the ongoing efforts to reduce smoking rates.     

温室中生菜生长动态及生产潜力的模拟模型

以作物生理生态过程为基础,以试验所得的数据为主要作物参数,用Ｃ语言编程,建立了温室生菜生产的模拟模型．根据对周年１１茬生菜进行模拟的结果,作物光温生产潜力比现实生产力高１４．９％,作物的抽苔期精确度达到与实际抽苔期仅差±１天的水平．只需对模型中的部分作物参数进行修改,就可用该模型进行其它叶菜类作物的生长动态模拟和预测．     

Plant Derived Antiviral Products for Potential Treatment of COVID-19: A Review

COVID-19 caused by SARS-CoV-2 is declared global pandemic. The virus owing high resemblance with SARS-CoV and MERS-CoV has been placed in family of beta-coronavirus. However, transmission and infectivity rate of COVID-19 is quite higher as compared to other members of family. Effective management strategy with potential drug availability will break the virus transmission chain subsequently reduce the pressure on the healthcare system. Extensive research trials are underway to develop novel efficient therapeutics against SARS-CoV-2. In this review, we have discussed the origin and family of coronavirus, structure, genome and pathogenesis of virus SARS-CoV-2 inside human host cell; comparison among SARS, MERS, SARS-CoV-2 and common flu; effective management practices; treatment with immunity boosters; available medication with ongoing clinical trials. We suggest medicinal plants could serve as potential candidates for drug development against COVID-19 infection.     

Erratum to: New Biocomposite Materials Based on Hydrocarbon-Oxidizing Microorganisms and Their Potential for Oil Products Degradation

Microbiology - An Erratum to this paper has been published: https://doi.org/10.1134/S0026261722300142     

静脉注射吸毒人群HIV／AIDS数学模型分析

建立了四川省西昌市静脉注射吸毒人群HIV／AIDS传播的数学模型,给出了模型的理论分析和数值模拟结果．通过必要的分析,给出了各类平衡点的存在性和稳定性,系统的一致持续生存,以及基本再生数的数学表达式和具体取值．揭示了该静注人群中的HIV／AIDS有进一步蔓延的趋势,但如果采取适当的干预措施,该静注人群中HIV／AIDS流行可得到有效的控制．     

Autoimmune Thyroid Disease in the Use of Alemtuzumab for Multiple Sclerosis: A Review

ObjectiveThe monoclonal antibody alemtuzumab has been demonstrated to reduce the risks of relapse and accumulation of sustained disability in multiple sclerosis (MS) patients when compared to β-interferon. The development of autoimmune diseases, including thyroid disease, has been reported in the literature with a frequency of 20 to 30%. In this article, we describe 4 cases of alemtuzumab-induced thyroid disease in patients with MS. We also performed a systematic review of the available literature.MethodsFour patients who had received alemtuzumab for MS and subsequently developed thyroid dysfunction are presented. We compared our patients' clinical courses and outcomes to established disease patterns. We also undertook a systematic review of the published literature.ResultsAll 4 patients presented with initial hyperthyroidism associated with elevated thyroid-stimulating hormone (TSH) receptor antibodies (TRAb). In 2 cases, hyperthyroidism did not remit after a total of 24 months of carbimazole therapy, and they subsequently underwent subtotal thyroidectomy. The third case subsequently developed biochemical hypothyroidism and required thyroxine replacement, despite having a markedly raised initial TRAb titer. Autoimmunity following alemtuzumab therapy in MS appears to occur as part of an immune reconstitution syndrome and is more likely in smokers who have a family history of autoimmune disease.ConclusionManagement of alemtuzumab-induced thyroid disease is similar to the management of “wild-type” Graves’ disease. The use of alemtuzumab in this setting will necessitate close monitoring of thyroid function and early intervention when abnormalities are developing. (Endocr Pract. 2013;19:821-828)     

Effect of Tobacco Control Policies on Information Seeking for Smoking Cessation in the Netherlands: A Google Trends Study

Background

The impact of tobacco control policies on measures of smoking cessation behaviour has often been studied, yet there is little information on their precise magnitude and duration. This study aims to measure the magnitude and timing of the impact of Dutch tobacco control policies on the rate of searching for information on smoking cessation, using Google Trends search query data.

Methods

An interrupted time series analysis was used to examine the effect of two types of policies (smoke-free legislation and reimbursement of smoking cessation support (SCS)) on Google searches for ‘quit smoking’. Google Trends data were seasonally adjusted and analysed using autoregressive integrated moving average (ARIMA) modelling. Multiple effect periods were modelled as dummy variables and analysed simultaneously to examine the magnitude and duration of the effect of each intervention. The same analysis was repeated with Belgian search query data as a control group, since Belgium is the country most comparable to the Netherlands in terms of geography, language, history and culture.

Results

A significant increase in relative search volume (RSV) was found from one to four weeks (21–41%) after the introduction of the smoking ban in restaurants and bars in the Netherlands in 2008. The introduction of SCS reimbursement in 2011 was associated with a significant increase of RSV (16–22%) in the Netherlands after 3 to 52 weeks. The reintroduction of SCS in 2013 was associated with a significant increase of RSV (9–21%) in the Netherlands from 3 to 32 weeks after the intervention. No effects were found in the Belgian control group for the smoking ban and the reintroduction of SCS in 2013, but there was a significant increase in RSV shortly before and after the introduction of SCS in 2011.

Conclusions

These findings suggest that these tobacco control policies have short-term or medium-term effects on the rate of searching for information on smoking cessation, and therefore potentially on smoking cessation rates.     

Myelin Basic Protein Citrullination in Multiple Sclerosis: A Potential Therapeutic Target for the Pathology

Multiple sclerosis (MS) is a multifactorial demyelinating disease characterized by neurodegenerative events and autoimmune response against myelin component. Citrullination or deimination, a post-translational modification of protein-bound arginine into citrulline, catalyzed by Ca²⁺ dependent peptidylarginine deiminase enzyme (PAD), plays an essential role in physiological processes include gene expression regulation, apoptosis and the plasticity of the central nervous system, while aberrant citrullination can generate new epitopes, thus involving in the initiation and/or progression of autoimmune disorder like MS. Myelin basic protein (MBP) is the major myelin protein and is generally considered to maintain the stability of the myelin sheath. This review describes the MBP citrullination and its consequence, as well as offering further support for the “inside-out” hypothesis that MS is primarily a neurodegenerative disease with secondary inflammatory demyelination. In addition, it discusses the role of MBP citrullination in the immune inflammation and explores the potential of inhibition of PAD enzymes as a therapeutic strategy for the disease.     

Jet Riemann-Lagrange几何分析静脉注射吸毒人员HIV/AIDS模型(英文)

介绍并应用Jet Riemann-Lagrange几何,通过解一类Kaldor流方程去分析静脉注射吸毒人员HIV/AIDS模型,我们得到几个有意义的结果.