东北地区水稻机械化种植模式

为解决东北地区年积温小、水稻安全生长期短、种植模式多样化等特点对水稻机械化种植模式影响的问题，通过对东北地区水稻种机械化种植模式中的机插秧、机直播、机抛秧进行对比分析，并采用一种钵苗行栽技术，实现了钵苗的有序浅栽，增产增效效果显著。田间试验表明，钵苗行栽技术满足水稻种植的农艺要求，增产8％～10％，比常规人工种植节约成本约20％。研究认为，机械化插秧与钵苗行栽是2种适合东北地区的水稻种植模式，对该地区水稻机械化种植有一定的促进作用。

基于无人机数字图像的棉花出苗信息提取

为及时准确地获取棉花出苗信息,首先,利用无人机搭载数字成像设备获取棉花出苗期图像,通过超绿算法和手动阈值法分割出棉苗;然后,应用图像去相关拉伸和K均值聚类算法实现对地膜区域的分割,分析地膜垂直投影统计图,准确获得棉苗行数和地膜规划区域,实现对地膜规划区域外杂草的去除和棉苗区域的分组;最后,应用最小二乘法对棉苗进行直线拟合,实现了苗行的精确检测和单条苗行直线距离。通过棉苗位置距离中位数获得株距,从而得到棉花播种数。结果显示,出苗行数检测准确,误差为0,棉花出苗率检测准确率最高为90.45%,棉花播种数误差仅为5%。所提出的方法实现了大面积棉田出苗信息的快速提取,为棉苗管理的精细农业提供技术支持,为田间苗行检测提供新方法。

Analysis of an Epidemic Model with Age of Vaccination

A simple SI epidemic model with age of vaccination is discussed in this paper.Both vexing birth rate, the mortality rate caused by disease and vaccine waning rate areconsidered in this model. We prove that the global dynamics is completely determined bythe basic reproductive number R（ψ）（ψ denotes per capita vaccination rate）. If R（0） 〈 1,the disease-free equilibrium is a global attractor; If R（ψ） 〈： 1, the disease-free equilibriumis locally asymptotically stable; If R（ψ） ：〉 1, an unique endemic equilibrium exists and islocally asymptotically stable under certain condition.

Inflammatory bowel disease in travelers:Choosing the right vaccines and check-ups

The majority of patients with inflammatory bowel disease (IBD) achieve good control of the inflammatory activity using available therapies. When remission is achieved and quality of life recovered, a considerable proportion of IBD patients express their desire to travel abroad, be it for business, academic or leisure purposes. Their physicians should help and encourage them whenever possible. However, preventive measures are warranted to minimize the risk, since IBD patients are exposed to the same infections affecting the general population, plus opportunistic infections (OI) related to the immunosuppression. There are a large number of potential OI that might affect patients with IBD. The true prevalence of these infections is unknown, and can vary from country to country. Therefore, reactivation or de novo acquisition of infections such as tuberculosis, malaria, and viral hepatitis will be much more frequent in endemic areas. Therefore, physicians should beaware of these aspects when planning specific preventive measures for patients traveling to a particular country. This includes good control of environmental exposure, chemoprophylaxis when indicated, and the use of a specific vaccination program to prevent endemic infections. In addition, it should be noted that, though the risk of acquiring an infectious disease is probably greater for IBD patients traveling from a developed to a developing country, the inverse situation can also occur; it depends on the previous acquired immunity of the host against infections in any particular environment.

Effect of Seed Drying on Germination Behavior and Seedling Growth of Sweetsop （Annona squamosa）

An experiment was conducted at the Department of Horticulture, College of Agriculture and Natural Resources, Kwame Nkrumah University of Science and Technology, Kumasi （KNUST） Ghana from September, 2009 to April, 2010, to determine the most appropriate drying method, as a post harvest practice, that would ensure high percentage germination ofAnnona squamosa seeds and its subsequent effect on seedling growth. The seeds were sun-dried, air-dried under shade or kept in the fresh state. Five treatments were used, namely, Freshly Sown seeds （Treatment 1, control）, Seeds Air-Dried under Shade for one day （Treatment 2）; Seeds Sun-Dried for one day （Treatment 3）; Seeds Air-Dried under Shade for three consecutive days （Treatment 4）; Seeds Sun-Dried for three consecutive days （Treatment 5）. The experiment was arranged in a Completely Randomized Design （CRD） and replicated three times. Drying of Annona squamosa seeds had significant effect on earliness and number of seeds germinated. Air drying under shade and sun-drying for three consecutive days improved earliness to germination （26 days after sowing） and percent total germination but air-drying under shade had better effect on total seed germination, achieving 90% germination in 42 days after sowing. Furthermore, the prevailing ambient temperature of 30 ℃-32 ℃ enhanced germination of Annona squamosa seeds. The study concluded that for optimum germination, seeds of Annona squamosa should be either air-dried or sun-dried for three consecutive days and be incubated in an ambient temperature range of 30 ℃-32 ℃. In terms of growth, seedling growth in leaf production was better from seeds sun-dried for three consecutive days.

Effects of dendritic cell vaccines on hematogenous micrometastasis of bladder cancer carrying for PBL-SCID mice

Objective： To study the effect of dendritic cells loaded with whole tumor antigen on hematogenous micrometastasis of bladder cancer model in hu-PBL-SCID mice. Methods： T24-3 ceil subset was selected from human bladder transitional cell carcinoma T24 cell line by Boyden chamber system. The SCID mice intraperitoneally injected with 4 × 10^7 hu-PBL and subcutaneously injected with 3 × 10^6 T24-3 cells were named hu-PBL-T24-3-SCID model. Human IgG level in the blood plasma of mice was detected by ELISA, and human CD3^＋, CD4^＋, CD8^＋ T cells in blood and spleen cells of mice were detected by FCM analysis for human immune reconstruction study. Human CK20 mRNA expression in mice peripheral blood was detected by RT-PCR to investigate metastasis of tumor cells. The PBMCs were isolated from human peripheral blood, and were induced into DCs by co-culture with rhGM-CSF and rhlL-4 in vitro. The DC vaccines were produced by co-culturing with whole tumor antigen which was purified through freezing and melting T24-3 cell subset. After T24-3 cells injected into SCID mice for 5 weeks, the mice were treated with DC vaccines. Results： All mice were initially treated at 5th week. The expression of CK20 mRNA in peripheral blood of DC vaccines treated mice was the lowest. There was 2 mice showing CK20 mRNA expression and 3 mice with metastasis tumor in PBS group. MMP-7 mRNA expression in tumor tissues of DC vaccines treated mice was statistically lower than that of PBS group （P 〈 0.01）. Conclusion： DC vaccines have a good effect on hu-PBL-SCID mice bladder cancer model by reducing hematogenous micrometastasis.

学者猫江江的新书发布会

《宠物世界·猫迷》"喵行天下"栏目作者左刀刀同学又出书啦!《功夫猫:酷咪奶牛的搞笑生活》已于目前完成出版工作.正式与广大"牛粉"们见面。奶牛不是牛,而是一只黑白花的土猫,能吃擅睡爱晒太阳,视妙鲜包高于一切。它没有名贵血统但照样洋洋自得.

A MULTI-GROUP SVEIR EPIDEMIC MODEL WITH DISTRIBUTED DELAY AND VACCINATION

In this paper, based on a class of multi-group epidemic models of SEIR type with bilinear incidences, we introduce a vaccination compartment, leading to multi-group SVEIR model. We establish that the global dynamics are completely determined by the basic reproduction number R0V which is defined by the spectral radius of the next generation matrix. Our proofs of global stability of the equilibria utilize a graph-theoretical approach to the method of Lyapunov functionals. Mathematical results suggest that vaccination is helpful for disease control by decreasing the basic reproduction number. However, there is a necessary condition for successful elimination of disease. If the time for the vaccines to obtain immunity or the possibility for them to be infected before acquiring immunity is neglected in each group, this condition will be satisfied and the disease can always be eradicated by suitable vaccination strategies. This may lead to over evaluation for the effect of vaccination.

Global stability of an SEIR epidemic model with vaccination

In this paper, an SEIR epidemic model with vaccination is formulated. The results of our mathematical analysis indicate that the basic reproduction number plays an important role in studying the dynamics of the system. If the basic reproduction number is less than unity, it is shown that the disease-free equilibrium is globally asymptotically stable by comparison arguments. If it is greater than unity, the system is permanent and there is a unique endemic equilibrium. In this case, sufficient conditions are established to guarantee the global stability of the endemic equilibrium by the theory of the compound matrices. Numerical simulations are presented to illustrate the main results.

Stability analysis and optimal control of an epidemic model with vaccination

In this paper, we have developed a compartment of epidemic model with vaccination. We have divided the total population into five classes, namely susceptible, exposed, infective, infective in treatment and recovered class. We have discussed about basic properties of the system and found the basic reproduction number （R0） of the system. The stability analysis of the model shows that the system is locally as well as globally asymptotically stable at disease-free equilibrium E0 when R0 〈1. When R0 〉1 endemic equilibrium E1 exists and the system becomes locally asymptotically stable at E1 under some conditions. We have also discussed the epidemic model with two controls, vaccination control and treatment control. An objective functional is considered which is based on a combination of minimizing the number of exposed and infective individuals and the cost of the vaccines and drugs dose. Then an optimal control pair is obtained which minimizes the objective functional. Our numerical findings are illustrated through computer simulations using MATLAB. Epidemiological implications of our analytical findings are addressed critically.

TRAVELING WAVES OF AN EPIDEMIC MODEL WITH VACCINATION

An epidemic model with vaccination and spatial diffusion is studied. By analyzing the corresponding characteristic equations, the local stability of each of feasible steady states to this model is discussed. The existence of a traveling wave solution is established by using the technique of upper and lower solutions and Schauder＇s fixed point theorem. Numerical simulations are carried out to illustrate the main results.

Existence of Positive Periodic Solutions for the SIV Epidemic Model with Impulsive Vaccination and Infection-Age

In this paper, we discuss the SIV epidemic model with impulsive vaccination and infection-age. Bifurcation theory and Lyapunov-Schmidt series expansion are used to show the existence of the positive periodic solutions under some conditions.

Impacts of Tourists’Attachment Styles on Emotional Experiencesand Behavioral Intentions to Attractions of Tourism Destination:The Case of Xijiang Qianhu Miao Village,China

Existing studies of tourists’behaviors of tourism destination focus on place attachment.Although tourists’attachment is related to tourists’emotional experiences at the attractions of a tourism destination(ATDs),the rolethat tourists’attachment styles play in establishing their emotional experiences and behavioral intentions towarddifferent ATD types have not been verified.This study used the Xijiang Qianhu Miao Village as a typical tourismdestination to examine these effects.Based on research on attachment styles,emotional experiences,and behavioral intentions,a conceptual model of the relationships among tourists’attachment styles,emotional experiences of,and behavioral intentions toward ATDs was constructed.The impact of tourists’attachment styles between their emotional experiences of and behavioral intentions toward ATDs was then studied empirically.Theimpact pathways of tourist attachment styles on different ATD types were tested.The results indicate that tourists’emotional experiences of ATDs had no significant or direct impacts on their behavioral intentions in terms of relationship closeness and diversive exploration.Both their emotional experiences of and their behavioral intentionstoward ATDs were affected by the mediating effects of attachment anxiety and avoidance,which were full and partial,respectively.Further,the paths of the mediating effects of tourists’attachment styles on the emotional experiences of and behavioral intentions toward different types of ATDs varied significantly.Tourists’emotion-behaviorpaths when experiencing a TD were clarified,providing a theoretical basis to satisfy their real needs for experiencing ATDs.