On the existence and exponential attractivity of a unique positive almost periodic solution to an impulsive hematopoiesis model with delays

In this paper, a generalized model of hematopoiesis with delays and impulses is considered. By employing the contraction mapping principle and a novel type of impulsive delay inequality, we prove the existence of a unique positive almost periodic solution of the model. It is also proved that, under the proposed conditions in this paper, the unique positive almost periodic solution is globally exponentially attractive. A numerical example is given to illustrate the effectiveness of the obtained results.Comment: Accepted for publication in AM

Establishment of a memory B cell assay using recombinant Flavivirus protein for determinant of specific antiviral immunity

Tick-borne encephalitis virus (TBEV) is a serious viral infection that affects the central nervous system. It was estimated that between 1990 and 2009 a total of 169,937 cases of TBE were recorded in Europe. TBEV belongs to genus Flavivirus that comprises over 70 viruses, many of them are important human pathogens. Most members are either transmitted by mosquitoes e.g. West Nile virus (WNV), Dengue virus (DENV) or ticks e.g. TBEV. Due to the extensive antigenic cross-reactivity among flaviviruses serological diagnosis of TBE infections is commonly difficult in areas where more than one virus type circulates. Particularly, a situation now exists in Europe, where TBEV and WNV are endemic in many countries Thus, this thesis focused on the one hand on optimization of serological test systems using recombinant envelope protein domain III (rED3). It represents domain 3 of the major antigen, the surface protein E, which additionally has been shown to induce flavivirus specific neutralizing antibodies. Therefore rED3 was expressed and purified and its application as antigen in ELISA for TBEV diagnosis was verified. On the other hand a memory B-cell assay was established to analyse antiviral immunity after TBEV-vaccination. Here rED3 was used as antigen to determine the frequency of rED3 specific antibody-secreting cells (ASCs). Vaccination is the most effective method of preventing TBE disease and is currently recommended for all those who live and work or travel to areas of TBE endemicity. An essential requirement of any vaccine is the induction of long-term protective immunity. Several vaccines have defined levels of serum antibody (as measured by ELISA, haemagglutination inhibition test, or neutralisation test) that serve as correlates or surrogates of protective immunity. But this does not take account of vaccine induced memory B cells. Although, not providing direct protection against infection, they represent an important second line of immune defence that is initiated only if pre existing antibody levels are too low to prevent infection or if the invading pathogen is able to circumvent the pre-existing antibody response. A thorough understanding of the frequencies of antigen-specific memory B cells and their relationship with the antibodies in serum serological memory is likely to be critical to give information about the long-term efficacy of vaccine as well as its correlates of protection. This thesis focuses on the establishment of a recombinant protein based ELISA and of a memory B cell assay for analysis of specific antiviral immunity after vaccination with the following two objectives: (1) Expression and purification of recombinant envelope protein domain 3 (rED3) and verification of its application as antigen in ELISA for TBEV diagnosis; (2) Establishment of a memory B cells assay using rED3 for determination of frequency of rED3 specific antibody-secreting cells (ASCs) in individuals vaccinated against TBE. In this study, TBEV- and WNV-specific antigen ED3 was expressed in E. coli as MBP fusion proteins with C-terminal histidine tag using pMAL-c2x vector. By purification with amylose affinity chromatography followed by nickel affinity chromatography, highly purified TBEV rED3 and WNV-rED3 were obtained. Nevertheless, using TBEV-rED3 protein in Western Blot unspecific reaction with serum antibodies of negative serum was detected and a differentiation between WNV infection and TBEV was impossible, probably due to the MBP moiety. However, using the purified rED3 protein as antigen in ELISA, TBE virus-specific antibodies were detected specifically. Twenty-three serum samples predefined as TBEV positive were tested positive by rED3-based ELISA and commercial IgG ELISA. Five predefined negative serum samples were tested negative by rED3-based IgG ELISA as well as commercial IgG ELISA. But cross reactivity of WNV and DENV positive sera was detected in 15 of 18 sera by commercial ELISA. On the other hand, these samples were found negative in TBEV rED3-based ELISA. Thus, TBEV-rED3-based ELISA allows a differentiation of infections caused by TBE serogroup and mosquito-borne flaviviruses but not the inactivated virus based commercial ELISA. Interestingly, compared to neutralisation test the specificity of rED3-based ELISA obtained 100% with a sensitivity of 91.6%. In contrast, the commercial ELISA obtained 100 % sensitivity but a low specificity with only 42.8%. In order to determine frequency of antigen-specific antibody secreting cells (ASCs) produced by individuals who received the vaccination against TBE, peripheral blood mononuclear cells (PBMCs) were isolated from blood samples. Subsequently, memory B cells were activated with R848 (Resiquimod) and human recombinant IL-2 (hrIL-2) for 72 hours in 37°C, 5% CO2, 90% humidity. After 72 hours of incubation, Enzyme-Linked Immunospot (ELISPOT) detected antigen-specific memory B cells. In order to evaluate specificity of TBEV-rED3 in ELISPOT, other antigens including WNV-rED3, Maltose binding protein (MBP) and Influenza Nucleoprotein (NP) were included. Study subjects could be separated into two groups: last vaccination before 5 years or longer than 10 years. TBEV-rED3 specific ASCs could be detected in 11 of 12 TBE vaccinated individuals with different vaccination history and even low serum anti-TBE antibodies levels. TBEV-rED3 specific ASCs were found with frequency of ranging 0.016-0.188 % per total IgG ASCs and lower than frequency of Influenza-NP specific ASCs (between 0.012-0.51%). But TBE-specific memory B cells could be maintained for more than 20 years of post-vaccination. There was a significant difference in number of ASCs between vaccinated and non-vaccinated group (p10 years (mean of 16.5 years) since vaccination (p>0.05). These finding proved that memory B cells have been stable for years and are maintained up to 25 years since last vaccination. A statistic analysis showed that there was no significant correlation between serum levels of anti-TBEV antibodies and the frequency of rED3 specific IgG ASCs (p>0.05, Spearman’s coefficient r = 0.36). A similar result was also indicated for influenza-vaccinated individuals (p>0.05, Spearman’s coefficient r = 0.27). These findings revealed that memory B cells and plasma cells maybe play an independently role in maintaining of immunological memory. Anyway, neutralizing antibodies have been found in all vaccines (a Geometric mean titre (GMT) of 96.04, 95% confident interval (CI): 52.76-174.8) and thus were maintained for a long time since last vaccination. Interestingly, the quantitative determination of specific IgG in TBE post-vaccination sera by rED3-based ELISA exhibits a good correlation with neutralizing antibody titres. The presence of specific antibodies in rED3-based ELISA is therefore highly predictive for the presence of neutralizing antibodies, and this correlation can probably be used in the future to establish guidelines for recommendations of booster vaccinations. Additionally, it became apparent that the number of previous booster vaccinations correlated strongly with the frequency of circulating memory B cells. As expected, individuals who received a booster increased both the specific antibody titre and frequency of antigen specific memory B cells. This suggests that immunological long-term memory induced by booster immunizations is better reflected by the circulating memory B cells than the amount of the antibody titre. Thus, memory B cells seem to be a more reliable parameter for the assessment of long-term immunity. Taken together, a highly antigenic rED3 using the bacterial expression system was produced and it is a promising alternative to whole inactivated virus in ELISA. Notably, rED3 was a reliable antigen for detecting antigen-specific memory B cells in individuals who have been previously TBEV vaccinated. This study provides data on immunological memory for TBE vaccination and might be useful for reconsideration of recommendations for booster dose. In conclusion, boosters of vaccination should be recommended for all individuals who live and work or travel to areas of TBE endemicity. As consequently, vaccine-induced protection is enhanced by both strong humoral and cell-mediated immune responses. If pace of pathogenesis is rapidly growing, pre-existing virus-specific antibodies represent the first line of defence against infection before the memory response is fully activated and implemented. They clearly function best together to efficiently protect against disease

ESTIMATION OF WAVE CHARACTERISTICS IN EAST VIETNAM SEA USINGWAM MODEL

WAM (WaveModeling) is a third generation wave model developed by WAMDI Group which describes the evolution of a two-dimensional ocean wave spectrum under the effects of winds, currents, bottom and non-linear wave-wave interactions. The model runs for deep and shallow waters and includes depth and current refraction. This study used the WAM cycle 4.5 with model domain which is covered from 990E to 1210E and 00N to 250N with a resolution of ∆X = ∆Y = 0.250. Bathymetry of East Vietnam Sea (EVS) was taken from ‘ETOPO5’ data set of National Geophysical Data Center, Colorado, USA with resolution of 5’ (≈ 9 km). Wind velocities were obtained from 6 hourly NCEP/NCAR reanalysis data, USA with resolution of ∆X = ∆Y = 0.250. Study results show that during NE monsoon period, the main wave direction in EVS was NE and vice versa during SW monsoon period. Regions of greatest wave height were in the central and northern part of the EVS. Statistic of computed wave characteristics from 1987 to 2011 shows that wave regime in the offshore region of Nhatrang coast has two main wave directions that are NE with 40.82% of occurrence, SSW with 20.15% of occurrence. NE monsoon wave dominated from October to April of the next year, SW monsoon wave dominated from June to August. May and September are transitional periods. Assimilation of wind data with resolution of ∆X = ∆Y = 0.250 permits the model to be used to simulate the wave field during typhoon activity in EVS

PERFORMANCE OF H2O2 - AERATED BIOFILTER IN TREATMENT OF WASTEWATER CONTAINING HUMIC ACID

This work presents the results of adding H2O2 into a modified aerated biofilter (ABF) for treatment of refractory organic constituents in wastewater. The activated sludge, taken from wastewater treatment system of Hue Beer Company, was long-time cultured in laboratory with beef extract-peptone solution. The synthetic wastewater was prepared from solutions of glucose, ammonium acetate, sodium bicarbonate, potassium dihydrogen phosphate, sodium chloride, potassium chloride, calcium chloride and magnesium sulphate. As a refractory organic compound, humic acid (HA) was added into the wastewater; and parameters of chemical oxygen demand (COD) and color were measured to estimate the treatment performance. The experiments were conducted in continuous mode to observe the effects of H2O2 concentration (25–100 mg/L) and hydraulic retention time (HRT: 24–18 hours; according to organic loading rate, OLR: 0.51–0.67 kg-COD/m3/d) on the aerated biofilter system, under identical treatment conditions (COD: 505 ± 10 mg/L, HA concentration: 25 mg/L, pH: 7.0 ± 0.2, temperature: 25 ± 3.0 oC, and air flow rate: 1.0 ± 0.1 L/min). At the concentration of H2O2 50 mg/L and HRT of 24 hours, the ABF reactor yielded highyielded highyielded high yielded high yielded highyielded highyielded highyielded highyielded highest treatment est treatmentest treatmentest treatmentest treatmentest treatment est treatmentest treatmentest treatment efficienc efficiencefficiencefficiencefficiencefficienc efficiency (95(95 % COD and COD and COD and COD and COD and COD and COD and 74 % color colorcolorcolor). Consequently, H2O2 could be used to improve the effectiveness of activated sludge process in treatment of wastewater containing refractory organic compounds

Evaluation of Trans-femoral Prosthesis Function Using Finite Element Analysis

芝浦工業大学2017年

Organisational Baseline Study: Overview report for My Loi CSV, Vietnam (VN02)

This report covers the Organisational Baseline Study (OBS) for the CCAFS climate-smart village My Loi in central Viet Nam. During October and November 2014 interviews were conducted with ten organisations working or collaborating with farmers and/or the community in Ky Anh district in Ha Tinh province. The My Loi research site lies in the uplands of the north central coast. The region has four but increasingly variable seasons, increase in frequency and magnitude of storms and tropical low-pressure systems, increase in intensity of dry and hot westerly wind (Laos wind). The main farming systems comprise a blend of crop-livestock systems with the main crops being rainfed rice, cassava, peanut, and acacia. This OBS report supplements the qualitative village baseline studies at the same location. The objectives of the organisational baseline study are to: Provide indicators to monitor changes in behaviours and practices of locally relevant organisations that have climate change related activities in Ha Tinh over time Understand the provision of information/services at the local level that informs farmers’ decision making about their livelihood strategies in response to climate chang

Participatory identification of climate-smart agriculture priorities

With the concept climate-smart agriculture (CSA) being relatively new, there is a need to test and develop practical and systematic methodologies and approaches for documenting and evaluating CSA practices in the field. The implementation of CCAFS’ Climate-Smart Villages (CSV) involves identifying, assessing and selecting climate-smart farming practices. This report contains three sections: (i) a framework for identifying and assessing CSA in the field with a long list of CSA indicators in identifying and monitoring CSA interventions; (ii) cost-benefit analysis of some selected climate-smart farming systems; and (iii) the participatory process of prioritizing CSA options with the villagers. The work builds on our experiences from the My Loi CSV and its scaling domains in Ky Anh district, Ha Tinh province, in the north-central region of Viet Nam. English version: https://cgspace.cgiar.org/bitstream/handle/10568/75542/Participatory%20CSA_ICRAF_Final.pd