COEXISTENCE FOR MULTIPLE LARGEST REPRODUCTION RATIOS OF A MULTI-STRAIN SIS EPIDEMIC MODEL

In this paper, to complete the global dynamics of a multi-strains SIS epidemic model, we establish a precise result on coexistence for the cases of the partial and complete duplicated multiple largest reproduction ratios for this model.

Vaccine breakthrough and rebound infections modeling:Analysis for the United States and the ten U.S.HHS regions

A vaccine breakthrough infection and a rebound infection cases of COVID-19 are studied and analyzed for the ten U.S.Department of Health and Human Services(HHS)regions and the United States as a nation in this work.An innovative multi-strain susceptible-vacci-nated-exposed-asymptomatic-symptomatic-recovered(SVEAIR)epidemic model is devel-oped for this purpose for a population assumed to be susceptible to n-different variants of the disease,and those who are vaccinated and recovered from a specific strain k(kn)of the disease are immune to present strain and its predecessors j=1,2,…,k,but can still be infected by newer emerging strains j=k+1,k+2,…,n.The model is used to estimate epidemiological parameters,namely,the latent and infectious periods,the transmission rates,vaccination rates,recovery rates for each of the Delta B.1.617.2,Omicron B.1.1.529,and lineages BA.2,BA.2.12.1,BA.4,BA.5,BA.1.1,BA.4.6,and BA.5.2.6 for the United States and for each of the ten HHS regions.The transmission rate is estimated for both the asymptomatic and symptomatic cases.The effect of vaccines on each strain is analyzed.Condition that guarantees existence of an endemic with certain number of strains is derived and used to describe the endemic state of the population.

Overview of key operation factors and strategies for improving fermentative volatile fatty acid production and product regulation from sewage sludge

In recent years,volatile fatty acid(VFA)production through anaerobic fermentation of sewage sludge,instead of methane production,has been regarded as a high-value and promising roadmap for sludge stabilization and resource recovery.This review first presents the effects of some essential factors that influence VFA production and composition.In the second part,we present an extensive analysis of conventional pretreatment and co-fermentation strategies ultimately addressed to improving VFA production and composition.Also,the effectiveness of these approaches is summarized in terms of sludge degradation,hydrolysis rate,and VFA production and composition.According to published studies,it is concluded that some pretreatments such as alkaline and thermal pretreatment are the most effective ways to enhance VFA production from sewage sludge.The possible reasons for the improvement of VFA production by different methods are also discussed.Finally,this review also highlights several current technical challenges and opportunities in VFA production with spectrum control,and further related research is proposed.

Lyapunov function and global st ability for a two-strain SEIR model with bilinear and non-monotone incidence

In this paper,we study a multi-strain SEIR epidemic model with both bilinear and nonmonotone incidence functions.Under biologically motivated assumptions,we show that the model has two basic reproduction numbers that we noted R0,1 and R0,2;and four equilibrium points.Using the Lyapunov method,we prove that if R0,1 and R0,2 are less than one then the disease-free equilibrium is Globally Asymptotically Stable,thus the disease will be eradicated.However,if one of the two basic reproduction numbers is greater than one,then the strain that persists is that with the larger basic reproduction number.And finally if both of the two basic reproduction numbers are equal or greater than one then the total endemic equilibrium is globally asymptotically stable.A numerical simulation is also presented to illustrate the influence of the psychological effect,of people to infection,on the spread of the disease in the population.This simulation can be used to determine the status of different diseases in a region using the corresponding data and infectious disease parameters.

Evaluation of kefir as a potential probiotic on growth performance,serum biochemistry and immune responses in broiler chicks

This experiment was conducted to evaluate the effect of milk or molasses kefir as a probiotic on growth performance, carcass traits, serum biochemistry and humoral immune responses in broiler chickens. A total of 192 one-d-old as hatched broiler chicks(Ross 308) were randomly allotted to 4 treatments, each with 4 replicate pens of 12 chicks. The following treatments were applied: 1) a basal diet(C) and normal drinking water, 2) 2% milk kefir in drinking water, 3) 2% molasses kefir in drinking water, and 4) the diet C supplemented with commercial probiotic. At d 42, eight birds per treatment were killed for determination of carcass traits. Broilers at 28 days of age were bled for measuring antibody titers against Newcastle disease virus(NDV) and avian influenza virus(AIV), at 30 days of age for antibody titers against sheep red blood cell(SRBC), and at 42 days of age for biochemical analysis. Supplementing 2%milk kefir increased body weight of broilers at 28 and 42 days of age(P < 0.05). Supplementing 2%molasses kefir improved feed conversation ratio(FCR) of broilers during growth period(P < 0.05), but FCR of broilers in other periods was not affected. Daily feed intake, internal organ weights, and carcass traits were not influenced by the treatments except for small intestine and ceca length. Small intestinal length significantly decreased in broilers supplemented with milk and molasses kefir(P < 0.05). Molasses kefir supplementation significantly(P < 0.05) increased antibody titer against SRBC at 31 days of age but other immune related parameters were not statistically different among treatments. Biochemical parameters including serum protein, albumin, and triglyceride concentrations were not statistically(P> 0.05) influenced. Broilers supplemented with molasses kefir, had a significantly lower concentration of serum total cholesterol, low density lipoprotein cholesterol and elevated high density lipoprotein cholesterol at 42 days of age(P < 0.05). In conclusion, the results indicated that inclusion of 2% milk kefir in drinking water would improve growth performance of broiler chickens.