An analysis of the quasi-static expansion of a cylindrical or spherical cavity in an infinite dilatant elastic-plastic soil is presented. Closed form solutions for the stress and displacement fields in the soil during the expansion of the cavity are given. The soil is modelled as linear elastic-perfectly plastic, using a non-associated Mohr-Coulomb yield criterion. An explicit solution for the pressure-expansion relationship is obtained with no restriction on the magnitude of the deformation. It is found, in particular, that the radius of the cavity increases indefinitely as the cavity pressure approaches a finite limiting value. This limiting pressure can be determined analytically with the help of a single expansion of an infinite series. The novelty of the new solution lies in the introduction of dilation to the analysis of large strain expansion. Examples of the implications of the new analysis in geotechnical engineering are discussed. L'article présente une analyse de l'expansion quasistatique d'une cavité cylindrique ou sphérique dans un sol élastoplastiue de dilatance infinie. Des solutions de forme fermée sont présentées pour les champs de contrainte et de déplacement dans le sol au tours de l'expansion de la cavité. Le sol est modelisé comme élastique linéaire/parfaitement plastique, en employant un critére de rendement non-associé type Mohr-Coulomb. Une solution explicite pour la relation pression/expansion est ohtenue sans restriction sur la valeur de la déformation. On trouve plus particuliérement que le rayon de la cavité augmente de faqon indkfinie au fur et á mesure que la pression de cavité s'approche d'une valeur limite finie. Cette pression limite peut se déterminer par analyse á l'aide d'une seule expansion d'une série infinie. La nouveauté de la nouvelle solution réide dans l'inclusion de la dilatation dans l'analyse des expansions de déformation de valeur élevée. On examine des exemples des implications de la nouvelle analyse pour la construction géotechnique.

BackgroundBacillary dysentery caused by bacteria of the genus Shigella is a significant public health problem in developing countries such as China. The objective of this study was to analyze the epidemiological pattern of bacillary dysentery, the diversity of the causative agent, and the antimicrobial resistance patterns of Shigella spp. for the purpose of determining the most effective allocation of resources and prioritization of interventions.MethodsSurveillance data were acquired from the National Infectious Disease Information Reporting System (2004–2014) and from the sentinel hospital-based surveillance system (2005–2014). We analyzed the spatial and temporal distribution of bacillary dysentery, age and sex distribution, species diversity, and antimicrobial resistance patterns of Shigella spp.ResultsThe surveillance registry included over 3 million probable cases of bacillary dysentery during the period 2004–2014. The annual incidence rate of bacillary dysentery decreased from 38.03 cases per 100,000 person-years in 2004 to 11.24 cases per 100,000 person-years in 2014. The case-fatality rate decreased from 0.028% in 2004 to 0.003% in 2014. Children aged <1 year and 1–4 years were most affected, with higher incidence rates (228.59 cases per 100,000 person-years and 92.58 cases per 100,000 person-years respectively). The annual epidemic season occurred between June and September. A higher incidence rate of bacillary dysentery was found in the Northwest region, Beijing and Tianjin during the study period. Shigella flexneri was the most prevalent species that caused bacillary dysentery in China (63.86%), followed by Shigella sonnei (34.89%). Shigella isolates were highly resistant to nalidixic acid (89.13%), ampicillin (88.90%), tetracycline (88.43%), and sulfamethoxazole (82.92%). During the study period, isolates resistant to ciprofloxacin and cefotaxime increased from 8.53 and 7.87% in 2005 to 44.65 and 29.94% in 2014, respectively.ConclusionsThe incidence rate of bacillary dysentery has undergone an obvious decrease from 2004 to 2014. Priority interventions should be delivered to populations in northwest China and to individuals aged <5 years. Antimicrobial resistance of Shigella is a serious public health problem and it is important to consider the susceptibility profile of isolates before determining treatment.

To determine the seroprevalence and seroconversion of avian influenza virus (AIV) antibodies in poultry workers, we conducted a seroepidemiologic study in 7 areas of China during December 2014–April 2016. We used viral isolation and reverse transcription PCR to detect AIVs in specimens from live poultry markets. We analyzed 2,124 serum samples obtained from 1,407 poultry workers by using hemagglutination inhibition and microneutralization assays. We noted seroprevalence of AIV antibodies for subtypes H9N2, H7N9, H6N1, H5N1-SC29, H5N6, H5N1-SH199, and H6N6. In serum from participants with longitudinal samples, we noted seroconversion, with >4-fold rise in titers, for H9N2, H7N9, H6N1, H5N1-SC29, H6N6, H5N6, and H5N1-SH199 subtypes. We found no evidence of H10N8 subtype. The distribution of AIV antibodies provided evidence of asymptomatic infection. We found that AIV antibody prevalence in live poultry markets correlated with increased risk for H7N9 and H9N2 infection among poultry workers.

We used national sentinel surveillance data in China for 2005–2016 to examine the lineage-specific epidemiology of influenza B. Influenza B viruses circulated every year with relatively lower activity than influenza A. B/Yamagata was more frequently detected in adults than in children.

We compared the epidemiology of hepatitis A and hepatitis E cases in China from 1990–2014 to better inform policy and prevention efforts. The incidence of hepatitis A cases declined dramatically, while hepatitis E incidence increased. During 2004–2014, hepatitis E mortality rates surpassed those of hepatitis A.

We compared the epidemiology of hepatitis A and hepatitis E cases in China from 1990-2014 to better inform policy and prevention efforts. The incidence of hepatitis A cases declined dramatically, while hepatitis E incidence increased. During 2004During -2014, hepatitis E mortality rates surpassed those of hepatitis A.

Implementation of an effective regulatory system for testing donors would decrease the occurrence of donor-derived infectious diseases.

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