Replacement Phenomena Research Articles

Does Inequality Have Momentum? The Implications of Convex Inequality Regimes for Mortality Dynamics

AbstractFor decades, educational inequalities in mortality have widened and mortality among the least educated has stalled, even as overall mortality has improved, and an increasing proportion of young people have completed secondary and tertiary education. While researchers recognize that these trends are in part related to changing selection into education groups, there has been no unifying framework for understanding why the trends may be related. This article provides a unifying framework by introducing a concept called the “convex inequality regime,” a diminishing returns relationship between relative education and mortality. In populations where convex inequality regimes prevail, even without any changes in the institutions governing inequality or any changes in overall mortality conditions, education transitions result in an increase in mortality for the less educated and an increase in mortality inequality between education groups. The model also shows that lifespan variation increases for lower education groups because convex inequality regimes tend to increase relative mortality more rapidly at younger ages during an education transition. Even after an education transition is complete, inequality between education groups will continue to increase for decades due to the momentum of inequality, a cohort replacement phenomenon where younger more unequal cohorts replace older more equal cohorts.

Experimental investigation on forced imbibition characteristics of shale oil reservoir based on nuclear magnetic resonance method

After large-scale fracturing of shale reservoirs, the fracturing fluid will imbibe in the reservoir. In order to clarify the characteristics of imbibition and the distribution characteristics of crude oil in the stage of forced imbibition, this paper selects the core of some blocks in Qinghai and Gulong areas to carry out the shale forced imbibition experiment. Nuclear magnetic resonance technology is used to monitor the variation of crude oil. And the influence of core permeability and contact angle on forced imbibition is further analyzed. The results of the study show that the shale has a strong imbibition effect on the fracturing fluid. The content of oil phase in the core decreases, and the phenomenon of oil-water replacement occurs. Priority porosity for fracking fluids exists in the process of imbibition, where fracturing fluid preferentially enter smaller pores and can cause a short-term increase in the oil phase content in larger pores. With the continuous process of imbibition, the rate of imbibition oil gradually slowed down, and the fracturing fluid gradually permeates evenly into the rock sample. Both permeability and wettability affect the imbibition capacity of fracturing fluid in the forced imbibition stage.

Analysis of the Change of Accounting Firms by Listed Companies- -Take New Asia Manufacturing Process (Zhejiang) Co., Ltd. as an Example

In the current market economic environment, the phenomenon of frequent replacement of accounting firms in China has attracted wide attention inside and outside the industry. On the one hand, this trend reflects the change of market competition and corporate business needs. On the other hand, it may also affect investors 'decisions and the public's trust in listed companies. Therefore, it is obviously necessary to study the motivation behind the replacement of accounting firms in listed companies. This paper aims to explore the motivation of Chinese listed companies to change accounting firms and their potential influence. Firstly, through large-scale data collection and analysis, this paper described the basic status of changing accounting firms by listed companies in China in recent years.Then, we discussed the various possible reasons for listed companies to replace their accounting firms. After in-depth research and analysis, we find that although the replacement of accounting firms can enhance the credibility of the financial reports. Therefore, this paper put forward a series of regulatory countermeasures. The main significance of this study lies in the in-depth discussion of the phenomenon of listed companies changing accounting firms, which provides more detailed market data and rich empirical analysis framework for future research.

Graphite, Sheelite and Cassiterite Mineralized Skarns of Frag Al Ma, Sidi Bou Othmane District, Jebilet, Morocco

Sidi Bou Othmane region in the Central Jebilet is formed by a Devonian schistose series. The polyphase Hercynian deformation in this area is characterised by penetrative, subvertical, synmetamorphic schistosity (S1), accompanied by folding. Syntectonic granitic intrusions, hidden in the Sidi Bou Othmane region, is marked by a contact of metamorphism, which responsible for the replacement phenomena observed essentially in the limestones of the region which are transformed into graphitic Sn-W exoskarns. Syn-tectonic, skarnification is polyphase : (i) prograde stage (T= 500- 750°C) : with graphite, garnets, idocrase, pyroxene, wollastonite, quartz, scheelite and molybdenite, crossed by a network of successive veins (garnet, idocrase, wollastonite, quartz and calcite; (ii) retrograde stage (T= 400-500°C): with garnet, idocrase, pyroxene wollastonite, quartz, calcite, epidote scheelite and cassiterite; (iii) hydrothermal alteration stage (T ≤400°C) : with sericite and clay accompanied by abundant scheelite and cassiterite, favoured by the high oxidation rate. Therefore, they would have formed in a reduced environment, in relation to large batholiths or stocks of quartz diorites and/or granites in syn, late- to post-orogenic to anorogenic contexts, in the absence of any cogenetic volcanism. The economic mineralisation of graphite was formed mainly during prograde stage, under reducing conditions. It was formed by devolatilization of a bituminous origin linked to the reef limestones and organic matter, trapped in the shales according to the following reaction:

Comparative genomic analysis of two ST320 Streptococcus pneumoniae isolates, representing serotypes 19A and 19F

BackgroundStreptococcus pneumoniae (pneumococcus) represents an important human pathogen, responsible for respiratory and invasive infections in the community. The efficacy of polysaccharide conjugate vaccines formulated against pneumococci is reduced by the phenomenon of serotype replacement in population of this pathogen. The aim of the current study was to obtain and compare complete genomic sequences of two pneumococcal isolates, both belonging to ST320 but differing by the serotype.ResultsHere, we report genomic sequences of two isolates of important human pathogen, S. pneumoniae. Genomic sequencing resulted in complete sequences of chromosomes of both isolates, 2,069,241 bp and 2,103,144 bp in size, and confirmed the presence of cps loci specific for serotypes 19A and 19F. The comparative analysis of these genomes revealed several instances of recombination, which involved not only S. pneumoniae but also presumably other streptococci as donors.ConclusionsWe report the complete genomic sequences of two S. pneumoniae isolates of ST320 and serotypes 19A and 19F. The detailed comparative analysis of these genomes revealed the history of several recombination events, clustered in the region including the cps locus.

Temporal and spatial variation of petroleum hydrocarbons and microbial communities during static release of oil pollution sediments

The migration and transformation of the petroleum hydrocarbons from sediments into water columns is an important basis for assessing the impact on marine environment. In this paper, a static release experiment of crude oils from the Bohai Sea was carried out to evaluate the temporal and spatial variation of petroleum hydrocarbons and microbial communities. The results showed C1 phenanthrene (C1-P) can be used as an evaluation index of different crude oils during static release of oil pollution sediments and their trends of the static release were similar. The crude oil with higher C1-P content released C1-P into the water body significantly higher. After 72 hours, the C1-P release degree of crude oil with a smaller viscosity was more obvious. In the crude oil with the smallest viscosity and the higher viscosity, the bacterial phyla abundance increase was greater. And more importantly, the top 10 abundance of the microbial communities in the water columns and sediments appeared partial (3 species) replacement phenomenon. The research results can deep understanding the migration and transformation of the petroleum hydrocarbons from oil pollution sediments and understanding of the interaction between extreme weather events and human activities by incorporating an eco-evolutionary perspective.

The phonemic replacement in the authentic ten recitations

Phonemic replacement is a common linguistic phenomenon in Arabic language, it means the substitution of one letter or sound instead of another with keeping the rest sounds ,this practice exists in Arabic language since the revelation of the Glorious Quran, The Almighty Allah eased the recitation of His book for Arab Muslims or non-Arabs by practicing a phenomenon like this. All the Ten reliable Quranic recitations included the phenomenon of phonemic replacement in different places for simplification and easiness. Also, it is in all dialects of Arab tribes which is attributed to the closeness of articulation

Investigating Semantic Change of Arabic Loanwords in Turkish

This study aims at tracking the various semantic changes of Arabic loanwords in Turkish (ALTs). The loanword data of the study were collected from a number of dictionaries including Sapan’s (2005) dictionary and Webster's Turkish-English Thesaurus Dictionary. Six types of semantic change are found at work in ALTs, the most frequent of which is radical semantic shift which represents more than 64% of the total loanword data followed by the processes of narrowing (20%) and widening (8%). The other three types have marginal roles to play in the semantic change process. Radical shifts involve some interesting cases which are peculiar to Turkish and are pertaining to the phenomenon of semantic replacement. The linguistic and extralinguistic factors like lexical need, the diachronic factor, the speaker’s miscomprehension and ignorance upon loanword incorporation are among the factors that lead to and affect the direction of semantic change of ALTs.

Analysis of pneumococcal serotypes distribution to determine a model composition for a Russian pneumococcal conjugate vaccine

Diseases caused by Streptococcus pneumoniae, as well as antibiotic resistance of its serotypes, are the leading cause of death amongst children worldwide. To prevent pneumococcal infection, the population is immunised with conjugate vaccines containing different amounts of polysaccharides of certain serotypes. Development of a full-cycle Russian vaccine is vital because the active pharmaceutical ingredients for the vaccines registered in the Russian Federation are produced abroad, and only the final stages of production of vaccines of this group are performed in the territory of the Russian Federation. Considering the phenomenon of serotype replacement associated with the long-term widespread use of pneumococcal conjugate vaccines, it is necessary to carefully select the serotype composition for the new vaccine. The aim of this work was to analyse the serotype distribution of pneumococci in the Russian Federation and other countries in order to select optimal serotypes for the Russian vaccine for human use, taking into account vaccination schedules for each age group. This review presents an analysis of the pneumococcal serotype distribution in the Russian Federation in the pre-vaccination era, as well as after the introduction of routine vaccination. In addition, the review includes data on the serotype distribution in the Eurasian Economic Union countries. The authors described a model composition containing at least sixteen serotypes. It will increase effectiveness of immune protection of the population, providing a more complete coverage of serotypes, considering their prevalence in the Russian Federation. Based on the analysis, the serotype composition for the sixteen-valent pneumococcal conjugate vaccine is proposed for further production and preclinical and clinical trials. A new Russian pneumococcal conjugate vaccine will ensure vaccination of all population groups within the National Immunisation Schedule of the Russian Federation.

Partitioning of beta-diversity reveals distinct assembly mechanisms of plant and soil microbial communities in response to nitrogen enrichment.

Nitrogen (N) deposition poses a serious threat to terrestrial biodiversity and alters plant and soil microbial community composition. Species turnover and nestedness reflect the underlying mechanisms of variations in community composition. However, it remains unclear how species turnover and nestedness contribute to different responses of taxonomic groups (plants and soil microbes) to N enrichment. Here, based on a 13‐year consecutive multi‐level N addition experiment in a semiarid steppe, we partitioned community β‐diversity into species turnover and nestedness components and explored how and why plant and microbial communities reorganize via these two processes following N enrichment. We found that plant, soil bacterial, and fungal β‐diversity increased, but their two components showed different patterns with increasing N input. Plant β‐diversity was mainly driven by species turnover under lower N input but by nestedness under higher N input, which may be due to a reduction in forb species, with low tolerance to soil Mn2+, with increasing N input. However, turnover was the main contributor to differences in soil bacterial and fungal communities with increasing N input, indicating the phenomenon of microbial taxa replacement. The turnover of bacteria increased greatly whereas that of fungi remained within a narrow range with increasing N input. We further found that the increased soil Mn2+ concentration was the best predictor for increasing nestedness of plant communities under higher N input, whereas increasing N availability and acidification together contributed to the turnover of bacterial communities. However, environmental factors could explain neither fungal turnover nor nestedness. Our findings reflect two different pathways of community changes in plants, soil bacteria, and fungi, as well as their distinct community assembly in response to N enrichment. Disentangling the turnover and nestedness of plant and microbial β‐diversity would have important implications for understanding plant–soil microbe interactions and seeking conservation strategies for maintaining regional diversity.

Sedimentology, Metallographic Characteristics and Geodynamic Evolution of the Merija Copper Deposit (Marginal Folds Basin, Eastern High Atlas, Morocco)

The Merija copper deposit is located in the Marginal Folds of the Moroccan Eastern High Atlas. It is a stratiform deposit hosted in sandstone-conglomerate formations of the Infra-Cenomanian, consisting of copper carbonate and sulphide mineralization (malachite, azurite, traces of chalcopyrite, chalcocite, and covellite). This mineralization exhibits different forms: dissemination in the sandstone-conglomerate host rocks and fillings of centimetric veins, sometimes with calcite. Moreover, microscopic examination shows that the mineralization is disseminated in the carbonate matrix, filling of the inter-granular spaces of the sandstone-conglomeratic material. The mineralogical association is composed of: a primary paragenesis with chalcopyrite ، a secondary cementation paragenesis with chalcocite and covellite and a secondary oxidation paragenesis with malachite. This latter is the most dominant mineral presenting a micro-fibrous texture surrounding the sulphides of the primary and secondary paragenesis, composed of chalcopyrite, chalcocite and covelite. It is associated with a quartz-calcite gangue. The copper mineralization at Merija is heterogeneously distributed within the surrounding sandstone-conglomerate formation due to the diversity of paleocurrents carrying the leached copper. The rich paleocurrents trends S, SW, and SE, whereas the poor ones present an N and NW directions. These paleocurrents are derived from a fluvio-deltaic channel system that controlled sedimentary deposition in the area during the Infra-Cenomanian. This sedimentary type mineralization is probably related to a process of alteration and deposition of detrital materials loaded with copper minerals and derived from a protore copper-bearing. This alteration process gave rise to the malachite and azurite mineralization resulting from the replacement phenomenon of chalcopyrite, chalcocite and covellite.

P320 LEFT DOMINANT ARRHYTHMOGENIC CARDIOMYOPATHY: HOW TO STRATIFY THE ARRHYTHMIC RISK? EARLY ONSET CLINICAL CASE

Abstract Introduction Arrhythmogenic cardiomyopathy (ACM) is a genetic disease characterized by the progressive replacement of myocardiocytes by fibroadipose tissue that becomes a susbstrate for ventricular arrhythmias with risk of sudden cardiac death. Arrhythmogenic cardiomyopathy can manifest itself through three different phenotypes: the classic phenotype, the most frequent, involving only the right ventricle, the biventricular variant with possible right or left dominance and the rare variant involving only the left ventricle. We present a case of left ventricular arrhythmogenic cardiomyopathy. Case Report 16–year–old male patient in complete physical well–being, with no significant medical history and a negative family history of heart disease and/or sudden cardiac death (Fig. 1). He practiced competitive sports for years with periodic medical–sports visits. In 2017, ventricular extrasystole was detected on the electrocardiogram, for which he performed cardiological investigations. On electrocardiogram: sinus rhythm with QRS fragmented into DIII and aVL and negative T waves from V4 to V6 (Fig. 2). On transthoracic echocardiography, evidence of normal cavity dimensions, ejection fraction at lower normal limits (42%) and left ventricular trabeculation, in the absence of significant valvulopathy. He then performed a cardiac MRI that showed: left ventricle moderately dilated and hypokinetic with widespread alterations of myocardial signal secondary to fibroadipose replacement phenomena, configuring a picture of left ventricular dilation and dysfunction referable to arrhythmogenic left ventricular cardiomyopathy (Fig. 3). The patient was also subjected to genetic analysis aimed at searching for mutations of genes involved in arrhythmic heart disease, which was negative. In light of the absence of conclusive scientific evidence on the implantation of a defribrillator in primary prevention in clinical–instrumental cases such as the present, the risk of infection and the risk of inappropriate discharges, it was proposed the implantation of a loop–recorder in order to monitor and record any arrhythmic events, starting beta–blocker therapy. The possibility of continuing competitive physical activity was therefore denied. Conclusions Currently, guidelines on ACM and diagnostic criteria focus mainly on the right variant, so there are no clear indications to stratify arrhythmic risk in left ventricular ACM.

Quantification of CO2 Replacement in Methane Gas Hydrates: A Molecular Dynamics Perspective

Extraction of methane from natural gas hydrates whilst storing CO2 via gas replacement is a promising approach for reducing anthropogenic CO2 emissions during energy generation. In this study, molecular dynamic simulations were performed to identify the influence of temperature, pressure, and the initial CO2 concentration of sweep gas on the gas replacement characteristics. Simulations were performed under selected pressure and temperature conditions using five different initial CO2 concentrations. The simulation results clearly portray the replacement phenomena where methane molecules are released into the free gas layer while CO2 get enclathrated in hydrate structure. During gas replacement, minor structural changes in hydrate structure can also be observed, but they are quite insignificant as demonstrated through the alterations in Tetrahedrality order parameter. The variations of the number densities of gas and water molecules during gas replacement were used to quantify the methane recovery and CO2 storage. Based on the numerical comparisons, the replacement process is found to be strongly dependant on the temperature, yielding a higher methane recovery at higher temperatures; however, the CO2 storage capacity is found to be diminishing with increasing temperature. Having a higher initial CO2 concentration in the sweep gas may facilitate greater penetration of CO2 into the hydrate structure, eventually resulting in a higher methane recovery and improved CO2 storage.

1047. Development of a Next Generation 30+ Valent Pneumococcal Conjugate Vaccine (VAX-XP) Using Site-Specific Carrier Protein Conjugation

BackgroundDue to the diversity of serotypes, exacerbated by the phenomenon of serotype replacement, there remains an unmet medical need for a pneumococcal conjugate vaccine (PCV) containing additional serotypes. Using a cell-free protein synthesis (CFPS) platform to produce an enhanced carrier protein (eCRM®) based on the CRM197 sequence, Vaxcyte is developing a PCV encompassing over 30 serotypes. The eCRM carrier protein contains multiple insertions of the non-native amino acid para-azidomethyl-L-phenylalanine (pAMF) that facilitates site-specific conjugation of the pneumococcal polysaccharides (PS) to eCRM. Unlike conventional methodologies, site-selective conjugation enhances process consistency and increases capacity for inclusion of additional serotypes in a PCV without promoting carrier suppression. Using this platform, the aim of the current study was to employ CFPS technology to construct a 31-valent PCV and evaluate its immunogenicity in New Zealand White (NZW) rabbits. MethodsThe eCRM carrier protein was individually conjugated to each of 31 selected pneumococcal PSs using copper-free click chemistry to produce 31 Conjugate Drug Substances (DS), which were then mixed with aluminum phosphate to produce the VAX-XP Drug Product. 24 of the DS conjugates in VAX-XP were generated at manufacturing scale. Two doses of VAX-XP were administered to NZW rabbits at 0 and 21 days to assess its ability to elicit anti-capsular IgG antibodies. Additionally, rabbits were also administered either Prevnar13 or a mixture of Pneumovax 23 and 8 incremental PS in isotonic saline, as comparators.ResultsVAX-XP showed conjugate-like immune responses for all 31 serotypes, as demonstrated by superior responses to PS-based vaccines and comparable responses to Prevnar13. IgG responses for VAX-XP compared with Prevnar13 and Pneumovax 23 at 14 days post dose 2 ConclusionThese results demonstrate that increasing the number of pneumococcal serotypes does not result in immunological attenuation in any of the serotypes contained in VAX-XP relative to the current standard of care. Furthermore, the data confirm the scalability and reproducibility of the CFPS platform in the production of VAX-XP conjugates, creating the foundation for a next generation broad-valency PCV.Disclosures Chris Behrens, PhD, Vaxcyte, Inc. (Employee) Jeff Fairman, PhD, Vaxcyte, Inc. (Employee) Paresh Agarwal, PhD, Vaxcyte, Inc. (Employee) Shylaja Arulkumar, MS, Vaxcyte, Inc. (Employee) Sandrine Barbanel, MS, Vaxcyte, Inc. (Employee) Leslie Bautista, n/a, Vaxcyte, Inc. (Employee) Aym Berges, PhD, Vaxcyte, Inc. (Employee) John Burky, BS, Vaxcyte, Inc. (Employee) Peter Davey, MS, Vaxcyte, Inc. (Employee) Chris Grainger, PhD, Vaxcyte, Inc. (Employee) Sherry Guo, PhD, Vaxcyte, Inc. (Employee) Sam Iki, MS, Vaxcyte, Inc. (Employee) Mark Iverson, BS, Vaxcyte, Inc. (Employee) Neeraj Kapoor, PhD, Vaxcyte, Inc. (Employee) Olivier Marcq, PhD, Vaxcyte, Inc. (Employee) Thi-Sau Migone, PhD, Vaxcyte, Inc. (Employee) Lucy Pill, MS, Vaxcyte, Inc. (Employee) Mohammed Sardar, n/a, Vaxcyte, Inc. (Employee) Paul Sauer, MBA, Vaxcyte, Inc. (Employee) James Wassil, MS MBA, Vaxcyte, Inc. (Employee)

Epidemiological Investigation of Salmonella enterica Isolates in Children with Diarrhea in Chengdu, China

Background: Children with the immature intestinal immune system are prone to Salmonella infection through the fecal-oral route causing diarrhea. Non-typhoid Salmonella (NTS) is difficult to treat and eliminate due to its zoonosis. Salmonella typhi, including typhoid and paratyphoid A, B, and C, only infect humans and cause invasive infectious diseases. Salmonella typhi infection is serious and requires antibiotic treatment. The bacterial resistance caused by conventional antibacterial drugs brings great difficulties to treatment. Objectives: This study aimed to investigate the epidemiology of S. enterica in children with diarrhea in Chengdu, China. Methods: Fresh stool specimens or rectal swabs from 6656 children aged 1 day to 13 years with diarrhea were collected, cultured, identified, and tested for antimicrobial susceptibility. Analytical Profile index 20E was used for biochemical identification, and the Kirby-Bauer method was used for the bacterial sensitivity test. The whole process was conducted in accordance with the fourth edition of the National Clinical Examination procedures, and the drug sensitivity test was conducted in accordance with the Clinical and Laboratory Standards Institute 2020 guidelines. Results: A total of 649 Salmonella strains were isolated from 6656 children with suspected Salmonella infection, among which the isolation rates of NTS and S. typhi were 8.92% and 0.83%, respectively. The infection rate of S. typhimurium was the highest every year (74.88%). Salmonella infections are on the rise, especially typhimurium, Dublin, Typhi, and London. Paratyphi is unstable, presenting a phenomenon of transition and replacement (the male to female ratio:1.12:1). The infection rate was the lowest within 1 day and 6 months (P < 0.05). Salmonella mainly infected children under 3 years of age, and the positive rate was reported as 88.29%. Within June-September, the infection rate of Salmonella was the highest, with a positive rate of 72.73%. The isolated 649 Salmonella strains had good susceptibility to cefotaxime and ciprofloxacin (87.67% and 79.20%, respectively), almost no susceptibility to ampicillin, and a drug resistance rate of 92.91%. Conclusions: The typhoid and paratyphoid vaccines should be considered together, and vaccines should focus on children under 3 years of age. Antibiotics should be rationally selected according to the drug sensitivity test and disease condition.

Genotype Distribution Change After Human Papillomavirus Vaccination in Two Autonomous Communities in Spain.

ContextIt has been more than 10 years since the human papillomavirus (HPV) vaccination program was initiated in most advanced countries. Thus, it seems necessary to change the uterine cervical cancer screening strategy. Molecular-based tests are considered essential in this scenario.ObjectiveWe aimed to review the distribution of the HPV genotypes after the introduction of the vaccination program with Cervarix® and Gardasil 4® in two autonomous communities in Spain, looking for possible changes in distribution and the occurrence of a herd effect.DesignA cross-sectional study was performed in 45,362 samples that were processed in the Cantabria and Aragon communities during the period from 2002 to 2016. We compared the genotype distribution before and after the vaccination program was initiated.ResultsGenotypes HPV6 and HPV11 have decreased significantly after the introduction of the vaccine. HPV16 has had a decrease, but not a significant one in the statistical analysis. However, HPV31, HPV52, and HPV45 have increased in percentage. A replacement phenomenon with other genotypes not included in the vaccine has been observed in our population.ConclusionsContinued surveillance is needed to provide further indication of any changes over time in the genotypes in circulation. This will be facilitated by monitoring the genotyping results from the new model of cervical screening using primary HPV DNA testing.

Pneumonia and Invasive Pneumococcal Diseases: The Role of Pneumococcal Conjugate Vaccine in the Era of Multi-Drug Resistance.

Streptococcus pneumoniae related diseases are a leading cause of morbidity and mortality, especially in children and in the elderly population. It is transmitted to other individuals through droplets and it can spread to other parts of the human host, causing a wide spectrum of clinical syndromes, affecting between 10 and 100 cases per 100,000 people in Europe and the USA. In order to reduce morbidity and mortality caused by this agent, pneumococcal vaccines have been developed over the years and have shown incredible effectiveness in reducing the spread of this bacterium and the development of related diseases, obtaining a significant reduction in mortality, especially in developing countries. However, considerable problems are emerging mainly due to the replacement phenomenon, multi-drug resistance, and the high production costs of conjugated vaccines. There is still a debate about the indications given by various countries to different age groups; this is one of the reasons for the diffusion of different serotypes. To cope with these problems, significant efforts have been made in the research field to further improve vaccination serotypes coverage. On the other hand, an equally important commitment by health care systems to all age group populations is needed to improve vaccination coverage.

Mathematical assessment of the impact of cohort vaccination on pneumococcal carriage and serotype replacement

ABSTRACT Although pneumococcal vaccines are quite effective in reducing disease burden, factors such as imperfect vaccine efficacy and serotype replacement present an important challenge against realizing direct and herd protection benefits of the vaccines. In this study, a novel mathematical model is designed and used to describe the dynamics of two Streptococcus pneumoniae (SP) serotypes, in response to the introduction of a cohort vaccination program which targets one of the two serotypes. The model is fitted to a pediatric SP carriage prevalence data from Atlanta, GA. The model, which is rigorously analysed to investigate the existence and asymptotic stability properties of the associated equilibria (in addition to exploring conditions for competitive exclusion), is simulated to assess the impact of vaccination under different levels of serotype-specific competition and illustrate the phenomenon of serotype replacement. The calibrated model is used to forecast the carriage prevalence in the pediatric cohort over 30 years.

Un empiema pleurico, una occasione per fare il punto sulla vaccinazione antipneumococcica

The article describes the case of a 4-year-old girl present-ing with fever and dyspnea. Blood tests showed neutrophilic leukocytosis and a significant increase in inflammation markers. The antibiotic therapy (macrolide and amoxicillin) did not produce any clinical improvement. A chest X-ray and CT showed a pleural empyema associated to trilobar right pneumonia. An evacuative videothoracoscopy was then performed. Clinical evolution was positive with full remission. The real-time polymerase chain reaction enabled to isolate genetic sequences of Streptococcus pneumoniae type 3, one of the serotypes involved in the invasive pneumococcal disease and contained in the pneumococcal 13-valent conjugate vaccine (PCV13). The patient had completed a full PCV13 vaccination before two years of age. Despite antibiotic treatment and the spread of vaccinations, pleural empyema is still a frequent complication of pneumonia to date. Several studies suggest a poor effective-ness of the pneumococcal vaccine against the serotype 3. Moreover, the implementation of PCV13 may have influenced the distribution of serotypes of S. pneumoniae not included in this vaccine and the phenomenon of serotype replacement. Nonetheless, the phenomenon of serotype replacement does not seem to be exclusively due to the effect of vaccination programmes.

Commitment and Replacement of Existing SaaS-Delivered Applications: A Mixed-Methods Investigation

As the highest level of cloud computing delivery model, Software-as-a-Service (SaaS) has gained considerable popularity in the industry as a new way of deploying IT solutions, due to its low cost and high elasticity. However, the new business model associated with SaaS highlights the importance for SaaS vendors to understand how to retain customers in a hyper-competitive market. In particular, increasing customer retention and preventing customers from replacing the adopted SaaS applications has become a crucial task for all SaaS vendors. In this study, using a mixed-methods approach, and drawing on the cognitive–affective–conative– action (CACA) framework, we investigate the IS replacement phenomenon in the context of SaaS-delivered applications. Our qualitative study allows us to develop an IS-centric view of customer commitment by differentiating between organizations’ commitment to the SaaS application and to the cloud computing technology in general, while the subsequent quantitative study validates the difference between the two types of commitment and helps understand how they together influence organizations’ intentions to replace a SaaS application. Our results generate important theoretical implications for research on IS replacement and clarifies the concept of customer commitment. We also offer practical guidelines to SaaS vendors on how to retain customers so as to survive/thrive in this competitive market.