This paper empirically investigates how review moderation transparency affects the volume, length, and negativity of reviews. A change to the Yelp platform in 2010, introducing review moderation and ...displaying filtered reviews, created a natural experiment. We used a panel dataset of online reviews from the same set of restaurants on both the Yelp and TripAdvisor platforms in a difference-in-differences (DID) model to test how review moderation transparency affected our outcome variables. We found that increasing review moderation transparency negatively affects review volume but positively affects review negativity. The results also indicate that providing review moderation transparency reduces review length, especially for reviews with positive sentiment. Our findings suggest that providing review moderation transparency induces users to invest less effort in review contributions, especially when they are submitting positive reviews. We discuss the theoretical and practical implications of these results as they relate to the design and use of online review platforms.
It has been argued that the theory borrowing practices in IS research have become workmanlike—appropriate and effective, but lacking innovation. This concern is particularly salient at a time when ...digital phenomena are profoundly transforming society. Therefore, it is legitimate to ask: Are our theory borrowing practices hampering our ability to grapple with revolutionary developments in IS, and if so, what can be done? Through an investigation of the field’s borrowing of transaction cost economics theory, we find extant IS research largely (1) borrows for theory testing within the IS context, (2) develops models that uninspiringly reflect the borrowed theory, and (3) treats the IS as an exogenous actor. In this article, we propose an alternative approach to theory borrowing, inspired by conceptual blending theory. Our approach focuses on the structural nature of IS phenomena and borrowed theories. Such a structure-based approach can reveal correspondence between IS phenomena and unexpected reference theories while also highlighting discrepancies that serve as an opportunity for novel integrations of an information system into the reference theory. We contend that this approach can infuse flexibility into our theory borrowing practices in ways that will increase our capacity for developing innovative explanations of emerging phenomena.
A(H1N1)pdm09 influenza A viruses predominated in the 2013-2014 USA influenza season, and although most of these viruses remain sensitive to Food and Drug Administration-approved neuraminidase (NA) ...inhibitors, alternative therapies are needed. Here we show that monoclonal antibody CD6, selected for binding to the NA of the prototypic A(H1N1)pdm09 virus, A/California/07/2009, protects mice against lethal virus challenge. The crystal structure of NA in complex with CD6 Fab reveals a unique epitope, where the heavy-chain complementarity determining regions (HCDRs) 1 and 2 bind one NA monomer, the light-chain CDR2 binds the neighbouring monomer, whereas HCDR3 interacts with both monomers. This 30-amino-acid epitope spans the lateral face of an NA dimer and is conserved among circulating A(H1N1)pdm09 viruses. These results suggest that the large, lateral CD6 epitope may be an effective target of antibodies selected for development as therapeutic agents against circulating H1N1 influenza viruses.
Apical membrane antigen-1 (AMA1) is a micronemal protein of apicomplexan parasites that appears to be essential during the invasion of host cells. In this study, a full-length cDNA of AMA1 was ...identified from Eimeria tenella (Et) using expressed sequence tag and the rapid amplification of cDNA ends technique. EtAMA1 had an open reading frame of 1608 bp encoding a protein of 535 amino acids. Quantitative real-time PCR analysis revealed that EtAMA1 was expressed at higher levels in sporozoites than in the other developmental stages (unsporulated oocysts, sporulated oocysts and second-generation merozoites). The ectodomain sequence was expressed as recombinant EtAMA1 (rEtAMA1) and rabbit polyclonal antibodies raised against the rEtAMA1 recognized a 58-kDa native parasite protein by Western Blotting and had a potent inhibitory effect on parasite invasion, decreasing it by approximately 70%. Immunofluorescence analysis and immunohistochemistry analysis showed EtAMA1 might play an important role in sporozoite invasion and development.
The dead space fraction (VD/VT) has proven to be a powerful predictor of higher mortality in acute respiratory distress syndrome (ARDS). However, its measurement relies on expired carbon dioxide, ...limiting its widespread application in clinical practice. Several estimates employing routine variables have been found to be reliable substitutes for direct measurement of VD/VT. In this study, we evaluated the prognostic value of these dead space estimates obtained in the first 7 days following the initiation of ventilation.
This retrospective observational study was conducted using data from the Chinese database in intensive care (CDIC). Eligible participants were adult ARDS patients receiving invasive mechanical ventilation while in the intensive care unit between 1st January 2014 and 31st March 2021. We collected data during the first 7 days of ventilation to calculate various dead space estimates, including ventilatory ratio (VR), corrected minute ventilation (V˙Ecorr), VD/VT (Harris–Benedict), VD/VT (Siddiki estimate), and VD/VT (Penn State estimate) longitudinally. A time-dependent Cox model was used to handle these time-varying estimates.
A total of 392 patients (median age 66 interquartile range: 55–77 years, median SOFA score 9 interquartile range: 7–12) were finally included in our analysis, among whom 132 (33.7%) patients died within 28 days of admission. VR (hazard ratio HR=1.04 per 0.1 increase, 95% confidence interval CI: 1.01 to 1.06; P=0.013), V˙Ecorr (HR=1.08 per 1 increase, 95% CI: 1.04 to 1.12; P < 0.001), VD/VT (Harris–Benedict) (HR=1.25 per 0.1 increase, 95% CI: 1.06 to 1.47; P=0.006), and VD/VT (Penn State estimate) (HR=1.22 per 0.1 increase, 95% CI: 1.04 to 1.44; P=0.017) remained significant after adjustment, while VD/VT (Siddiki estimate) (HR=1.10 per 0.1 increase, 95% CI: 1.00 to 1.20; P=0.058) did not. Given a large number of negative values, VD/VT (Siddiki estimate) and VD/VT (Penn State estimate) were not recommended as reliable substitutes. Long-term exposure to VR >1.3, V˙Ecorr >7.53, and VD/VT (Harris–Benedict) >0.59 was independently associated with an increased risk of mortality in ARDS patients. These findings were validated in the fluid and catheter treatment trial (FACTT) database.
In cases where VD/VT cannot be measured directly, early time-varying estimates of VD/VT such as VR, V˙Ecorr, and VD/VT (Harris–Benedict) can be considered for predicting mortality in ARDS patients, offering a rapid bedside application.
Maximum power point tracking (MPPT) is an important strategy to increase the power output from photovoltaic (PV) systems. Partial shading of PV panels is a serious problem which leads to multiple ...local maximum power points (MPPs) on the power versus voltage (P-V) curve. These multiple MPPs can result in conventional MPPT algorithms becoming trapped at a local MPP, resulting in a significant power loss. This paper presents a hybrid MPPT method to optimize the power output for the PV system under non-uniform conditions. It samples the operating point at locations on the I-V curve when partial shading is detected and uses these values to predict the global MPP region. After that, a conventional MPPT algorithm efficient for unimodal functions, such as P&O or extremum seeking control (ESC), is applied to the local area so that the system reaches the global MPP. Since it does not require irradiance sensors and can directly predict the MPP region, it features a relatively low cost, fast response, and simple structure. The effectiveness of the proposed MPPT method is verified with simulation results. A comparison with other popular MPPT techniques shows the advantages with respect to its fast tracking speed and high accuracy.
A(H3N2) virus predominated recent influenza seasons, which has resulted in the rigorous investigation of haemagglutinin, but whether neuraminidase (NA) has undergone antigenic change and contributed ...to the predominance of A(H3N2) virus is unknown. Here, we show that the NA of the circulating A(H3N2) viruses has experienced significant antigenic drift since 2016 compared with the A/Hong Kong/4801/2014 vaccine strain. This antigenic drift was mainly caused by amino acid mutations at NA residues 245, 247 (S245N/S247T; introducing an N-linked glycosylation site at residue 245) and 468. As a result, the binding of the NA of A(H3N2) virus by some human monoclonal antibodies, including those that have broad reactivity to the NA of the 1957 A(H2N2) and 1968 A(H3N2) reference pandemic viruses as well as contemporary A(H3N2) strains, was reduced or abolished. This antigenic drift also reduced NA-antibody-based protection against in vivo virus challenge. X-ray crystallography showed that the glycosylation site at residue 245 is within a conserved epitope that overlaps the NA active site, explaining why it impacts antibody binding. Our findings suggest that NA antigenic drift impacts protection against influenza virus infection, thus highlighting the importance of including NA antigenicity for consideration in the optimization of influenza vaccines.
Serine protease inhibitors (serpins) mediate many biological processes, including immune responses to pathogenic infection. In this study, a member of the serpin superfamily was identified from the ...common poultry parasite
Eimeria tenella
by expressed sequence tag analysis and the rapid amplification of cDNA ends technique. The full-length cDNA was 1,918 bp and had an open reading frame of 1,248 bp encoding a polypeptide of 415 amino acids with the theoretical isoelectric point of 5.26 and predicted molecular weight of 45.5 kDa. Real-time quantitative PCR analysis revealed that the serpin gene was expressed at higher levels in sporozoites than in the other developmental stages (unsporulated oocysts, sporulated oocysts, and second-generation merozoites). The sequence encoding the mature protein was amplified by PCR, cloned into the pET28(a) vector, and expressed in
Escherichia coli
. Specific antiserum generated against the recombinant protein was prepared and used to determine invasion inhibition capacity and localization; the results suggested that the serpin may play an important role in invasion and survival of the sporoziotes in the host.
Protein disulfide isomerase (PDI) and PDI-like proteins are members of the thioredoxin superfamily. They contain thioredoxin-like domains and catalyze the physiological oxidation, reduction and ...isomerization of protein disulfide bonds, which are involved in cell function and development in prokaryotes and eukaryotes. In this study, EtPDIL, a novel PDI-like gene of Eimeria tenella, was cloned using rapid amplification of cDNA ends (RACE) according to the expressed sequence tag (EST). The EtPDIL cDNA contained 1129 nucleotides encoding 216 amino acids. The deduced EtPDIL protein belonged to thioredoxin-like superfamily and had a single predicted thioredoxin domain with a non-classical thioredoxin-like motif (SXXC). BLAST analysis showed that the EtPDIL protein was 55-59% identical to PDI-like proteins of other apicomplexan parasites. The transcript and protein levels of EtPDIL at different development stages were investigated by real-time quantitative PCR and western blot. The messenger RNA and protein levels of EtPDIL were higher in sporulated oocysts than in unsporulated oocysts, sporozoites or merozoites. Protein expression was barely detectable in unsporulated oocysts. Western blots showed that rabbit antiserum against recombinant EtPDIL recognized only a native 24 kDa protein from parasites. Immunolocalization with EtPDIL antibody showed that EtPDIL had a disperse distribution in the cytoplasm of whole sporozoites and merozoites. After sporozoites were incubated in complete medium, EtPDIL protein concentrated at the anterior of the sporozoites and appeared on the surface of parasites. Specific staining was more intense and mainly located on the parasite surface after merozoites released from mature schizonts invaded DF-1 cells. After development of parasites in DF-1 cells, staining intensified in trophozoites, immature schizonts and mature schizonts. Antibody inhibition of EtPDIL function reduced the ability of E. tenella to invade DF-1 cells. These results suggested that EtPDIL might be involved in sporulation in external environments and in host cell adhesion, invasion and development of E. tenella.
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