Turbine endwall single cylinder program

Measurements of the flow field in front of a large-scale single cylinder, mounted in a wind tunnel are discussed. Static pressures on the endwall and cylinder surfaces, extensive five-hole probe pressures in front of and around the cylinder, and velocity fluctuations using a hot-wire probe where the flow is steady enough to yield meaningful results are included

Measurements of a turbulent horseshoe vortex formed around a cylinder

An experimental investigation was conducted to characterize a symmetrical horseshoe vortex system in front of and around a single large-diameter right cylinder centered between the sidewalls of a wind tunnel. Surface flow visualization and surface static pressure measurements as well as extensive mean velocity and pressure measurements in and around the vortex system were acquired. The results lend new insight into the formation and development of the vortex system. Contrary to what has been assumed previously, a strong vortex was not identified in the streamwise plane of symmetry, but started a significant angular distance away from it. Rather than the multiple vortex systems reported by others, only a single primary vortex and saddle point were found. The scale of the separation process at the saddle point was much smaller than the scale of the approaching boundary layer thickness. Results of the present study not only shed light on such phenomena as the nonsymmetrical endwall flow in axial turbomachinery but can also be used as a test case for three-dimensional computational fluid mechanics computer codes

SARS coronavirus replicase proteins in pathogenesis

Much progress has been made in understanding the role of structural and accessory proteins in the pathogenesis of severe acute respiratory syndrome coronavirus (SARS-CoV) infections. The SARS epidemic also brought new attention to the proteins translated from ORF1a and ORF1b of the input genome RNA, also known as the replicase/transcriptase gene. Evidence for change within the ORF1ab coding sequence during the SARS epidemic, as well as evidence from studies with other coronaviruses, indicates that it is likely that the ORF1ab proteins play roles in virus pathogenesis distinct from or in addition to functions directly involved in viral replication. Recent reverse genetic studies have confirmed that proteins of ORF1ab may be involved in cellular signaling and modification of cellular gene expression, as well as virulence by mechanisms yet to be determined. Thus, the evolution of the ORF1ab proteins may be determined as much by issues of host range and virulence as they are by specific requirements for intracellular replication

A live, impaired-fidelity coronavirus vaccine protects in an aged, immunocompromised mouse model of lethal disease

Live-attenuated RNA virus vaccines are efficacious but subject to reversion to virulence. Among RNA viruses, replication fidelity is recognized as a key determinant of virulence and escape from antiviral therapy; increased fidelity is attenuating for some viruses. Coronavirus replication fidelity is approximately 20-fold greater than that of other RNA viruses and is mediated by a 3′-5′ exonuclease activity (ExoN) that likely functions in RNA proofreading. In this study, we demonstrate that engineered inactivation of SARS-CoV ExoN activity results in a stable mutator phenotype with profoundly decreased fidelity in vivo and attenuation of pathogenesis in young, aged, and immunocompromised mouse models of human SARS. The ExoN inactivation genotype and mutator phenotype are stable and do not revert to virulence, even after serial passage or long-term persistent infection in vivo. Our approach represents a strategy with potential for broad applications for the stable attenuation of coronaviruses and possibly other RNA viruses

Bat lung epithelial cells show greater host species-specific innate resistance than MDCK cells to human and avian influenza viruses

Background With the recent discovery of novel H17N10 and H18N11 influenza viral RNA in bats and report on high frequency of avian H9 seroconversion in a species of free ranging bats, an important issue to address is the extent bats are susceptible to conventional avian and human influenza A viruses. Method To this end, three bat species (Eidolon helvum, Carollia perspicillata and Tadarida brasiliensis) of lung epithelial cells were separately infected with two avian and two human influenza viruses to determine their relative host innate immune resistance to infection. Results All three species of bat cells were more resistant than positive control Madin-Darby canine kidney (MDCK) cells to all four influenza viruses. TB1-Lu cells lacked sialic acid α2,6-Gal receptors and were most resistant among the three bat species. Interestingly, avian viruses were relatively more replication permissive in all three bat species of cells than with the use of human viruses which suggest that bats could potentially play a role in the ecology of avian influenza viruses. Chemical inhibition of the JAK-STAT pathway in bat cells had no effect on virus production suggesting that type I interferon signalling is not a major factor in resisting influenza virus infection. Conclusion Although all three species of bat cells are relatively more resistant to influenza virus infection than control MDCK cells, they are more permissive to avian than human viruses which suggest that bats could have a contributory role in the ecology of avian influenza viruses

Seroprevalence of anti-SARS-CoV-2 IgG antibodies, risk factors for infection and associated symptoms in Geneva, Switzerland: a population-based study.

Aims: To assess SARS-CoV-2 seroprevalence over the first epidemic wave in the canton of Geneva, Switzerland, as well as risk factors for infection and symptoms associated with IgG seropositivity. Methods: Between April and June 2020, former participants of a representative survey of the 20-74-year-old population of canton Geneva were invited to participate in the study, along with household members aged over 5 years. Blood samples were tested for anti-SARS-CoV-2 immunoglobulin G. Questionnaires were self-administered. We estimated seroprevalence with a Bayesian model accounting for test performance and sampling design. Results: We included 8344 participants, with an overall adjusted seroprevalence of 7.8% (95% credible interval 6.8-8.9). Seroprevalence was highest among 18-49 year-olds (9.5%), and lowest in 5-9-year-old children (4.3%) and individuals >65 years (4.7-5.4%). Odds of seropositivity were significantly reduced for female retirees and unemployed men compared to employed individuals, and smokers compared to non-smokers. We found no significant association between occupation, level of education, neighborhood income and the risk of being seropositive. The symptom most strongly associated with seropositivity was anosmia/dysgeusia. Conclusions: Anti-SARS-CoV-2 population seroprevalence remained low after the first wave in Geneva. Socioeconomic factors were not associated with seropositivity in this sample. The elderly, young children and smokers were less frequently seropositive, although it is not clear how biology and behaviours shape these differences

Promotion of arterial stiffness by childhood cancer and its characteristics in adult long‐term survivors

BACKGROUND Vascular alterations induced by antineoplastic treatment might be considered as a possible underlying mechanism of increased cardiovascular sequelae in childhood cancer survivors (CCSs). We aimed to evaluate arterial stiffness among long‐term CCSs and to compare the data against a population‐based sample. METHODS AND RESULTS Arterial stiffness was assessed by digital photoplethysmography (stiffness index; m/s) among 1002 participants of the CVSS (Cardiac and Vascular Late Sequelae in Long‐Term Survivors of Childhood Cancer) study, diagnosed with neoplasia (1980–1990) before an age of 15 years. A population‐based sample from the GHS (Gutenberg Health Study) (n=5252) was investigated for comparison. All subjects underwent a comprehensive, standardized clinical examination in the same study center. CCSs had higher stiffness index (β=0.66 m/s; 95% CI, 0.51–0.80 m/s) in multivariable linear regression analysis after adjustment for cardiovascular risk factors compared with the population sample of comparable age range. Stiffer vessels were found among CCSs also in absence of arterial hypertension (β=0.66; 95% CI, 0.50–0.81) or history of chemotherapy/radiotherapy (β=0.56; 95% CI, 0.16–0.96) in fully adjusted models. Moreover, stiffness index differed by tumor entity, with highest values in bone and renal tumors. Almost 5.2‐fold higher prevalence of stiffness index values exceeding age‐specific, population‐based reference limits was observed among CCSs compared with GHS participants. CONCLUSIONS This is the first study demonstrating increased arterial stiffness among long‐term CCSs. The data suggest that vascular compliance might differ in survivors of childhood cancer from the established development concept for arterial stiffness in the population; cancer growth and antineoplastic treatment might be relevant determinants of the pathobiological features

Detection of a novel human coronavirus by real-time reverse-transcription polymerase chain reaction

We present two real-time reverse-transcription polymerase chain reaction assays for a novel human coronavirus (CoV), targeting regions upstream of the E gene (upE) or within open reading frame (ORF)1b, respectively. Sensitivity for upE is 3.4 copies per reaction (95% confidence interval (CI): 2.5-6.9 copies) or 291 copies/mL of sample. No cross-reactivity was observed with coronaviruses OC43, NL63, 229E, SARS-CoV, nor with 92 clinical specimens containing common human respiratory viruses. We recommend using upE for screening and ORF1b for confirmation