Potential structural material problems in a hydrogen energy system

Potential structural material problems that may be encountered in the three components of a hydrogen energy system - production, transmission/storage, and utilization - were identified. Hydrogen embrittlement, corrosion, oxidation, and erosion may occur during the production of hydrogen. Hydrogen embrittlement is of major concern during both transmission and utilization of hydrogen. Specific materials research and development programs necessary to support a hydrogen energy system are described

Performance Of Third Harmonic Ground Fault Protection Schemes For Generator Stator Windings

The paper shows how the normally generated third-harmonic voltage can be used to protect the lower ten to twenty percent of generator stator windings against ground faults. A method of determining the applicability of the scheme to a given machine is described which takes into account the design of the generator and its externally connected apparatus. The effects of finite resistence ground faults are also investigated and other advantages of the scheme, such as protection of the neutral, are also highlighted. Copyright © 1981 by The Institute of Electrical and Electronics Engineers, Inc

Prediction of stillbirth from maternal demographic and pregnancy characteristics

Objectives: To develop a model for prediction of stillbirth based on maternal characteristics and components of medical history and evaluate the performance of screening of this model for all stillbirths and those due to impaired placentation and unexplained causes. Methods: This was a prospective screening study of 113,415 singleton pregnancies at 11+0-13+6 and 19+0-24+6 weeks’ gestation. The population included 113,019 live births and 396 (0.35%) antepartum stillbirths; 230 (58%) were secondary to impaired placentation and 166 (42%) were due to other or unexplained causes. Multivariate logistic regression analysis was used to determine the factors from maternal characteristics and medical history which provided a significant contribution to the prediction of stillbirth. Results: The risk for stillbirth increased with maternal weight (OR 1.01 per kg after 69 kg), was higher in women of Afro-Caribbean race (OR 2.01), assisted conception (OR 1.79), cigarette smokers (OR 1.71), those with a history of chronic hypertension (OR 2.62), SLE/APS (OR 3.61) or diabetes mellitus (OR 2.55) and was increased in parous women with a history of previous stillbirth (OR 4.81). The model predicted 26% of unexplained stillbirths and 31% of those due to impaired placentation at FPR of 10%; within the impaired placentation group the DR of stillbirth at 37 weeks (38% vs 28%). Conclusions: A model based on maternal characteristics and medical history recorded in early pregnancy can potentially predict one third of subsequent stillbirths. The extent to which such stillbirths could be prevented remains to be determined

Effect of transient pinning on stability of drops sitting on an inclined plane

We report on new instabilities of the quasi-static equilibrium of water drops pinned by a hydrophobic inclined substrate. The contact line of a statically pinned drop exhibits three transitions of partial depinning: depinning of the advancing and receding parts of the contact line and depinning of the entire contact line leading to the drop's translational motion. We find a region of parameters where the classical Macdougall-Ockrent-Frenkel approach fails to estimate the critical volume of the statically pinned inclined drop

Effects of passion, experience, and cultural politics on classical musicians’ practice during the COVID-19 pandemic

The widespread cancelation of cultural events during the early 2020 stages of the COVID-19 pandemic led professional performing musicians across the world to experience an increasing economic fragility that threatened their health and wellbeing. Within this “new normal,” developing countries have been at a higher risk due to their vulnerable health systems and cultural policies. Even in such difficult times, the music profession requires musicians to keep up their practicing routines, even if they have no professional commitments. This is because high level technical and expressive skills are crucial to sustaining a music career at a high performance level. However, it could be expected that not all musicians might have had the same engagement with music practice during lockdowns. In this study, we studied the experiences of 309 professional classical musicians based in European and Latin American countries with different levels of performing experience to examine their passionate (or lack thereof) engagement with music practice. Through the mixed methods combination of multigroup invariance and narrative analyses, we identified distinct profiles of musicians who displayed more harmonious or more obsessive passion orientations before and at the peak of the pandemic. We observed that musicians with higher levels of harmonious passion in particular were more capable of sustaining their practice at the peak of the pandemic and that these musicians were mostly located in Latin America—a paradox, considering that cultural politics supporting the careers of professional performing musicians and entrepreneurial education in Latin America are lacking to a great extent, especially in comparison with the European context. We explain this in terms of the “forced” self-management embraced by musicians in Latin American countries who want to engage with music practice both before and during the COVID-19 pandemic even if the music profession does not generate enough revenue for them

Inhibition of protein crystallization by evolutionary negative design

In this perspective we address the question: why are proteins seemingly so hard to crystallize? We suggest that this is because of evolutionary negative design, i.e. proteins have evolved not to crystallize, because crystallization, as with any type of protein aggregation, compromises the viability of the cell. There is much evidence in the literature that supports this hypothesis, including the effect of mutations on the crystallizability of a protein, the correlations found in the properties of crystal contacts in bioinformatics databases, and the positive use of protein crystallization by bacteria and viruses.Comment: 5 page

Variation in ampicillin dosing for lower respiratory tract infections and neonatal bacterial infections in US children\u27s hospitals

OBJECTIVE: We examined ampicillin dosing in pediatric patients across 3 conditions: (1) bacterial lower respiratory tract infections (LRTIs) in infants and children \u3e3 months, (2) neonates with suspected or proven sepsis, and (3) neonates with suspected central nervous system (CNS) infections. We compared our findings to dosing guidance for these specific indications. DESIGN: Retrospective cohort study. SETTING: The study included data from 32 children\u27s hospitals in the United States. METHODS: We reviewed prescriptions from the SHARPS study of antimicrobials, a survey of antibiotic prescribing from July 2016 to December 2017. Prescriptions were analyzed for indication, total daily dose per kilogram, and presence of antimicrobial stewardship program (ASP) review. LRTI prescriptions were compared to IDSA recommendations for community-acquired pneumonia. Neonatal prescriptions were compared to recommendations from the American Academy of Pediatrics (AAP). Prescriptions were categorized as optimal (80%-120% of recommended dosing), suboptimal (\u3c80% of recommended dosing), or excessive (\u3e120% of recommended dosing). RESULTS: Among 1,038 ampicillin prescriptions, we analyzed 88 prescriptions for LRTI, 499 prescriptions for neonatal sepsis, and 27 prescriptions for neonatal CNS infection. Of the LRTI prescriptions, 77.3%were optimal. Of prescriptions for neonatal sepsis, 81.6% were excessive compared to AAP bacteremia recommendations but 78.8% were suboptimal compared to AAP meningitis guidelines. Also, 48.1% of prescriptions for neonatal CNS infection were suboptimal, and 50.6% of prescriptions were not reviewed by the ASP. CONCLUSIONS: LRTI dosing is generally within the IDSA-recommended range. However, dosing for neonatal sepsis often exceeds the recommendation for bacteremia but is below the recommendation for meningitis. This variability points to an important opportunity for future antimicrobial stewardship efforts

Mesh inlay, mesh kit or native tissue repair for women having repeat anterior or posterior prolapse surgery: randomised controlled trial (PROSPECT)

Funding The project was funded by the National Institute for Health Research Health Technology Assessment Programme (Project Number 07/60/18). The Health Services Research Unit and the Health Economics Research Unit are funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates. Acknowledgements The authors wish to thank the women who participated in the PROSPECT study. We also thank Margaret MacNeil for her secretarial support and data management; Dawn McRae and Lynda Constable for their trial management support; the programming team in CHaRT, led by Gladys McPherson; members of the Project Management Group for their ongoing advice and support of the study; and the staff at the recruitment sites who facilitated the recruitment, treatment and follow up of study participants.Peer reviewedPublisher PD

Two-mirror Schwarzschild aplanats. Basic relations

It is shown that the theory of aplanatic two-mirror telescopes developed by Karl Schwarzschild in 1905 leads to the unified description both the prefocal and the postfocal systems. The class of surfaces in the ZEMAX optical program has been properly extended to ascertain the image quality in exact Schwarzschild aplanats. A comparison of Schwarzschild aplanats with approximate Ritchey-Chretien and Gregory-Maksutov aplanatic telescopes reveals a noticeable advantage of the former at fast focal ratio of the system.Comment: 19 page