Gradual electroforming and memristive switching in Pt/CuO_<i>x</i>/Si/Pt systems

Wei, L L,Shang, D S,Sun, J R,Lee, S B,Sun, Z G,Shen, B G IOP Pub 2013 Nanotechnology Vol.24 No.32

<P>We report a memristive switching effect in Pt/CuO<SUB><I>x</I></SUB>/Si/Pt devices prepared by the rf sputtering technique at room temperature. Differently from other Cu-based metal filament switching systems, a gradual electroforming process, marked by a gradual increase of the device resistance and a gradual decrease of the device capacitance, was observed in the current–voltage and capacitance characteristics. After the gradual electroforming, the devices show a uniform memristive switching behavior. By Auger electron spectroscopy analysis, a model based on the thickness change of the SiO<SUB><I>x</I></SUB> layer at the CuO<SUB><I>x</I></SUB>/Si interface and Cu ion migration is proposed for the gradual electroforming and uniform memristive switching, respectively. This work should be meaningful for the preparation of forming-free and homogeneous memristive devices.</P>

Maternal vaccine hesitancy towards COVID-19 immunisation of children in Qatar: a population-based cross-sectional study

Reagu Shuja,Weill Cornell Medicine,Awwad Johnny,Alabdulla Majid 한국역학회 2022 Epidemiology and Health Vol.44 No.-

OBJECTIVES: This study was conducted in Qatar to explore beliefs and attitudes among mothers towards coronavirus disease 2019 (COVID-19) vaccination for their children and to understand major factors influencing vaccine hesitancy among these mothers. METHODS: A population-based, online cross-sectional survey was conducted between 15 October and 15 November 2020. A composite questionnaire incorporating a validated vaccine hesitancy tool was developed and administered in both English and Arabic. Approval was obtained from the local ethics committee. Participation was voluntary and offered to all adult residents of Qatar through an online link available on social media platforms and local news portals. Only adult respondents who self-identified as mothers were included in the present study. No personal identifying data were collected. RESULTS: Of the mothers surveyed, 29.4% exhibited COVID-19 vaccine hesitancy regarding their children. This exceeded these mothers’ rate of personal vaccine hesitancy (27.5%). Hesitancy rates varied significantly with ethnicity, with the highest among Qatari mothers (51.3%). Intention to vaccinate children did not differ significantly between mothers who accepted the vaccine for themselves and those who did not. Overall, the main reported concerns related to long-term vaccine safety. To a significant extent, mothers relied most on self-directed research on vaccine safety for decision-making. CONCLUSIONS: The rate of maternal COVID-19 vaccine hesitancy exceeded both those mothers’ rate of personal vaccine hesitancy and the hesitancy rate in the general population. The intention to vaccinate children was independent of maternal vaccination history. Factors influencing maternal vaccine hesitancy differ from those influencing personal hesitancy and require an informed public health response.

Substance P stimulates human airway submucosal gland secretion mainly via a CFTR-dependent process

Choi, Jae Young,Khansaheb, Monal,Joo, Nam Soo,Krouse, Mauri E.,Robbins, Robert C.,Weill, David,Wine, Jeffrey J. American Society for Clinical Investigation 2009 The Journal of clinical investigation Vol.119 No.5

<P>Chronic bacterial airway infections are the major cause of mortality in cystic fibrosis (CF). Normal airway defenses include reflex stimulation of submucosal gland mucus secretion by sensory neurons that release substance P (SubP). CFTR is an anion channel involved in fluid secretion and mutated in CF; the role of CFTR in secretions stimulated by SubP is unknown. We used optical methods to measure SubP-mediated secretion from human submucosal glands in lung transplant tissue. Glands from control but not CF subjects responded to mucosal chili oil. Similarly, serosal SubP stimulated secretion in more than 60% of control glands but only 4% of CF glands. Secretion triggered by SubP was synergistic with vasoactive intestinal peptide and/or forskolin but not with carbachol; synergy was absent in CF glands. Pig glands demonstrated a nearly 10-fold greater response to SubP. In 10 of 11 control glands isolated by fine dissection, SubP caused cell volume loss, lumen expansion, and mucus flow, but in 3 of 4 CF glands, it induced lumen narrowing. Thus, in CF, the reduced ability of mucosal irritants to stimulate airway gland secretion via SubP may be another factor that predisposes the airways to infections.</P>

Molecular Surveillance Identifies Multiple Transmissions of Typhoid in West Africa

Wong, Vanessa K.,Holt, Kathryn E.,Okoro, Chinyere,Baker, Stephen,Pickard, Derek J.,Marks, Florian,Page, Andrew J.,Olanipekun, Grace,Munir, Huda,Alter, Roxanne,Fey, Paul D.,Feasey, Nicholas A.,Weill, F Public Library of Science 2016 PLoS neglected tropical diseases Vol.10 No.9

<▼1><P><B>Background</B></P><P>The burden of typhoid in sub-Saharan African (SSA) countries has been difficult to estimate, in part, due to suboptimal laboratory diagnostics. However, surveillance blood cultures at two sites in Nigeria have identified typhoid associated with <I>Salmonella enterica</I> serovar Typhi (<I>S</I>. Typhi) as an important cause of bacteremia in children.</P><P><B>Methods</B></P><P>A total of 128 <I>S</I>. Typhi isolates from these studies in Nigeria were whole-genome sequenced, and the resulting data was used to place these Nigerian isolates into a worldwide context based on their phylogeny and carriage of molecular determinants of antibiotic resistance.</P><P><B>Results</B></P><P>Several distinct <I>S</I>. Typhi genotypes were identified in Nigeria that were related to other clusters of <I>S</I>. Typhi isolates from north, west and central regions of Africa. The rapidly expanding <I>S</I>. Typhi clade 4.3.1 (H58) previously associated with multiple antimicrobial resistances in Asia and in east, central and southern Africa, was not detected in this study. However, antimicrobial resistance was common amongst the Nigerian isolates and was associated with several plasmids, including the IncHI1 plasmid commonly associated with <I>S</I>. Typhi.</P><P><B>Conclusions</B></P><P>These data indicate that typhoid in Nigeria was established through multiple independent introductions into the country, with evidence of regional spread. MDR typhoid appears to be evolving independently of the haplotype H58 found in other typhoid endemic countries. This study highlights an urgent need for routine surveillance to monitor the epidemiology of typhoid and evolution of antimicrobial resistance within the bacterial population as a means to facilitate public health interventions to reduce the substantial morbidity and mortality of typhoid.</P></▼1><▼2><P><B>Author Summary</B></P><P>Typhoid fever, a serious bloodstream infection caused by the bacterium <I>Salmonella</I> Typhi, is a major cause of disease and death around the world. There have been limited data on the epidemiology of typhoid in many countries in sub-Saharan African, including Nigeria. Recent evidence, however, showed that typhoid was an important cause of bacteraemia in children residing in two regions of Nigeria. Here, we analyzed the whole genome sequences of 128 <I>S</I>. Typhi isolates from two studies in order to elucidate the population structure and characterize the genetic components of antimicrobial resistance. We found that the multiple <I>S</I>. Typhi genotypes identified were closely related to other <I>S</I>. Typhi from neighboring regions of Africa and that multidrug resistance (MDR) was common among these isolates, and in many cases was associated with the IncHI1 plasmid known to cause MDR typhoid. These results provide evidence that typhoid was established in Nigeria as a result of several independent introductions into the country and that there has been extensive exchange of <I>S</I>. Typhi in and around the region of West Africa. This study emphasizes the importance of surveillance to improve our understanding of the epidemiology of typhoid, which is needed to underpin public health measures to reduce the spread of disease and facilitate patient management.</P></▼2>

Phylogeographical analysis of the dominant multidrug-resistant H58 clade of Salmonella Typhi identifies inter- and intracontinental transmission events

Wong, Vanessa K,Baker, Stephen,Pickard, Derek J,Parkhill, Julian,Page, Andrew J,Feasey, Nicholas A,Kingsley, Robert A,Thomson, Nicholas R,Keane, Jacqueline A,Weill, Franç,ois-Xavier,Edwards, Dav Nature Pub. Co 2015 Nature genetics Vol.47 No.6

The emergence of multidrug-resistant (MDR) typhoid is a major global health threat affecting many countries where the disease is endemic. Here whole-genome sequence analysis of 1,832 Salmonella enterica serovar Typhi (S. Typhi) identifies a single dominant MDR lineage, H58, that has emerged and spread throughout Asia and Africa over the last 30 years. Our analysis identifies numerous transmissions of H58, including multiple transfers from Asia to Africa and an ongoing, unrecognized MDR epidemic within Africa itself. Notably, our analysis indicates that H58 lineages are displacing antibiotic-sensitive isolates, transforming the global population structure of this pathogen. H58 isolates can harbor a complex MDR element residing either on transmissible IncHI1 plasmids or within multiple chromosomal integration sites. We also identify new mutations that define the H58 lineage. This phylogeographical analysis provides a framework to facilitate global management of MDR typhoid and is applicable to similar MDR lineages emerging in other bacterial species.