16,267 research outputs found
Recommended from our members
Oxygen targeting in preterm infants: a physiological interpretation.
Randomized controlled trials evaluating low-target oxygen saturation (SpO2:85% to 89%) vs high-target SpO2 (91% to 95%) have shown variable results regarding mortality and morbidity in extremely preterm infants. Because of the variation inherent to the accuracy of pulse oximeters, the unspecified location of probe placement, the intrinsic relationship between SpO2 and arterial oxygen saturation (SaO2) and between SaO2 and partial pressure of oxygen (PaO2) (differences in oxygen dissociation curves for fetal and adult hemoglobin), the two comparison groups could have been more similar than dissimilar. The SpO2 values were in the target range for a shorter period of time than intended due to practical and methodological constraints. So the studies did not truly compare 'target SpO2 ranges'. In spite of this overlap, some of the studies did find significant differences in mortality prior to discharge, necrotizing enterocolitis and severe retinopathy of prematurity. These differences could potentially be secondary to time spent beyond the target range (SpO2 <85 or >95%) and could be avoided with an intermediate but wider target SpO2 range (87% to 93%). In conclusion, significant uncertainty persists about the desired target range of SpO2 in extremely preterm infants. Further studies should focus on studying newer methods of assessing oxygenation and strategies to limit hypoxemia (<85% SpO2) and hyperoxemia (>95% SpO2)
Testing the robustness of laws of polysemy and brevity versus frequency
The pioneering research of G.K. Zipf on the relationship between word frequency and other word features led to the formulation of various linguistic laws. Here we focus on a couple of them: the meaning-frequency law, i.e. the tendency of more frequent words to be more polysemous, and the law of abbreviation, i.e. the tendency of more frequent words to be shorter. Here we evaluate the robustness of these laws in contexts where they have not been explored yet to our knowledge. The recovery of the laws again in new conditions provides support for the hypothesis that they originate from abstract mechanisms.Peer ReviewedPostprint (author's final draft
Modelling Tensile Behaviour of Stir-cast Aluminium Matrix Composites (AMCs) Using Factorial Design of Experiments
Aluminium based metal matrix composites (MMCs) with ceramic reinforcement are finding extensive applications in aerospace, automobile, agricultural farm machinery and other areas which demand combination of properties such as high strength, stiffness, wear resistance, high temperature resistance, etc. In particular, components comprising Al7075 alloy matrix, reinforced with alumina (Al2O3) particulates, are reported to excel their monolithic counterparts. Liquid metal route and powder metallurgy are the most widely used fabrication techniques to produce these MMCs. The former has advantages such as easy adaptability, low cost and possibility of subjecting the cast components to secondary processes like forging, rolling and extrusion for producing the final components. This paper presents the details of developing a mathematical model to predict the tensile behavior like ultimate tensile strength (UTS) and percentage elongation of the as-cast Al7075/Al2O3 in terms of size and % fraction of Al2O3, holding temperature and holding time; using factorial design of experiments (DoE). Adequacy of the models was tested using Fisher's F-test. UTS of the composite was increased by 20%compared to that of matrix and % elongation was reduced by around 30%. Keywords: MMC, UTS, % elongation, Design of experiments, Modelling
Building sustainable score (BSS) - A hybrid process approach for sustainable building assessment in China
Sustainable building in China has gained attention both domestically and abroad. Despite the fast increase in sustainable assessment tools developed locally or adopted from overseas, there are still criticisms about the current situation of weak implementation and lack of comprehensive consideration. The lack of consideration of economic and social as-pects or building performance on whole building life cycle all lead to departure from the true meaning of sustainable development. And lack of participation on the part of stakeholders makes it too theoretical to be carried out. This re-search aims to develop a model to address this problem. This research started with review of current sustainable as-sessment tools applied in China. As the assessment indicators have clear regional disparities, and almost no current tool considers all three pillars of environmental, economic and social in building life cycle. An industry survey was therefore designed for generation of indicators at different building stages, and personal interviews relevant to different occupa-tion in building industry were conducted to complement the questionnaire survey. After that, the model Building Sus-tainable Score (BSS) was developed based on the stakeholders participation. Finally, the model is verified by a case study
Quantifying and assessing impacts of building processes in a triple bottom line approach
The paper is based on a research project undertaken by the University of Technology, Sydney in examining the integration of economic, social and environmental considerations throughout the building process of a development. The project comprises the first stage, a literature review and model development, followed by the second stage, model implementation through case studies. The paper presents the first stage of the research project in a literature review and model development. The paper reviews the current application of environmental building assessment tools and their impacts on the construction industry. The importance of building process in environmental assessment is also indicated. The paper also seeks to analyze building performance using a triple bottom line approach on a life cycle perspective. The major activities in the building process are identified and presented on how they influence sustainable performance. Finally the paper presents a model that combines economic, social and environmental assessments into a single indicator to aid decision making
Towards an Understanding of Factors Controlling Seed Bank Composition and Longevity in the Alpine Environment
The ability of seeds to regenerate from soil seed banks has long been recognized as a key survival strategy for plants establishing new niches in highly variable climates of alpine environments. However, the fundamental aspects of evolutionary/selective forces for seed bank development in alpine ecosystems are largely unknown. Here, we developed a model that describes dormancy, a high temperature requirement and a specific light/darkness regime at the time of seed shedding can preclude autumn germination, thus contributing to seed persistence until the next growing season. The benefits of these factors synchronising germination with the growing season are reviewed. Additionally, the importance of climatic variations of maternal environment affecting some of these factors is also discussed. It is suggested that the environmental conditions during the growing season partly control the seed persistence and seeds that fail to germinate are carried over to the next season. Species that have small (<3 mg) and round-shaped seeds tend to persist more easily in soil for over five years, than do the large or flat seeds. However, some large-seeded species also have the potential to establish short-term persistence bank. A literature survey reveals 88% of the alpine seeds have a mass <3 mg. Seed size has only a weak relationship with mean germination timing (MGT) indicating that reduced persistence in large-seeded species cannot be counteracted by quicker germination, but combined effects of other factors stimulating germination remain an open area to be studied. It is proposed that long distance dispersal (LDD) is limited in most-but not all-species, primarily due to the absence of specialized dispersal structures. However, among numerous dispersal modes, most species tend to be dispersed by wind. Thus, spermatophytes of alpine environments have a greater tendency to establish seed banks and spread the risk of germination to many years, rather than being dispersed to other micro-climates
A retrospective study on long-term efficacy of intranasal lysine-aspirin in controlling NSAID-exacerbated respiratory disease
Purpose:
Aspirin treatment after desensitization (ATAD) represents an effective therapeutic option suitable for NSAID-exacerbated respiratory disease (N-ERD) patients with recalcitrant disease. Intranasal administration of lysine-aspirin (LAS) has been suggested as a safer and faster route than oral ATAD but evidence for its use is less strong. We investigated nasal LAS therapy long-term efficacy based on objective outcomes, smell function, polyp recurrence and need for surgery or rescue therapy. Clinical biomarkers predicting response to intranasal LAS, long-term side effects and consequences of discontinuing treatment have been evaluated.
Methods:
A retrospective analysis of a database of 60 N-ERD patients seen between 2012 and 2020 was performed in March 2021. They were followed up at 3-months, 1-, 2- and 3-years with upper and lower airway functions assessed at each follow-up.
Results:
Higher nasal airflow and smell scores were found at each follow-up in patients taking LAS (p < 0.001 and p = 0.048 respectively). No influence of LAS on pulmonary function measurements was observed. Patient on intranasal LAS showed a lower rate of revision sinus surgery when compared to those who discontinued the treatment (p < 0.001). None of the variables studied was found to influence LAS treatment response.
Conclusion:
Our study demonstrates the clinical effectiveness of long-term intranasal LAS in the management of N-ERD in terms of improved nasal airflow and olfaction and a reduced need for revision sinus surgery. Intranasal LAS is safe, being associated with a lower rate of side effects when compared to oral ATAD. However, discontinuation of the treatment at any stage is associated with a loss of clinical benefit
Transcriptional adaptation of Mycobacterium tuberculosis within macrophages: Insights into the phagosomal environment
Little is known about the biochemical environment in phagosomes harboring an infectious agent. To assess the state of this organelle we captured the transcriptional responses of Mycobacterium tuberculosis (MTB) in macrophages from wild-type and nitric oxide (NO) synthase 2–deficient mice before and after immunologic activation. The intraphagosomal transcriptome was compared with the transcriptome of MTB in standard broth culture and during growth in diverse conditions designed to simulate features of the phagosomal environment. Genes expressed differentially as a consequence of intraphagosomal residence included an interferon � – and NO-induced response that intensifies an iron-scavenging program, converts the microbe from aerobic to anaerobic respiration, and induces a dormancy regulon. Induction of genes involved in the activation and �-oxidation of fatty acids indicated that fatty acids furnish carbon and energy. Induction of �E-dependent, sodium dodecyl sulfate–regulated genes and genes involved in mycolic acid modification pointed to damage and repair of the cell envelope. Sentinel genes within the intraphagosomal transcriptome were induced similarly by MTB in the lungs of mice. The microbial transcriptome thus served as a bioprobe of the MTB phagosomal environment
Role of circulating exosomal biomarkers and their diagnostic accuracy in pancreatic cancer
Background and Aim: New biomarkers have the potential to facilitate early diagnosis of pancreatic cancer (PC). Circulating exosomes are cell-derived protein complexes containing RNA that can be used as indicators of cancer development. The aim of this review is to evaluate the current literature involving PC patient groups for highly accurate exosomal biomarkers. Methods: The literature search followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eight-hundred and seventy-five studies were identified across various databases (Ovid MEDLINE, Embase, and Cochrane) published between 2009 and 2020. Nine studies fulfilled the inclusion criteria: human PC patients, diagnosis as outcome of interest, serum biomarker of exosomal content, reporting of diagnostic values, and disease progress. Area under the curve (AUC) of the exosomal biomarker was compared against that of CA19-9. Results: Nine papers were reviewed for relevant outcomes based on the inclusion criteria. These studies involved 565 participants (331 PC, 234 controls; male/female ratio 1.21; mean age 64.1). Tumor staging was reported in all studies, with 45.6% of PC patients diagnosed with early-stage PC (T1–2). The mRNA panel (ARG1, CD63, CK18, Erbb3, GAPDH, H3F3A, KRAS, ODC1) and GPC 1 reported the highest performing sensitivity and specificity at 100% each. The microRNA panel (miR-10b, miR-21, miR-30c, miR-181a, and miR-let7a), mRNA panel (ARG1, CD63, CK18, Erbb3, GAPDH, H3F3A, KRAS, ODC1), and GPC 1 showed a perfect AUC of 1.0. Five studies compared the AUC of the exosomal biomarker against CA19-9, each being superior to that of CA19-9. Conclusion: The potential of exosomal biomarkers remains promising in PC diagnosis. Standardization of future studies will allow for larger comparative analyses and overcoming contrasting findings
Dramatic Increases in Obesity and Overweight Prevalence and Body Mass Index Among Ethnic-Immigrant and Social Class Groups in the United States, 1976–2008
This study examined trends in US obesity and overweight prevalence and body mass index (BMI) among 30 immigrant groups, stratified by race/ethnicity and length of immigration, and among detailed education, occupation, and income/poverty groups from 1976 to 2008. Using 1976–2008 National Health Interview Surveys, differentials in obesity, overweight, and BMI, based on self-reported height and weight, were analyzed by using disparity indices, logistic, and linear regression. The obesity prevalence for the US population aged ≥18 tripled from 8.7% in 1976 to 27.4% in 2008. Overweight prevalence increased from 36.9% in 1976 to 62.0% in 2008. During 1991–2008, obesity prevalence for US-born adults increased from 13.9 to 28.7%, while prevalence for immigrants increased from 9.5 to 20.7%. While immigrants in each ethnic group and time period had lower obesity and overweight prevalence and BMI than the US-born, immigrants’ risk of obesity and overweight increased with increasing duration of residence. In 2003–2008, obesity prevalence ranged from 2.3% for recent Chinese immigrants to 31–39% for American Indians, US-born blacks, Mexicans, and Puerto Ricans, and long-term Mexican and Puerto Rican immigrants. Between 1976 and 2008, the obesity prevalence more than quadrupled for those with a college education or sales occupation. Although higher prevalence was observed for lower education, income, and occupation levels in each period, socioeconomic gradients in obesity and overweight decreased over time because of more rapid increases in prevalence among higher socioeconomic groups. Continued immigrant and socioeconomic disparities in prevalence will likely have substantial impacts on future obesity trends in the US
- …