Pyrolysis of Large Black Liquor Droplets

This paper presents the results of experiments involving the pyrolysis of large black liquor droplets in the NASA KC-135 reduced gravity aircraft. The reduced gravity environment facilitated the study of droplets up to 9 mm in diameter extending the results of previous studies to droplet sizes that are similar to those encountered in recovery boilers. Single black liquor droplets were rapidly inserted into a 923 K oven. The primary independent variables were the initial droplet diameter (0.5 mm to 9 mm), the black liquor solids content (66.12% - 72.9% by mass), and the ambient oxygen mole fraction (0.0 - 0.21). Video records of the experiments provided size and shape of the droplets as a function of time. The results show that the particle diameter at the end of the drying stage (D(sub DRY) ) increases linearly with the initial particle diameter (D(sub O)). The results further show that the ratio of the maximum swollen diameter (D(sub MAX)) to D(sub O) decreases with increasing D(sub O) for droplets with D(sub O) less than 4 mm. This ratio was independent of D(sub O) for droplets with D(sub O) greater than 4 mm. The particle is most spherical at the end of drying, and least spherical at maximum swollen size, regardless of initial sphericity and droplet size

The factor validity of the Western Ontario Rotator Cuff Index

BACKGROUND: The Western Ontario Rotator Cuff Index (WORC) is a self-report questionnaire developed specifically to evaluate disability in persons with pathology of the rotator cuff of the shoulder. The authors created items in 5 categories based on a model of quality of life, but never validated this structure. The purpose of this study was to examine the validity of the original 5-domain model of the WORC by performing factor analysis. METHODS: Three hundred twenty nine subjects (age, mean: 52, SD: 12) were tested prior to undergoing surgery for rotator cuff pathologies. They completed the WORC, a self-report questionnaire, which has 21 items on the effect of the rotator cuff problem on symptoms, activities and emotions. Statistical calculations included correlations between items, Cronbach's alpha of the total scale and subscales, and principal component factor analysis with oblique rotation. RESULTS: Correlations ranged from .09 to .70 between all the items, from .29 to .70 between items within a subscale, and from .53 to .72 between subscale scores. Cronbach's alpha was .93 for the total scale, and .72 to .82 for the subscales. The factor analysis produced 3 factors that explained 57% of the variance. The first factor included symptoms and emotional items, the second included strength items and the third included daily activities. CONCLUSION: The results of this study did not support the 5-domain model of the WORC

Use of rapid-deployment extracorporeal membrane oxygenation for the resuscitation of pediatric patients with heart disease after cardiac arrest

AbstractIntroduction: We have recently used extracorporeal membrane oxygenation as a means of rapidly resuscitating pediatric patients with heart disease after cardiopulmonary arrest, in whom conventional resuscitation measures have failed. Methods: We developed a fully portable extracorporeal membrane oxygenation circuit that is maintained vacuum and carbon dioxide–primed at all times. When needed, the circuit is crystalloid-primed and can be ready for use within 15 minutes. Since February 1996, we have used this rapid-deployment circuit to resuscitate 11 pediatric patients in full cardiopulmonary arrest. Results: The median age of the 11 patients was 120 days (2 days to 4.6 years). Nine patients had a cardiac arrest after cardiac surgery. One patient had a cardiac arrest during cardiac catheterization and one patient had a cardiac arrest before cardiac surgery. Median duration of cardiopulmonary resuscitation was 55 minutes (range 20 to 103 minutes), with no difference in the duration of cardiopulmonary resuscitation between survivors and nonsurvivors. Ten of 11 patients (91%) were weaned from extracorporeal membrane oxygenation and seven (64%) survived to hospital discharge. Six patients are long-term survivors, five of whom are in New York Heart Association class I; one survivor is in class II. Seven patients resuscitated with extracorporeal membrane oxygenation before the use of this rapid-deployment circuit had a median duration of cardiopulmonary resuscitation of 90 minutes, with two (28.6%) survivors. Conclusions: The use of rapid-deployment extracorporeal membrane oxygenation results in shorter resuscitation times and improved survival in pediatric patients with heart disease after cardiopulmonary arrest. (J Thorac Cardiovasc Surg 1998;116:305-11

Environmental Sensor Placement with Convolutional Gaussian Neural Processes

Environmental sensors are crucial for monitoring weather conditions and the impacts of climate change. However, it is challenging to maximise measurement informativeness and place sensors efficiently, particularly in remote regions like Antarctica. Probabilistic machine learning models can evaluate placement informativeness by predicting the uncertainty reduction provided by a new sensor. Gaussian process (GP) models are widely used for this purpose, but they struggle with capturing complex non-stationary behaviour and scaling to large datasets. This paper proposes using a convolutional Gaussian neural process (ConvGNP) to address these issues. A ConvGNP uses neural networks to parameterise a joint Gaussian distribution at arbitrary target locations, enabling flexibility and scalability. Using simulated surface air temperature anomaly over Antarctica as ground truth, the ConvGNP learns spatial and seasonal non-stationarities, outperforming a non-stationary GP baseline. In a simulated sensor placement experiment, the ConvGNP better predicts the performance boost obtained from new observations than GP baselines, leading to more informative sensor placements. We contrast our approach with physics-based sensor placement methods and propose future work towards an operational sensor placement recommendation system. This system could help to realise environmental digital twins that actively direct measurement sampling to improve the digital representation of reality.Comment: In review for the Climate Informatics 2023 special issue of Environmental Data Scienc

Antibiotics induce sustained dysregulation of intestinal T cell immunity by perturbing macrophage homeostasis

Macrophages in the healthy intestine are highly specialized and usually respond to the gut microbiota without provoking an inflammatory response. A breakdown in this tolerance leads to inflammatory bowel disease (IBD), but the mechanisms by which intestinal macrophages normally become conditioned to promote microbial tolerance are unclear. Strong epidemiological evidence linking disruption of the gut microbiota by antibiotic use early in life to IBD indicates an important role for the gut microbiota in modulating intestinal immunity. Here, we show that antibiotic use causes intestinal macrophages to become hyperresponsive to bacterial stimulation, producing excess inflammatory cytokines. Re-exposure of antibiotic-treated mice to conventional microbiota induced a long-term, macrophage-dependent increase in inflammatory T helper 1 (T 1) responses in the colon and sustained dysbiosis. The consequences of this dysregulated macrophage activity for T cell function were demonstrated by increased susceptibility to infections requiring T 17 and T 2 responses for clearance (bacterial and helminth infections), corresponding with increased inflammation. Short-chain fatty acids (SCFAs) were depleted during antibiotic administration; supplementation of antibiotics with the SCFA butyrate restored the characteristic hyporesponsiveness of intestinal macrophages and prevented T cell dysfunction. Butyrate altered the metabolic behavior of macrophages to increase oxidative phosphorylation and also promoted alternative macrophage activation. In summary, the gut microbiota is essential to maintain macrophage-dependent intestinal immune homeostasis, mediated by SCFA-dependent pathways. Oral antibiotics disrupt this process to promote sustained T cell-mediated dysfunction and increased susceptibility to infections, highlighting important implications of repeated broad-spectrum antibiotic use

Propionic acid promotes the virulent phenotype of Crohn's disease-associated adherent-invasive Escherichia coli

Propionic acid (PA) is a bacterium-derived intestinal antimicrobial and immune modulator used widely in food production and agriculture. Passage of Crohn’s disease-associated adherent-invasive Escherichia coli (AIEC) through a murine model, in which intestinal PA levels are increased to mimic the human intestine, leads to the recovery of AIEC with significantly increased virulence. Similar phenotypic changes are observed outside the murine model when AIEC is grown in culture with PA as the sole carbon source; such PA exposure also results in AIEC that persists at 20-fold higher levels in vivo. RNA sequencing identifies an upregulation of genes involved in biofilm formation, stress response, metabolism, membrane integrity, and alternative carbon source utilization. PA exposure also increases virulence in a number of E. coli isolates from Crohn’s disease patients. Removal of PA is sufficient to reverse these phenotypic changes. Our data indicate that exposure to PA results in AIEC resistance and increased virulence in its presence

Induced pseudoscalar coupling of the proton weak interaction

The induced pseudoscalar coupling $g_p$ is the least well known of the weak coupling constants of the proton's charged--current interaction. Its size is dictated by chiral symmetry arguments, and its measurement represents an important test of quantum chromodynamics at low energies. During the past decade a large body of new data relevant to the coupling $g_p$ has been accumulated. This data includes measurements of radiative and non radiative muon capture on targets ranging from hydrogen and few--nucleon systems to complex nuclei. Herein the authors review the theoretical underpinnings of $g_p$, the experimental studies of $g_p$, and the procedures and uncertainties in extracting the coupling from data. Current puzzles are highlighted and future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic