Analytical and Quantitative Aspects of Surface Moisture Transport and Plastic Shrinkage Cracking

The drying rate of porous materials such as hydrating cement paste during early hydration stages is studied using analytical and experimental procedures. Effects of micro and macro fibers as they change the nature of restrained shrinkage cracking are also documented. A methodology based on vacuum drying experiments is developed to measure the rate of evaporation from the surface of fresh paste and mortar mixtures that leads to restrained shrinkage cracking. Stages of microcrack coalescence due to plastic shrinkage cracking are quantitatively analyzed using digital image correlation. A model for internal moisture transfer simulates initial constant drying rate followed by a vapor diffusion transport phenomena. A fluid mechanics approach for water evaporation from the boundary-layer in terms of mass transfer, diffusion, and convection is used. Effect of temperature, wind speed, and relative humidity are studied. Results of these two experiments are then integrated with an analytical approach for the restrained ring specimen which correlates the moisture diffusion in the specimen with the rate of evaporation and shrinkage strain. The model incorporates key influential parameters of diffusion, evaporation, shrinkage, creep, aging, and microcracking, in the stress analysis of a restrained concrete section. The formulation addresses the effect of geometry of the specimen, the humidity and shrinkage conditions, and the restraint offered by stiffness of the steel ring. Finally the modelling is extended to simulate a slab on ground and predict multiple transverse cracking as well as slab curling using a finite difference model

Optimal behavior of responsive residential demand considering hybrid phase change materials

Due to communication and technology developments, residential consumers are enabled to participate in Demand Response Programs (DRPs), control their consumption and decrease their cost by using Household Energy Management (HEM) systems. On the other hand, capability of energy storage systems to improve the energy efficiency causes that employing Phase Change Materials (PCM) as thermal storage systems to be widely addressed in the building applications. In this paper, an operational model of HEM system considering the incorporation of more than one type of PCM in plastering mortars (hybrid PCM) is proposed not only to minimize the customerâ s cost in different DRPs but also to guaranty the habitantsâ  satisfaction. Moreover, the proposed model ensures the technical and economic limits of batteries and electrical appliances. Different case studies indicate that implementation of hybrid PCM in the buildings can meaningfully affect the operational pattern of HEM systems in different DRPs. The results reveal that the customerâ s electricity cost can be reduced up to 48% by utilizing the proposed model.The work of M. Shafie-khah and J.P.S. Catalão was supported by FEDER funds through COMPETE and by Portuguese funds through FCT, under FCOMP-01-0124-FEDER-020282 (Ref. PTDC/EEA-EEL/118519/2010) and UID/CEC/50021/2013, and also by the EU 7th Framework Programme FP7/2007-2013 under Grant agreement No. 309048 (project SiNGULAR)

Nonalcoholic fatty liver disease and liver fibrosis in bariatric patients: Tehran obesity treatment study (TOTS)

Background: Non-alcoholic fatty liver disease (NAFLD) has become a leading cause of chronic liver disease worldwide. We aimed to study this condition and liver fibrosis in bariatric patients at baseline using ultrasound, NAFLD fibrosis score (NFS), and fibrosis index-4 (FIB-4). Methods: Adult patients with morbid obesity without other possible causes of liver pathology were evaluated. Liver biopsy was performed in a subset of patients. Diagnostic accuracy of tests was assessed using area under the receiver operating-characteristic curve (AUROC). Results: Overall, 1944 patients with mean age of 38.3 ± 10.8 years and body mass index of 44.6 ± 6.4 kg/m2 comprised the study population. Liver Biopsyshowed features of NAFLDin 70; 60.3 hadnonalcoholic fatty liver and9.6 steatohepatitis. Older age and higher transaminase levels were associated with higher NAFLD activity score. Fibrosis was present in 23.3 with the majority having F1. Ultrasound detected steatosis in 76.8, with two-thirds having grade I to II fatty liver. Metabolic syndrome, hemoglobin A1c, age, and alanine transaminase were the strongest risk factors for fatty liver. Ultrasound showed an AUROC of 0.75 (95 confidence interval 0.63-0.86) for NAFLD with a sensitivity and specificity of 72.5 and 68.2, respectively (cutoff of grade II). For diagnosis of fibrosis, FIB-4 had an AUROC of 0.72 (0.58-0.86) with 93.3 sensitivity and 43.1 specificity (cutoff of 0.50). NFS failed to show a significant AUROC curve for diagnosing fibrosis. Conclusions: Our findings confirmed a high prevalence of NAFLD in morbidly obese patients. Despite this high prevalence, fibrosis was uncommon and low-grade. This study questions the use of current cutoffs for NFS and FIB-4 in all patients. © 2018, Hepatitis Monthly

Nonalcoholic fatty liver disease and liver fibrosis in bariatric patients: Tehran obesity treatment study (TOTS)

Background: Non-alcoholic fatty liver disease (NAFLD) has become a leading cause of chronic liver disease worldwide. We aimed to study this condition and liver fibrosis in bariatric patients at baseline using ultrasound, NAFLD fibrosis score (NFS), and fibrosis index-4 (FIB-4). Methods: Adult patients with morbid obesity without other possible causes of liver pathology were evaluated. Liver biopsy was performed in a subset of patients. Diagnostic accuracy of tests was assessed using area under the receiver operating-characteristic curve (AUROC). Results: Overall, 1944 patients with mean age of 38.3 ± 10.8 years and body mass index of 44.6 ± 6.4 kg/m2 comprised the study population. Liver Biopsyshowed features of NAFLDin 70; 60.3 hadnonalcoholic fatty liver and9.6 steatohepatitis. Older age and higher transaminase levels were associated with higher NAFLD activity score. Fibrosis was present in 23.3 with the majority having F1. Ultrasound detected steatosis in 76.8, with two-thirds having grade I to II fatty liver. Metabolic syndrome, hemoglobin A1c, age, and alanine transaminase were the strongest risk factors for fatty liver. Ultrasound showed an AUROC of 0.75 (95 confidence interval 0.63-0.86) for NAFLD with a sensitivity and specificity of 72.5 and 68.2, respectively (cutoff of grade II). For diagnosis of fibrosis, FIB-4 had an AUROC of 0.72 (0.58-0.86) with 93.3 sensitivity and 43.1 specificity (cutoff of 0.50). NFS failed to show a significant AUROC curve for diagnosing fibrosis. Conclusions: Our findings confirmed a high prevalence of NAFLD in morbidly obese patients. Despite this high prevalence, fibrosis was uncommon and low-grade. This study questions the use of current cutoffs for NFS and FIB-4 in all patients. © 2018, Hepatitis Monthly

COVID-19 symptoms at time of testing and association with positivity among outpatients tested for SARS-CoV-2

Introduction Symptoms associated with SARS-CoV-2 infection remain incompletely understood, especially among ambulatory, non-hospitalized individuals. With host factors, symptoms predictive of SARS-CoV-2 could be used to guide testing and intervention strategies. Methods Between March 16 and September 3, 2020, we examined the characteristics and symptoms reported by individuals presenting to a large outpatient testing program in the Southeastern US for nasopharyngeal SARS-CoV-2 RNA RT-PCR testing. Using self-reported symptoms, demographic characteristics, and exposure and travel histories, we identified the variables associated with testing positive using modified Poisson regression. Results Among 20,177 tested individuals, the proportion positive was 9.4% (95% CI, 9.0–9.8) and was higher for men, younger individuals, and racial/ethnic minorities (all P<0.05); the positivity proportion was higher for Hispanics (26.9%; 95% CI. 24.9–29.0) compared to Blacks (8.6%; 95% CI, 7.6–9.7) or Whites (5.8%; 95% CI, 5.4–6.3). Individuals reporting contact with a COVID-19 case had the highest positivity proportion (22.8%; 95% CI, 21.5–24.1). Among the subset of 8,522 symptomatic adults who presented for testing after May 1, when complete symptom assessments were performed, SARS-CoV-2 RNA PCR was detected in 1,116 (13.1%). Of the reported symptoms, loss of taste or smell was most strongly associated with SARS-CoV-2 RNA detection with an adjusted risk ratio of 3.88 (95% CI, 3.46–4.35). The presence of chills, fever, cough, aches, headache, fatigue and nasal congestion also significantly increased the risk of detecting SARS-CoV-2 RNA, while diarrhea or nausea/vomiting, although not uncommon, were significantly more common in those with a negative test result. Symptom combinations were frequent with 67.9% experiencing ≥4 symptoms, including 19.8% with ≥8 symptoms; report of greater than three symptoms increased the risk of SARS-CoV-2 RNA detection. Conclusions In a large outpatient population in the Southeastern US, several symptoms, most notably loss of taste or smell, and greater symptom burden were associated with detection of SARS-CoV-2 RNA. Persons of color and those with who were a contact of a COVID-19 case were also more likely to test positive. These findings suggest that, given limited SARS-CoV-2 testing capacity, symptom presentation and host characteristics can be used to guide testing and intervention prioritization

Trends of obesity and abdominal obesity in Tehranian adults: a cohort study

<p>Abstract</p> <p>Background</p> <p>Considering the increasing trend of obesity reported in current data, this study was conducted to examine trends of obesity and abdominal obesity among Tehranian adults during a median follow-up of 6.6 years.</p> <p>Methods</p> <p>Height and weight of 4402 adults, aged 20 years and over, participants of the Tehran Lipid and Glucose Study (TLGS), were measured in 1999-2001(phase I) and again in 2002-2005(phase II) and 2006-2008 (phase III). Criteria used for obesity and abdominal obesity defined body mass index (BMI) ≥ 30 and waist circumference ≥ 94/80 cm for men/women respectively. Subjects were divided into10-year groups and the prevalence of obesity was compared across sex and age groups.</p> <p>Results</p> <p>The prevalence of obesity was 15.8, 18.6 and 21% in men and 31.5, 37.7 and 38.6% in women in phases I, II and III respectively (p < 0.001). The prevalence of abdominal obesity in men was 36.5, 57.2 and 63.3% and in women was 76.7, 83.8 and 83.6% in the three periods mentioned (p < 0.001). Men aged between 20-29 years had highest increase rates of obesity and abdominal obesity in phase III in comparison with phase I (with a respective rates of 2.2- and 3.3-fold). In both sexes, an increased trend was observed between phases I and II, whereas between phases II and III, this trend was observed in men, but not in women.</p> <p>Conclusion</p> <p>This study demonstrates alarming rises in the prevalences of both obesity and abdominal obesity in both sexes especially in young men, calling for urgent action to educate people in lifestyle modifications.</p

Evaluation of a COVID-19 convalescent plasma program at a U.S. academic medical center

Amidst the therapeutic void at the onset of the COVID-19 pandemic, a critical mass of scientific and clinical interest coalesced around COVID-19 convalescent plasma (CCP). To date, the CCP literature has focused largely on safety and efficacy outcomes, but little on implementation outcomes or experience. Expert opinion suggests that if CCP has a role in COVID-19 treatment, it is early in the disease course, and it must deliver a sufficiently high titer of neutralizing antibodies (nAb). Missing in the literature are comprehensive evaluations of how local CCP programs were implemented as part of pandemic preparedness and response, including considerations of the core components and personnel required to meet demand with adequately qualified CCP in a timely and sustained manner. To address this gap, we conducted an evaluation of a local CCP program at a large U.S. academic medical center, the University of North Carolina Medical Center (UNCMC), and patterned our evaluation around the dimensions of the Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) framework to systematically describe key implementation-relevant metrics. We aligned our evaluation with program goals of reaching the target population with severe or critical COVID-19, integrating into the structure of the hospital-wide pandemic response, adapting to shifting landscapes, and sustaining the program over time during a compassionate use expanded access program (EAP) era and a randomized controlled trial (RCT) era. During the EAP era, the UNCMC CCP program was associated with faster CCP infusion after admission compared with contemporaneous affiliate hospitals without a local program: median 29.6 hours (interquartile range, IQR: 21.2–48.1) for the UNCMC CCP program versus 47.6 hours (IQR 32.6–71.6) for affiliate hospitals; (P<0.0001). Sixty-eight of 87 CCP recipients in the EAP (78.2%) received CCP containing the FDA recommended minimum nAb titer of ≥1:160. CCP delivery to hospitalized patients operated with equal efficiency regardless of receiving treatment via a RCT or a compassionate-use mechanism. It was found that in a highly resourced academic medical center, rapid implementation of a local CCP collection, treatment, and clinical trial program could be achieved through redeployment of highly trained laboratory and clinical personnel. These data provide important pragmatic considerations critical for health systems considering the use of CCP as part of an integrated pandemic response

Expected Performances of the NOMAD/ExoMars instrument

NOMAD (Nadir and Occultation for MArs Discovery) is one of the four instruments on board the ExoMars Trace Gas Orbiter, scheduled for launch in March 2016. It consists of a suite of three high-resolution spectrometers – SO (Solar Occultation), LNO (Limb, Nadir and Occultation) and UVIS (Ultraviolet and Visible Spectrometer). Based upon the characteristics of the channels and the values of Signal-to-Noise Ratio obtained from radiometric models discussed in [Vandaele et al., Optics Express, 2015] and [Thomas et al., Optics Express, 2015], the expected performances of the instrument in terms of sensitivity to detection have been investigated. The analysis led to the determination of detection limits for 18 molecules, namely CO, H2O, HDO, C2H2, C2H4, C2H6, H2CO, CH4, SO2, H2S, HCl, HCN, HO2, NH3, N2O, NO2, OCS, O3. NOMAD should have the ability to measure methane concentrations <25 parts per trillion (ppt) in solar occultation mode, and 11 parts per billion in nadir mode. Occultation detections as low as 10 ppt could be made if spectra are averaged [Drummond et al., Planetary Space and Science, 2011]. Results have been obtained for all three channels in nadir and in solar occultation

SARS-CoV-2 seroprevalence among a southern U.S. population indicates limited asymptomatic spread under physical distancing measures

Characterizing the asymptomatic spread of SARS-CoV-2 is important for understanding the COVID-19 pandemic. This study was aimed at determining asymptomatic spread of SARS-CoV-2 in a suburban, Southern U.S. population during a period of state restrictions and physical distancing mandates. This is one of the first published seroprevalence studies from North Carolina and included multicenter, primary care, and emergency care facilities serving a low-density, suburban and rural population since description of the North Carolina state index case introducing the SARS-CoV-2 respiratory pathogen to this population. To estimate point seroprevalence of SARS-CoV-2 among asymptomatic individuals over time, two cohort studies were examined. The first cohort study, named ScreenNC, was comprised of outpatient clinics, and the second cohort study, named ScreenNC2, was comprised of inpatients unrelated to COVID-19. Asymptomatic infection by SARS-CoV-2 (with no clinical symptoms) was examined using an Emergency Use Authorization (EUA)-approved antibody test (Abbott) for the presence of SARS-CoV-2 IgG. This assay as performed under CLIA had a reported specificity/sensitivity of 100%/99.6%. ScreenNC identified 24 out of 2,973 (0.8%) positive individuals among asymptomatic participants accessing health care during 28 April to 19 June 2020, which was increasing over time. A separate cohort, ScreenNC2, sampled from 3 March to 4 June 2020, identified 10 out of 1,449 (0.7%) positive participants. IMPORTANCE This study suggests limited but accelerating asymptomatic spread of SARS-CoV-2. Asymptomatic infections, like symptomatic infections, disproportionately affected vulnerable communities in this population, and seroprevalence was higher in African American participants than in White participants. The low, overall prevalence may reflect the success of shelter-in-place mandates at the time this study was performed and of maintaining effective physical distancing practices among suburban populations. Under these public health measures and aggressive case finding, outbreak clusters did not spread into the general population