The particle migration was analyzed by applying two methods: sampling hardened concrete exposed to pumping and performing X-ray microcomputed tomography (μCT) and image analysis to determine the thickness of the lubricating layer due to SIPM. The results indicate that the first approach is unsuitable due to the nearly equal molecular density of particles and matrix. The second approach indicated that the actual thickness of the lubricating layer depends on the discharge rate as well as on ϕ and viscosity of concrete bulk; hence, it cannot be defined as a constant parameter for all concrete mixtures. Additionally, the concrete pipe-flow pattern, i.e., plug versus shear flow, was captured and studied while considering pumping pressure and discharge rate. It was concluded that particle migration is essential in the cases of both flowable and very flowable concretes with a high volume-fraction of solids. The changes in rheological properties caused by SIPM are severe enough to influence the definition of the flow pattern as plug or shear and the discharge rate of pumped concrete as well.In this paper, the authors have focused on shear-induced particle migration (SIPM), its effect on concrete flow patterns, and lubricating layer formation during pumping. For this purpose, various volume-fractions  In concrete rheology, the granular nature of concrete is often neglected when performing rheological investigations or studying flow behavior with respect to various applications. This being so, it is generally assumed that the concrete’s constituents are uniformly distributed throughout the sampling volume during rheological measurements with wide-gap rheometers ,2. AnothConcrete as a viscous granular suspension is a manifestation of the migration of solid inclusions in an inhomogeneous flow field occurring during pumping. According to , the floPhillips et al.  proposedTo investigate the influence of SIPM on coarse particles of concrete during pumping, the authors focused on particles larger than 1 mm, assuming that aggregates of an irregular shape with continuous size distribution are suspended in a fine homogenous, cementitious mortar. This paper treats the experimental analysis of the SIPM of aggregates larger than 1 mm and its influence on the pumping behavior of conventional vibrated concrete (CVC) and self-compacting concrete (SCC). New approaches for capturing the thickness of the lubricating layer and the non-uniform particle distribution resulting from SIPM during pumping are introduced. According to the results the current methodologies which generally consider concrete as two homogeneous fluids—concrete bulk and lubricating layer—with defined rheological properties determined using rheometers are insufficient for predicting the pumping behavior of modern concretes ,18,19. BThe rate of deformation for any fluid undergoing shear stress depends on its apparent viscosity itten as :(1)τ=η and (3). One fluid is a thin layer of fine mortar that is formed in the vicinity of the wall . This so3/s) in a pipeline of length Considering the rheological properties of both concrete bulk and the lubricating layer, the relationship between pumping pressure loss tion 6) :(6)Q=∫RLng layer . The ΔP− :(6)Q=∫Rigations ,24.The multiphase approach is more complex in comparison to its single-phase version. Here, the impact of the granular phase and interparticle interactions on the properties of concrete bulk and the lubricating layer during pumping must be considered and implemented in the flow formulations. The shear-induced particle migration (SIPM) and the wall-effect are addressed as the main mechanisms behind the formation of the lubricating layer. The rheological properties of concrete and the lubricating layer as well as the thickness of the lubricating layer are investigated with regards to SIPM. Consequently, the derived pumping formulation is linked to changes in the granular phase. To do so, deeper insights and more experimental evidence on shear-induced particle migration of concrete during pumping are required.Shear-induced particle migration occurs when the granular phase of concrete is subject to non-uniformly distributed shear stresses and shear rates; see Due to the non-uniform distribution of shear stresses over the cross-section, forces of different magnitudes are acting on the various particle surfaces. The resultant forces induce a radial displacement of the particle in addition to its transient displacement along the pipeline . The larormation .The suspension balance model  and diffBased on the diffusive flux model, Phillips et al.  developey et al.  adapted Spangenberg et al.  showed tTwo types of concrete were considered: conventional vibrated concrete (CVC) and self-compacting concrete (SCC). The mixture compositions are given in The name of each mixture is composed of a capital letter indicating whether the concrete is of type CVC or SCC and a number giving the volume-fraction of aggregates larger than 1 mm in size. For example, C52 is a CVC mixture with aggregates larger than 1 mm taking 52% of its volume. The additional “c” in C47c and S42c marks the replacement of round 8–16 mm size aggregates with crushed basalt aggregates of 8–11 mm and 11–16 mm. Since according to Equation (7) the volume-fraction of aggregates is one of the most decisive parameters in evaluating SIPM ,9, it waMixing and testing were performed in the laboratory at a temperature of 26.6 ± 2 °C and a relative humidity of 49% ± 7%. The water and aggregates were cooled prior to mixing to achieve a concrete temperature of 20 ± 2.5 °C. The maximum packing density of the aggregates was determined by de Larrard’s approach  and resu as ϕ/ϕc , was calRheological measurements were carried out on concrete and constitute mortar within an age span of 30–40 min. The fine mortar was obtained by wet-screening of the concrete on a 1-mm sieve ,32.T of the material is measured while applying a rate-controlled hysteresis loop with predefined rotational velocity N. The maximum rotational velocity was chosen to attain an approximated shear rate of 10 s−1 in the sample. For data evaluation, the methods listed in oR, i,R and H correspond to outer and inner radii, and the height of the sampling volume, respectively.−7 Pa shear stress. Obviously, differences in the values of yield stress and plastic viscosity should be considered only if measured above the resolution range. For SCC mixtures with shear-thickening behavior, the modified Bingham (MB) model was used for calculating the rheological parameters . For CVC3/h for CVC and 540 m3/h for SCC mixtures [Kasten  developemixtures . Indeed,mixtures . More inmixtures ,36.The lubricating layer is usually defined either as the region with highest velocity gradient or as the region consisting of a fine cementitious mortar at the interface between concrete in relative motion and the pipe wall. In this work the lubricating layer and its thickness are defined as the region with very fine mortar containing aggregates smaller than 1 mm. To capture the real thickness of the lubricating layer, a combined approach was implemented: concrete sampling in the Sliper device and X-ray microcomputed tomography of the interface transition zone. Both methods are described below.Direct visual observation is a natural approach when studying particle motion. The shear-induced particle migration was reproduced by means of experiments with the Sliper at various velocities. During measurement in the sliding pipe, the deformation of the top surface of concrete was recorded to track the flow pattern for various discharge rates, i.e., for plug flow, partial shear, and full shear of concrete bulk. The initial evaluation of the videos indicated that with partial and full shear flows, the particles at the surface move/rotate toward the pipe wall. While inside the sample each particle is restricted from all sides, the particles positioned at the surface can move more freely. Still, the deformation on the free surface could represent deformations within the sample: On the free surface, the displacements of the particles are greater and the plug radius is smaller than inside the sample.Theoretically, such radial and angular displacements can be traced back to the parabolic velocity profile of the sample during pumping, which consists of a non-zero resultant velocity vector on one side of the particle. The cross product of the particle lever arm by the resultant velocity vector renders the angular velocity. The superimposition of this angular displacement on the main longitudinal displacement results in the radial displacement of the particle. The radial and angular displacements increase with an increase in the size of particles. At the same time, the displacement of a particle in a densely packed suspension is limited by the rheological properties of its surroundings. According to Hagen-Poiseuille law the velocity magnitude over radius correlates with All things considered, the authors assumed that the radial velocity of the particles at the top is related to the degree and intensity of the curvature in the velocity profile generated under specific pressure loss or e.g., .To determine the radial velocity of particles, a single stroke was chosen with a discharge rate of approximately It is noteworthy that the radial displacement of each aggregate particle is influenced by its size, mass, and shape. The irregular shapes of the particles result in rotational motion in addition to the radial displacement. One of the reasons for assuming spherical particles in granular science is to avoid complications such as this.Prior to each measurement with Sliper, a tube with Thin discs were cut from the cylinders. They were purposely divided into nine circular sectors for X-ray microcomputed tomography (μCT). The two remaining cylinders were longitudinally cut along the A–A axis. The resulting half-cylinders (1 + 2 and 3 + 4) were visually assessed in respect of their lubricating layer thicknesses. The examples of the A–A cross-section in The contrast observed between aggregates and the matrix during the visual assessment of the half-cylinders offered the possibility to determine the lubricating layer thickness over the whole length of the Sliper samples. To analyze the images the software ImageJ (version 1.52m) was used. The maximum and minimum diameters were calculated to distinguish between different aggregate fractions. A short ruler later used as the scale for determining length was captured in all images. The distances between aggregates larger than 1 mm and the pipe wall, as marked in The visible particles larger than 1 mm were marked and the distance between the center of each particle to the wall was determined; see ented in ,26 hold The technique of X-ray microcomputed tomography (μCT) was applied to the concrete samples (“pizza slices”) to screen the interface transition zone between pipe and concrete. The primary goal was to determine quantitatively the thickness of the lubricating layer and the size and volume of the aggregates. Data from numerous X-ray radiographs was also processed to produce 3D images of the volumes under investigation. Various resolutions were applied to capture the distribution of particles in the lubricating layer and its transition to the plug region based on density differences between matrix and aggregates. 2D images and computed 3D images specified most aggregates larger than 4 mm. Aggregates with sizes between 2 and 4 mm were detectable in some cases. However, the margins between the coarser aggregates and the surrounding fine mortar could not be assessed quantitatively. The authors also observed that particles smaller than 2 mm—sand, fine sand, unhydrated binder, and hydration products—were densely packed, and therefore it was difficult to distinguish the position of these particles. Hence, the methodology was found unsuitable for deriving the thickness of the lubricating layer containing particles finer than 1 mm.In this study, the authors considered the mortar as the suspending medium (liquid phase) and the aggregates as the suspended phase (solid phase) of the concrete. The measured Bingham parameters for the both mortar and concrete are summarized in For the sake of clarity, the rheological parameters are also represented using rheographs in Based on the composition, the ratios among the solid constituents, the water-to-binder ratio (w/b), and the dosage of superplasticizer were kept constant for the mortars. C42 and S37 with volumetric aggregate content reduced by 5% showed similar rheological behavior to that of C47 and S42; see Investigation of the concrete mixtures shows very clear tendencies: an increase in the volume-fraction of aggregates or replacement of round aggregates with crushed ones results in significant growth of yield stress and plastic viscosity for both CVC and SCC. The arrows in ickening . By incrDuring each stroke of the Sliper, only 0.5 m height of the material is being deformed (“pumped”) during the experiment. By dividing the observed pressure values by 0.5 m, the pressure loss per unit length in a DN125 pipe can be calculated and drawn at different discharge rates and for each composition. The thickness of the lubricating layer milar to . The rheNote that the values listed in s et al.  showed ts et al. .The actual thickness of the lubricating layer for each mixture can be obtained using the half-cylinder specimen tested in the Sliper; see For each value reported in With an increasing volume-fraction of coarse particles, the thickness of the lubricating layer decreases: the migration of coarse particles is hindered when the local volume-fraction of particles in the neighboring region reaches 0.8 ϕc ,9. With With an increasing rate of discharge, the thickness of the lubricating layer increases: at higher discharge rates, shear rate, and its changes with respect to radial axis  of the expected values . In Newtonian fluids, the velocity profile and discharge rates can be calculated as:The velocity profiles were calculated using Equation (6) for all mixtures and are shown in In the case of S47, with a yield stress of 6 Pa and plastic viscosity of 130 Pa·s, the authors observed distinct plug flow with particle displacements of less than 5 mm during the drop. This mixture had the greatest amount of solid particulate with 83.86% by volume in total and 62% of particles larger than 0.06 mm, without binders. The maximum packing fraction of solids larger than 0.06 mm was determined experimentally as 79.74%, which results in initial ified asγsample=Hd stress . Any furComparison of Until now most researchers have assumed that the variations in rheological parameters due to SIPM are not significant enough to influence the flow properties inside a pipeline. Thus, the assumption of two immiscible single-phase fluids—concrete bulk and the lubricating layer—with constant rheological parameters was sufficient to predict pumping behavior. However, the results observed in this discussion indicate that for mixtures such as S47 with a high volume-fraction of solid particles, the changes in the local volume-fraction of solids, and as a consequence, the changes in the local rheological properties are severe enough to alter the pipe-flow regime. Therefore, it is of utmost importance that the variations of local rheological parameters due to SIPM be considered in the pipe-flow equations.The Bingham rheological parameters of concrete increase with increasing aggregates’ volume-fraction . Two approaches were suggested for capturing the lubricating layer thickness of concrete. Additionally, the rheological properties and pumping behavior of concrete mixtures were investigated with respect to the volume-fraction of aggregates. The experimental outputs were compared with the state-of-the-art in concrete pumping and the analytical flow formulations developed for concrete mixtures. Finally, the flow patterns captured on the surface of the “pumped” samples in the Sliper device were studied with respect to rheological properties and particle migration. The following conclusions can be drawn:Understanding and implementation of SIPM for a polydispersed suspension such as concrete with a continuous particle size distribution in analytical flow formulation requires further experimental investigation. In the next phase, it is planned to replace coarse aggregates by colored and spherical glass beads. This approach should increase the accuracy in investigating the influence of aggregates’ content and properties on particle distribution due to SIPM and the thickness of the resultant lubricating layer.


To appraise European guidelines for acute otitis media (AOM) in children, including methodological quality, level of evidence (LoE), astrength of recommendations (SoR), and consideration of antibiotic stewardship.Systematic review of the literature.Three-pronged search of (1) databases: Medline, Embase, Cochrane library, Guidelines International Network and Trip Medical Database; (2) websites of European national paediatric associations and (3) contact of European experts. Data were collected between January 2017 and February 2018.National guidelines of European countries for the clinical management of AOM in children aged <16 years.Data were extracted using tables constructed by the research team. Guidelines were graded using AGREE II criteria. LoE and SoR were compared. Guidelines were assessed for principles of antibiotic stewardship.AOM guidelines were obtained from 17 or the 32 countries in the European Union or European Free Trade Area. The mean AGREE II score was ≤41% across most domains. Diagnosis of AOM was based on similar signs and symptoms. The most common indication for antibiotics was tympanic membrane perforation/otorrhoea . The majority  recommended a watchful waiting approach to antibiotics. Amoxicillin was the most common first-line antibiotic . Recommended treatment duration varied from 5 to 10 days. Seven countries advocated high-dose (75–90 mg/kg/day) and five low-dose (30–60 mg/kg/day) amoxicillin. Less than 60% of guidelines used a national or international scale system to rate level of evidence to support recommendations. Under half of the guidelines  referred to country-specific microbiological and antibiotic resistance data.Guidelines for managing AOM were similar across European countries. Guideline quality was mostly weak, and it often did not refer to country-specific antibiotic resistance patterns. Coordinating efforts to produce a core guideline which can then be adapted by each country may help improve overall quality and contribute to tackling antibiotic resistance. The methodology includes the use of a comprehensive three-pronged search strategy with no language restrictions to identify guidelines from across Europe, the use of a standardised and internationally recognised guideline appraisal tool (AGREE II), the assessment of levels of evidence and strength of recommendations and the assessment of whether antibiotic stewardship, a key measure to reduce antimicrobial resistance (AMR), was considered.The review focused only on AOM without complications; guidelines for complex otitis media requiring specialist otolaryngology input were not included. Another limitation is the consideration of whether guidelines developers used country-specific AMR patterns to assess if the recommendations of antibiotics were based on AMR data. However, there is often wide heterogeneity in terms of AMR patterns within each country.Acute otitis media (AOM) is one of the most common infections in childhood9The rationale for antibiotic prescription includes symptom control18To promote antibiotic stewardship, the WHO recommends the development of treatment guidelines and the monitoring of local antibiotic resistance to inform the choice of antibiotics.To ensure a comprehensive review of nationally endorsed guidelines, we used a three-pronged approach that included (1) a systematic database search; (2) a website search of European national societies and (3) expert consultation.First, a systematic search of databases was carried out using Medline, Embase, Cochrane library, Guidelines International Network and Trip Medical Database from April 2017 to February 2018. Search terms were a combination of synonyms for (1) acute otitis media and (2) guidelines. Guidelines were included if they met the following eligibility criteria: (1) they were pertaining to the management of simple AOM, excluding the management of chronic or complex otitis media cases requiring specialist otolaryngology input; (2) they were national guidelines or endorsed by the national medical society from a European Union (EU) or European Free Trade Area (EFTA) country and (3) published from the year 2000 to present. The American Association of Pediatrics (AAP)10.1136/bmjopen-2019-035343.supp1Supplementary data10.1136/bmjopen-2019-035343.supp2Supplementary dataThis systematic review was performed without patient involvement.The AGREE II instrument was used independently by two reviewers (HS and JED) to determine the quality of each national guideline.National scales for grading levels of evidence (LoE) and SoR were converted to Oxford Centre for Evidence Based Medicine (OCEBM) LoE and SoR see . However10.1136/bmjopen-2019-035343.supp3Supplementary data10.1136/bmjopen-2019-035343.supp4Supplementary dataet al.25As we were unable to find a standard scoring system to assess if a clinical guideline includes consideration of antibiotic stewardship, we based our methodology on a study by Elias The search retrieved 7340 records . Of thesOf note, 15 of 17 (88%) European guidelines outlined the signs and symptoms for diagnosing AOM see  with con10.1136/bmjopen-2019-035343.supp5Supplementary dataExamination tools including standard otoscopy were advised by 15 of 17 (88%) European guidelines see . Pneumat10.1136/bmjopen-2019-035343.supp6Supplementary dataNo guidelines advised routine laboratory or radiographic investigations see . Of note10.1136/bmjopen-2019-035343.supp7Supplementary dataThere were two approaches towards antibiotic administration: a watchful waiting approach and immediate antibiotic prescription . FifteenOf note, 14 of 17 (82%) European guidelines recommended oral amoxicillin as an option for first-line treatment , of whic10.1136/bmjopen-2019-035343.supp8Supplementary dataIn case of treatment failure, per oral/intravenous amoxicillin-clavulanic acid  and intravenous/intramuscular ceftriaxone  were the most commonly recommended antibiotics. In case of penicillin allergy, guidelines advised either oral clarithromycin  or oral trimethoprim–sulfamethoxazole  see .All guidelines were appraised using the AGREE II Criteria . In four10.1136/bmjopen-2019-035343.supp9Supplementary dataOf note, 10 of 17 European guidelines (59%) based their certainty of evidence  and SoR on a variety of methodologies . The onlThe majority of guidelines provided diagnostic criteria for AOM, specifications on when to start antibiotics, the route of administration and the duration of treatment . HoweverApproximately half of the 32 EU/EFTA countries have AOM guidelines. Diagnosis of AOM was based on similar signs and symptoms. Tympanocentesis was commonly reserved for treatment failure. The vast majority of European guidelines advocated for a watchful waiting approach to antibiotic therapy with the most common indications for treatment being TM perforation and severity of symptoms. Amoxicillin was the most commonly recommended first-line antibiotic but with differences in terms of recommended duration and dosage. Our quality assessment found low mean AGREE II scores of ≤41% in most domains. Less than 60% of guidelines used a national or international system to rate LoE to support recommendations. Less than half of the guidelines referred to country-specific patterns of AMR.Strengths of our study include the comprehensiveness of our three-pronged search strategy, the use of AGREE II, an internationally recognised guideline appraisal tool and an assessment of which LoE and SoR were used. Our analysis also included a qualitative assessment of whether antibiotic stewardship was considered in the development of guidelines based on five criteria. In order to provide a broad sense on whether AMR data were considered, one of the criteria was whether the antibiotic recommendations referred to national-level AMR data. However, the limitation of this is that there is often wide heterogeneity in AMR patterns within each country, therefore guidelines should ideally recommend that the antibiotic choice be adapted to available local AMR data. Another limitation is our focus on simple AOM and exclusion of guidelines about complex cases requiring otolaryngology specialist input.et al also used AGREE II scores to assess quality of upper respiratory tract infections guidelines including three AOM guidelines from Japan, USA and UK.et al and ourselves for UK SIGN and US AAP AOM guidelines. This may indicate inter-user variability in AGREE II scoring.et al assessed global infectious diseases guidelines and found that local AMR patterns were taken into account in 50%–75% of recommendations which is similar to our findings.Previously published works demonstrated a common consensus in criteria for AOM diagnosis, and that a watchful waiting period was the standard of care in Europe; amoxicillin was also found to be the most commonly recommended antibiotic.The development of clinical guidelines according to the high standards of the AGREE II criteria is a resource -intensive exercise and this may be one of the reasons why we did not identify any guidelines from some countries. Many guidelines in this study received low AGREE II scores. Many of the resource-intensive initial steps in guidelines development are universal, for example defining the objectives, the clinical questions, the target populations of patients and end users and designing a comprehensive search strategy to identify relevant evidence from the literature, a process to appraise the evidence, a way to present recommendations unambiguously and strategies to successfully implement guidelines. Replicating this process in each country to reach similar conclusions does not seem necessary nor efficient, and it may make sense for these or some of these processes to be undertaken by a core group of experts from across Europe. This is already the case for other medical specialities, for example the European Joint Task Force for cardiovascular disease prevention provides guidelines that can be used across Europe.Review of guidelines reveals major similarities in AOM management recommendations across Europe. Existing European guidelines scored poorly in most AGREE II domains, including items related to how evidence was gathered and appraised. Consideration of country-specific antibiotic resistance patterns appears to be limited. Centrally produced guidelines adapted for local care pathways, user and patient preferences, and for local antimicrobial resistance patterns may provide more targeted recommendations, reduce unnecessary antibiotic administration and help reduce the spread of antibiotic resistance.


We aimed to evaluate recording of antibiotic prescribing from two primary care electronic health record systems.Cohort study.UK general practices contributing to the Clinical Practice Research Datalink (CPRD) databases: CPRD GOLD (Vision data) and CPRD Aurum (EMIS data). English CPRD GOLD general practices were analysed as a subgroup, as all CPRD Aurum practices were located in England.158 305 patients were randomly sampled from CPRD Aurum and 160 394 from CPRD GOLD.Antibiotic prescriptions in 2017 were identified. Age-standardised and sex-standardised antibiotic prescribing rates per 1000 person years were calculated. Prescribing of individual antibiotic products and associated medical diagnoses was evaluated.There were 101 360 antibiotic prescriptions at 883 CPRD Aurum practices and 112 931 prescriptions at 290 CPRD GOLD practices, including 112 general practices in England. The age-standardised and sex-standardised antibiotic prescribing rate in 2017 was 512.6 (95% CI 510.4 to 514.9) per 1000 person years in CPRD Aurum and 584.3 (582.1 to 586.5) per 1000 person years in CPRD GOLD (505.2 (501.6 to 508.9) per 1000 person years if restricted to practices in England). The 25 most frequently prescribed antibiotic products were similar in both databases. One or more medical codes were recorded on the same date as an antibiotic prescription for 72 989 (74%) prescriptions in CPRD Aurum, 84 756 (78%) in CPRD GOLD and 28 471 (78%) for CPRD GOLD in England. Skin, respiratory and genitourinary tract infections were recorded for 39 035 (40%) prescriptions in CPRD Aurum, 41 326 (38%) in CPRD GOLD, with 15 481 (42%) in English CPRD GOLD practices only.Estimates for antibiotic prescribing and infection recording were broadly similar in both databases suggesting similar recording across EMIS and Vision systems. Future research on antimicrobial stewardship can also be conducted using primary care data in CPRD Aurum. The study drew on two databases that include large nationwide samples of general practice registered populations.Clinical Practice Research Datalink (CPRD) GOLD has UK-wide coverage and comprises data recorded using the Vision practice management system only. At the time of this study, CPRD Aurum general practices were located in England only and included data recorded using the EMIS practice management system. This may contribute to differences between databases.We excluded general practices that migrated from Vision to EMIS software system during the study period.We employed consistent data definitions and analysis methods across the two databases.We analysed data for a single 12-month period; it is possible that changes over time may differ between the two data sources.The study only investigated antibiotic prescribing, and related clinical coding; further studies are needed to address other topics of clinical and public health concern.Primary care electronic health records (EHRs) provide an important source of longitudinal population-based data for public health research and population health surveillance.While the research community has nearly 30 years of experience of using Vision data from CPRD GOLD, with numerous studies reporting on data quality,Antibiotic prescribing in primary care has been the subject of increasing interest in recent years because of the growing awareness that unnecessary prescription of antibiotics in primary care is contributing to the problem of antimicrobial resistance.The CPRD GOLD database collects data from the four countries of the UK, with 30% of contributing practices located in England at the time of this study. The CPRD GOLD database has been well describedA sample of 158 305 patients in CPRD Aurum was taken by randomly selecting ‘n’ patients from each stratum of general practice, gender and age group. The value of n=9 was selected to provide an appropriate total sample size of just over 150 000. This sampling approach ensured that each general practice was equally represented in the analysis and that age-specific rates would be estimated with equal precision. Age was calculated as the difference between year of birth and 2017. Age groups were categorised as 0–4, 5–14, 15–24, 25–34, 35–44, 45–54, 55–64, 65–74, 75–84 and 85 years and over.A comparison cohort of patients was extracted from the October 2019 release of CPRD GOLD using the online interface. In this release, there were 290 general practices contributing data to CPRD GOLD throughout 2017, including 112 in England. A sample of 160 394 patients was taken by randomly selecting n=30 patients from each stratum of general practice, gender and age group. Patients were required to have at least 12 months of follow-up in the database estimated as the difference between the latest of their registration start date and 1 January 2017, and the earliest of registration end, practice last collection date, CPRD derived death date and 31 December 2017. General practices that migrated from Vision to EMIS practice systems during 2017 were excluded.We evaluated antibiotic prescribing for the year 2017 because this was the most recent complete year that we included in a larger study of antibiotic prescribing that we report elsewhere.For CPRD GOLD, we employed a list of 2627 antibiotic drugs that were identified from searches of the CPRD GOLD product dictionary browser made by all authors. Searches were made on the drug substance name, product name, BNF chapter and BNF codes. To identify the corresponding products in CPRD Aurum, dm +d codes  associated with individual product codes in the CPRD GOLD dictionary browser were mapped to the corresponding dm +d codes in the CPRD Aurum product dictionary browser. A more complete search of the CPRD Aurum product dictionary browser was additionally undertaken on term, product name and drug substance. We also conducted searches using approximate string matching (‘fuzzy matching’) to match the CPRD Aurum product name to the CPRD GOLD product name or drug substance name from the CPRD GOLD antibiotic code list. The ‘agrep’ command was used in the R program,We analysed medical codes recorded on the same date as antibiotic prescriptions. Medical diagnoses were identified by searching the CPRD GOLD medical dictionary browser for Read terms and inspecting the associated Read chapter hierarchy. As previously reported, all medical codes were subsequently classified as respiratory infections, genitourinary infections, skin infections, eye infections and ‘other codes’.Age-specific rates were estimated with 95% CIs from the Poisson distribution. Age-standardised and sex-standardised rates, and associated 95% CIs, were calculated per 1000 person years using the 2013 European Standard Population as reference. Null hypothesis significance testing was not undertaken. Instead, we present estimates and 95% CIs to enable the reader to judge whether differences between the databases may be of clinical or epidemiological importance. Potential differences between databases were evaluated using Bland-Altman plots and 95% CIsThere was no patient or public involvement in the study including development of the research question, selection of outcome measures, study design, conduct or dissemination of findings.In the CPRD Aurum sample, there were 158 305 participants from 883 general practices with 101 360 antibiotic prescriptions during 2017. In the CPRD GOLD sample, there were 160 394 patients from 290 general practices with 112 931 antibiotic prescriptions during 2017. This included 112 general practices in England and 178 in Scotland, Wales or Northern Ireland. The age-standardised and sex-standardised antibiotic prescribing rate was 512.6 (95% CI 510.4 to 514.9) per 1000 PYs in CPRD Aurum and 584.3 (582.1 to 586.5) per 1000 PYs in CPRD GOLD. The rate for CPRD GOLD practices in England was 505.2 (501.6 to 508.9) per 1000 PYs, which is similar to the rate observed in CPRD Aurum.This analysis shows that antibiotic prescribing estimates from EMIS-derived data in CPRD Aurum are broadly similar to those obtained through analysis of Vision-derived data in CPRD GOLD. This similarity includes the rates of antibiotic prescriptions for subgroups of age and gender, the drug name and strength of antibiotic products prescribed, and the recording of medical diagnoses on the same day as the antibiotic prescription. We noted that antibiotic was more frequently prescribed in CPRD GOLD than in CPRD Aurum, but this was not the case when the CPRD GOLD sample was restricted to general practices in England. This suggests that antibiotic prescribing may be higher in Wales, Northern Ireland and Scotland where prescription charges have been abolished since 2007, 2010 and 2011, respectively,Previous primary care database studies have revealed that antibiotic prescriptions are often issued without specific reasons being coded into EHRs. A high proportion of antibiotic prescriptions in the THINOne major strength of our study is that we used real-world data from primary care to estimate rates of antibiotic prescribing. Using data from primary care is likely to provide a reliable picture of prescribing patterns given that about 80% of all antibiotic prescribing in the UK’s National Health Service takes place in primary care.This study finds that analysis of EMIS-derived data in CPRD Aurum gives broadly similar estimates for antibiotic prescribing and infection recording to those reported for Vision-derived data in CPRD GOLD. CPRD GOLD includes general practices in Scotland, Wales and Northern Ireland which have slightly higher antibiotic prescribing than either EMIS or Vision general practices in England. Based on these results, we believe that future research studies can be conducted in CPRD Aurum, informed by previous results from CPRD GOLD or THIN. It may also be possible to combine data from CPRD GOLD English practices with CPRD Aurum data in research on antibiotic prescribing. As CPRD Aurum includes an increasing number of general practices, this database will become increasingly important for public health research. However, further work is needed to better understand the quality and completeness of information recorded in areas such as dosing regimen and treatment duration which are important in estimating treatment exposure in pharmacoepidemiology and pharmacovigilance research.


This study analyses the deterioration of mechanical properties in lightweight concrete after exposure to room temperature (20 °C) and high temperature, i.e., up to 1000 °C, including changes in visual appearance, loss of mass, and compressive strength. All-lightweight shale ceramsite aggregate concrete (ALWAC) and semi-lightweight shale ceramsite aggregate concrete (SLWAC) are prepared using an absolute volume method to analyse the relationships between relative ultrasonic pulse velocity, loss rate of compressive strength, damage degree, and temperature levels. Our results show that, under high temperature, the lightweight aggregate ceramsite concrete performs better compared to normal concrete. After exposure to 1000 °C, the ALWAC shows a strength loss of no more than 80%, while the normal concrete loses its bearing capacity, with a similar strength loss as the SLWAC. Furthermore, the relative ultrasonic pulse velocity and damage degree are used to evaluate the effects of high temperature on the concretes, including the voids and cracks on the surface and inside of the specimens, which induces the deterioration of mechanical properties and contributes to the thermal decomposition of the cementing system and the loss of cohesion at the aggregate interface. Based on internal structure analyses, the results from this study confirm that the lightweight aggregate concrete shows a high residual compressive strength after exposure to the high temperature. Lightweight aggregate, mixed with concrete to form lightweight aggregate concrete, has been widely used in building insulation walls, tall buildings, and bridge construction ,2. CompaThe high temperature characteristics of ceramsite concrete have been widely researched. For instance, Zhou et al. analysed the residual strength, appearance characteristics, and microstructure of all-lightweight concrete after experiencing high temperature . Jiang eFurthermore, in recent studies, many modern laboratory methods have been used to reveal concrete deterioration mechanism after exposure to high temperature ,16. For This study aims to (1) investigate the performance of all-lightweight and semi-lightweight shale ceramsite concrete under high temperature, (2) analyse the strength loss rate of the lightweight aggregate concrete after exposure to various temperatures, (3) investigate the microstructural changes of the interfacial transition zone, using SEM, and (4) explore the mechanism of degradation of the lightweight aggregate concrete after exposure to high temperature.Cement and fly ash are used as cementitious materials. The cement, used in this study, is made of Huainan Bagongshan P·C 42.5 composite Portland cement , with 3-day and 28-day compressive strength of 29.9 MPa and 47.7 MPa, respectively. The fly ash is Grade Ⅰ, produced by Huainan Pingwei Power Plant . Furthermore, fine sand is used as a fine aggregate, with a fineness modulus of 2.8. Coarse aggregate, used in this study, includes the lightweight aggregate and limestone gravel, both with a continuous gradation of 5–15 mm. The lightweight aggregate is shale ceramsite, produced by Anhui Jinrui Building Materials . The basic performance parameters of the shale ceramsite are presented in Shale ceramsite is a kind of artificial porous lightweight aggregate, in which the outer surface has a coarse ceramic structure, with visible open pores and cracks . After dAccording to JGJ55-2011 “Normal Concrete Mix Design Specification”  and JGJ53, the thermal conductivity of the LC-100 is 42.4% lower than that of the NC, and the compressive strength reduces by 63.4%.As shown in Following Kong and Yu , the ligBefore the high temperature treatment, all the test specimens were dried in a drying baker at 105 ± 5 °C for 24 h to eliminate the influence of moisture content and to avoid excessive moisture content causing burst during heating . The tesHowever, after 900 °C and above, coarse crack, peeling, and scaling are observed only in the NC specimen. Subsequently, after 48 h, the internal cracks penetrate the surface, resulting in a severe break of the specimen a. MoreovThe mass loss of each raw material and concrete specimens after exposure to different temperatures are presented in The cement fly ash test specimen (10% fly ash content) shows a large mass loss rate below 600 °C, followed by a gentle decrease. The mass loss after exposure to 1000 °C is nearly 20% a. Since 3, which decomposes into CaO and CO2 at 600 to 820 °C, resulting in a significant mass reduction [The mass of gravel remains unchanged below 600 °C. Between 600 and 800 °C, the mass loss is about 5%. Above 900 °C, the mass loss decreases sharply, reaching 40% after exposure to 1000 °C a. After eduction .The shale ceramsite shows no mass loss after exposure to the high temperature. Indeed, the shale ceramsite is produced by high temperature sintering of shale, where the temperature of the sintering process exceeds 1000 °C. Comparing the appearance of gravel and shale ceramsite at the temperature of 1000 °C, the gravel’s colour changes from bluish-white to snow-white and the strength loss is considerable a,b. In cFrom The relative residual compressive strength of each concrete specimen after exposure to high temperature are presented in In addition, as it can be seen from Rv is relative ultrasonic pulse velocity, Tv is ultrasonic pulse velocity after exposure to high temperature (m/s), v0 is ultrasonic pulse velocity before exposure to high temperature (m/s), and D is damage degree.Ultrasonic testing is performed to evaluate the internal damage of concrete specimens after exposure to high temperature. Following Gong et al. (2018) and Gong and Zhang (2019), the relative ultrasonic pulse velocity and damage degree are used as evaluation parameters to eliminate the influence of aggregate type, particle size, cement type, and dosage on the ultrasonic propagation characteristics ,40, as fAs can be seen in According to 2 is greater than 0.90, and the fitting result is good, indicating that the non-destructive testing method is feasible to evaluate the compressive strength loss rate with the relative ultrasonic pulse and damage degree. In addition, similar to the fitting relationship between the ultrasonic parameters and heating temperature, with decreasing ceramsite content in the semi-lightweight aggregate concrete, the fitting relationship is closer to the NC.Ceramsite is an excellent high temperature resistance material. Microscopic characteristics of shell and core at the room temperature   and afteCompared to the normal concrete, the all-lightweight shale ceramsite aggregate concrete has a great advantage, due to its high temperature performance. Based on our experimental research, after exposure to 1000 °C, the all-lightweight shale ceramsite aggregate concrete specimen remains intact, without any damage and peeling. Under this temperature, the mass and compressive strength loss are 11.56% and 71.7%, respectively, while under the same temperature, these values for the normal concrete are 27.01% and 88.5%, respectively. Furthermore, the strength loss rate of the semi-lightweight shale ceramsite aggregate concrete is similar to the normal concrete, because of the multiple effects of high temperature softening of calcareous gravel, high temperature decomposition, and decomposition of the cement paste. In contrast, the ceramsite lightweight aggregate is an excellent high temperature resistant material, resulting in a limited loss of mass and strength after exposure to the high temperature.A comparative analysis of the relationship between relative ultrasonic pulse velocity, damage degree, heating temperature, and compressive strength loss rate suggest that with increasing the heating temperature, the relative ultrasonic pulse velocity decreases gradually, while the damage degree and the compressive strength loss rate increase. The fitting effect of the regression formula is good, suggesting that it is reasonable and feasible to use relative ultrasonic pulse velocity and damage degree as evaluation parameters to judge the performance degradation of concrete after exposure to high temperature.Microscopic analysis of the interfacial transition zone between the cement paste and the lightweight aggregate after exposure to different temperatures show that as the temperature increases, the cement gel is loosened and dispersed from compaction and the bond strength with the aggregate is gradually lost, resulting in loss of macroscopic strength. However, the lightweight aggregate ceramsite is not significantly damaged after exposure to high temperature, suggesting its excellent high temperature resistant property, which is the main reason that the residual strength of the lightweight aggregate concrete is higher than that of normal concrete after exposure to the high temperature.In addition, through experimental research, it can be concluded that there is an objective relationship between the deterioration of mechanical properties, damage degree, and microstructure changes of the lightweight aggregate concrete. After undergoing different degrees of high temperature, the cement hydrates are thermally decomposed, causing voids and cracks on the surface and inside of the concrete specimen, which is the primary reason for the deterioration of mechanical properties and the increase of damage degree.


The average KAP score of veterinarians, poor farm management practices, lack of awareness among farmers on prudent antibiotic use, and lack of antibiotic stewardship are the significant factors that need attention to combat the rising AMR in veterinary sector in India.The indiscriminate usage of antimicrobials in the animal health sector contributes immensely to antimicrobial resistance (AMR). The present study aims to assess the antimicrobial usage pattern and risk factors for AMR in animal husbandry sector of India. A cross-sectional survey about Knowledge, Attitude, and Practices (KAP) among veterinarians was carried out using a questionnaire comprising of 52 parameters associated with antibiotic use and the emergence of AMR in dairy herds. Respondents’ KAP scores were estimated to rank their level of knowledge, attitude, and practice. Furthermore, risk factors associated with treatment failure were analyzed by univariable and multivariable analyses. Out of a total of 466 respondents, the majority had average knowledge (69.5%), neutral attitude (93.2%), and moderate practice (51.3%) scores toward judicious antibiotic usage. Veterinarians reported mastitis (88.0%), reproductive disorders (76.6%), and hemoprotozoan infections (49.6%) as the top three disease conditions that require antibiotic usage. Most of the veterinarians (90.6%) resorted to their “own experience” as the main criteria for antibiotic choice. The use of the highest priority critically important antimicrobials (HPCIA) listed by the World Health Organization (WHO) in animals, particularly quinolones (76.8%) and third-generation cephalosporins (47.8%), has been reported. On multivariable regression analysis of the risk factors, the lack of cooperation of the dairy farmers in the completion of a prescribed antibiotic course by the veterinarian and the demand for antibiotic use even in conditions not requiring antibiotic use were found to be significantly associated with the outcome variable “treatment failure” having respective odds of 1.8 (95%CI: 1.1–3.0) and 3.6 (95%CI: 2.3–5.8) ( Antimicrobial resistance is one of the greatest public health threats that has been projected to cause globally 10 million deaths and US$100 trillion economic loss by 2050 . The widIndia is bestowed with huge livestock wealth comprising of 193.5 million cattle and 109.9 million buffaloes . The emeWhile the reliability of data on the usage of antibiotics in the animal husbandry sector is questioned in general, some developing countries including India have a negligible amount of data ,13. In tThe descriptive study was designed as a questionnaire-based cross-sectional analysis among the veterinarians of India during February 2020 to June 2020. A comprehensive review of the literature has been conducted to identify the factors influencing knowledge, attitude, and practices (KAP) on antimicrobial usage and resistance among veterinarians ,15,16. TThe questionnaire was divided into five sections: (1) Personal information; (2) Health services; (3) Knowledge, attitude, and practices toward antibiotic use; (4) Knowledge, attitude, and practices toward antimicrobial resistance; and (5) Miscellaneous section covering practices and recommendations for combating antimicrobial resistance.The preliminary draft of the questionnaire having 58 questions was reviewed by five expert researchers to identify ambiguity and content validity. Later, the questionnaire was piloted among 20 veterinarians to assess its duration, clarity, and sequence. During the processing, six questions were omitted that were inappropriate, resulting in a total of 52 questions in the final questionnaire .http://www.raosoft.com/samplesize.html?nosurvey). The sample size of 377 was estimated based on 50% response distribution, a 5% margin of error, and a 95% confidence interval. The expected response proportion of 50% was assumed based on the fact that both responses and response rates were completely unknown, since there are no previously published similar studies from India. Thereby, a total of 800 questionnaires were sent to the veterinarians selected through registered emails and/or personal contacts from professional societies and social media groups. The questionnaire was administrated by using the online interface of Google Forms  to the target population, and the survey remained open from May 2020 to June 2020. The source population of the present study comprised of registered veterinarians (Veterinary Council of India and/or State Veterinary Council) of India, and the study population included veterinarians who fulfilled the inclusion criteria of being farm animal practitioners. The sample size was calculated using the ‘Raosoft calculator’  calculated in an iterative manner. The associations between the selected variables for multivariable analysis had a VIF of less than 2. The interactions between the predictors were checked and were found to be non-significant. The model was constructed by considering all these explanatory variables using the backward stepwise approach using the Likelihood Ratio Test (LRT). The analyses were conducted using SPSS version 24.0 .The completed questionnaires were manually checked for data quality before coding on Microsoftn = 7) and vague information (n = 5) were excluded from the study.A total of 478 (59.7%) responses were received out a total of 800 questionnaires, of which 466 were with complete information. The questionnaires that contained incomplete , reproductive disorders (n = 343), and hemoprotozoan infections (n = 231) as the top three disease conditions in bovines where antibiotics are widely used. Major disease conditions found in bovines requiring antibiotic usage are listed in The decision over the choice of antibiotics in various diseases/conditions in bovines was influenced by different factors . The majviz., quinolones , third-generation cephalosporins , and fourth-generation cephalosporins  (n = 335) were the most commonly prescribed antibiotic for mastitis followed by third-generation cephalosporins  (n = 259) followed by tetracycline  and quinolones  were the top three commonly used antibiotics  mentioned by World Health Organization (WHO)  in their n = 28) a. The qun = 299) b. In casibiotics c. However, 45.5% of the veterinarians were aware of the ‘critically important list of antimicrobials’ of the WHO , while 5p-value: 0.00). The knowledge of the respondents on antimicrobial use and resistance was assessed by scoring eleven questions, with the score 1 given to correct answer while 0 was given to incorrect or not sure response . The knoAttitude toward antibiotic use and associated resistance was assessed by four questions  with scop-value: 0.00) and knowledge scores .The practice scores were assessed for thirteen questions  with a sH statistic: 10.9, df: 4, p-value: 0.03) score in the <30-year age group. Post hoc analysis revealed that the knowledge scores of veterinarians having age <30 differed significantly from the other age groups. The veterinarians with PhD degrees had significantly higher knowledge scores , and on post hoc analysis, the knowledge scores of all the groups having different educational qualifications differed significantly from each other. Moreover, a higher knowledge  score was observed among veterinarians having less than 10 years of experience, and post hoc analysis revealed that the knowledge score of veterinarians having less than 10 years of experience and veterinarians with 20–30 years of experience differed significantly from the knowledge score of veterinarians with 30–40 years of experience. The knowledge and attitude scores had no significant difference between the regions, while a higher practice score was observed amongst the veterinarians from the Western region , and post hoc analysis revealed that the practice score of veterinarians of the Western region differed significantly from that of respondents of the Northern and Eastern region. The veterinarians working in veterinary polyclinics had higher knowledge scores than those working in veterinary hospitals .The association of demographic characteristics and KAP scores were analyzed using the Mann–Whitney U test/Kruskal–Wallis H test . A signir  =  0.23, p  <  0.000), knowledge–practice , and attitude–practice  as per the criteria by Cohen (2013)  [The present study revealed weak linear correlations between knowledge–attitude (elation) .Most of the veterinarians (86.0%) admitted about ongoing antibiotic abuse in therapeutics, and 98.7% considered antimicrobial resistance as a serious public health issue. Frequent treatment failure has been reported by 21.7% of veterinarians, and therapeutic failure has been observed in mastitis treatment against HPCIA such as quinolones (13.5%), third-generation cephalosporins (11.4%), and high-priority antimicrobials such as synthetic penicillin (11.6%), penicillin (11.4%), and aminoglycosides (9.2%). For metritis treatment, veterinarians reported therapeutic failure against quinolones (2.4%), tetracyclines (2.1%), synthetic penicillins (1.9%), and third-generation cephalosporins (1.7%). The failure of effective therapeutic response to antimicrobials other than antibiotics was reported by 66.1% of veterinarians for antiparasitic drugs and 9.4% for antifungal drugs.The majority of the veterinarians (86.5%) attributed unauthorized practitioners  followed by farmers and para-vets (43.6% each) as responsible for irrational use of antimicrobials in livestock . The praAround 16.3% of veterinarians considered themselves responsible for the injudicious use of antimicrobials, and 39.1% of veterinarians used antibiotics for prophylaxis, especially to prevent outbreaks. The majority of the veterinarians (62.2%) rarely performed antibiotic susceptibility testing to complement their treatment, while 70.6% of veterinarians reported lack of laboratory facilities for performing antibiotic sensitivity testing in/near their hospital. Moreover, only 20.8% veterinarians were aware about the recommendations of the National Antimicrobial Resistance Plan of 2017, India [The univariable analysis for frequent treatment failure associated risk factors pertaining to veterinarian’s and farmer’s practices was carried out by calculating the odds ratio . All thep-value: <0.05)  , the final model contained two variables as depicted in : <0.05) a. The ad: <0.05) b. The Ho: <0.05) .The respondents were asked to provide a single best suggestion to combat antimicrobial resistance. The suggestions overlapped in many cases, and the duplicate suggestions were removed and are categorized into field level, policy level, and research level suggestions in In developing countries, possible factors for antibiotic resistance include increased and indiscriminate use of antibiotics in animal production, poor farm biosecurity, inadequate infection control practices in consort with lack of compliance with regulatory frameworks . In IndiThere are limited studies from India on antibiotic usage patterns for various conditions in animal husbandry . The preWhile choosing the antibiotics, previous experience of veterinarians remained the topmost criteria, which is in accordance with previous studies where veterinarian’s prior experience of a drug was decisive for antibiotic selection . MoreoveIn the present study, 69.5% of veterinarians had average knowledge score similar to earlier regional study from India, where 58.3% of veterinarians had a medium level of awareness on antibiotic resistance . The majThe highest consumption of antimicrobials in livestock has been reported in low- and middle-income countries where antibiotics are used for therapeutics, growth promotion, and prophylaxis . In the The reliability on diagnostic and antibiotic sensitivity testing is posited to be crucial for responsible antimicrobial use, while in the present study, 37.8% of veterinarians resorted to bacterial culture and susceptibility test results for choosing antibiotics. In addition, 70% veterinarians were not having access to well-equipped laboratory facilities for antibiotic susceptibility testing. This is in accordance with previous studies where in both veterinary ,33 and hThe majority of veterinarians (87%) believed there is an ongoing antibiotic abuse in therapeutics in India, while a lower proportion of Australian livestock veterinarians opined the current usage of antibiotics as “significant” for antibiotic resistance . MoreoveThe present study analyzed the possible risk factors of farmers and veterinarians for the development of treatment failure. The “illegitimate demands of farmers for antibiotic use” was significantly associated with treatment failure in accordance with the earlier studies, where around 33% veterinarians reported explicit demand of farmers for antibiotics . On contThe majority of the veterinarians (82.8%) reported the purchase of antibiotics without prescription by farmers in accordance with earlier studies from India, where the lack of adequate knowledge among farmers and easy access to antibiotics without prescriptions were considered as possible drivers of this risk practice . Around In accordance with earlier studies where the Australian veterinarians have highlighted the need for cost-effective culture and susceptibility testing as well as rapid and affordable diagnostic tests for facilitating judicious antibiotic use , the preTo conclude, the facilitating changes in the attitude and practices of veterinarians can be augmented by the implementation of continuing veterinary education programs. The effective flow of information from veterinarians to farmers can create a paradigm shift in the perceptions of the farmers for judicious antibiotic use as well as less reliability on quacks. There is need to strengthen the laboratory surveillance networks, research and diagnostics, and judicious antimicrobial stewardship. More stringent guidelines on the use of HPCIA in the animal sector and the compliance with responsible antimicrobial prescription behaviors by veterinarians need to be implemented. A “One Health” framework facilitating behavioural change interventions in farmers and veterinarians by bringing all the stakeholders together and promoting prudent antimicrobial use and judicious antimicrobial stewardship is the need of the hour.


The compressive characteristics of the steel-slag concrete were investigated through an experimental test. The term “steel-slag concrete” in this research work was defined as a kind of concrete using steel-slag material as a coarse aggregate replacement. Three types of the steel-slag concretes were examined under compression as follows: XT01, XT02, XT03 with their cement/water ratios of 1.76, 2.00, 2.21, respectively. The coarse aggregate used in producing concrete was steel-slag material, while the fine aggregate was traditional river sand; the ratio of coarse aggregate to fine aggregate was kept constant at a value of 1.98. Firstly, the age-dependent compressive strength of the steel-slag concretes were investigated up to one year; it was clear that the concrete strength increased rapidly in 7 days, then more and more slowly after that. Secondly, the modulus of elasticity and Poisson’s ratio of the steel-slag concretes were explored at the 28-day age. Thirdly, there was an important size and shape effect on the compressive strength of the XT02, and its significance of brittleness in failure was analytically analyzed. Lastly, the effects of water amount added in the XT02 on its compressive strength and slump were evaluated at the 28-day age. Industrial wastes and by-products have become a serious issue related to the environment, therefore, recycling them has really been attractive to researchers, owing to clear benefits: reducing construction cost, reducing negative environment impact, and serving natural energy and resources. Steel-slag is an industrial waste generated from steel manufacturing, specifically, as one ton of steel is produced, about 160 kg of steel-slag will be created  and PoulIn Vietnam, there is a high and urgent demand in recycling steel-slag, owing to huge quantities in the steel manufacturing industry, e.g., only in Ba Ria-Vung Tau province in southern Vietnam, the annual production capacity from thirteen steelmaking plants was about 3.75 million tons of billet accompanied with steel-slag amount up to 412,000–562,000 tons per year . Up to n(a) The compressive strength is always the key parameter of normal concrete and/or high-performance concrete. This is due to their strengths under compression being much greater than those under tension, even for strain-hardening fiber-reinforced concrete with its high tensile strength more than 10 MPa ,29,30. O(b) The scale effect of traditional concrete has been investigated for decades: the mechanical properties of traditional concrete were highly size and shape-dependent due to its brittle nature ,32,33,34(c) For traditional concrete, Poisson’s ratio was reported to be from 0.15 to 0.2 for normal-weight (ACI 318 ). Is theThe above questions have motivated this investigation, with specific objectives listed as follows: (1) to discover the age-dependent compressive strength of the steel-slag concretes, (2) to investigate the modulus of elasticity and Poisson’s ratio of steel-slag concrete, (3) to explore size and shape-dependent compressive strength of the steel-slag concrete, and, (4) to investigate the effect of water amount added in mixture on compressive properties of steel-slag concrete. Except objective 1, the other objectives were studied with experimental tests at the 28-day age.In the previous studies ,26, the A laboratory mixer with a volume of 150 liters was used to mix materials. All casted specimens were placed for 24 h in a laboratory with a temperature of 28 ± 5 °C prior to demolding, and after that, they were cured in water with temperature of 25 ± 5 °C. It was noticed that the temperature in laboratory and in the water tank mentioned above were very common in southern Vietnam, thus it was very suitable to practically apply the steel-slag concrete referring to the test results. The curing time depended upon the study objective. Next, the cured specimens were moved out of the water tank and dried at room temperature. For each series, at least three specimens were examined and then averaged for investigating the material properties. A MATEST machine with 150-ton capacity, as shown in t). As shown in t, the relationship between t should be mathematically modeled. Based on the shapes of testing performances on In order to predict the a and b are the constants characterizing material properties. To obtain the values of a and b, Equation (2) was changed into Equation (3).Here a and b can be obtained. Equation (4) and Equation (3) was in linear relationship with a common expression of Under uniaxial compression, the –3 times , and low–3 times . Both Po–3 times . Accordi–3 times , modulus3) and 3.In Equation (6), In this part, all specimens were tested using series XT02 at the testing age of 28 days. approach ,42. BothA representative theory for statistical approach of size effect is Weibull’s size effect law. According to this law, the strength of brittle material is not constant, it is size-dependent: strength of a small specimen would be comparatively higher than that of a large specimen. The statistical approach of size effect can be visibly explained by a model of chain under tension and a model of brick stack under compression, as illustrated in Equation (7) performs the relationship of two specimens having different effective volumes of In the analysis,  to 24.2 .Bažant’s size effect law has representatively performed the deterministic approach for quasibrittle materials based on the theory of fracture mechanics . AccordiThough Bažant’s size effect law was primarily established for specimens subjected to tensile and flexural loading, Kim et al.  proposedThere has been a great demand for converting compressive strength between various sizes and shapes of specimens. This is due to the fact that many standard codes are still available using different standard specimens. From the testing data measured in this research, the conversion factors (Here, There is a strong correlation between C/W and compressive strength in addition to workability of concrete. More water than its requirement for completing hydration would cause a reduction in strength because of more water-filled pore spaces between the grains. On the contrary, less water than its requirement would not be enough for hydrating all cement in the mixture. In this section, the mixture XT02, presented in Regardless of testing age, the order of steel-slag concretes in term of compressive strength was not changed as follows: XT03 > XT02 > XT01. The compressive strength at 7 days and 28 days were about 55–66% and 69–73% of compressive strength at 365 days, respectively.The axial strain capacities of the steel-slag concretes were in a range between 2.60‰ and 2.82‰. The lateral strain capacities of the steel-slag concretes were higher than axial strain capacities from 1.23 to 1.68 times. The derived Poisson’s ratios and moduli of elasticity of the steel-slag concretes were usual in comparison with traditional concrete.The studied steel-slag concrete demonstrated clear size effects on compressive strength, in both cube specimens and cylinder specimens, i.e., the smaller-sized specimen would produce the higher compressive strength.According to Weibull’s size effect law, the obtained Weibull modulus for the compressive strength of the steel-slag concrete, In Bažant’s size effect law, the obtained material parameter of the steel-slag concrete were as follows: The conversion factors for compressive strength using different sizes and shapes of the steel-slag concrete were explored. Generally, the conversion factors of the steel-slag concrete were slightly lower than those of traditional concrete, however, their differences were comparatively small.The slump value of the steel-slag concrete decreased with increasing of the cement/water ratio, while its compressive strength was different: it increased with increasing of cement/water up to 2.5 and decreased after that, the optimal cement/water was 2.5 to obtain the highest strength. The relationship between the compressive strength and cement/water ratio of the steel-slag concretes was almost inside the bound zone of traditional concrete.In this research, the compressive characteristics of the steel-slag concretes were investigated focusing on four objectives. Some conclusions could be drawn as follows:


A diagnostic survey on the precast prestressed bridge Nižná confirmed significant deterioration due to environmental distress. Evidently, decisive failures of the structure have a similar character as in the previous precast prestressed bridge in Podbiel in the northern part of Slovakia. These failures result from the unsuitable concept of the first generation of precast prestressed concrete beams, which was used in the former Czechoslovakia in the second half of the 20th century. Subsequently, experimental verification using the proof-load test was also executed. This bridge was built in 1956, so at the time of testing, it was 60 years old. The paper presents the indirect determination of prestressing level in one precast post-tensioned concrete beam using the saw-cut method. Experimental measurement was executed during the bridge demolition. Subsequently, a 2D numerical model in ATENA 2D Software, with the assumption of nonlinear material behavior for verification of experimental results, was performed. Finally, the residual prestressing force was evaluated and compared with the expected state of prestressing according to Eurocodes after 60 years of service. In the early 1960s in former Czechoslovakia, the precast and prestressing technology have initiated to develop . CurrentNowadays, the research activities of the Department of Structures and Bridges are focused on reliability assessments and investigation of existing steel and concrete bridges, along with their possible rehabilitation . CorrosiThe currently available methods for determining the state of the prestressing force can be classified according to their influence on the structure or approach to the evaluation of the level of prestressing. The classification of some methods is questionable because the line between destructive, semi-destructive, and non-destructive approaches is narrow. In general, methods with no or only minimal impact on the structural integrity are considered non-destructive ,16,17,18Fortunately, early intervention and the decision to close the bridge resulted in the avoidance of fatal consequences. A low level of maintenance quality in combination with heavy traffic on the bridge contributed to the failure of the bridge, in addition to degradation. Due to the failed condition, the Nižná bridge was demolished and replaced with a new one. Before demolition, in situ measurements were taken on the selected beam.y of 380.0 MPa was used as a conventional reinforcement.The bridge structure consisted of four simply supported spans with an effective length of 17.18 m; the total length of beams was 17.88 m, see The precast post-tensioned concrete beam in a visually good condition was selected. This beam seemed to be the least degraded and had a favorable approach from the underside, which was necessary to perform the experimental measurements. Specifically, it was the edge beam in the first span of the bridge, which was already out of order at that time. The beam under investigation is shown in During demolition, the remaining material on the upper flange of the beam could not be completely removed. Therefore, in the analysis, it was necessary to consider the load resulting from the material that remained on the beam. Namely, this consisted of a concrete layer with an average thickness of approximately 50 mm. This layer can be seen in The longitudinal prestressing of the beam was unbonded, and therefore, transfer was provided only in the anchorage area. Very rarely was the cement grout endoscopically discovered, and in such cases this was only locally at the lower surface of the cable duct; even in these areas the grout fell off the prestressing wires after a gentle tapping with a hammer. Hence, it was reasonable to assume that the bond between the cement grout and the prestressing wires was not ensured. From the photographs provided by the endoscope—which was inserted into the cable ducts—it can be seen that the prestressing wires of the selected beam were in good condition almost without any sign of corrosion. This fact confirmed the primary assumption of the good state of the selected post-tensioned concrete beam, determined by visual assessment. Following the experimental measurements, some prestressing wires were also inspected destructively. Once again, it was possible to visually confirm the good condition of the prestressing wires without corrosion. Prestressing wires after exposure are shown in After exposing the anchorage area, considerable corrosion of anchorages was observable. This corrosion can be credited to insufficient protection of the anchorages by the concrete, and thus, to the easy access of water to this area. The anchorage area is shown in In cases where the material properties are not available, it is almost impossible to determine the actual state of prestressing ,23. HencConcrete’s compressive strength was roughly determined non-destructively based on Schmidt hammer rebound. The obtained results are listed in n = 1.98; sr = 2.94βc, which is necessary for the calculation of stress based on the strain measurement. Nevertheless, in the case of determining the residual value of prestressing force on the structure—which should be put into operation again—it is suitable to use mainly non-destructive methods for determining the mechanical characteristics of materials. In research practice, the most suitable approach is the combination of non-destructive, semi-destructive, and destructive methods and the subsequent comparison of the obtained results.Since this method does not provide the exact compressive strength of concrete, three cylinders with a diameter of 100 mm were removed from the beam prior to demolition and later tested in the laboratory. This test was particularly important in order to obtain the secant modulus of elasticity of concrete Ec,cyl was 31.5 MPa and the secant modulus of elasticity Ec was 33,980 MPa. The results are presented in As a result of concrete mechanical properties testing, the cylindrical compressive strength f−/ms) and recalculated to the estimated quantity of cement (Cl−/mc) [−/mc) [The content of chloride ions above a certain limit significantly increases the risk of corrosion of the reinforcement. Therefore, in situ measurement of the chloride ion content of concrete was provided using the rapid chloride test (RCT) system by Germann Instruments . This me(Cl−/mc) . Obtaine) [−/mc) .pt was 1647 MPa, the mean yield strength fy was 1160 MPa, and the modulus of elasticity Ep was 190,000 MPa. The cross-sectional area of a wire was 15.9 mm2.After demolition of the beam, the anchorages and prestressing wires were removed for material testing. Subsequently, based on the laboratory tensile test, the mean measured tensile strength of the prestressing wires fThe saw-cut method was applied to determine the residual prestressing force. The scheme of a selected post-tensioned precast concrete beam is illustrated in −6/K) with a measuring grid length of 50.0 mm and a total length of 63.6 mm were used to record the strain. The linear foil strain gauges were installed in the middle of the axial distance between the saw-cuts. Transversely, they were applied to the center of the lower flange of the beam. The measurement was finalized after stabilization of the recorded values on both used linear foil strain gauges. The maximum value of the change in stress Δσ, measured by the strain gauge SG1 (related to the pair of saw-cuts SC1), was 3.13 MPa and the strain gauge SG2 (related to the pair of saw-cuts SC2) was 4.21 MPa.Two pairs of saw-cuts with an identical axial distance of 120 mm were performed in the beam, see As part of the evaluation of the residual prestressing force, a nonlinear numerical analysis in ATENA 2D Software  was performed ,29,30. IThe post-tensioned precast prestressed concrete beam was modelled as a 2D finite element, which is shown in Concrete :c,cube = 37.0 MPa; fc,cyl = 31.5 MPa; ft = 2.7 MPa; Ec = 33,980 MPa; ν = 0.20fPrestressing Wires (Reinforcement–Bilinear):y = 1160 MPa; Ep = 190,000 MPafSaw-cuts (Plane Stress Elastic Isotropic):SC = 1.0 kPa; ν = 0.30EThe following material parameters were considered in the 2D numerical analysis:The stress–strain curves that were used are presented in The principle of the numerical analysis was based on an iterative change of the value of prestressing force until a satisfactory agreement with the experimentally measured results was achieved. The results from the strain gauge SG1 corresponded with a numerical analysis of 99%. This value was 96% in the case of the strain gauge SG2 . The strc,0) and after the application of saw-cuts on the beam , and the difference between these two values (Δσc) are presented in m60,actual), as a result, was determined using Equation (2). The ideal cross-sectional characteristics of the beam  was –5.04 MPa.The stress before and after application of saw-cuts is shown in G = 327.45 kNmMThe stress in the tendons, including the expected value of prestressing losses after 60 years of service , was determined according to Eurocode 2 . The valm60,theoretical) in the precast post-tensioned prestressed concrete beam—determined according to Eurocode 2 [m60,theoretical) in compliance with Eurocode 2 [m60,actual) and subsequent nonlinear numerical analysis in ATENA 2D Software, there is a difference of 13.32% (ΔP). The values of the change in stress after application of the saw-cuts, which were recorded during the measurement, are presented in The expected value of the prestressing force based on the expected stress in individual tendons after 60 years of operation (Procode 2 —was 1090rocode 2  and valuThe expected stress in the individual tendons of the investigated bridge in compliance with Eurocode 2  after 60This research study focused on the application of the saw-cut method on a precast post-tensioned beam. Based on the in situ performed test and numerical analysis, the following conclusions can be summarized:One of the advantages of the presented method is that it can be performed with or without the application of an external load. Consequently, if the investigated structure is not loaded by an external load, the determination of the dead load is not complicated. The measurement can be performed quickly and easily in situ and does not require expensive tools.In the case of older prestressed concrete bridges in service, concrete cover can be immensely low in comparison with today’s standards. This fact can also influence the maximal depth of saw-cuts. Specifically, deeper saw-cuts should initiate full isolation with respect to the structure’s reinforcement especially in the case of large diameter reinforcement. Obtained results suggest that a relatively small intervention into the concrete structure could lead to notable local stress relief. The saw-cut with a depth of 31 mm is negligible in comparison to the cross-section of the beam. Therefore, the integrity of the structure was preserved, and simultaneously, important information including the state of residual prestressing force was recorded. The results indicate that only the 31 mm deep saw-cuts at the axial distance of 120 mm can cause almost full isolation of the concrete block from the acting forces. The saw-cuts with a depth of 23 mm in the axial distance of 120 mm released more than half of the initial stress in the adjacent area. The value of the residual prestressing force, based on the standard evaluation according to Eurocode 2  and the Given that our findings are based on a limited number of performed saw-cuts, the results from such an experiment should, therefore, be treated with considerable caution. In the future, it is necessary to perform further experimental measurements, both in the laboratory and in situ, with various specimen dimensions and mechanical properties. A large number of ageing, prestressed, short- and medium-span concrete bridges consist of individual beams. Therefore, the future application of this non-destructive approach is very promising.


Medical emergency teams (METs) bring critical care expertise to the bedsides of hospital ward patients who may be deteriorating. Diurnal variation in MET activation rates may identify inconsistencies in the detection of patients needing intervention. We aimed to determine whether such variation exists at our tertiary care children’s hospital.In this retrospective cohort study, we collected data including date and time of MET and disposition following MET for all inpatients at Cincinnati Children’s Hospital Medical Center with a MET call between January 2008 and May 2014. The analysis compared the MET rate between days and nights, weekdays and weekends, and before and after nursing shift change.P < 0.001). There were also more METs per day on weekdays than weekends . Daytime METs were more likely to lead to transfer to the intensive care unit or operating room than those called at night . MET activation rates did not differ significantly in the 2 hours before nursing shift change compared to the 2 hours after.The number of METs per hour varied throughout the day. More METs were called during the day than at night (0.7 calls/shift ± 0.95 vs 0.6 ± 0.9, At our large tertiary care children’s hospital, there are both diurnal variations and variations across weekdays versus weekends in the MET activation rate. This difference may indicate variations in our ability to detect deteriorating patients on the wards and be further studied. Over the past 15 years, METs have been instituted in hospitals nationwide and have decreased mortality and cardiopulmonary arrest rates outside of the intensive care unit (ICU).14 Although the reason for the difference in calls is not well understood, several investigators have suggested that it might correlate with increased monitoring. Perhaps, deteriorating patients are identified more often during the day and on weekdays, when staffing is better, and monitoring may be more robust.13 More limited research conducted in children’s hospitals suggests a predominance of MET calls during the day.17 These studies were complicated by the inclusion of codes and other emergent events in the analysis15 and the relative infrequency of MET calls (25% of ICU transfers).16 No study has been designed and powered to examine diurnal variation in MET calls at a children’s hospital with a well-established MET system.Several studies in hospitals that care primarily for adults have identified variation in the rate of MET calls across days versus nights and weekdays versus weekends.1 We identify deteriorating patients on the wards using a Pediatric Early Warning Score (PEWS), along with nurse, physician, or family concerns.7 In this report, our objective was to compare the rate of MET calls across days and nights and weekdays and weekends to identify potential lapses in the detection limb of our rapid response system. We hypothesized that we would find an increased rate of MET calls during the day and on weekdays, corresponding to the increased staff availability.At our tertiary care children’s hospital, we have had a MET system in operation since 2005; it has been associated with a decrease in codes outside of the ICU.am, 3:00 pm, 7:00 pm, and 11:00 pm.We conducted the study at Cincinnati Children’s Hospital Medical Center (CCHMC). This tertiary care children’s hospital serves as a regional referral center for the Midwestern United States and a community hospital for the greater Cincinnati area. At the time of the study, the hospital had 482 inpatient beds, including a 35-bed pediatric ICU (PICU), a 25-bed cardiac ICU (CICU), and a 59-bed neonatal ICU (NICU). Patient care teams include a bedside nurse, the floor charge nurse, and a physician team that is generally comprised 3–4 interns, 1–2 senior residents, a fellow, and an attending physician. The patient-to-nurse ratios increase by approximately 50% on nights and weekends. On nights, residents often function without support from an in-house fellow or attending, who commonly take night-call from home. The number of residents in the hospital generally also decreases by 50%–75% on nights and weekends. Nurses on the floor work 8- or 12-hour shifts, and potential shift changes occur at 7:00 The MET includes the floor team caring for the patient, the hospital nurse manager, and the responding PICU-based team—fellow, resource nurse, and respiratory therapist. When a MET is called, the PICU team has a maximum of 15 minutes to arrive at the patient’s bedside, although internal audits show an average response time of approximately 7 minutes. The group then collaborates to determine the best management plan for the patient. If the team determines that the patient would benefit from the escalation in care, they transfer the patient, and the ICU team assumes primary responsibility for the patient. Historically, 50%–60% of MET calls result in transfer to the ICU at our institution. Our emergency response system includes the Code Blue, activation of which brings the hospital-wide code team to the patient’s bedside as quickly as possible. Transfer from the hospital floor to the ICU at CCHMC requires emergency response activation, either Code Blue or MET. Criteria for MET calls include nurse, physician, patient, or family concerns. The PEWS is designed to support clinical decision-making regarding the need for escalation in care but is not a trigger for a MET call. When a patient has a total PEWS of 7 or above, clinical decision support in the electronic health record alerts the nurse that a MET should be called. In our experience, however, nurses commonly choose to alert the team and ask for a bedside assessment but do not ask for a MET to be called solely based on the PEWS. If a MET call does not result in a transfer, hospital culture encourages members of the MET to regroup at a prespecified time—often 1–2 hours following the initial call—to reassess and determine whether the patient’s disposition remains appropriate. Our quality improvement work aims to empower all bedside team members to call a MET if they have concerns about a patient and express those concerns when the MET meets.am to 6:59 pm; nighttime was defined as the period from 7:00 pm to 6:59 am. Disposition following the MET call was a dichotomous variable defined as either continuation of care on the floor or escalation of care—transfer to the PICU, NICU, CICU, or operating room (OR). If the transfer occurred within 2 hours of MET call, disposition was considered an escalation of care. If the transfer occurred more than 2 hours after MET call, even later on the same day, then disposition was considered a continuation of care on the floor.We collected data retrospectively from a secure database of all METs called between January 2008 and May 2014. All patients requiring a MET during this period were included in the study, with no additional inclusion or exclusion criteria. Data obtained included patient age and gender, unit location, date and time of MET call, and disposition following the call. Daytime was defined as the period from 7:00 To determine the difference in MET call rates during the day and night, we first divided the 24-hour day into 1-hour intervals. We graphically displayed the absolute number of MET calls that occurred over each 1-hour block for the entire 6-year study interval, dividing each total number by the number of months in the study period to give METs called per hour per month. We then calculated an average and SD for the number of MET calls during the 12-hour day and night. We then compared these averages using Student’s t-test. Similarly, to determine the difference in the rate of MET calls on weekdays versus weekends, we calculated the average and SD for the rate of MET calls on weekdays and weekends. We compared them using Student’s t-test.To look for a possible effect of nursing shift changes on the rate of MET calls, we examined the average rate of MET calls before and after a shift change. Specifically, we compared the average rate of MET calls in the 2 hours before a potential nursing shift change with the rate of METs called in the 2 hours following a potential nursing shift change.To determine the difference in disposition following a MET activation, we measured the total number of MET calls resulting in escalation versus continuation of care on weekdays and weekends, and days and nights, and calculated the percentage of MET calls at these times resulting in an escalation of care. We compared disposition on weekdays versus weekends and days versus nights using the chi-square test.P < 0.001). There was also a higher rate of MET calls on weekdays than weekends, with the average number of MET calls per 24 hours on weekdays 1.4  and on weekends 1.2  (P < 0.001).Over our 2,313-day study period, there were 1,652 weekdays and 661 weekend days. During this period, there were a total of 3,115 MET calls. Of these, 1,442 were at night, and 1,673 were during the day. There were 2,337 METs on weekdays and 778 on weekends. There was no significant difference in age or gender of patients who had METs called during the day versus night or on weekends versus weekdays (Table P < 0.001). On weekends, 60.3% of MET activations (468 events) resulted in escalation to a higher level of care versus 56.9% on weekdays (1328 events); this difference did not reach statistical significance (P = 0.10).Those METs called during the day were significantly more likely to lead to an escalation of care than those called at night .To examine the potential effect of nursing shift changes on the MET call rate, we compared the average rates of MET calls before and after nursing shift change. The proportion of all MET calls in the 2 hours following nursing shift change (34.3%) and the proportion in the 2 hours before nursing shift change (32.8%) were similar . At our hospital, we have worked to improve communication between bedside nursing staff and physician teams using inpatient huddles, unit huddles, and “robust plans” for high-risk patients.9 Still, it is possible that the environment overnight, in which physicians and nurses may feel more overwhelmed or less supported, causes decreased situation awareness and communication between members of the care team. This possibility could make it less likely that a MET would be called, even in the setting of concern on the part of one or more members of the care team. There is also potential that teams recognizing lower staffing at night pre-emptively activate METs during the day shift, rather than letting lingering concerns have further opportunity to deteriorate. Last, it is possible but perhaps less likely that the patient census during the day has higher acuity or complexity than the patient population remaining in the hospital overnight.On the other hand, it is not necessarily true that a decreased MET activation rate represents a failure to detect patient deterioration, as has previously been noted.13 Scheduled nursing handovers have also been peak times for MET calls, as compared with the average MET call rate the rest of the day.12 We saw a gradual increase in MET call rate starting from approximately 6 am, when resident teams begin their morning handover, through 10 am, generally midway through morning rounds (Fig. Previous studies have shown a gradual increase in the MET call rate in the morning, beginning at the time of morning handover and physician rounds.In addition to diurnal variation in the rate of MET calls, our data show a corresponding variation in disposition following a MET call. A higher proportion of MET activations during the day results in an escalation of care. We might hypothesize that some of this difference is due to the spike in MET calls that we see in the early morning through morning rounds. These METs may be called on patients who went unrecognized throughout the night. An increased proportion of them may require an escalation in care. Alternatively, it may be that faculty physicians’ greater presence during the day results in more successful advocacy to transfer intermediately an ill patient to the ICU. However, our hospital default is that unless there is team consensus on staying, the patient will transfer to the ICU.Further work will need to be done to understand this diurnal variation in MET disposition. If a higher proportion of patients require transfer to an intensive care setting, we may be close to missing our window of intervention, thus increasing the likelihood of preventable code events or delayed transfer to the ICU. To test this hypothesis in our future work, we will need to correlate the transfer time to the ICU with the severity of illness scores and the need for invasive ventilation or pressor support upon transfer.9 We also attempted to examine the effect of nursing shift changes using hospital-wide nursing shift change times. However, we did not have patient-specific data on when nurses caring for particular patients were changing shifts. This deficiency may have limited our ability to detect an effect of nursing shift change on MET activation rates.This study has several limitations. We cannot conclude the causes of diurnal variation in MET rates based on this retrospective observational study. Second, we used data collected over 6 years to identify patterns in MET activation rates. There were changes over this time in characteristics of our MET system, along with hospital and ICU bed capacity, and the typical acuity of patients on the wards that may have led to changes in the MET activation patterns over time, potentially confounding our data. One notable change in the fall of 2009 was our elimination of the “curbside” PICU consult and the development of a system of proactive identification of watcher patients. These changes led to a special cause change in the rate of our MET calls from a median of 8–40 calls per month.am, so that in some cases the daytime residents may have assumed care of a patient before our defined day-night cutoff was reached. Additionally, although we did not appreciate differential bed availability between days and nights, we did not have access to bed availability to control for this variable. Last, data from our tertiary care children’s hospital may not generalize to other hospitals nationwide with different patient profiles and staffing capacities or MET criteria.Similarly, residents often begin morning hand-off before 7 Our hospital instituted a “watcher” system in 2009 to create situation awareness among providers caring for patients felt to be at increased risk for deterioration. Plans are made for these patients that include specific criteria for which a MET will be called. We have more recently implemented “sepsis huddles” that aim to establish a mental model and expedite treatment for septic patients. We might expect such interventions to improve the detection of sicker ward patients regardless of staffing changes and decrease diurnal variation in the MET rate. As quality improvement work continues, it may be useful to examine its effect on the baseline diurnal variation that we have identified here. Also, it may be useful to examine seasonal changes in MET call rates and outcomes, as patient acuity, hospital census, and trainee experience vary significantly throughout the year. Last, broadening these analyses to include multiple children’s hospitals may aid our ability as a community to develop robust systems for identifying and expediently treating the sickest patients on our hospital wards.We have shown diurnal variability in the rate of MET activation at our tertiary care children’s hospital. This variation indicates a possible decrease in the detection of deteriorating patients in our system overnight and on weekends, perhaps correlated with decreased staffing. It will be essential to analyze this variation to determine its clinical significance and whether ICU outcomes are also different at these times. It will also be essential to optimize our ability to monitor patients at all times of the day and keep lines of communication open despite varying hospital staffing.The authors have no financial interest to declare in relation to the content of this article.