Persons of African and Middle-Eastern origin living in European countries have a high prevalence of type 2 diabetes, accompanied by high prevalence of obesity among women but not always among men. The aim of this study was to examine whether there are differences in the association between anthropometric measures and glucose levels measured with glycated haemoglobin and fasting blood glucose among persons of migrant origin in Finland.n = 293, Somali origin n = 184, Kurdish origin n = 275). The reference group were non-diabetic participants in the Health 2011 Survey (n = 653), representative of the general Finnish population. Anthropometric measures included body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR) and waist-to-hip ratio .Cross-sectional population-based data of the 30–64 year-old participants in the health examination of the Migrant Health and Wellbeing Study was used, selecting persons without diabetes (Russian origin p = 0.044 for WC and p = 0.040 for WHtR).Depending on whether continuous or categorical anthropometric measures were used, age, sex and anthropometrics explained 13–18% of variation in HbA1c among persons of Russian origin, 5–10% among persons of Somali origin, 1–3% among persons of Kurdish origin and 11–13% among the general population. Also depending on whether continuous or categorical anthropometric measures were used, age, sex and anthropometrics explained 13–19% of variation in fasting blood glucose among persons of Russian origin, 15–20% among persons of Somali origin, 13–17% among persons of Kurdish origin and 16–17% among the general population. With exception for BMI, strength of the association between continuous anthropometric measures and HbA1c was significantly lower among persons of Kurdish origin compared with the general Finnish population (A low degree of association between anthropometric measures and HbA1c was observed among persons of Kurdish origin. Findings of this study suggest caution is warranted when using HbA1c as a screening tool for glucose impairment among persons without diabetes in populations of diverse origin.The online version of this article (10.1186/s12889-019-6698-0) contains supplementary material, which is available to authorized users. According to 2015 estimates, 415 million persons have been diagnosed with type 2 diabetes (T2D) and a further 193 million persons were unaware of having the condition , whereasIt is estimated that 65–80% of T2D cases can be prevented through a reduction of overweight and obesity . For thiMajority of studies on the association between obesity and T2D have been conducted among predominantly White populations in high-income countries , 15. WitDifferences in the exposures over the life course among migrating populations as well as the effect of migration process in itself may alter biological pathways to disease, leading to varying disease profiles among migrating populations both in comparison with populations in the country of origin and the general population in the country of migration , 28. DisThere is also increasing awareness that there are significant differences in body fat distribution, body shape and size among persons of Middle-Eastern and African origin compared with the general population in European countries, which limits particularly the applicability of abdominal obesity measured with a single measure of WC as a key indicator of the increased risk for T2D among these population groups , 21, 32.In order to reduce the high societal and economic burden of T2D in the population as a whole, emphasis should be placed on accurate identification of persons with increased risk for T2D taking into account diverse population groups . FurtherThis study is based on cross-sectional data of the Migrant Health and Wellbeing Study (Maamu). The study is described in more details elsewhere . BrieflyThe reference group consists of participants in the Health 2011 Survey representing the general Finnish population. Health 2011 Survey is a population-based health examination survey based on a national stratified random sample drawn from the National Population Register . The curThe current study is limited to 30–64 year-old health examination participants of the Maamu Study and the Health 2011 Survey. Maamu Study and Health 2011 Survey data were supplemented with register-based data from the Social Institution of Finland on reimbursement rights for diabetes medication and the Finnish Care Register for Health Care on inpatient and outpatient hospital care for diabetes . The Socn = 146) as their medication affects glucose levels. Type 1 or type 2 diabetes were identified based on having at least one of the following: special reimbursement rights for diabetes medication, diabetes  codes E10 or E11) as reason for healthcare visit/care, self-reported diabetes diagnosis made by a physician, self-reported use of diabetes medications, HbA1c ≥6.5% (48 mmol/mol) or fasting glucose of ≥7.0 mmol/l based on biochemical analysis of blood included in the health examination. Persons without T2D, for whom all the variables used in this study were intact without missing data, and whose glucose fasting was within the 4-17 h fasting range, were included into the study. Therefore, the study is based on the data of 293 Russian origin, 184 Somali origin and 275 Kurdish origin participants in the Maamu Study and 653 participants in the Health 2011 Survey. Mean fasting duration was 13 h for persons of Russian origin, 12 h for persons of Somali and Kurdish origin and 9 h for the general population.Participation rate in the health examination was 48% for Russian, 40% for Somali, 59% for Kurdish origin migrants and 56% for participants in the Health 2011 Survey. Persons with type 1 and type 2 diabetes were excluded from this study  conducting the analyses took part in the External Quality Assessment Schemes organised by Labquality, Helsinki, Finland.2, with values 25–29.9 kg/m2 for overweight and ≥ 30 kg/m2 for obesity. WHR was calculated as waist circumference in cm divided by hip circumference in cm. Values of ≥0.90 for men and ≥ 0.85 for women were regarded as obesity [Age was used as a binary variable (30–44 years vs. 45–64 years) . Both co obesity . For WC, obesity . WHtR wa obesity .All analyses accounted for stratified sampling and finite population correction . Sudaan 2) presented in Tables Linear regression was applied for analysing continuous response variables in Table Age-adjusted characteristics of the study participants are presented in Table p < 0.05) and for WC, WHtR and WHR in relation to HbA1c among Somali origin men (p < 0.05). Further analyses showed that there was no significant association between HbA1c and anthropometric measures in the younger age group (30–44 years) among Russian origin women. However, in the older age group (45–64 years), the associations were significant for all anthropometric measures. Among Somali origin men, the effect was reversed, with significant or almost significant associations found in the younger age group only.Interaction between sex, age and each of the anthropometric measures in relation to HbA1c were tested for each study group separately using the models: Model 1 HbA1c = sex + anthropometric measure + age + sex*anthropometric measure, Model 2 HbA1c = sex + anthropometric measure + age + age*anthropometric measure and Model 3 (men and women separately) HbA1c = anthropometric measure + age + age*anthropometric measure. No statistically significant interactions were found in Model 1 and Model 2. In Model 3, a positive interaction between age and each of the anthropometric measures in relation to HbA1c was found among Russian origin women (p < 0.05). In Model 3, a positive interaction was found for WC and WHR among Somali origin men (p < 0.05), for BMI and WC among Kurdish origin men (p < 0.05) and for WC among women in the general population (p < 0.05). Upon further analyses, the associations between anthropometric measures and fasting blood glucose were stronger for the older age group (45–64 years) among Kurdish origin men and women in the general population. For Somali origin men, however, the association was stronger in the younger age group and no significant association between anthropometric measures and fasting blood glucose were found in the older age group.Interactions between sex, age and each of the anthropometric measures in relation to fasting blood glucose were also tested for each study group using the same models. No interaction was found for Model 1 in any of the study groups. A positive interaction was found in Model 2 among the general population for BMI and WC  and WHtR (p = 0.040). The difference was statically significant for WC only (p = 0.031) when comparing these two groups using categorical anthropometric measures. No statistically significant differences in the association between continuous or categorical anthropometric measures and fasting blood glucose were found across any of the studied groups (results not shown).Strength of the association between continuous anthropometric measures and HbA1c was relatively similar among persons of Russian, Somali and Kurdish origin , whereas variation to which extent age and sex explained variations in HbA1c ranged from < 1% among the Kurdish origin to 10% among the Russian and Somali origin populations Table . AnthropCoefficients of determination for the association between categorical anthropometric measures and HbA1c as well as fasting glucose are presented in Table Persons of Kurdish origin had a statistically significantly lower strength of the association between anthropometric measures and HbA1c compared with the general Finnish population, whereas no significant differences were observed across the study groups when examining the strength of the association between anthropometric measures and fasting blood glucose. Although anthropometric measures explained a lower degree of variation in HbA1c also among persons of Somali origin compared with the general population, no statistically significant differences were found in the strength of the association. Therefore, a lower degree of variation is more likely to be due to sample size restrictions rather than actual differences in the degree of the association. There was some variation in whether continuous or categorical anthropometric measures performed better in explaining variation in HbA1c and fasting blood glucose depending on the study group and the specific anthropometric measure examined.This is a first study examining the association between anthropometric measures and glucose levels among persons without T2D of Russian, Somali and Kurdish origin that have migrated to a high-income country. The association is examined from different angles using several established anthropometric indicators, both categorical and continuous, and two widely used measures of glucose levels (fasting blood glucose and HbA1c). This study provides new insights concerning differences in the association between anthropometric measures and HbA1c among the studied population groups, raising a number of important questions that need to be addressed in future research. While fasting blood glucose and HbA1c are commonly used indicators of glucose levels and are recommended for use in determining the presence of T2D, there are contradicting views whether HbA1c is sufficiently reliable for measuring long term glucose levels also among persons without T2D , 6. WorlGenetic factors and disturbances in protein metabolism may cause a higher degree of discordance between fasting blood glucose and HbA1c . HbA1c lHaemoglobinopathies are common among some African  and MiddThe extent to which haemoglobinopathies or other possibly co-occuring conditions influence the findings cannot be ascertained in the current study. Further studies should confirm the findings on the low degree of association between anthropometric measures and HbA1c particularly among persons of Kurdish origin. Further studies should also explore the observed association between BMI and HbA1c among Kurdish origin women. Until further studies shed more light on the subject, findings of this study support the cautiousness of WHO experts  and hencThe proportion of persons identified as normal weight were similar among the general Finnish population and the Russian origin study groups. Differences in the sensitivity of anthropometric measures to identify persons with overweight and general or abdominal obesity were observed across different anthropometric measures in the Somali and Kurdish origin study groups. A significantly higher proportion of persons of Somali and Kurdish origin were identified as normal weight using a single WC measurement compared with measures of BMI and WHtR. This may reflect challenges related to the appropriateness of cut-offs established among predominantly White European populations also discussed in previous studies , 45, 46.Considering concerns related to applicability of categorical anthropometric measures established among predominantly White European populations for assessment of overweight and obesity among persons of African and Middle-Eastern origin, it may be feasible to use continuous anthropometric measures in addition to categorical ones when examining the prevalence and risk factors for obesity among populations of diverse origin. Ultimately, however, efforts should be put into setting up prospective cohort studies also among migrant origin populations that will produce data enabling identification of appropriate cut-offs for overweight and obesity also among persons of African and Middle-Eastern origin.Accumulation of adverse exposures over the life course, including events prior and leading to migration, the migration process itself as well as post-migration exposures may all influence pathways to health among migrating populations . While tSignificant strengths of this study include randomised sampling and inclusion of several diverse population groups into the analyses. Availability of self-report data, biological samples and register-based data allowed for a comprehensive identification of persons with T2D. Further strengths include availability of HbA1c, fasting blood glucose and several objectively measured standardised anthropometric measurements. The use of continuous anthropometric measures reduces bias created by the lack of evidence-based cut-offs for persons of African and Middle-Eastern origin.This study also has some limitations. The relatively small sample size especially among the Somali origin participants in our study reduces the power of the analyses leading to widened confidence intervals and reduced statistical significance of the findings. Our findings need to be confirmed in a larger sample. Fasting glucose was measured with fluoride citrate plasma among the migrant origin population and with serum among the general Finnish population. While standardization procedures have been taken to reduce the measurement bias, serum samples tend to produce slightly lower glucose values than plasma glucose . FollowiThere is a minor possibility of misclassification of participants of this study as belonging to a certain group as the Health 2011 Survey data did not include information on the country of birth, only mother tongue. Mother tongue alone is an insufficiently reliable determinant of first-generation migrants who were included into the sample of the Maamu Study. However, the proportion of those speaking other languages than Finnish or Swedish, which are the two official languages in Finland, was very low among the Health 2011 Survey participants included into this study (< 2%). Out of altogether 11 who spoke a language other than Finnish or Swedish, two persons spoke Russian, none spoke Somali and one spoke Kurdish as their mother tongue. Therefore, it is highly unlikely that this had significant influence on the findings concerning comparison of migrant origin population of the Maamu Study with the general Finnish population of the Health 2011 Survey.In conclusion, we found a low degree of association between age, sex and anthropometric measures and HbA1c among persons of Kurdish origin. In contrast, a similar degree of association was observed for age, sex and fasting blood glucose in this study group as in the general population. Based on this observation, use of HbA1c as an indicator of glucose levels appears to be limited among persons of Kurdish origin in the current study. Further studies should explore the underlying mechanisms for this observation. Possible sex differences in the degree of the association between anthropometric measures and glucose indices should also be explored. The degree of the association between anthropometrics and HbA1c also needs to be explored in more detail among persons of Somali origin.Additional file 1:Figure S1. Association between anthropometric measures and glycated haemoglobin (HbA1c) among men. The association between anthropometric measures  among men of Russian, Somali and Kurdish origin and the general Finnish population. (TIFF 14668 kb)Additional file 2:Figure S2. Association between anthropometric measures and glycated haemoglobin (HbA1c) among women. The association between anthropometric measures  among women of Russian, Somali and Kurdish origin and the general Finnish population. (TIFF 21117 kb)Additional file 3:Table S1. Regression results for the association between continuous anthropometric measures and fasting blood glucose among the studied populations. Age and sex adjusted regression results for the association between continuous anthropometric measures  and fasting blood glucose among persons of Russian, Somali and Kurdish origin and persons belonging to the general Finnish population. Table S2. Regression results for the association between continuous anthropometric measures and glycated haemoglobin (HbA1c) among the studied populations. Age and sex adjusted regression results for the association between continuous anthropometric measures  and HbA1c among persons of Russian, Somali and Kurdish origin and persons belonging to the general Finnish population. Table S3. Regression results for the association between categorical anthropometric measures and fasting blood glucose among the studied populations. Age and sex adjusted regression results for the association between categorical anthropometric measures  and fasting blood glucose among persons of Russian, Somali and Kurdish origin and persons belonging to the general Finnish population. Table S4. Regression results for the association between categorical anthropometric measures and glycated haemoglobin (HbA1c) among the studied populations. Age and sex adjusted regression results for the association between categorical anthropometric measures  and HbA1c among persons of Russian, Somali and Kurdish origin and persons belonging to the general Finnish population. (DOC 251 kb)


The use of recycled concrete aggregates (RCA) in high performance concrete (HPC) was analyzed. The paper presents the experimental studies of model reinforced concrete beams with a rectangular section using high-performance recycled aggregates. Two variable contents of recycled aggregate concrete were used in this study: 50% and 100%. The experimental analyses conducted as immediate studies concerned the following issues: short time loads-deflection, load-carrying capacity of beams, deformation of concrete, cracks, and long-term loads-deflection. The comparative analysis involves the behavior of beams made of high performance concrete-high strength concrete (HPC-HSC) recycled aggregates with model control elements made of regular concrete based on natural aggregates. The deflection values for the recycled aggregate beams were 20% higher than in the case of the control beams made of HPC-HSC exclusively. Replacement of aggregate with recycled concrete aggregate resulted in a large decrease in the value of these two parameters, i.e., compression strength by about 42% and modulus of elasticity by about 33%. The modern construction industry should meet the requirements of providing durable and ecological structures. There are a number of factors that prevent concrete structures from meeting the basic standards of sustainable development.Special attention should be paid to the problems of climate changes, depletion of natural resources, and non-environmentally-friendly cement production. During the cement production process, a large amount of gases is released into the environment, contributing to the global greenhouse effect and climate changes in many parts of the Earth. Moreover, large quantities of particularly valuable natural resources such as gravel, sand, crushed rock aggregate, and water, are used in the course of concrete production. It is estimated that, in order to produce Portland cement, approximately 1,000,000,000 tons of raw materials are used each year.Over the last 30 years, a rapid development has occurred in terms of designing, optimizing and improving formulas of high-performance concrete. This type of concrete has been increasingly widely used in practice. The future of HPC is high and super-high buildings . NowadayAnother reason for the increased interest in high-performance concrete involves stronger and stronger trends connected to implementation of recycling in construction ,12. In aAs a consequence of ecological practices, a growing tendency for the application of recycled materials can be observed in many areas of industry. Using construction and demolition debris as a substitute for natural aggregate in the production of concrete mixtures is gaining popularity due to both economic and ecological reasons. The use of construction and demolition debris means limiting the use of expensive natural aggregate, and thus minimizing the negative impact on the natural environment. The maximum benefit is achieved when the greatest possible amount of recycled aggregate is used in the production of concrete ,20,21,22It can be assumed that, because of the growing social emphasis on ecological aspects, the recycled aggregate will be increasingly widely applied as a construction concrete component of full value. Even though HPC is used for building structures, they may have to be demolished at some point in the future. The obtained debris may be reused as recycled aggregate made of high-performance concrete of which the structural elements had been made. The issue pertaining to the reuse of building rubble from demolition or reconstruction has been a long-standing concern in industrialized countries ,30,31,32The aspects connected to protecting the natural environment gain importance with time; therefore, the interest in alternative construction solutions has been growing. The idea of reusing concrete debris is increasingly often taken into consideration as people are against establishing another open-pit mine to mine aggregate, since they have a significant negative impact on large areas.Two fundamental reasons leading to the popularization of recycling are the continuous growth of the amount of concrete waste and the constant increase in the use of concrete as a construction material ,33.Górażdże are presented in The concrete was prepared using CEM I 52.5 R Portland cement. The technical parameters of applied Portland cement Natural rinsed quartz sand (0–2 mm), natural basalt aggregate (BA) (2–8 mm), recycled aggregate (2–8 mm), and silica fume (SF) were utilized for concrete preparation. The grain size of BA and RA is shown in Three concrete mixtures were prepared with the composition presented in The chemical composition of the natural quartz is shown in −3. The properties of basalt and recycled aggregate are shown in The density of quartz sand amounted to 2.65g∙cmThe chemical composition of the basalt is shown in The chemical composition of the silica fume is shown in −3. The properties of the superplasticizer are given in The density of silica fume amounted to 2.40 g∙cmIn order to determine the physical properties of each concrete type, 18 cubic samples with an edge length of 150 mm were prepared (6 for each concrete). They were used to determine the apparent density, absorption of water and bulk density. The bulk density was determined according to the PN-EN 12390-7 standard . In ordeConcrete porosity was tested by capillary mercury injection (MICP) using AutoPore IV 9520 t  to test pores between 2 nm and 200 μm in diameter . Cubic sG—deformation at the upper range of the force level, amounting to 250 kN ; the measurement base—100 mm, εD—deformation at the lower range of the force level, amounting to 20 kN ; the measurement base—100 mm, σG—stress at the upper range of the force level, σD—stress at the lower range of the force level.In accordance with the PN-EN 12390-3 standard , the comThe bending tensile strength test was carried out in accordance with the PN-EN 12390-5 standard  on the cCarrying capacity, deformations and deflections were determined on 9 cuboid reinforced concrete beams with the dimensions of 80 mm × 120 mm × 1100 mm after 28 days of samples maturing . The reiThe research elements were placed on the test stand. The tests on the beams were performed using a universal testing machine, with a simple-supported beam as the static diagram. The momentary load consisted of two concentrated forces applied at one-third of the beam spans. After the beams had been placed on the test stand and the appropriate sensors had been set to measure the particular parameters, the measurements began. The force was applied slowly, and it was increased by 5 kN; then, the necessary measurements were conducted. The strength tests of the investigated reinforced concrete beams were performed until their destruction. The deformations of concrete were measured with an extensometer. The measurements were carried out at the two levels: 1 (in the compression zone) and 2 (in the tension zone), each time after the load force value had increased.The measurements of the deflection of the reinforced concrete beams were carried out using dial gauges with 0.001 mm resolution. The gauges were placed at three locations: on the left support, in the beam midspan, and on the right support. The deflection was measured each time after the force level had been increased by 5 kN. The long-term measurements consisted of measuring the deflection of the bent concrete elements. The aim of this research was to analyze the deformability of the beams under study in the function of time, with the constant loading value. The bars with the dimensions of 40 mm × 40 mm × 500 mm were the test samples for the long-term experiments (3 for each concrete). The test elements were placed in the test stand designed specifically for the purpose of this research. A load was applied to the beams in a room maintained under constant temperature conditions. The deflections of the bars under research were read every day over approximately 100 days.The physical properties of the recycled aggregate concrete and the HSC-HPC concrete adopted for the examination are shown in −3 g∙mm−2 after 72 h, while the recycled concrete with 50% and 100% substitutes, showed a value of 1.68–2.83 × 10−3 g∙mm−2 and 1.84–3.43 × 10−3 g∙mm−2 [The use of recycled aggregate resulted in a reduction in the apparent density of REC-1 and REC-2 concrete by 4% and 7%, respectively, compared to the reference concrete. Moreover, a clear influence of the recycled aggregate addition on water absorptivity can be observed; an increase of 18% was recorded for the REC-1 concrete and 49% for REC-2. The use of recycled aggregate has also contributed to an increase in open porosity by 15% for REC-1 and by 38% for REC-2, which affects lower compression strength, as shown in 3 g∙mm−2 , respectIn the water absorption and sorption tests carried out by Zega and Di Maio, these parameters for recycled aggregate concretes (RACs) were 15% higher than those for the reference concrete, while, in the water penetration test, all concrete types show a similar behavior. This is due to the different water transport mechanisms in each of these concretes .According to Zhang et al. , the RACc value of 56 MPa is found in the concrete with the highest recycled aggregate content (REC-2 100%). It is 30% lower than for the concrete with 50% recycled aggregate content and as much as 43% lower than for the basalt concrete. After 14 days and after 28 days of ripening of all three concrete types, the basalt concrete still showed the best compression strength results. The worst compression strength after 7, 14, and 28 days was recorded for the concrete with 100% recycled aggregate content, which was 43%, 35%, and 43% lower than the reference concrete, respectively.Other researchers, e.g., Çakır , also noThe compression strength of RACs was least dependent on the quality and quantity of RAC than in studies carried out by other authors. After 90 days of concrete ripening, RACs showed higher increases in the compression strength than NAC. According to some authors ,19, imprc decreased faster with the increase of the recycling rates of aggregate under autoclaving conditions than under standard conditions of its ripening. In the latest research of Wang et al. [As noted by Zhang et al. , fc decrg et al. , the comg et al. ,56,57,58In the study by Fonseca et al. , it was cm) after 7, 28, and 56 days was 42.8, 49.8, and 51.6 MPa, respectively. In general, after 7 and 28 days of curing, the samples showed about 80% and 95% of their 56-day compression strength [As shown by Fonseca et al. , the com2 = 0.988 and relatively low errors in the intercept. The obtained correlations can be described by the equation: y = 0.325x + 13.90.Flexible modulus of elasticity is closely related to the compressive strength of concrete. The highest parameters were achieved with the concrete comprising the HSC-HPC natural aggregate. Replacement of the aggregate with recycled concrete aggregate resulted in a large decrease in the value of these two parameters—compression strength by about 42% and modulus of elasticity by about 33%.c of concrete barely grows after 28 days. Ec after 50 years is only 6% higher than Ec after 28 days, according to EC2 [c value of 45 MPa with a recycled fine aggregate, the modulus of elasticity E varies between 17 GPa and 35 GPa with a 109% difference, while E varies between 15.6 GPa and 36.2 GPa with a 132% difference for coarse recycled aggregate concrete. In addition, the E value decreases by an average of 23% and 32% when the natural aggregate is replaced by the recycled aggregate in 50 and 100%, respectively [Concrete is generally considered to be a composite material consisting of three phases: aggregate, cement paste and ITZ . Elasticg to EC2 . The litg to EC2  showed tectively ,64,65,66As shown by Fonseca et al. , the 28-Zhang et al. , similarAjmani et al.  tested tThe strength tests of the reinforced concrete beams under investigation were performed until the tested beams were destroyed. At that moment, in each case, a sudden decrease in the rigidity of the beams was observed, as well as a rapid increase in the number of cracks that became much wider, which was indicative of the reinforcement in the tension zone becoming more susceptible to fatigue, and the concrete in the compressed zone was destroyed. The beams were destroyed suddenly, which was accompanied by a characteristic cracking sound. There are many factors that influence the fact that the cracking of reinforced concrete structures is a complex phenomenon. Monitoring of cracking in the reinforced concrete elements is very important because the presence of cracks may indicate the loss of the load-bearing capacity of a structure, which would lead to the concrete being destroyed. Performing the measurements of the width and character of cracks influences the evaluation of the construction safety. The cracking was monitored simultaneously with the deflection and deformation measurements of the tested elements, carried out by the authors of the present paper. Each time, after the loading force had been increased by 5 kN, the appearance and penetration of the formed cracks were marked, with the loading force value inscribed at the end of each crack. The first cracks were observed when the value of the applied loading force was approximately 30% of the critical load, which amounted to 10 kN and 15 kN for the recycled aggregate beams and natural aggregate beams, respectively. The mean experimental values of rupture force and breaking moments of the recycled aggregate concrete and the HSC-HPC concrete adopted for the examination are shown in sd.2 + 0.0143x + 6.53 indicate a good coefficient of determination R2 = 0.954. Bending tensile strength and breaking moment Msd of concrete also depend on the type and quantity of aggregate used. The best strength parameters were achieved by the concrete with basalt aggregate. As the amount of recycled aggregate in the concrete increases, the bending strength and the breaking moment causing the beams to break down decrease. This moment is approximately 10% lower for the REC-2 concrete than for the HSC-HPC concrete.The correlations described by the polynomial formula y = 0.0169xHaving analyzed the above-mentioned results and deformation graphs, it can be concluded that the recycled aggregate beams under study showed greater deformation than the tested natural aggregate beams for the respective values of the loading force. After comparison of the obtained results, it was concluded that the observed mean deformations in the compressed zones of the recycled aggregate beams were, on average, 39% greater than in the case of the natural aggregate beams, while the deformation values in the tension zones were greater by 20% for the recycled aggregate beams in comparison to these for the natural aggregate beams.p takes values < 0.05 . The ANOVA test showed no significant differences in the deflection values between REC-1 and REC-2 (p = 0.765).On the basis of the test results shown in Having analyzed the obtained results of the long-term tests consisting in measuring the deflection of the bent concrete elements, it was concluded that the deflection values of the elements made of the recycled aggregate concrete were, on average, 45% higher than the values of the elements which were made solely of high-performance concrete.Similar observations on deflections and long-term deflections were made by Łapko A. and Grygo . In theiIn contrast to others, Łapko and Grygob  based thIn several studies ,76,77,78Recycled aggregate is viable for use as a substitute of coarse aggregate in concrete structures. Attention has to be paid, however, to the deterioration of some concrete parameters, such as the increased deformability.When designing compositions of concrete mixtures with the use of recycled material, a larger safety margin has to be provided for.The use of recycled aggregate resulted in a reduction in the apparent density of REC-1 and REC-2 concrete by 4% and 7%, respectively, compared to the reference concrete.A clear influence of the recycled aggregate on water absorptivity can be observed; an increase of 18% was recorded for the REC-1 concrete and 49% for REC-2.The use of recycled aggregate contributed to an increase in open porosity by 15% for REC-1 and by 38% for REC-2, which affects the lower compression strength.Replacement of aggregate with the recycled concrete aggregate resulted in a large decrease in the value of these two parameters—in the compression strength by about 42% and modulus of elasticity by about 33%.As the amount of recycled aggregate in the concrete increases, the bending strength decreases.The deflection values for the recycled aggregate beams were 20% higher than in the case of the control beams made solely of HPC-HSC.The long-term tests consisting of measuring the deflection of the bent concrete elements, showed that the deflection values of the elements made of recycled aggregate concrete were on average 45% higher than the values of the elements, which were made of high-performance concrete exclusively.Replacement of basalt with recycled aggregate resulted in the changes in the concrete structure, which affects its physical and strength parameters.It can be assumed that the recycled aggregate will be increasingly commonly used as a construction concrete component of full value because of the increasing social emphasis on the ecological aspects.Hopefully, the continuous development of technologies in the construction sector will lead to a reduction in the amount of waste produced as well as an increase in the number of materials which can be recycled and reused in concrete manufacturing.The following key conclusions can be drawn from this study:


The antimicrobial resistance (AMR) crisis and HIV/AIDS epidemic exhibit many parallels. In both, infectious diseases have caused millions of deaths worldwide, with AMR expected to kill even more people each year than HIV/AIDS did at its peak. In addition, both have required or will require new classes of drugs for control. For HIV/AIDS, development of vital antiretroviral drugs (ARVs) was accomplished in several stages: expanding public awareness about the disease, gathering commitment from the international community to tackle the problem, and eventually establishing policies and global funds to deliver new therapeutics. For AMR, the pursuit of new antimicrobials appears to be following a similar trajectory. This paper examines how lessons and processes leading to ARVs might be applied to developing AMR drugs, in particular bacteriophages (phages). These possess many essential characteristics: inexpensive manufacture, rapid drug development, and a ready means to prevent phage-resistant microbes from emerging. However, the broad application of phage-based products has yet to be fully demonstrated, and will require both international coordination and modified regulatory policies. HIV/AIDS spurred the deadliest epidemic in modern history. At its peak, the disease caused 1.9 million deaths per year worldwide . As withNotably, when the HIV/AIDS epidemic began, there were no effective drugs available to treat the emerging infectious disease. Similarly, there are now no conventional treatment options in the face of antimicrobial resistance. Just as new drug classes—namely antiretrovirals (ARVs)—were needed to mitigate HIV/AIDS, new antimicrobial drugs will be required to tackle AMR.Phages—viruses that can kill both antibiotic-sensitive and antibiotic-resistant bacteria—are a key drug class that could save many lives threatened by the AMR crisis. Phages have been used as antibacterial agents for nearly 100 years in the former Soviet Union, and they are now undergoing a renaissance in other countries due to the growing AMR problem ,4,5,6,7.Substantial funding and appropriate regulatory structures would be needed to develop and deploy phage products to the vast number of people who will be impacted, as was necessary for ARVs. This publication examines what lessons from the HIV/AIDS epidemic might be applied to phages and the AMR crisis; specifically, what funding programs and regulatory modifications enabled rapid research and development of a new class of drugs, followed by large-scale manufacturing and distribution of those drugs to developing countries.The worldwide response to the HIV/AIDS crisis was unprecedented in terms of the speed with which ARVs were developed and applied clinically, especially in low and middle income countries (LMIC). These drugs ultimately transformed HIV/AIDS from a disease whose sufferers had a life expectancy of approximately one year to our current situation, in which HIV-positive individuals can experience a nearly normal life span . An estiThe first AIDS case was diagnosed in 1981, and the first ARV to treat HIV/AIDS, azidothymidine (AZT), was approved in 1987, with much of the initial funding coming from the US government . Once thARVs were eventually deployed to the developing world. The global community went through several stages of grappling with the problem before achieving some success: first comprehending the massive scale of the disease and disseminating that information; then mobilizing global resolve to address the issue; and eventually, establishing substantial international funding sources, particularly to deliver ARVs to LMIC . MillionAs early as 1983, the World Health Organization (WHO) convened its first meeting on HIV/AIDS and began formal international surveillance of the disease . Two yeaNew governmental organizations and processes were set up to coordinate policy development and global activities to tackle HIV/AIDS. Most notable of these was the Joint United Nations program on HIV/AIDS (UNAIDS), which began operations in 1996 . In 2001Financing for the HIV/AIDS crisis came in stages of increasingly larger investments. The World Bank Multicountry AIDS Program (MAP), established in 2000, was the first international program, with disbursements totaling $500 million in the initial funding round . After tIn addition to gathering the financial resources needed, several regulatory modifications were enacted to facilitate faster and therefore more cost-effective delivery of ARVs to the developing world. In 1997, the US Congress passed the FDA Modernization Act in order to accelerate the drug approval process and loosen restrictions on communications regarding off-label use for potential HIV drugs . And in New financial and legal resolutions were also put in place to help reduce the costs of ARVs. In 2000, the UNAIDS and WHO negotiated the Accelerating Access Initiative, an agreement with five major pharmaceutical companies to provide HIV/AIDS drugs to developing countries at decreased prices . In addiWhile these various support mechanisms for LMIC were initially funded by industrialized countries, developing countries themselves eventually began to underwrite the local delivery of ARVs. By 2013, roughly half of all costs for HIV treatment in sub-Saharan Africa were covered by in-country sources . And in As the world has been coming to grips with AMR, we have begun to progress through similar stages as with the HIV/AIDS epidemic. However, as discussed below, we are still at a relatively early point in this overall process. In order to effectively fund new drug development for AMR, including for phages, the global community will need to first more fully comprehend the scale of the crisis, which will then motivate international commitment to combat the problem, finally leading to the establishment of the financial resources and regulatory modifications needed.Resistant strains to the first small molecule antibiotic, penicillin, were identified even before penicillin was introduced in 1943 . As new Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pneumoniae, Nontyphoidal Salmonella, Shigella, and Neisseria gonorrhoea [Over the past decades, the scientific and public health communities have been documenting the growing rates of antibiotic resistance in specific bacterial strains and geographic regions. The WHO’s first report on AMR, published in 2014, summarized the global resistance patterns for seven bacteria of major concern: norrhoea . StrikinReview on Antimicrobial Resistance were astounding: by 2050, AMR is expected to cause over 10 million deaths each year and cost the global economy a total of $100 trillion [By July 2014, this data and others had prompted the UK Prime Minister to commission a study analyzing the key components of the crisis and proposing tangible steps that the international community could take to surmount it. Funded in partnership with the Wellcome Trust, the predictions from the resulting trillion . In additrillion .Review on Antimicrobial Resistance emphasized that there is still a primary need for AMR awareness-raising campaigns globally, despite the fact that numerous organizations have been spreading knowledge about AMR for decades. One of the earliest was the Alliance for the Prudent Use of Antibiotics, founded in 1981 by Dr. Stuart Levy, a leading researcher on molecular antibiotic efflux mechanisms [These reports served as wake-up calls for many, and the authors of the chanisms . In 2001chanisms . This evchanisms . More rechanisms . Two monchanisms .Nature calling for the establishment of an intergovernmental panel on antimicrobial resistance [Calls to action have come from various authoritative sources. In 2004 and 2008, the Infectious Diseases Society of America highlighted key causes and dangers of AMR, and proposed specific ways to stimulate investment in antibiotic research and development ,32. And sistance .To date, a global panel for AMR has not been formed. An oversight body of this type could more effectively coordinate international efforts, analogous to the role of UNAIDS for HIV/AIDS. In the meantime, worldwide forums have issued formal declarations on AMR, and both international and national bodies have created action plans. In May 2015, the World Health Assembly approved the Global Action Plan for Antimicrobial Resistance, which enumerates key strategies, including the need to increase AMR awareness globally and to develop policies for attracting more investment into new medical interventions . It alsoReview on Antimicrobial Resistance estimated that $40 billion will be needed over 10 years to adequately address the global AMR problem. This represents only about 0.05% of the total amount that G20 countries currently spend on healthcare, and it is quite small compared to the projected $100 trillion that will be needed if AMR is not addressed. Of the total $40 billion proposed for AMR, likely $16 billion would be necessary to boost a new antibiotic pipeline, assuming a traditional drug development process and associated costs. However, phage manufacturing could be less expensive, and thus, do more with less.In order to stall HIV/AIDS to the current level, PEPFAR, the largest funder for this disease, has spent over $70 billion since 2004 . By compReview on Antimicrobial Resistance called for establishment of a Global Innovation Fund for AMR, with seed funding of $2 billion for 5 years. The UK and China responded by initiating such a fund in 2015, with each country pledging £50 million ; the Bill & Melinda Gates Foundation also agreed to contribute. While this falls far short of the recommended amount, it is a start. Recall that the analogous HIV funding began with $500 million before eventually growing to over $70 billion.As an incremental step toward gathering the financial support, the (1)Global Research Fund to build up infrastructure and increase the number of scientists working in the AMR field ($200 million/year for 10 years)(2)Global Development Fund to provide forgivable loans primarily to small and medium-sized enterprises with the goal of pushing ten “high-need” products to market over a decade ($200 million/year for 10 years)(3)Global Launch Reward of $1 billion for successfully delivering a commercial product that meets pre-specified AMR therapeutic goalsIn early 2017, the Global Union for Antibiotics Research and Development (GUARD) published its own set of recommendations on specific steps for addressing AMR . Its proReview on Antimicrobial Resistance and the GUARD report recommended a balance of so-called “pull” vs. “push” financial incentives. Push incentives, such as grants and forgivable loans, would help move the initial stages of R&D forward. Pull incentives, typified by the Global Launch Reward, would motivate companies to progress through the final, more costly stages of drug development by providing a monetary award that essentially lowers the financial risk. Economic experts generally agree that numerous push incentives are currently available, but pull incentives are sparse.Both the Other large AMR financing mechanisms have been established in Europe and the US. NewDrugs4BadBugs (ND4BB) was created in 2012 by the European public–private partnership Innovative Medicines Initiative (IMI). The goal of ND4BB is to bring together academic, industry and biotech groups to find new ways to overcome the practical challenges of developing new antimicrobial drugs . To dateIn the US, much of the funding for AMR comes through the Biomedical Advanced Research and Development Authority (BARDA), which was established in 2010 to address a number of public health emergencies. BARDA works through public-private partnerships with pharmaceutical and biotech companies, providing non-dilutive funding to help companies develop new antimicrobials. In 2016, BARDA partnered with the Wellcome Trust and the AMR Centre in the UK, as well as with the US NIAID, to launch a global business accelerator program called the Combating Antibiotic-Resistant Bacteria Biopharmaceutical Accelerator (CARB-X) . To dateAnother financial instrument, InnovFin Infectious Diseases, was founded in 2015 under the European Investment Bank, with estimates suggesting that it may provide up to $350 million . And in Review on Antimicrobial Resistance have proposed a tax on pharmaceutical companies, with the collected levies used to fund pull incentive awards for successful commercialization of new antimicrobials [Several other strategies have been launched or proposed to foster new drug development. In 2012, the Generating Antibiotic Incentives Now (GAIN) legal provision was enacted in the US to incentivize pharmaceutical companies . This lacrobials . The ratcrobials .Given that the first significant finances for AMR have only been committed in the past few years, the global community is still in the early stages of fundraising. Realistically, most of the money for LMIC will need to come from industrialized countries, as was the case for HIV/AIDS; developing countries simply do not have the resources. Of course, AMR truly is a global problem, since bacteria readily move across borders.Nonetheless, the fundraising goals appear achievable, as evidenced by the worldwide response to HIV/AIDS. Now is the key time to strategize about how to use funds most efficiently. While conventional development of new antibiotics will certainly be important, that approach is typically an expensive and lengthy one. In addition, bacteria will undoubtedly continue to evolve resistance mechanisms to new classes of drugs. An ideal solution would be to invest in low-cost drugs that reduce development of resistance.Phage-based drugs already provide such an option in the Eastern European countries of Georgia, Poland, and Russia ,5,7. LetUnlike ARVs for HIV/AIDS, which were very expensive drugs to develop, phages are inherently inexpensive to isolate. Indeed, therapeutic phages were first developed for patients in the 1920s using the relatively simple laboratory equipment that was available at that time ,7. In thmagistral preparations was approved for phages in Belgium in early 2018 [Phages in Georgia, Poland, and Russia are manufactured under conditions that do not meet formal Western cGMP (Current Good Manufacturing Practice) requirements, but that do adhere to a different set of strict quality control standards—a key reason why phages are available in those countries at relatively low prices. These products have been used for decades with no reported major adverse events. Another non-cGMP regulatory system called rly 2018 . Under tAcinetobacter baumannii [Another key attribute of phages is that these products can be developed in very short time frames, which can both help to keep costs down and enable rapid responses to infection outbreaks. As an example, in 2016, a patient in San Diego, California, received emergency phage treatment after contracting a multi-drug resistant strain of aumannii . The seaaumannii . During Several tactics have been utilized to minimize the possibility that bacteria will eventually develop resistance to phages. The most common are mixing phages that target different bacterial epitopes and rotating the phage combinations at regular intervals . Recall Phage treatments are most effectively made of routinely shifting, carefully selected mixtures (termed “cocktails”) that target multiple bacterial epitopes proliferating in a given locality . Thus, wIt is critically important to select appropriate phages for each cocktail. This includes avoiding phages that can transduce virulence genes through their local environment , as well as excluding phages that contain toxin genes which potentially could be transferred to the bacterial hosts. Regulatory systems must address these possible risks by rigorously controlling for them.An ideal situation might be to have banks of pre-approved phages in each country or region. Centralized laboratories could regularly test those phages against bacterial populations currently circulating in each country, modifying the selected phage combinations as needed, and routinely adding new phages to the banks through certified approval processes. Local institutions and universities could potentially contribute phages to the banks, thereby providing incentives and opportunities for in-country development. Such a system would both address the need for altering phage mixtures to avoid resistance development, and also enable rapid responses to sudden disease outbreaks.This is essentially the arrangement that has been in place the former Soviet Union for decades, and it has proven to be effective. It is notable that Georgia—which is officially categorized by the World Bank as an LMIC—is already showing how this system of delivering reasonably-priced, routinely-updated phage products can be accomplished in a developing country.AMR knows no national boundaries, so overcoming it will take coordinated efforts from countries worldwide working together, likely overseen by a centralized international panel. Innovations in science, financing mechanisms, and regulatory processes will all be required to expedite the path forward. In this context, phage-based products could be an important part of the solution, since they can potentially provide effective and affordable options for killing antibiotic-resistant bacteria, with reduced probability of resistance development.However, if the global response to AMR follows a similar pattern as that for HIV/AIDS, the worldwide community must focus more on raising awareness and motivating national and international commitment to the problem before sufficient funds will become available. Realistically, many other factors must also be in place to overcome AMR, such as improvements in water sanitation, appropriate use of existing antibiotics, suitable low-cost diagnostics, adequate surveillance, and effective local health systems, amongst others. It is an overwhelming, complex crisis, but the achievements that have been realized with the HIV/AIDS epidemic demonstrate that the global community is capable of bringing together the resources and creative solutions to surmount a problem as big as AMR.


Recently, device-free human activity–monitoring systems using commercial Wi-Fi devices have demonstrated a great potential to support smart home environments. These systems exploit Channel State Information (CSI), which represents how human activities–based environmental changes affect the Wi-Fi signals propagating through physical space. However, given that Wi-Fi signals either penetrate through an obstacle or are reflected by the obstacle, there is a high chance that the housing environment would have a great impact on the performance of a CSI-based activity-recognition system. In this context, this paper examines whether and to what extent housing environment affects the performance of the CSI-based activity recognition systems. Activities in daily living (ADL)–recognition systems were implemented in two typical housing environments representative of the United States and South Korea: a wood-frame apartment (Unit A) and a reinforced concrete-frame apartment (Unit B), respectively. The experimental results show that housing environments, combined with various environmental factors , generate a significant difference in the accuracy of the applied CSI-based ADL-recognition systems. This outcome provides insights into how such ADL systems should be configured for various home environments. In order to advance smart home environments that can deliver elderly healthcare, energy savings, and home security, systems must first be able to accurately recognize human activity in daily living (ADL) ,2. TradiIn recent years, device-free activity-recognition approaches have been the focus of ADL-recognition systems , with WiWi-Fi signal-based ADL-recognition approaches exploit fine-grained Wi-Fi signal signatures. Specifically, Wi-Fi signals propagate from a transmitter to receivers, so human activity may affect the signals’ propagation paths, which in turn cause the signals to be changed at receivers. For example, Received Signal Strength (RSS) has been used for fingerprint-based localization systems ,10,11,12Unlike RSS which has a superimposition layer of multipath signals, Channel State Information (CSI) exploits channel information between the AP and the receiver at the individual subcarrier level. Specifically, CSI represents a channel response to the physical environmental changes, which depicts the multipath effects of signals. Consequently, CSI is more stable and robust than RSS, and CSI data can be captured from commodity Wi-Fi devices using a Linux CSI 802.11n tool . RecentlDespite these advantages, these CSI-based ADL-recognition systems environments still need further verification in terms of their performance in various real-world housing environments; Most previous studies ,20,21,22Recently, exploiting Wi-Fi signals for activity detection has risen in popularity due to the availability and ubiquitous distribution of these wireless networks and their corresponding commercial devices. Human-body movements cause Wi-Fi signals to change when the signals are reflected from the body, which results in variations at the Wi-Fi receiver and, consequently, opportunities to estimate human activities by analyzing the signal variance. This approach further benefits from the fact that Wi-Fi signal–based ADL-recognition systems do not require LOS for the activities since Wi-Fi signals propagate through walls. Thus, systems such as Wi-Vi  and WiSeWhile such RSS approaches have been successfully used for gross-level ADL recognition, CSI manifests even greater sensitivity to fine-activity differentiation. CSI is more stable and robust than RSS , and theTo-date, CSI-based ADL-recognition systems have been applied to various activity-detection tasks. Firstly, CSI has been used for indoor localization. Location detection indoors is required in various settings, such as in hospitals (patient tracking) and disaster areas (personnel locating). Wu et al.  comparedAnother CSI-based approach, Wi-Chase , recogniFor more diverse in-place activities and for walking-direction recognition, Wang et al.  proposedBuilding upon these successes, researchers have applied CSI-based ADL-recognition solutions to various smart home healthcare systems. Wang et al.  proposedIn keeping with the healthcare applications, CSI has been exploited to detect vital signs such as respiration and heartbeat rates. PhaseBeat  used CSICSI-based ADL-recognition systems have also been used in place of human-device interactions. Various smart home gadgets control such home appliances as TVs, laptops, and mobile phones. Alternatively, Nandakumar et al.  used CSIThese successfully developed and verified CSI-based ADL-recognition systems benefit from CSI’s stability and accessibility. However, Wi-Fi signals are affected by various environmental factors, which can in turn have impact on the performance of CSI-based ADL-recognition systems. Thus, in order to advance the opportunities for applying CSI to human ADL recognition in smart homes, studies must verify that these systems’ performances will yield consistent accuracy in different housing environments.As Wi-Fi signals propagate in physical space, the signals reach receivers (Wi-Fi devices) through various routes, a concept known as multipath. Mathematically, the CSI matrix, tion (1) .(1)Yi=HCSI has several subcarriers that are divided by Orthogonal Frequency Division Multiplexing (OFDM) . Thus, tIn order to examine whether and how CSI-based ADL-recognition systems can be resistant to varying housing environment, two different housing environments were selected: A wood-frame, low-rise apartment in the United States (Unit A), and a reinforced concrete-frame, high-rise apartment in South Korea (Unit B). These two housing environments show clear differences in construction materials and population densities. The exterior walls in Unit A were composed of wood framing and insulation, and wood sheathing, and its interior walls were also composed of wood framing and drywalls with painting finishes. Unit B was built with reinforced concrete structure and its interior walls were masonry and drywall, and wallpapers were used for the interior wall finishing. While Unit A is also a part of low-rise multi-family housing, the population density of the high-rise apartment complex that Unit B belongs to is much higher. The layouts of two units present clear differences, as shown in Two subjects were recruited for the experiments at each Unit; Recruiting for the experiment at each Unit was conducted separately due to the geographical distance. All the four subjects participating in both Units were male having similar physical characteristics; Their heights ranged from 175 cm to 180 cm, while their weights range from 68 kg to 70 kg. During the experiments, the subjects were instructed to perform the identical activities, and tests were performed by one subject at a time. Each subject walked in ten rounds, as indicated by the arrows, and performed eating and typing in ten rounds in the dining room and living room, respectively. Each round required 10 s of activity and 20 s of no-activity. The 20 s interval between activities clearly differentiated the multiple activity rounds. During the test, the activities were recorded using a camera and were labelled with time stamps for the activities to establish the ground truth. As shown in 11n tool , the CSIThe raw CSI data contains high frequency noise, outliers, and artifacts introduced by rate adaptation rather than by human activities—high frequency noise manifests when the radios are switched to different modulation and coding schemes. Thus, a second-order, low-pass Butterworth filter was used to remove high frequency noise from the raw CSI data. The filter was configured to keep the sampling rate at 10 packets/s, and the cut-off frequency was set at 1 Hz. Although the walking activity causes higher Doppler shift than 1 Hz, the phase shift caused by occupant’s activity would be rotated due to hardware imperfection. Thus, the 1 Hz filtered CSI still contained the variation caused by walking activity. The variation in the filtered CSI was distinguished from other activities . Figure As shown in As developing high-efficiency activity-segmentation algorithms is beyond the scope of this study, to increase recognition accuracy, the walking and in-place activities were manually segmented by referring to ground truth. A total of 400 data samples were segmented.Activity-classification approaches exploit various activity-recognition models to classify the segmented activity data. In this study, two different algorithms were used for activity classification: SVM and EMD reconstructed from literature ,15,18,30Unlike an SVM, an EMD finds the minimum cost of matching one distribution into another and thereby represents to what extent two distributions are similar to each other. Notably, under EMD, the same activity will have similar distributions across the CSI amplitudes, whereas different activities will have distinctive distributions. In this study, to determine the impact of environmental factors on the accuracy of two different CSI-based ADL-recognition systems, two subjects performed a walking activity and two in-place activities in different housing environments. To recognize activities, the authors used two different activity-recognizing approaches, an SVM-based model and an EMD-based model. The activity-recognition accuracy of the SVM-based model was 94.38% for Unit A and 87.50% for Unit B, whereas the EMD-based model showed 68.75% and 60.25% accuracy levels for Unit A and Unit B, respectively. Under the SVM-based model, features used for activity classification related to the amplitude of signal variance. Thus, even though an activity signal forms a specific waveform, its amplitude appeared to be low, so the SVM classifier considered the activity as no activity. The confusion matrix for Unit B showed 15 ‘no-activity’ data were predicted as examples of ‘typing activity,’ which mainly reduced the model’s accuracy. ‘Typing activity’ is one of the smallest movements in daily life, since when people type, they only move their fingers and arms a small amount. Thus, the signal variance of the ‘typing activity’ has a low amplitude, and if the signal power is reduced by environmental factors, the ‘typing activity’ signal may be too weak to differentiate from a ‘no activity’ signal. Accordingly, we expected—and observed—that Unit B environment would have a greater impact on signal propagation than Unit A environment. Under the EMD-based model, the distribution of the signals’ amplitudes has more impact on the activity classification than the amplitudes’ variance within the signal, since the EMD-based model classifies unknown activities based on the distributions’ similarity to known distributions. As shown in The results also show that the EMD-based model has lower average accuracies compared to the SVM-based model. The SVM-based approach exploits 60% of the total 400 activities data to train the model and classified the remaining 40% activity data—160 samples. On the other hand, the EMD-based approach does not need training data, and consequently evaluates activity data for the full 400 samples. Thus, the actual number of recognized activities evaluated by the EMD-based model is greater than the number recognized by SVM-based model, which means the EMD-based model has more opportunities to make false predictions than the SVM-based model. Also, the SVM-based model used 60% of the total data as reference data, whereas the EMD-based model exploits only one reference datum for each activity to calculate the similarity of the known activity against the unknown activity data. Consequently and foreseeably, the EMD-based model does not cope with the variability of unknown activity data as well as the SVM-based model does.To investigate the effect of time-dependency or subject-dependency of the result, we split data into each subject data and classified activities for each subject data; Each subject performed the experiment in different days. The results in different data segmentation showed that the accuracy of Unit A was generally higher than Unit B and the accuracy of SVM was higher than EMD, meaning that the time dependency and subject dependency did not have much impact on this result.It is important to note that rather than identify effective ADL-recognition methods, this study compares the effect different environmental factors have on the performance of CSI-based ADL-recognition systems. Even though the SVM-based model and EMD-based model both show different accuracy levels for activity recognition, the results clearly indicate that both CSI-based ADL-recognition systems show less accuracy for the Unit B environment, meaning that the Unit B environment mediates the accuracy of the CSI-based ADL-recognition systems more than the Unit A environment does. We further discuss this important finding about the environmental effects mediating performance of the CSI-based ADL-recognition systems in the next section.The results indicate that both of the tested CSI-based ADL-recognition models are quite sensitive to the difference of housing environment and yield significantly different accuracies between two units. Here, we mainly discuss the potential factors that affect the performance of the CSI-based ADL-recognition systems. While these factors may appear to be limitations to the present study, they serve—in fact—as a further defense of the justification of this study, since smart-home engineers must mediate these factors when designing tools within different environments.One potential factor contributing the performance of ADL recognition is the difference of building materials. The main building materials of Unit B were reinforced concrete and concrete masonry, which is one of the hardest building materials for wireless signals to penetrate , while UThe household item  is another potential factor for Wi-Fi signal propagation. Depending on the materials of household items, Wi-Fi signal is reflected from the object more or a lot of energy is absorbed. Unit B had more small and medium sized household items, which were not all made of metal, the more reflective objects compared to the wooden or plastic materials. Thus, the small and medium sized objects absorbed more energy of the Wi-Fi signal in Unit B than Unit A, which resulted in a reduced amplitude of the CSI. The decreased variation in the CSI, then, became hard to distinguish from no-activity or other activities in Unit B. The other contributing factor is the difference of population densities. Just as people can access home networks from outside their walls, people outside of a house can affect the Wi-Fi network environment inside. Thus, neighbors’ activities or outdoor movements will conceivably affect the performance of CSI-based ADL-recognition systems. Unit B had more nearby units than Unit A. Significantly, for Unit B, neighboring households shared walls on both sides of the apartment, whereas Unit A only had neighbors five meters away on one side of the testbed. Also, the elevator located next to Unit B continuously ran, which influenced the signals within Unit B; Unit A had no elevator. Thus, more movements unrelated to the test activities took place in proximity to Unit B, which could affect the received signals used for activity detection. Unit B was in a higher population apartment complex than Unit A testbed, meaning that there were more Wi-Fi networks around to influence the test. Thus, the surrounding Wi-Fi signals had a higher chance to interfere with the testing Wi-Fi signals in Unit B than Unit A. However, as mentioned in the previous section, such interference from surrounding Wi-Fi signals might have been alleviated by the building materials of Unit B, although Unit B had many openings.In this section, we will discuss possible solutions for coping with the housing environmental effects influencing the accuracy of the CSI-based ADL-recognition system, including (1) using multiple receivers; (2) filtering external noise; and (3) using Wi-fi-friendly construction materials.While our experimental setting used only one receiver, using additional receivers would improve the recognition accuracies of CSI-based systems by augmenting the variance of the received signals. In larger houses or those with multiple rooms, the strength of the signals arriving at the receivers becomes weaker, as the signals have to penetrate through multiple walls ,23,24. UIn order to address the effects resulting from a neighbor’s activity, advanced filtering methods must be proposed and used. While such filtering would represent a great challenge, developers may conceivably be able to distinguish the signal changes due to a neighbor’s activities in another unit, especially as such signals would have to penetrate multiple walls  and a neighbor’s activities may manifest different patterns in the frequency domain . Lee et al.  demonstrAs smart homes become more popular, Wi-Fi-friendliness will play an important role in the design and selection of construction materials . The perAs this study intended to examine the effect of actual housing environments of existing homes on CSI-based ADL-recognition systems, various environmental factors were less controlled, and the results from such the experimental settings represent the combined effects of all possible environmental factors. Thus, the effect of each individual environmental factor is still unknown, although the experiment results confirm the significant effect of housing environment on CSI-based ADL-recognition systems. In addition, although two representative ADL-recognition algorithms were used in this study, the effect of housing environment could be largely dependent on algorithms.The two robust CSI-based activity-recognition algorithms yielded lower accuracy in Unit B than Unit A, a result that speaks to the mediating influence of environment on CSI-based ADL-recognition systems. This result highlights that the effects of the housing environments should be considered when designing and implementing CSI-based ADL-recognition systems in various home environments. However, further research is necessary to analyze the isolated effects of various housing environmental factors and understand the impact of possible mitigation strategies on such environmental effects.


Truck pulling is one of the common manual materials handling tasks which contribute to musculoskeletal disorders. The maximum endurance time (MET) for two-handed truck pulling tasks has been rarely discussed in the literature. The objectives of this study were to explore the development of muscular fatigue when performing two-handed pulling task and to establish models to predict the MET. A simulated pallet truck pulling experiment was conducted. Sixteen healthy adults including eight females and eight males participated. The participants pulled a handle simulating that of a pallet truck using two hands until they could not pull any longer under two postures. The forces applied for females and males were 139.65 N and 170.03 N, respectively. The maximum voluntary contractions (MVC) of the pulling strength both before and after the simulated pull were measured. After each trial, both the MET and subjective ratings of muscular fatigue on body segments were recorded. The results showed that posture significantly affected MVC of pull both before and after the trial. It was found that foot/shank of the front leg had higher subjective ratings of muscular fatigue than the other body segments. The MET equations employing both power and logarithmic functions were developed to predict the MET of the two-handed pulling tasks. Predictive models established in this study may be used to assess the MET for two-handed pulling tasks. Manual Material handlings (MMH) are common at workplaces. They contribute to the occurrence of work-related musculoskeletal disorders (MSDs) . Carts, Manual-operated pallet trucks are widely used for materials handling . Mack etved exertion have been widely used for such assessments [There are many symptoms associated with MSDs. Frequent muscular fatigue is one of them. Muscular fatigue can be defined as “reduction in the ability to exert force in response to voluntary effort” . It can essments .The maximum endurance time (MET) is also associated with muscular fatigue and has been adopted in ergonomic guidelines . It reprA pallet truck may be pulled using either one hand or two hands. Two-handed pulling is adopted for heavy materials handling. It, as compared with the one-handed pulling, is associated with more forceful exertions which could result in more muscular fatigue problems. Although the literature has discussed muscular fatigue for pulling tasks , 23–25, The objective of this study was to investigate the developing of muscular fatigue for static two-handed truck pulling tasks via measuring the pulling strength both before and after the pull. The METs and subjective ratings of muscular fatigue were examined. In addition, predictive models were established as tools to predict the MET for two-handled pulling tasks. These models are significant as they may be used to predict the MET so as to determine the work-rest allowance for workers where two-handed pulling tasks are performed.A simulated pallet truck pulling experiment was conducted in the laboratory of the Hunan Institute of Technology in China. This study was approved by an Ethical Review Committee of the Institute. The temperature and humidity during the experiment were 17.35°C (SD = 4.02) and 87.45% (SD = 11.68), respectively.A call for participations in the experiment was announced in the campus where the authors served. Any adult without self-reported MSDs problems within a year of the study was welcomed. Sixteen participants  joined voluntarily. All of them were right-handed. The research personnel explained the purposes and procedure of the experiment to the participants at their first appearance in the laboratory. All the participants read and signed informed consent before participating in the experiment. They wore their own sport shoes in the study. Fundamental anthropometric data of these participants are shown in A simulated pulling experiment was designed. The authors have fabricated a steel T-bar mimic the stick and handle of a real pallet truck available in the market , 27. ThiThe weight was 40 kg and 50 kg for female and male participants, respectively. The forces required to counterbalance the back swing forces for these two loads were 139.65 N and 170.03 N, respectively. The reason to select these two loads was that we wanted to control each of the experimental trial lasting no more than 15 min. In practice, a one-time handling of materials lasting more than 15 min is preferably to be handled using an powered pallet jack which is not within the scope of our study. The literature [® Inc., FG-5100), and a handle 3 cm in diameter. When the participant pulled the handle  in different body segments of the participant after each pulling trial. This scale is easy to administer and has been adopted in the literature –28, 32 cFor each participant, a practice was carried out before the experiment. The participant pulled a real truck without external load to get familiar with the posture of truck pulling. The participant adopted and maintained this posture in the following simulated truck pulling tasks.before.Before each trial, the participant was required to do a warm-up exercise, following an aerobic fitness video, for 5 minutes. Then, the maximum pulling strengths of the participant was measured. In this measurement, the participant was instructed to pull the handle using their hands as hard as he or she could for 4 to 6s without jerking see . The reaafter. The CR-10 of the left hand (LH), left shoulder (LS), right hand (RH), right shoulder (RS), waist (WT), left foot/shank (LF) and right foot/shank (RF) were recorded. After completing one trial, the participant was dismissed and was requested to return for the next trial the next day or after. There was a pause of at least 12 hours between any two trials. The participants were instructed not to take strenuous exercise or activities at least four hours before they came to the laboratory for the experiment.After the strength measurement, the participant put the handle down on the floor and jointed a simulated truck pulling task. In this task, the participant pulled the T bar duplicating the posture in the real truck pulling conditions see  until hebefore, MVCafter, MET and CR-10 scores were calculated. To determine the effects of posture and gender on MVCbefore, MVCafter, and MET, analyses of variance (ANOVA) were carried out. The rank-based Kruskal-Wallis tests were performed to test the effects of posture on the CR-10 score. Regression analyses were conducted to establish the MET models. These models were verified by comparing measured data, predicted data of our models and that of the models in the literature. The data collected was processed using Excel 2010. SAS 9.4 software were adopted for statistical analyses. Statistical significance was set at p<0.05.A total of 64 pulling strengths and METs (2 postures×2 repetitions×2 genders × 8 participants) and 448 CR-10 scores (2 postures×2 repetitions×2 genders ×8 participants×7 body segments) were measured to explore the developing of muscular fatigue in simulated pallet truck pulling task. Test of normality for the pulling strength data was performed using the Kolomogorov-Smirnov test. Descriptive statistical analysis was conducted. Pearson correaltion coefficients among MVCMVC = %MVC/100) required by the task[MVC relationship has been long recognized to be negative nonlinear and has been fitted using three mathematic functions [MET is normally calculated using the %MVC or relative force ,,2), Eqs x = ln(fMVC), we haveFor Eq , let x =MVC are known. To compare the difference between the measured and predicted MET, a mean absolute deviation (MAD) was often used [Eqs  to 3) m m3) may ten used , 35,MADp>0.15). before, MVCafter, and MET over gender and postures conditions. We assumed that posture significantly affected muscular fatigue progressing. The results, however, showed that posture only affected the MVCbefore  = 4.58, p<0.05) and MVCafter  = 5.2, p<0.05) significantly. The MVCbefore and MVCafter for all participants of posture 1  were significant lower than those of posture 2 . Normally, right-hander involuntarily put their right foot on the front when they pulled. They could exert more force with their right foot on the front than that of left foot on the front. This might contribute to the difference for both the MVCbefore and MVCafter between posture 1 and posture 2. A comparison of the MVCbefore between genders was conducted. The MVCbefore of males (304.02 N) was significant higher  = 13.73, p<0.001) than those of females (279.09 N). The MVCbefore of females was 92% to that of their male counterparts. Person correlation results showed that posture was insignificant to the MET (p>0.05).The Kolomogorov-Smirnov test results confirmed the normality of the pulling strength data  and RF . The CR-10 ratings on the leading foot were significantly higher than that of the lag foot. The effects of posture on the CR-10 rating on all other body segments were not significant. p>0.05) while the CR-10 of the other body segments  were significant with a low correlation coefficient  to the MET.Posture was insignificant to overall CR-10 rating. The effects of posture on the CR-10 rating for each body segment were tested. Posture was found to be significant to the CR-10 ratings for both LF (χp = 0.70). Regression analyses were performed for Eqs  and 9.61 min (SD = 2.31), respectively. The difference between the two genders was not statistically significant. The MET differences between repeated trials ranged from 0.067 to 4.9 min, with average value of 2.14 (SD = 1.28) min and average coefficient of variation (CV) (%) of 13.27 (SD = 8.15). The CV of the MET for each participant between two trials ranged from 0.59% to 31.07%, with an average of 14.91% (SD = 8.61). The Shapiro-Wilk test result supported the normality of the MET  and 9.64 min (SD = 2.31) for females and males, respectively. This implied that k in the two-handed pulling task should be lower than 1. Actually, since it was easier to pull with two hands than one hand, fatigue rate k for two-handed pulls would be lower than that of singe-handed ones. By calculating average predicted MET and MAD, we found best fitted MET could be obtained when assigning k = 0.125, 0.115 for females and males participants. The corresponding MAD was 2.22 min (SD = 1.69) and 2.07 min (SD = 1.53), respectively. Although MET under fMVC between females and males were significantly (p<0.05) different in our pulling task, k was approximately the same for the two genders. Therefore, k might be task dependent.In Ma’s model , 37, k wng tasks , 1.02 fong tasks . In our In a previous study , the parPosture was insignificant to the MET. This contradicted to our hypothesis. For the subjective muscular fatigue, the CR-10 on feet/shanks ranked the highest, followed by hands. This implied that the participants terminated their pulling tasks mainly due to the fatigue on their feet/shanks. Muscular fatigue on feet/shanks, therefore, became dominant in determining the endurance time for the two-handed pulling tasks.The participants were requested to maintain the same posture while pulling the best they could. They, however, might adjusted their postures involuntarily especially when their muscle strength were becoming weak before the end of the trial. The literature  has founIn our simulated pulling experiment, walking was not considered due to the limitations of the space and technical difficult in data collection in the laboratory. When pulling using two hands, human gait involves cyclic movements on the lower extremities. Description of such a gait may require the measure of gait parameters such as cadence, stride length, and so on. Human gait could have cyclic effects on pulling force exertion. Such effects were, however, not considered in the current study and may be research topics in the future.before and MVCafter but was insignificant to MET. Feet/shanks were the body segments most likely to suffer muscular fatigue for the two-handed pulling, followed by hands and other body segments. MET models were obtained for females and males, respectively. The MET models are beneficial for job design and work-rest scheduling for workers where static two-handed pulling tasks are commonly performed.A simulated two-handed pulling experiment was performed. We found that posture significantly affected MVCS1 Raw Data(XLSX)Click here for additional data file.