Small-sized Samples Research Articles

A tensile property measuring system for miniaturized samples from 300 K to 70 K based on pulse tube cryocooler

With the rapid development and wide application of cryogenic, superconducting and space technologies in engineering fields, measurements of the mechanical properties especially the tensile properties of small-sized samples at cryogenic temperatures are more and more important. In this study, a tensile property measuring system for miniaturized samples was designed and built, where the samples can be measured from 300 K to 70 K with a resolution of 0.1 K. The cryogenic environment was provided by a pulse tube cryocooler. The force load applied to the sample was up to 10 N with a resolution of 0.001 N. The structure of the cryogenic system and sample holders were specially designed for miniaturized samples. A control and automatic data acquisition system was used to control and acquire data from all devices of the instrument. The simulations of the stretching part under load at cryogenic temperature were performed to ensure the measurement accuracy and reliability. To verify the performance and accuracy of the system, the tensile properties of two kinds of fine high-purity copper wires were measured at both 77 K and 300 K. The tensile measurement results were discussed and the measurement uncertainty of the system was analyzed. With different clamps more kinds of mechanical measurements of miniaturized samples can be carried out on this system.

Understanding Cognitive Deficits in People with Arthritis.

Cognitive deficits are commonly seen in people with arthritis. However, previous studies focused primarily on small-sized clinical samples. There is a need for cohort-based studies, which are characterized by high generalizability. In addition, these studies mainly focused on attention, memory, and executive function. However, cognition is not a single concept, but includes other cognitive domains, such as verbal fluency and arithmetic abilities. Thus, we aim to explore how arthritis can affect cognitive abilities, including episodic memory, semantic verbal fluency, fluid reasoning, and numerical ability by using a large cohort from the United Kingdom. The main findings were that people with arthritis have significantly lower immediate word recall (t(2257) = -6.40, p < 0.001, Cohen's d = -0.12, 95% C.I. = [-0.16, -0.08]), delayed word recall (t(2257) = -5.60, p < 0.001, Cohen's d = -0.11, 95% C.I. = [-0.14, -0.07]), semantic verbal fluency (t(2257) = -3.03, p < 0.01, Cohen's d = -0.06, 95% C.I. = [-0.10, -0.02]), fluid reasoning (t(2257) = -3.96, p < 0.001, Cohen's d = -0.07, 95% C.I. = [-0.11, -0.04]), and numerical ability (t(2257) = -3.85, p < 0.001, Cohen's d = -0.07, 95% C.I. = [-0.10, -0.03]) compared to what they would expect given their demographics. Interventions are needed to improve cognitive abilities in people with arthritis.

Investigating the time- and space- dependent mechanical, physical and chemical properties of aged polyethylene gas pipes using nanoindentation tests

Macroscopic tensile tests are conventionally used to obtain mechanical properties of aged polyethylene (PE) gas pipes, but cannot characterize the inhomogeneous aging behavior of the specimens caused by diffusion-limited oxidation (DLO). Nanoindentation test procedures have, therefore, been adopted to obtain time- and space-dependent mechanical properties of small-sized PE pipe samples, especially, creep properties directly from two types of the PE pipes in accelerated aging and natural conditions. The results indicate that the energy-based method to calculate the initial contact stiffness is not only suitable for cementitious materials and rocks, but also for PE materials. The combination of nanoindentation creep test and generalized Kelvin model can extract detailed parameters that are more representative of the differences in material deformation. The change of crystallinity with aging times probably leading to the difference of mechanical properties was revealed by physical and chemical properties obtained by the DSC and FITR technique. In addition, the correlation between nanoindentation results and structural information also indicates crystallinity plays a dominant role on mechanical performances of the PE pipe. This method using nanoindentation can significantly promote the accuracy of mechanical properties characterization and possess well fitness for PE pipes in accelerated aging conditions or in-service.

Influence of Dynamic Viscosity of a Lubricant Material on the Parameters of Adhesion Bond in the Systems of Materials "12KH2H4 - STEEL 45", "45KHN2MFA - Steel 45" when Boring and Borocement Steel 45

In this work, the regularities of the change in the shear strength of the adhesive bond τ0 and the piezoelectric coefficient β in the metal systems "12Kh2N4 (45KhN2MFA) - steel 45 + B", "12Kh2N4 (45KhN2MFA) - steel 45 + VS" were obtained during physical modeling of the shear of surfaces of small-sized samples and changes in dynamic viscosity environment of their interaction with the use of additional equipment of the SMTs-2 friction machine. It has been established that borating and boron carburizing of the surface of steel 45 leads to the absence of adhesion to the surfaces of steels 12Kh2N4 and 45KhN2MFA in certain ranges of normal pressures, at which τ0&gt; 0 and the dynamic viscosity of liquid and grease. It was found that the parameter τ0 when lubricating surfaces is determined to a greater extent for the system "12X2H4 - steel 45", and partially for borating steel 45 and low values of dynamic viscosity μ = 0.027 Pa•s. With an increase in the dynamic viscosity of the liquid phase of the lubricant in the "12X2H4 - steel 45" system, there is a tendency to an increase in the value of τ0. It was found that the absence of modification of steel 45 with boron and boron carbide predetermines the independence of the piezoelectric coefficient from the viscosity of the liquid lubricant and the shear rate. Boring and boron carburizing steel 45 predetermines an increase in the piezoelectric coefficient by an average of 1.6 times with an increase in dynamic viscosity from 0.027 Pa•s to 0.19 Pa•s at a shear rate of 10.16±0.8. At shear rate = 5.08±0.6 mm/s, the piezoelectric coefficient is relatively constant in the systems under study. With the transition to contact through a grease lubricant, there is an ambiguous manifestation of the rate of change of the piezoelectric coefficient.

YNAMIC VISCOSITY OF THE LUBRICANT AND ITS EFFECT ON STEEL MATERIALS WITH BORON

In this work, the regularities of the change in the shear strength of the adhesive bond τ0and the piezoelectric coefficient β in the metal systems "12Kh2N4 (45KhN2MFA) -steel 45 + B", "12Kh2N4 (45KhN2MFA) -steel 45 + VS" were obtained during physical modeling of the shear of surfaces of small-sized samples and changes in dynamic viscosity environment of their interaction with the use of additional equipment of the SMTs-2 friction machine. It has been established that boridingand boron carburizing of the surface of steel 45 leads to the absence of adhesion to the surfaces of steels 12Kh2N4 and 45KhN2MFA in certain ranges of normal pressures, at which τ0&gt; 0 and the dynamic viscosity of liquid and grease. It was found that the parameter τ0when lubricating surfaces is determined to a greater extent for the system "12X2H4 -steel 45", and partially for borating steel 45 and low values of dynamic viscosity μ = 0.027 Pa•s. With an increase in the dynamic viscosity of the liquid phase of the lubricant in the "12X2H4 -steel 45" system, there is a tendency to an increase inthe value of τ0. It was found that the absence of modification of steel 45 with boron and boron carbide predetermines the independence of the piezoelectric coefficient from the viscosity of the liquid lubricant and the shear rate. Вoridingand boron carburizing steel 45 predetermines an increase in the piezoelectric coefficient by an average of 1.6 times with an increase in dynamic viscosity from 0.027 Pa•s to 0.19 Pa•s at a shear rate of 10.16±0.8. At shear rate = 5.08±0.6 mm/s, the piezoelectric coefficient is relatively constant in the systems under study. With the transition to contact through a grease lubricant, there is an ambiguous manifestation of the rate of change of the piezoelectric coefficient

The Effects of the Large-Scale Factor on the Integrity Parameters of Monolithic Fire-Resistant Glass

Glass is widely used for the manufacture of the facades and interior glazing of buildings. Glass structures are subject to high fire safety requirements. Two methods are employed in this work: experimental studies of small-sized and large-sized samples and simulations of heating glass structures. The results showed that large-sized samples of monolithic tempered glass, with dimensions of 4250 × 2000 × 8 mm and 2000 × 3000 × 8, that were inserted in a steel frame, if properly installed, provided fire resistance limits of E30/E45 and E60, respectively, for loss of integrity, which proves the influence of the dimensions of the glass panel on the fire resistance of the facade structure. The small-sized samples of monolithic tempered glass with dimensions of 1000 × 700 × 8 mm provided a fire resistance limit of E60 for loss of integrity. A large-sized sample of monolithic tempered glass measuring 4250 × 2000 × 8 mm and inserted into an aluminum frame provided a fire resistance limit of E60, proving the effect of the frame on the fire resistance of the structure. According to the results of several simulations, a conclusion was formed about the possibility of predicting the fire resistance limits of tempered glass based on its thickness and dimensions. During operations, these structures will be able to prevent the spread of fire and combustion products for the required time after the loss of integrity. The results of the study allow for the estimation of the influence of the scale factor on the falling of the glass from the frame in a fire (loss of integrity).

Asymptotically Consistent Estimation of Preferential Attachments in Growing Networks

Preferential attachment, also referred to as the “rich-get-richer” mechanism, characterizes the ability of already existing nodes in an evolutionary network to acquire new connections from newly-coming nodes throughout the growing process of the network. This mechanism is responsible for the emergence of some critical structures in many real networks, such as the Saccharomyces cerevisiae protein-protein interaction network, scientific collaboration network, and bitcoin transaction network. Clearly, it is very important to accurately estimate the preferential attachment mechanism for a growing network in interest. Although it has long been aware that the existing widely-used methods yield significantly biased estimates of preferential attachments, the underlying mechanism is not completely understood and not well explained. By rewriting preferential attachment from a deterministic formulation to a stochastic one, this paper reveals two major problems existing in the current methodologies, thereby well explaining why traditional methods introduce biases to the estimates of preferential attachments. To avoid the negative effects of these two problems, a new method is proposed based on the Poisson Pseudo Maximum Likelihood method for estimating preferential attachments, which provides asymptotically consistent estimation to preferential attachments. More importantly, even with insufficient information, the new method can still provide an estimate with high precision, showing a significant advantage in measuring preferential attachments based on small-sized samples. The new method is also robust against network parameter changes. The findings may shed some lights onto deeper understanding of the evolutionary processes of real networks.

Design of the First μSR Spectrometer at China Spallation Neutron Source

The Phase II upgrade project of the China Spallation Neutron Source (CSNS) includes the construction of a surface muon beam line and a muon spin rotation/relaxation/resonance (μSR) spectrometer, which will be the first μSR spectrometer built in China. Here, we report the conceptual design of the spectrometer, including the detector arrangement, magnets, sample environment (SE) and sample chamber. Based on the design parameters of the muon beam (1 Hz, 105 μ+/pulse), the spectrometer possesses over 2500 detector units to maximize the counting rate. Three different types of magnets can generate a zero field (ZF), a longitudinal field (LF) within 5000 G, and a transverse field within 400 G. The SE consists of a cryostat and a closed-cycle refrigerator (CCR) to provide temperatures lower than 2 K in the current stage. It has potentials to be updated to 300 mK. The sample chamber is designed with a fly past structure to reduce the background for experiments with small-sized samples.

THE ACCURACY AND PRECISION OF SMALL-SIZED MODERN WOOD SAMPLES ANALYZED AT THE CHRONOS 14CARBON-CYCLE FACILITY

ABSTRACTTree-ring series offer considerable potential for the development of environment-sensitive proxy records. However, with traditional increment cores, only small amounts of wood are often available from annual tree-ring sequences. For this reason, it is important to understand the reliability (and reproducibility) of radiocarbon measurements obtained from small-sized samples. Here we report the F14C results from the Chronos 14Carbon-Cycle Facility of modern tropical Australian tree samples over a range of four graphite target sizes from the same rings. Our study shows that similar precision can be obtained from full-sized, half-sized, as well as small-sized graphite targets using standard pretreatment and analysis procedures. However, with a decline in sample size, there was an increase seen in the associated variance of the ages and the smallest target weights started showing a systematic bias. Wiggle-matching accuracy tests, comparing the Southern Hemisphere post-bomb atmospheric calibration curve to the different sample weight sequences, were all significant except for the 200 μgC graphite targets. Our results indicate that samples smaller than 350 μgC have limited accuracy and precision. Overall, reliable measurements of F14C sequences from tree-ring records across a range of sample sizes, with best results found using graphitized samples &gt;350 μgC.

The development of methods and instruments for thermal conductivity measurement of standard core samples for petrophysical studies

The problem of obtaining qualitative data on the thermal conductivity of standard rock samples for petrophysical studies is considered. It is shown that the existing instruments for thermal conductivity measurement do not allow one to obtain reliable and accurate values of the thermal conductivity of small-sized rock samples. A laboratory installation for thermal conductivity measurement of standard rock samples with a diameter not less than 30 mm has been created. The installation was assembled and tested on small samples. Possible problems in the development, design and exploitation of the laboratory installation were analyzed. A software that allows automated collection and processing of the data has been developed. The key factors, negatively affecting the accuracy and reliability of thermal conductivity measurement results, are identified and excluded. There were unshielded thermocouples, potential changes between the hot and cold junctions (due to uneven melting of the water-ice mixture in the Dewar vessel, where the cold junction is immersed), incorrectly selected dimensions and shape of the object of study and the nonequilibrium ratio of the heat input and dissipation. The installation was tested on samples of pure tin standard and brass LS59 with known thermal conductivity. The thermal conductivity of a small-sized rock sample was measured with an error within 5.6 %.

Insights into the interaction of a shale with CO2

Abstract. Caprock formations, such as shales, play a key role in safe underground CO2 storage since they serve as a hydromechanical barrier that prevents migration of the injected CO2 to the surface. While their hydromechanical response is important to ensure their sealing capacity, interaction with the injected CO2 involves additional thermo–hydro–chemo–mechanical (THCM) phenomena that may threaten the long-term integrity of the caprock. The low-transport properties of shales make them a suitable caprock material, but at the same time challenging to study due to the very long timescales (months/years) that are required for the various THCM processes to manifest. In this work, the long-term multiphysical interaction of the Opalinus Clay shale with liquid and supercritical CO2 is studied in 3D with live X-ray tomography. Three-dimensional analysis reveals the localised response of the coupled THCM processes that is often indistinguishable with conventional lab testing protocols. To improve spatial and temporal resolution while applying field-representative pressure and temperature conditions, small-sized samples are studied. Long-term injection of liquid CO2 resulted in significant fissuring of calcite-rich zones that were for the first time visualised and quantified from the X-ray images. Additionally, a re-arrangement of the pre-existing micro-fissures in the clay matrix was observed. The volumetric response during direct exposure of an Opalinus Clay sample to supercritical CO2 revealed an initial swelling at pre-fissured zones and initiation of new micro-fissures at areas of direct contact with the anhydrous CO2 due to pore water evaporation. Advanced 3D image analysis showed an increasing CO2 uptake in the caprock material with time, suggesting potential CO2 trapping in the material.

Investigation on the double-sided concurrent flame spread behavior of log planks

This paper presents an experimental and theoretical research on the double-sided concurrent flame spread behavior of inclined planks. Pine log planks with a size of 100 cm long, 30 cm wide and 1 cm thick were used with six angles of inclination (θ). Results showed that the flame and the pyrolysis front on the upper surface present an inverted "V" shape at θ =15° to 45°, and the lower surface flame is always clinging to the plank surface, which is significantly different from the combustion of small-sized wooden samples. The flame spread rate is positively correlated with θ. Besides, it is found that the pyrolysis length (Lpy), preheating length (Lpr) of upper surface and the flame length of lower surface (Lf,lowersurface) have a relation of Lf,lowersurface≈Lpy+Lpr, indicating the significant influence of the lower surface flame on the double-sided flame spread. Heat received by the upper surface is mainly the radiative heat flux from the flame on the surface, and a physical model considering flame sizes and shapes is established, whose results agree well with the experimental data. Theoretical analysis was conducted on the heat transfer from lower surface, and found the conductive heat flux from the lower surface flame is of the same order of magnitude with the radiative heat flux from the upper surface flame. It indicates the heat from the lower surface flame has large contribution to the flame spread behavior. In addition, the influence of tung oil, which is widely used in timber buildings, on the flame spread behavior was also researched. It shows that brushing tung oil on the plank surface could increase the flame size, spread rate and heat release rate.

Effect of dynamic fragmentation on microscopic pore structure in coal: New insights into CH4 adsorption characteristics

Tectonic coal is a necessary condition for coal and gas outburst, and its pore structure is dramatically altered. The pore structure of tectonic coal has unique characteristics in terms of mechanics and gas flow, which plays a critical role in eliminating outburst risk. Therefore, it is important to study the effects of dynamic fragmentation on microscopic pore structure and CH4 adsorption characteristics of coal body. In this study, coal samples from Xintian (XT) and Pingdingshan No.6 (P6) coal mines were crushed and sieved into three particle size fractions of 0.5–1 mm, 0.2–0.25 mm, 0.074–0.1 mm, respectively, simulating dynamic fragmentation by reducing the particle size. A novel index that evaluates the average single-particle equivalent pore length was proposed. This index, Lp, provides a more comprehensive quantitative characterization of the effects of dynamic fragmentation on microscopic pore structure by considering the dynamic particle size reduction process. The LP values of large-sized samples are 23.8 to 24.6 times that of medium-sized samples; the LP values of medium-sized samples are 12.8 to 17.1 times that of small-sized samples. The experimental results show that dynamic fragmentation significantly alters microscopic pore structure, as demonstrated by the positive correlation between the Lp and particle size. With the decrease in particle size, the amount of CH4 molecules adsorbed in XT samples increases from 105.870 × 1019 p/g to 106.934 × 1019 p/g, increasing by 1.0 %; that in P6 samples increases from 39.660 × 1019 p/g to 48.037 × 1019 p/g, rising by 21.1 %. Dynamic fragmentation has a relatively insignificant effect on CH4 adsorption capacity. The total adsorption equilibrium time for XT samples decreases from 242 h to 32 h, and that for P6 samples decreases from 1146 h to 100 h as the particle size decreases. Dynamic fragmentation significantly reduces CH4 adsorption equilibrium time. The results of this study contribute to the understanding of microscopic pore structure under the effects of dynamic fragmentation and new insights into CH4 adsorption characteristics, which are of great guiding significance to the occurrence mechanism of outburst prediction and risk.

Real-Time Risk Assessment for Road Transportation of Hazardous Materials Based on GRU-DNN with Multimodal Feature Embedding

In this paper, a gated recurrent unit–deep neural network (GRU-DNN) model integrated with multimodal feature embedding (MFE) is developed to evaluate the real-time risk of hazmat road transportation based on various types of data for contributing factors. MFE was incorporated into the framework of a deep learning model in which discrete variables, continuous variables, and images were uniformly embedded. GRU is a pre-trained sub-model, and the DNN is able to directly use the relative structure and weights of the GRU, improving the poor classification and recognition results due to insufficient samples. Additionally, the model is trained and validated based on hazmat road transportation database consisting of 2100 samples with 20 real-time contributing factors and four risk levels in China. The accuracy (ACC), precision (PR), recall (RE), F1-score (F1), and areas under receiver-operating-characteristic curves (AUC) of the proposed model and other commonly used models are compared as performance measurements in numerical examples. Finally, Carlini &amp; Wagner attack and three defenses of adversarial training, dimensionality reduction and prediction similarity are proposed in the training to improve the robustness of the model, alleviating the impact of noise and error on small-sized samples. The results demonstrate that the average ACC of the model reaches 93.51% and 87.6% on the training and validation sets, respectively. The prediction of accidents resulting in injury is the most accurate, followed by fatal accidents. Combined with the RE of 89.0%, the model exhibits excellent performance. In addition, the proposed model outperforms other widely used models based on the overall comparisons of ACC, AUC, F1 and PR-RE curve. Finally, prediction similarity can be used as an effective approach for robustness improvement, with the launched adversarial attacks being detected at a high success rate.

Study of physicochemical properties of polyethylene gas pipelines material with a prolonged service life

Every year the length of polyethylene (PE) pipelines with service life of 40–50 years are growing, wherein the limiting amount of service life is 50 years. Operating and state organizations responsible for industrial safety face an important question: is it possible to continue the safe operation of pipelines with an expired service life, or is it necessary to replace pipelines, which will require large investments. Studies were carried out to assess the prospects of using test methods in the technical diagnostics of polyethylene gas pipelines. The article presents the results of a study of small-sized samples of PE pipes of gas pipelines with various service life (from 24 to 55 years) using differential scanning calorimetry, X-ray diffraction analysis and infrared spectroscopy. The time and temperature of oxidative induction, the degree of crystallinity of the samples, and the size of the crystals were studied, and the IR spectra of each sample were obtained and analyzed. Based on the results of the study, it was concluded that the method of differential scanning calorimetry and X-ray diffraction analysis are informative in the study of the physicochemical properties of polyethylene pipelines with different service lives.

Fuzzy evaluation model for attribute service performance index

As the Internet of Things (IoT) becomes more and more popular and full-grown, diverse technologies for measurement and collection of business data continually improve as well. Effective data analysis of and applications can be helpful to stores to make smart and quick decisions in a jiffy, so that the percentage of customer satisfaction and in-store shopping can increase to raise the total revenue. Some researchers have suggested that the number of customers who enter a store refers to a Poisson process. Based on previous research, an attribute service performance index was proposed in this paper. This paper reviewed the fuzzy one-tailed testing model of the attribute service performance index and put forward a fuzzy two-tailed testing model of two indices based on the confidence interval to verify whether the improvement had a significant effect. Now that this fuzzy evaluation model is built on the confidence interval of the index, we can diminish the chance of misjudgment caused by sampling error. Its design can incorporate the past data or expert experience. Thus, the evaluation accuracy can be retained in the case of small-sized samples.

Cancer Subtyping via Embedded Unsupervised Learning on Transcriptomics Data.

Cancer is one of the deadliest diseases worldwide. Accurate diagnosis and classification of cancer subtypes are indispensable for effective clinical treatment. Promising results on automatic cancer subtyping systems have been published recently with the emergence of various deep learning methods. However, such automatic systems often overfit the data due to the high dimensionality and scarcity. In this paper, we propose to investigate automatic subtyping from an unsupervised learning perspective by directly constructing the underlying data distribution itself, hence sufficient data can be generated to alleviate the issue of overfitting. Specifically, we bypass the strong Gaussianity assumption that typically exists but fails in the unsupervised learning subtyping literature due to small-sized samples by vector quantization. Our proposed method better captures the latent space features and models the cancer subtype manifestation on a molecular basis, as demonstrated by the extensive experimental results.

Analysis of Energy Transmission and Deformation Characteristics of Coal-Rock Combined Bodies

A coal-rock system is a common combination form in coal mines. In order to explore the energy interchange law of a coal-rock combined body and the interaction relationship between the two bodies, loading tests of coal-rock combined bodies with different height ratios were carried out. The loading path of rock in coal-rock combined bodies was demonstrated by means of a single loading and unloading test of the same-sized rock sample. Furthermore, a method to calculate rock energy was proposed based on the area of the loading and unloading curve. The experimental results show that the greater the surrounding rock pressure is, the smaller increase rate of lateral and volumetric strain in the postpeak stage will be when the same height ratio is present. An increase in the surrounding rock pressure causes an increase in the total strain energy density of small-sized rock samples. However, the total strain energy density is always greater than the elastic strain energy density. And the elastic and dissipated strain energy densities also increase, along with the energy dissipation with unloading. When the proportion of coal bodies increases, the energy accumulation also shows an increasing trend. When the height of the coal is greater than half the height of the complete specimen, the coal energy proportion is greater than 60%. After reaching the yield load, the energy in the coal body is dissipated in forms such as plastic deformation, internal damage, block friction, radiation energy, and kinetic energy. Therefore, the energy released is, in part, reflected in the rock body.

Development of a quantification method for routine analysis of glucosinolates and camalexin in brassicaceous small-sized samples by simultaneous extraction prior to liquid chromatography determination

Glucosinolates and camalexin are secondary metabolites that, as phytoanticipins and phytoalexins, play a crucial role in plant defence. The present work proposes an improved analytical method for routine analysis and quantification of glucosinolates and camalexin in brassicaceous small-sized samples by using the very specific desulfation process of glucosinolates analysis and the specificity of fluorescence detection for camalexin analysis. The approach is based on a simultaneous ultrasound-assisted extraction followed by a purification on an anion-exchange column. Final analyses are conducted by HPLC-UV-MS for desulfo-glucosinolates and HPLC coupled to a fluorescence detector (HPLC-FLD) for camalexin. The method is linear for glucosinolates (50–3500 µM) and camalexin (0.025–5 µg.mL−1) with an LOD/LOQ of 3.8/12.6 µM and 0.014/0.046 µg.mL−1 respectively. The method demonstrated adequate precision, accuracy and trueness on certified reference rapeseed. A practical application of our approach was conducted on different Brassicaceae genera (Barbarea vulgaris, Brassica nigra, Capsella bursa-pastoris, Cardamine hirsuta, Coincya monensis, Sinapis arvensis, and Sisymbrium officinale) and Arabidopsis thaliana genotypes (Columbia and Wassilewskija). Futhermore, different plant organs (seeds and leaves) were analysed, previously inoculated or not with the pathogenic fungus Alternaria brassicicola.

Trends and Disparities in Adult Body Mass Index Across the 47 Prefectures of Japan, 1975-2018: A Bayesian Spatiotemporal Analysis of National Household Surveys.

BackgroundAmong high-income countries, Japan has a low prevalence of obesity, but little is understood about subnational trends and variations in body mass index (BMI), largely owing to the lack of data from representative samples of prefectures. We aimed to examine long-term trends and distributions of adult BMI at the prefecture level in Japan from the late 1970s using a spatiotemporal model.MethodsWe obtained cross-sectional data for 233,988 men and 261,086 women aged 20–79 years from the 44 annual National Health and Nutrition Surveys (NHNS) conducted during 1975–2018. We applied a Bayesian spatiotemporal model to estimate the annual time series of age-standardized and age-specific mean BMI by 20-year age group and sex for each of the 47 prefectures. We assessed socioeconomic inequalities in BMI across prefectures using the concentration index, according to population density.ResultsIn men, the age-standardized prefectural mean BMI ranged from 21.7 kg/m2 (95% credible interval, 21.6–21.9) to 23.1 kg/m2 (22.9–23.4) in 1975 and from 23.5 kg/m2 (23.3–23.7) to 24.8 kg/m2 (24.6–25.1) in 2018. In women, the age-standardized prefectural mean BMI ranged from 22.0 kg/m2 (21.9–22.2) to 23.4 kg/m2 (23.2–23.6) in 1975 and from 21.7 kg/m2 (21.6–22.0) to 23.5 kg/m2 (23.2–23.8) in 2018. Mean BMI was highest in the southernmost prefecture for most of the study period, followed by northeast prefectures. The increase in mean BMI was largest in southwest prefectures, which caught up with northeast prefectures over time. The concentration index was negative, indicating higher BMI in less-populated prefectures. Absolute values of the concentration index were greater in women than in men and increased over time.ConclusionsThere were variations in adult mean BMI across prefectures, and geographic distributions changed over time. Further national and local efforts are needed to address the rising trend in mean BMI, particularly among men in rural prefectures, and socioeconomic inequalities among women. Bayesian hierarchical modeling is useful for reconstructing long-term spatiotemporal trends of mean BMI by integrating small-sized survey samples at the prefecture level in the NHNS.