Longitudinal Variation Research Articles

The association between tree planting and mortality: A natural experiment and cost-benefit analysis

Several recent longitudinal studies have found that exposure to the natural environment is associated with lower non-accidental mortality. However, most of these studies used the normalized difference vegetation index (NDVI) as an exposure metric; and because NDVI might not be sensitive enough to adequately capture changes in urban vegetation, these studies might lack true longitudinal variation in exposure. Therefore, we used a natural experiment to assess the impact of 30 years of tree planting by the nonprofit Friends of Trees on non-accidental, cardiovascular, lower-respiratory, and accidental mortality in Portland, Oregon (mortality data were provided by the Oregon Health Authority). We estimated autoregressive mixed models of Census-tract level mortality rate (deaths per 100,000 population) associated with trees planted, including a tract-level random effect. All models used data from the American Community Survey to control for year, race, education, income, and age. Each tree planted in the preceding 15 years was associated with significant reductions in non-accidental (-0.21, 95 % CI: −0.30, −0.12) and cardiovascular mortality (-0.066, 95 % CI: −0.11, −0.027). Furthermore, the dose–response association between tree planting and non-accidental mortality increased in magnitude as trees aged and grew. Each tree planted in the preceding 1–5 years was associated with a reduction in mortality rate of −0.154 (95 % CI: −0.323, 0.0146), whereas each tree planted in the last 6–10 and 11–15 years was associated with a reduction in mortality rate of −0.262 (95 % CI: −0.413, −0.110) and −0.306 (95 % CI: −0.527, −0.0841) respectively. Using US EPA estimates of a value of a statistical life, we estimated that planting a tree in each of Portland’s 140 Census tracts would generate $14.2 million in annual benefits (95 % CI: $8.0 million to $20.4 million). In contrast, the annual cost of maintaining 140 trees would be $2,716–$13,720.

Local time and longitudinal variation of the ionospheric radial current: swarm observations and TIE–GCM simulations

Based on the high-precision vector magnetic field data of Swarm A and C satellites, we perform a statistical analysis of the diurnal and longitudinal variations of the ionospheric radial current (IRC) in the F layer at the magnetic equator from 2014 to 2018. The observations are compared with the simulations based on the Thermosphere–Ionosphere Electrodynamics–General Circulation Model (TIE–GCM). It is found that the noon IRC is radially outward, whereas the dusk IRC is radially inward. The time of the change from the inward to the outward direction occurred is earlier in June than in other seasons. The TIE–GCM results show that low atmospheric tides have an important effect on the seasonal change in the reverse time. The noon IRC is weakened primarily by the polarization current from migrating tides. The dusk IRC is mainly weakened by polarization current from nonmigrating tides in the equinox and December solstice and by dynamo current from migrating tides in the June solstice. Geomagnetic field configuration is the main reason for the longitudinal variation of IRC. The noon IRC have a wave-4 zonal structure, which is mainly caused by the outward propagation of migrating and nonmigrating tides. The dusk IRC in the western hemisphere shows a larger current density than that in the eastern hemisphere, resulting mainly from the neutral wind dynamo current. The competing effect of the wind dynamo current and polarization current determined the peak location of the total current in the western hemisphere.Graphical

An Investigation on the Longitudinal Variation in Mid‐Latitude Ionosphere Based on CHAMP Satellite Observations

AbstractThe longitudinal variations of the middle latitude ionosphere are investigated on the basis of in situ electron density observations from the Planar Langmuir Probe onboard the Challenging Minisatellite Payload satellite. This study specifically focused on the longitudinal variations of the ionosphere at geographic latitudes of 40° in both the Northern and Southern Hemispheres. The longitudinal variations of the ionosphere are decomposed into the spatial modes and corresponding temporal evolutions by employing the principal component analysis method, and an associated empirical model is developed. The model results indicate a significant seasonal and local time dependence of the longitudinal variation, which is obviously different in the Northern and Southern Hemispheres. Our preliminary analysis suggests that the interaction between the geomagnetic fields and the thermospheric winds results in the longitudinal variations in the ionosphere at the middle latitudes. In addition, the relative contributions of zonal and meridional winds are further discussed.

Road-Curvature-Range-Dependent Path Following Controller Design for Autonomous Ground Vehicles Subject to Stochastic Delays

In this paper, we investigate the PID controller design problem of path following for an autonomous ground vehicle (AGV). Firstly, a bicycle model is adopted and a vehicle offset model from the target path is integrated to the bicycle model. The PID controller considers the vehicle longitudinal speed variation for adaption to the road curvature and the stochastic delay induced by the network communication. This is realized by transforming the tuning problem of proportional-integral-derivative (PID) gains for path following into a design problem of a static-output-feedback (SOF) controller for a time-delayed linear parameter varying (LPV) model form. A sufficient condition is adopted to guarantee the stability of the closed-loop system. In order to achieve better tracking performance, we propose a strategy in which the PID gains are piecewise constant and are dependent on the road-curvature ranges. The stability of the switched system is guaranteed via the common Lyapunov function method. Grey wolf optimizer (GWO) is employed to solve the optimization problem with maximum absolute tracking error as the optimization objective and stability condition and actuator dynamics as constraints. Both simulation results based on the CarSim-Simulink joint platform and hardware-in-loop experiment results are used to verify the effectiveness of the proposed control strategy.

Analysis of the Aggregate Strength Variation along Different Sections of the River Basin

Purpose: There is high demand of aggregates material in the construction industry of Nepal. Till date, river borne aggregate material fulfills major part of the demand. Among various rivers, Biring River is one of the major rivers in Province 1. The objective of this research was to analyze the strength of Aggregate variation along the selected section river basin with a case of Biring. Design/Methodology/Approach: The selected section of Biring River is about 20 Km of Arjundhara Municipality from which 6 sites along the river was selected on the basis of accessibility and deposition for aggregate sources. Lab Test for Physical properties and mechanical properties were conducted on that sample to evaluate their quality for the construction works. Also 18 cubes (3 each from 6 selected sites) were casted to evaluate their compressive strength variation. A linear relationship between the ACV, AIV and LAA value with longitudinal variation of river was established. Also the economic analysis of revenue collected by selling the aggregate of Biring River was done. Findings/Result: After conducting the lab test of physical properties of aggregate, Fineness Modulus, Water Absorption and Specific Gravity were found in the range of (7.16-7.49)%, (0.72-1.15)% and and (2.616-2.712) %. A linear equation for the longitudinal variation in the LAA, AIV and ACV value was established. For a longitudinal variation equation for LAA value y=-0.352x+37.41 ACV value an equation y=-0.212x+29.88 and AIV value an equation y=-0.0189x+27.15 where y = Value of LAA, AIV and ACV value and x = distance in km from upstream origin point. The average compressive strength for 7 and 28 days of all cubes were found to be within standard required. The economic contribution of revenue collected by selling the river bed materials as aggregate of Biring River on the total internal revenue of Arjundhara Municipality was found to be significant that is about 30.86%. Originality/Value: The study contributes that the aggregate material becomes more suitable in their hardness, toughness and strength on moving from upstream towards the downstream along the Biring river. The lower part of stream was assessed to have somewhat better quality of aggregates. Paper Type: Applied Research

A longitudinal assessment of sex differences in the growth of the mandibular retromolar space

ObjectiveTo assess longitudinal variation in patterns of retromolar space growth, with regard to sex and cervical vertebrae maturation. DesignWe utilized serial lateral cephalograms from three craniofacial growth studies (Denver, Iowa, Oregon), measuring retromolar space and cervical vertebrae maturation in 99 subjects (56% male) from 8 to 18 years of age for each subject. Repeated measures ANOVA and a linear mixed effects model were used to assess retromolar space growth through time. ResultsOur analyses revealed an average increase in retromolar space of 8.73 mm from 8 to 18 years. While t-tests failed to find differences in retromolar space growth between males and females at the measured age points, repeated measures ANOVA and linear mixed effects models revealed modest differences in growth trends between sexes, with females having more growth earlier but a younger age of deceleration of growth (between 12 and 14 years of age). ConclusionsOur results confirm large increases in retromolar space through growth, reaching an average of 1.38 mm/year around puberty. Importantly, we add to the conversation regarding sex differences, showing differences in timing of growth. This highlights the importance of using longitudinal data and analytical approaches to address questions of this nature.

Natural Fracture Development Characteristics and Their Relationship with Gas Contents-A Case Study of Wufeng-Longmaxi Formation in Luzhou Area, Southern Sichuan Basin, China.

Natural fractures are critical factors that should be considered in shale reservoir evaluation, storage condition analysis, horizontal well design, and fracturing stimulation, which also play a non-negligible role in the occurrence state of shale gas in the reservoir. This paper discussed the influence of fracture development on gas-bearing properties based on the analysis results of core observation, scanning electron microscopy, mineral composition, and gas-bearing properties after the development characteristics of fractures and their longitudinal variation law were clarified. In this way, the development characteristics of organic-rich marine shale fractures in the Longmaxi Formation in the 203 well area of the Luzhou member of the Sichuan Basin and their effects on the gas-bearing properties can be analyzed. The results show that the Longmaxi Formation shale develops shear fractures, extensional fractures of tectonic origin, bedding fractures, dissolution fractures, and abnormally high-pressure fractures of nonstructural origin. Specifically, interlayer fractures, intercrystalline fractures, organic matter contraction fractures, and fractures between clay layers are microfractures. Fracture development is characterized by short longitudinal extension, small opening, high degrees of composite filling, and large density changes, with calcite and pyrite as the filling materials. The fracture density has a “three-stage” variation pattern longitudinally, and the bottom is dominated by thin siliceous shale development, together with a small amount of shale mixed with calcareous and calcareous materials. Moreover, the fracture is dominated by “splitting” and “shearing” failure, crossing stratification with the fracture density. The highest fracture density was found in the 2 sub-layer, featuring the joint development of horizontal and vertical fractures, which form the mesh fracture system through mutual cutting and restriction. The lithofacies in the 4 sub-layer are dominated by clay siliceous shale with a small amount of mixed shale of calcareous and siliceous materials. The formation of fractures always expands along the lamellation direction, which has concentrated development members of top and bottom fractures, with the development of horizontal fractures dominated and vertical fractures less developed. Furthermore, a synergistic effect can be found among the total organic carbon (TOC) content, fracture density, and gas-bearing property of the shale in Longmaxi Formation. It is worth noting that a high TOC content and siliceous content are conducive to the formation of microfractures, while the development of fracture contributes to the total gas-bearing property, especially to the increase in free gas content. To be concrete, the free gas content in the fracture development member accounts for more than 55% of the total gas content, thanks to a channel provided by fractures for the desorption of shale gas.

Rural and Urban Hispanic Patients of the Veterans Health Administration.

Hispanic Veterans are the largest growing racial and ethnic minority group in the Veterans Health Administration (VA) system. Though recent research has found increasing suicide rates in this population and a growing rural-urban disparity, literature on core population characteristics remains sparse. We used extensive patient demographic and clinical data from VA's electronic medical record repository to examine geographic and longitudinal variation in Hispanic VA patients from 2001 to 2018. As the first such detailed characterization of this population, this study was largely descriptive in nature, and included heatmaps of Hispanic patient residence across rural and urban US counties, along with descriptive measures of patient characteristics by rurality, and first year of VA use. We found that Hispanic patients (n = 722,893) represented 5.2% of new VA users between 2001 and 2018, a proportion which grew nearly 90% from 4.0% (2001-2006) to 7.5% (2013-2018). Hispanic patients were largely White, male, under age 50, and had minimal illness or disability. The highest prevalence of Hispanic patients was in the Southwest US/Mexico border region, while the Midwest experienced the largest growth of Hispanic patients. Rural Hispanic patients were more likely to be older, male, and to live in areas characterized by small foreign-born populations and high socioeconomic deprivation. Compared with Hispanic patients entering the VA system in 2001-2006, patients in 2013-2018 were younger, more likely to be female, and to live in urban areas. These findings illustrate the wide range of demographic, clinical, and geographic experiences in the growing VA Hispanic population and demonstrate that culturally competent care for Hispanic Veterans must reflect their intra-ethnic diversity.

The Spatial Variation of Water Clouds, NH3, and H2O on Jupiter Using Keck Data at 5 Microns

We obtained high-resolution spectra of Jupiter between 4.6 and 5.4 µm using NIRSPEC on the Keck 2 telescope in February 2017. We measured the spatial variation of NH3, H2O, and the pressure level of deep (p > 3 bar) clouds using two geometries. We aligned the slit north–south on Jupiter’s Central Meridian to measure the spatial variation of the gas composition and cloud structure between 66°N and 70°S. With the slit aligned east–west, we also examined the longitudinal variation at two regions of the North Equatorial Belt (NEB) at 18°N and at 8°N near the latitude of the Galileo Probe entry site. We used the integrated line absorption, also known as the equivalent width, of deuterated methane (CH3D) at 4.66 µm to derive the pressure level of deep clouds between 3 and 7 bar. From thermochemical models, these are most likely water clouds. At the location of a deep cloud revealed by HST methane-band imaging, we found spectroscopic evidence for an opaque cloud at the 5 bar level. We also identified regions on Jupiter that lacked deep clouds but exhibited evidence for upper clouds and enhanced NH3. We estimated column-averaged mole fractions of H2O and NH3 above the opaque lower boundary of the deep cloud. The meridional scan exhibited significant belt-zone structure with retrieved NH3 abundances in the 200–400 ppm range above the opaque lower cloud, except for a depletion (down to 90 ppm) in the NEB. Water in Jupiter’s belts varies from a maximum of 7 ppm at 8°S to a minimum of 1.5 ppm at 23°S. We found evidence for water clouds and enhanced NH3 and H2O in the South Equatorial Belt Outbreak region at 13°S. The NEB is a heterogeneous region with significant variation in all of these quantities. The NH3 abundance at 18°N and 8°N varies with the longitude with mole fractions between 120 and 300 ppm. The H2O abundance at these same latitudes varies with the longitude with mole fractions between 3 and 10 ppm. Our volatile mole fractions apply to the 5 to 8 bar pressure range (or to the level of an opaque cloud top where found at shallower pressure); therefore, they imply a deeper gradient continuing to increase toward higher concentrations detected by the Galileo Probe Mass Spectrometer at 11 and 20 bar. Hot Spots in the NEB exhibit minimal cloud opacity; however, they lack prominent anomalies in the concentrations of NH3 or H2O.

Understanding the efficiency of roll lubrication when rolling AD33 aluminium alloy bands in industrial twin mill 175Ч300

This paper describes the results of a study that looked at the effect of contact conditions (including the use of industrial oil I40 (5%) for roll lubrication) on the deformation performance and power draw of a twin cold mill 175×300 operated by the machine building site in Dong Nai, Vietnam, when rolling 0.55 mm thick bands made of aluminium alloy AD33. The initial band size is 0.7×100×2,000 mm. The authors considered reological properties of the aluminium alloy, as well as the roll lubrication environment, to come up with a rational rolling process designed for 0.55×100 mm bands made from 0.7×100×2,000 mm rolled steel. Due to the use of industrial oil I40 (5%) in the mill 175×300, the number of passes could be reduced from three to two. The use of industrial oil I40 (5%) in the twin mill 175×300 ensured the specified precision and helped reduce the loads. Compared with dry rolling, due to the use of industrial oil I40 (5%), the rolling force could be lowered by 6 kN (8.3%) in the first pass and the power draw – by 0.025 kW (3.34%). At the same time, the second pass saved 2.96 kN (5.24%) of rolling force and 0,017 kW (3.95%) of power while ensuring the preset band thickness at the mill exit. Compared with dry rolling, when using I40 oil, the rolling force distribution efficiency along the band length rises by 22.7% in the first pass and by 14.64% in the second pass. When using I40 oil (5%), the strain distribution u nevenness along the band length drops by 39.15% — from 2.35 to 1.43% in the first pass and by 70.08% — from 3.81 to 1.14% in the second pass. When using I40 oil (5%), the thickness distribution along the length of aluminium band at the mill exit is more even than when the rolls are dry or use water. It also results in a minimized longitudinal thickness variation δh – i.e. 0.01 mm. These findings helped develop a rational rolling process for AD33 aluminium alloy bands that relies on the use of industrial oil I40 (5%) to lubricate the rolls of an industrial twin mill, while cutting the loads and saving power.

Performance evaluation of an LED flatbed scanner for triple channel film dosimetry with EBT3 and EBT-XD film.

We investigate the properties of a light emitting diode (LED) flatbed scanner for use with EBT3 and EBT-XD film types in a clinical radiochromic film (RCF) dosimetry program with modern treatment techniques. The flatbed scanner was characterised in terms of lateral and longitudinal response, X-Y scaling integrity, scanning reproducibility, scanner warm up dependence and film orientation dependence. The preferred lateral response artefact (LRA) corrections are investigated for the LED light source. Supporting evidence is provided regarding the dose independent nature of the corrections while also providing results suggesting a potential film type independence. Results from 2D gamma analysis of four patient treatments were compared between the new 12000XL and existing 10000XL model. Lastly, a dose uncertainty analysis was performed for the film-scanner system combination. It may be concluded that the lateral response variation requires correction while the longitudinal response variation is insignificant. The linear scaling in the lateral and longitudinal directions are within 0.5% and the scanner reproducibility is stable. Scanner warm up dependence no longer exists, and effort should be made to maintain all film orientation in a study set within 15°. The LRA corrections are as reported substantially dose independent and there is evidence to support film type independence. Comparative gamma analysis of patient specific dose maps between the EPSON 10000XL (xenon fluorescent lamp) and 12000XL (LED) scanners showed that results are indistinguishable for both film types across the two scanner models when the necessary corrections are applied. Dose uncertainty is in agreement with the literature and can be kept below 3% with necessary corrections applied.

Measuring the effects of mind wandering in people with insomnia: A driving simulator study

PurposeStudies have shown that individuals with insomnia experience more frequent and longer episodes of mind wandering (MW) while driving. However, the effect of the interaction between insomnia and MW on driving behavior is not fully understood. This study aimed to gain deeper insights into the relationships among insomnia, MW, and driving behavior.Patients and methodsForty-two participants (21 diagnosed with insomnia and 21 controls) were recruited, and subjective sleep quality and cognitive function were assessed. A driving simulator experiment with a within-subject design was performed, involving two distraction tasks (no-distraction task versus MW task) and two driving scenarios (lane-keeping versus lane-changing).ResultsIn the lane-keeping scenario, there was no significant between-group difference (people with insomnia and controls) in longitudinal driving performance for the no-distraction task, although the interaction between MW and insomnia significantly increased drivers’ longitudinal control variation. Correlation analysis confirmed that longitudinal driving performance was positively correlated with sleep quality and the cognitive level. Unlike longitudinal driving performance, lateral driving performance was significantly weaker in people with insomnia than in controls under both distraction tasks. In the lane-changing scenario, although there was no between-group difference in driving performance, the MW task led to significant changes in driving performance within each group compared with the no-distraction task, and these findings were associated with cognitive function, but not with sleep quality.ConclusionThese findings show that insomnia and MW combined can lead to reduced driving performance. Further research is needed to elucidate the factors that influence this phenomenon.

Biological Variation in Peripheral Inflammation and Oxidative Stress Biomarkers in Individuals with Gaucher Disease.

The lack of reliable biomarkers is a significant challenge impeding progress in orphan drug development. For appropriate interpretation of intervention-based results or for evaluating candidate biomarkers, other things being equal, lower variability in biomarker measurement would be helpful. However, variability in rare disease biomarkers is often poorly understood. Type 1 Gaucher disease (GD1) is one such rare lysosomal storage disorder. Oxidative stress and inflammation have been linked to the pathophysiology of GD1 and validated measures of these processes can provide predictive value for treatment success or disease progression. This study was undertaken to investigate and compare the extent of longitudinal biological variation over a three-month period for various blood-based oxidative stress and inflammation markers in participants with GD1 on stable standard-of-care therapy (N = 13), treatment-naïve participants with GD1 (N = 5), and in age- and gender-matched healthy volunteers (N = 18). We utilized Bland–Altman plots for visual comparison of the biological variability among the three measurements. We also report group-wise means and the percentage of coefficient of variation (%CV) for 15 biomarkers. Qualitatively, we show specific markers (IL-1Ra, IL-8, and MIP-1b) to be consistently altered in GD1, irrespective of therapy status, highlighting the need for adjunctive therapies that can target and modulate these biomarkers. This information can help guide the selection of candidate biomarkers for future intervention-based studies in GD1 patients.

Liver fibrosis progression in a cohort of young HIV and HIV/ HBV co-infected patients: A longitudinal study using non-invasive APRI and Fib-4 scores.

BackgroundThe risk of liver fibrosis increases over time in HIV and HIV-HBV individuals even under antiretroviral treatment (ART), warranting a rigorous and periodic monitorization. Given the lower availability of transient elastography, we aimed to assess the longitudinal variation of two non-invasive liver fibrosis scores, APRI and Fib-4, in cases with HIV monoinfection, HIV-HBV co-infection and individuals with HBsAg-seroclearance.MethodsWe performed an observational retrospective study between 2013 and 2019 on 212 HIV patients including 111 individuals with HIV mono-infection, 62 individuals with HIV-HBV co-infection and positive HBsAg and 39 cases with HIV-HBV infection and HBsAg-loss. The groups were followed at 36, 48, and 60 months. Liver fibrosis was indicated by an APRI >0.5 or Fib-4≥1.45 score and advanced fibrosis by an APRI score >1.5 or Fib-4 >3.25. Logistic regression with generalized estimating equations (GEE) was used to assess the predictors for the presence of liver fibrosis over time.ResultsDuring a median follow-up of 58.5 months the prevalence of liver fibrosis in all patients increased with 0.5% reaching 11.3% using an APRI score and with 0.9% reaching 10.8% using the Fib-4 score. At the visit corresponding to 60 months the prevalence of liver fibrosis was higher in all HIV-HBV patients compared with individuals with HIV mono-infection, namely: 16.1% on APRI and 12.9% on the Fib-4 score in HIV-HBV/HBsAg-positive individuals, 12.8% on both APRI and Fib-4 scores in HIV-HBV/HBsAg-negative individuals vs. 8.1 and 9%, respectively in HIV mono-infection. The presence of liver fibrosis over the study period was independently associated with plasma HIV RNA, CD4+T cell counts, HIV-HBV co-infection (for APRI >0.5) and ART non-adherence (for Fib-4 >1.45). At the final visit, non-adherence to ART and CD4+T cell counts remained associated with liver fibrosis.ConclusionsThe study found a slow progression of APRI and Fib-4 scores over time in young PLWH with extensive ART. Liver fibrosis scores continued to increase in patients with HIV mono-infection yet remained lower than in HIV-HBV patients irrespective on the presence of HBsAg. The periodic follow-up using non-invasive scores on the long-term could help improve the surveillance in low-income settings and high scores should be followed by additional diagnostic methods.

Group B Streptococcus (GBS) colonization is dynamic over time, whilst GBS capsular polysaccharides-specific antibody remains stable.

Group B Streptococcus (GBS) is a leading cause of adverse pregnancy outcomes due to invasive infection. This study investigated longitudinal variation in GBS rectovaginal colonization, serum and vaginal GBS capsular polysaccharide (CPS)-specific antibody levels. Non-pregnant women were recruited in the UK and were sampled every 2 weeks over a 12-week period. GBS isolates were taken from recto-vaginal swabs and serotyped by polymerase chain reaction. Serum and vaginal immunoglobulin G (IgG) and nasal immunoglobulin A (IgA) specific to CPS were measured by Luminex, and total IgG/A by ELISA. Seventy women were enrolled, of median age 26. Out of the 66 participants who completed at least three visits: 14/47 (29.8%) women that were GBS negative at screening became positive in follow-up visits and 16/19 (84.2%) women who were GBS positive at screening became negative. There was 50% probability of becoming negative 36 days after the first positive swab. The rate of detectable GBS carriage fluctuated over time, although serum, vaginal, and nasal CPS-specific antibody levels remained constant. Levels of CPS-specific antibodies were higher in the serum of individuals colonized with GBS than in non-colonized, but similar in the vaginal and nasal mucosa. We found correlations between antibody levels in serum and the vaginal and nasal mucosa. Our study demonstrates the feasibility of elution methods to retrieve vaginal and nasal antibodies, and the optimization of immunoassays to measure GBS-CPS-specific antibodies. The difference between the dynamics of colonization and antibody response is interesting and further investigation is required for vaccine development.

Emergent evolutionary forces in spatial models of luminal growth and their application to the human gut microbiota

The genetic composition of the gut microbiota is constantly reshaped by ecological and evolutionary forces. These strain-level dynamics are challenging to understand because they depend on complex spatial growth processes that take place within a host. Here we introduce a population genetic framework to predict how stochastic evolutionary forces emerge from simple models of microbial growth in spatially extended environments like the intestinal lumen. Our framework shows how fluid flow and longitudinal variation in growth rate combine to shape the frequencies of genetic variants in simulated fecal samples, yielding analytical expressions for the effective generation times, selection coefficients, and rates of genetic drift. We find that over longer timescales, the emergent evolutionary dynamics can often be captured by well-mixed models that lack explicit spatial structure, even when there is substantial spatial variation in species-level composition. By applying these results to the human colon, we find that continuous fluid flow and simple forms of wall growth alone are unlikely to create sufficient bottlenecks to allow large fluctuations in mutant frequencies within a host. We also find that the effective generation times may be significantly shorter than expected from traditional average growth rate estimates. Our results provide a starting point for quantifying genetic turnover in spatially extended settings like the gut microbiota and may be relevant for other microbial ecosystems where unidirectional fluid flow plays an important role.

PD10: Longitudinal variation in phototherapy cabinets: how much is reaching the lower legs?

PD10: Longitudinal variation in phototherapy cabinets: how much is reaching the lower legs?

Numerical study of the effect of air curtains on smoke blocking and leakage heat flux in tunnel fires

Tunnel fires can result in serious casualties, and air curtains are crucial for tunnel fire prevention and control. This study adopts a theoretical analysis and Fire Dynamics Simulator (FDS) full-scale numerical simulation to investigate the longitudinal variation law of heat decay under natural ventilation and air curtain jet conditions, as well as the flow characteristics of the flow field, temperature rise, and smoke prevention efficiency changes under different air curtain jet effects. The results indicate that the air curtain can effectively isolate the diffusion of heat flow. As the jet velocity increases, the temperature difference between human height and the ceiling decreases. For the 20 MW heat release rate, the minimum jet velocity is 15 m/s, and the greater the jet velocity and width of the air curtain, the smaller the leakage heat flux and the greater the smoke prevention efficiency. The smoke prevention efficiency reduction rate gradually decreases as the jet angle increases, and dimensionless analysis is used to obtain the power-law equations of the leakage heat flux with the fire source, jet velocity of the air curtain, jet width, and jet angle. The error between the model prediction and measured leakage heat flux is within ±20%.

Gut Microbiota Composition and Diversity in Different Commercial Swine Breeds in Early and Finishing Growth Stages.

Simple SummaryThe gut microbiota are involved in the metabolism of nutrients, and the growth and development of pig is strongly influenced by the gut microbiome. To maintain the integrity of the intestinal barrier and promote the digestion and absorption of nutrients and other physiological activities, it is beneficial if the host has a stable gut microbial community. The composition of the gut microbiota is influenced by many factors, such as genetic and environmental factors, and it changes with age. Throughout pig growth and development, the porcine gut microbiota constantly changes in composition. This study investigated the regulation of growth and development of body weight and body size index. We further examined changes in gut microbiota during early and finishing growth stages in Duroc, Landrace and Yorkshire pigs. Results showed that the microbiota of Landrace and Yorkshire pigs were more similar compared with Duroc pigs. There were significant differences in gut microbiota in the early and late growth stages. This study underlines the longitudinal variation in breed and lateral variation in age in gut microbiota.The gut microbiota affects the metabolism, health and growth rate of pigs. Understanding the characteristics of gut microbiota of different pig breeds at each growth stage will enable the design of individualized feeding strategies. The present study aimed to compare the growth curves and development patterns of pigs of three different breeds (Duroc, Landrace and Yorkshire) using the mathematical models Gompertz, Logistic, Von Bertalanffy and Richards. For Duroc pigs, the Gompertz model showed the highest prediction accuracy (R2 = 0.9974). In contrast, the best models for Landrace and Yorkshire pigs were Richards (R2 = 0.9986) and Von Bertalanffy (R2 = 0.9977), respectively. Path analysis showed that body length (path coefficient = 0.507) and chest circumference (path coefficient = 0.532) contributed more significantly to the body weight of pigs at the early growth stage, while hip circumference (path coefficient = 0.312) had a greater influence on pig body weight in the late growth stage. Moreover, the composition of the gut microbiota of pigs at two growth stages (60 kg of body weight in the early growth stage and 120 kg in the finishing stage) was studied using 16S rRNA sequencing technology. Variations in gut microbiota composition of pigs at different growth stages were observed. KEGG pathway enrichment analysis of annotated metagenomes revealed that protein synthesis and amino acid metabolism pathways were significantly enriched in pigs at the early growth stage, which may be related to nutritional requirements of pigs during this stage. This study confirmed longitudinal variation in the gut microbiota of pigs pertaining to age as well as lateral variation related to pig breed. The present findings expand the current understanding of the variations in swine gut microbiota during production stages.

Empirical Model of Longitudinal Variation in Mid-Latitude Ionosphere Based on CHAMP observations

Empirical Model of Longitudinal Variation in Mid-Latitude Ionosphere Based on CHAMP observations