Single Lag Research Articles

Characteristics of Gas Permeation Behaviour in Multilayer Thin Film Composite Membranes for CO₂ Separation.

Porous, porous/gutter layer and porous/gutter layer/selective layer types of membranes were investigated for their gas transport properties in order to derive an improved description of the transport performance of thin film composite membranes (TFCM). A model describing the individual contributions of the different layers’ mass transfer resistances was developed. The proposed method allows for the prediction of permeation behaviour with standard deviations (SD) up to 10%. The porous support structures were described using the Dusty Gas Model (based on the Maxwell–Stefan multicomponent mass transfer approach) whilst the permeation in the dense gutter and separation layers was described by applicable models such as the Free-Volume model, using parameters derived from single gas time lag measurements. The model also accounts for the thermal expansion of the dense layers at pressure differences below 100 kPa. Using the model, the thickness of a silicone-based gutter layer was calculated from permeation measurements. The resulting value differed by a maximum of 30 nm to the thickness determined by scanning electron microscopy.

Cardiovascular and respiratory emergency dispatch due to short-term exposure to ambient PM10 in Dezful, Iran.

Introduction: This study was conducted to determine the relation between exposure to particulate matter less than 10 microns (PM10) caused by dust storms and the risk of cardiovascular, respiratory and traffic accident missions carried out by Emergency Medical Services (EMS). Methods: This was a time-series study conducted in Dezful city, Iran. Daily information on the number of missions by the EMS due to cardiovascular, respiratory and crash problems and data on PM10 were inquired from March 2013 until March 2016. A generalized linear model (GLM) with distributed lag models (DLMs) was used to evaluate the relation between the number of EMS missions and the average daily PM10. The latent effects of PM10 were estimated in single and cumulative lags, up to 14 days. Results: In the adjusted model, for each IQR increase in the average daily PM10 concentration, the risk of EMS missions in the total population in single lags of 2 to 7 days, and the cumulative lags of 0-7 and 0-14 days after exposure had a 0.8, 0.8, 0.8, 0.8, 0.7, 0.6, 6.7 and 1.4% significant increase. Also, for each IQR increase in the daily mean concentration of PM10 in single 1 to 7, and cumulative lags of 0-2, 0-7, and 0-14 days after exposure, respectively, a 2.4, 2.7, 2.8, 2.9, 2.9, 2.7, 2.5, 7.4, 23.5 and 33. 3 % increase was observed in the risk of EMS cardiovascular missions. Conclusion: Increase in daily PM10 concentrations in Dezful is associated with an increase in the risk of EMS missions in lags up to two weeks after exposure.

A Thoroughbred racehorse with a unicortical palmar lateral condylar fracture returned to training 14 days after surgery: a hypothesis on the role of a single bone screw on crack propagation.

ABSTRACTA 2-year-old Thoroughbred racehorse had LF lameness that began post high-speed exercise and persisted for two days before the horse once again became sound. Diagnostic analgesia localized the lameness to the LF distal metacarpus, and a standing MRI identified a unicortical condylar fracture. A single 5.5 mm cortical screw was placed in lag fashion. The horse began hand walking at 14 days, racetrack jogging at 30 days, and racing at 5 months after the day of surgery. Placement of a single lag screw ahead of the tip of the crack in unicortical condylar fracture may be useful for reducing the recovery period for horses returning to training and racing.

Short-term effects of air pollution on respiratory mortality in Ahvaz, Iran.

Background: Urban air pollutants may affect respiratory mortality. This study was conducted to investigate this effect in Ahvaz, one of the most polluted cities in the world. Methods: The impact of 7 major air pollutants including O3, PM10, NO2, CO, and SO2 were evaluated on respiratory mortality in different gender and age groups using a quasi-Poisson, second degree polynomial constrained, distributed lag model, with single and cumulative lag structures adjusted by trend, seasonality, temperature, relative humidity, weekdays, and holiday. Data were analyzed using the dlnm package in R x64 3.2.5 software. Significance level was set at less than 0.05. Results: In adjusted models, for each IQR increase of O3 in the total population, the risk ratio (RR) for respiratory deaths in 0 to 14- day lags was, respectively, 1.009 (95% CI:1.001-1.016) and 1.009 (95% CI:1.002-1.017), and it was 1.021 (95% CI: 1.002-1.040) in cumulative 0 to 14- day lags. For PM10, in the total population and in adjusted models after 0 to 14- day lags and in cumulative lags of 0 to 14 for an IQR increase in the mean concentration of PM10, the RR for respiratory deaths increased significantly and was, respectively, 1.027 (95% CI:1.002-1.051), 1.029 (95% CI:1.006-1.052), and 1.065 (95% CI:1.005-1.128). NO2 showed a significant association with respiratory deaths only in the 18 to 60 year- old age group and in 9- day lags (RR= 1.318, 95% CI:1.002-1.733). Finally, the results showed that for an IQR increase in the mean concentration of CO and SO2, the adjusted RR for respiratory deaths in 9- day lags in the total population was, respectively, RR= 1.058 (95% CI:1.008-1.111) and 1.126 (95% CI:1.034-1.220). Conclusion: Air pollution in Ahvaz is probably causing increased respiratory mortality.

Comparing the costs and outcomes of an integrated twin compression screw (ITCS) nail with standard of care using a single lag screw or a single helical blade cephalomedullary nail in patients with intertrochanteric hip fractures

BackgroundSurgical treatment is the optimal strategy for managing intertrochanteric fractures as it allows for early rehabilitation and functional recovery. The purpose of the study was to assess the cost-effectiveness of commonly used cephalomedullary nails for the treatment of unstable intertrochanteric hip fractures.MethodsA decision analytic model was developed from a US payer’s perspective using clinical data from a pairwise meta-analysis of randomised controlled trials (RCTs) and comparative observational studies comparing the integrated twin compression screw (ITCS) nail versus two single-screw or blade cephalomedullary nails [single lag screw (SLS) nail and single helical blade (SHB) nail]. The model considered a cohort of 1000 patients with a mean age of 76, as reported in the clinical studies over a 1-year time period. Cost data was obtained from the Center for Medicare and Medicaid Services website and published literature and adjusted for inflation. One-way and probabilistic sensitivity analyses were conducted to assess the effect of uncertainty in model parameters on model conclusions.ResultsThe model estimated 0.546 quality-adjusted life years (QALYs) and 0.78 complications avoided by using the ITCS nail and 0.455 QALYs and 0.67 complications avoided for the standard of care, using SLS or SHB nails. The cost per patient was $34,336 for patients treated with an ITCS nail and $37,036 for patients treated with the standard of care respectively, resulting in a cost saving of $2700 in favour of the ITCS nail. More savings were observed when the ITCS nail was compared to the SHB ($3280 per patient) and SLS ($1652 per patient). The findings were robust to a range of both one-way and the probabilistic sensitivity analyses.ConclusionIn conclusion, the ITCS nail can be considered a cost saving intervention in patients undergoing intertrochanteric fracture fixation with an intramedullary device. Clinicians and policy makers should be encouraged to adopt healthcare technologies such as ITCS that will help them to provide quality healthcare despite falling budgets.

Psychotropic Polypharmacy Among Children and Youth Receiving Medicaid, 2012-2015.

The rates of mental health diagnoses in children have increased. Children in poverty have the highest rates. The use of psychotropic medication for children has been increasing, which is concerning because of the unknown long-term effects and the increased burden on the health care system. The state of Kentucky ranks among the highest in the United States for children with mental health problems, children living in poverty, and children receiving psychotropic medication. To examine recent trends and determinants of interclass psychotropic polypharmacy (PP) use for children and youth receiving Medicaid to inform intervention development. A retrospective cohort study was conducted using 2012-2015 Kentucky Medicaid claims for children aged 0-17 years, with continuous enrollment for ≥ 90 days with at least 1 behavioral health diagnosis (N = 237,393). Interclass PP was defined as the presence of at least 2 psychotropic medication prescription fills for at least 2 different classes of medication that, if taken as directed, would be used concurrently for at least 90 consecutive days (allowing for a single 15-day lag). The outcome variables were the presence of any interclass PP and the number of months a child received interclass PP. We conducted a descriptive analysis and developed 2 separate generalized linear regression models to test for associations between individual characteristics of children treated with psychotropic medication for ≥ 90 days (n = 75,639) and each outcome of interest. For the sample of children with at least 90 days of psychotropic medication treatment, 38% had at least 3 covered months of PP over the 4 years studied. Children in foster care received alpha agonists (116 vs. 69 per 1,000 children) or antidepressants (225 vs. 176 per 1,000) at a higher rate than other children receiving Medicaid but received stimulants at a lower rate (403 vs. 638 per 1,000). The primary 2-drug class combinations were stimulants with either alpha agonists or antidepressants. Children in foster care (OR = 1.7, 95% CI = 1.58, 1.84, P < 0.001), with a bipolar disorder (OR = 2.24, 95% CI = 2.10, 2.38, P < 0.001), mood disorder not otherwise specified (OR = 1.11, 95% CI = 1.04, 1.17, P < 0.001), or autism spectrum disorders (OR = 1.17, 95% CI = 1.08, 1.26, P < 0.001) had increased the odds of ever receiving PP. Black children had lower odds (OR = 0.72, 95% CI = 0.67, 0.77, P < 0.001) of ever receiving PP. Children aged 6-11 years (beta = 3.08, 95% CI = 2.87, 3.29) and 12-17 years (beta = 1.61, 95% CI = 1.38, 1.83) had more covered months with PP compared with those aged 0-5 years. Black children had fewer covered months of PP compared with white children (beta = -1.36, 95% CI = -1.61, -1.11]. Children in foster care (beta = 1.83, 95% CI = 1.53, 2.13) had more covered months with PP. Children residing in nonurban areas had fewer months with PP (beta = -0.4, 95% CI = -0.54, -0.26) compared with those residing in urban areas, as did those children with depression (beta = -3.32, 95% CI = -3.55, -3.1), impulse control disorder (beta = -2.07, 95% CI = -2.28, -1.85), and conduct disorder (beta = -1.34, 95% CI = -1.64, -1.05). Children with bipolar disorder (beta = 3.62, 95% CI = 3.38, 3.86) and autism (beta = 2.04, 95% CI = 1.75, 2.33) had more covered months with PP. As comorbidity increased, the duration of PP treatment increased (beta = 2.49, 95% CI = 2.36, 2.62). The rates of PP are concerning, especially for children in foster care and children aged 6-11 years. Efforts to safeguard medication use are needed, as well as future exploration of racial differences in PP. This project was supported by the Kentucky Cabinet for Health and Family Services, Department for Medicaid; Norton Healthcare; and the School of Medicine, Department of Pediatrics; School of Public Health and Information Sciences; and Kent School of Social Work at the University of Louisville. Kentucky Medicaid approved the use of the data and granted permission to publish but played no role in the interpretation of data. Lui is employed by Kentucky Medicaid. The other authors report no potential conflicts of interest. An earlier version of this study was presented at the Pediatric Academic Societies' Annual Meeting in Baltimore, MD, on April 30-May 3, 2016. A poster presentation was given at the Society for Developmental and Behavioral Pediatrics in Cleveland, OH, on October 14-16, 2017.

Effects of growth stage and growing degree day accumulations on triticale forages: 2. In vitro disappearance of neutral detergent fiber

The use of winter triticale (X Triticosecale Wittmack) in dairy-cropping systems has expanded greatly in recent years, partly because of its value as a forage crop but also to improve land stewardship by providing winter ground cover. Our objectives were to use 2-pool and 3-pool nonlinear models to characterize in vitro disappearance of neutral detergent fiber (NDF) and then describe the relationship between estimated parameters from those models with plant growth stage or growing degree days (GDD) >5°C for winter triticale forages harvested during 2016 and 2017 in Marshfield, Wisconsin. Forages were harvested from replicated field plots each year at growth stages ranging from stem elongation to soft dough. All NDF analyses included use of sodium sulfite and heat-stable α-amylase with residual fiber corrected for contaminant ash (asNDFom). Nonlinear 3-pool models for in vitro disappearance of asNDFom that included fast (Bfast) and slow (Bslow) disappearance pools as well as an associated disappearance rate for each (Kdfast and Kdslow, respectively) were easily fitted provided that a single discrete lag time was applied to both Bfast and Bslow pools to reduce the number of parameters to be estimated. An unresolved issue related to fitting 3-pool decay models was the incomplete recovery of asNDFom from immature triticale forages at 0 h, which was partially resolved with 2 approaches that produced similar estimates of Kdfast and Kdslow. Most parameters obtained from 2- and 3-pool decay models for asNDFom could be related to growth stage or GDD using polynomial regression techniques, often with high coefficients of determination (R2). For 3-pool models of asNDFom disappearance, Bslow increased with plant maturity, but the associated Kdslow ranged narrowly from 0.011 to 0.015/h and could not be related to growth stage or GDD by quartic, cubic, quadratic, or linear regression models. Despite different cultivars coupled with substantial differences in precipitation across years, single endpoint estimates of in vitro disappearance of asNDFom after 24, 30, or 48 h of incubation were closely related (R2 ≥ 0.906) to growth stage and GDD by linear or quadratic regression models that were generally similar across production years. Typical recommendations for harvesting triticale at boot stage to facilitate the planting of a double crop are strongly supported by the extensive 30-h in vitro disappearance of asNDFom at that growth stage, which was 63.1 and 64.8% of asNDFom during 2016 and 2017, respectively.

Short-term effects of ambient air pollution exposure on lung function: A longitudinal study among healthy primary school children in China

BackgroundShort-term exposure to ambient air pollution has been associated with reduced lung function among asthmatic children. However, there is little information about the effects among healthy children, especially in areas with relatively high exposure background. ObjectiveTo examine the association between short-term effects of ambient air pollutants and lung function among healthy primary school-aged children in China. MethodsA total of 334 healthy children (7–11 years) from four cities (Chengdu (Southwest China), Guangzhou (Southern China), Wuhan (Central China), and Xi'an (Northwest China)) in China with repeated lung function measurement in 2014–2016 were included. Daily ambient concentrations of PM2.5, PM10, NO2, SO2, mean temperature, and relative humidity data were obtained. Linear mixed model was used to estimate the percent change in lung function associated with per inter-quartile range (IQR) exposure (up to 3 days) increase after adjusting for confounders. ResultsAmbient PM2.5 and PM10 exposure were associated with decrements in lung function measurements. The moving average exposures generally showed stronger effect estimates than the single lag day exposures. An IQR increase in two-day average (lag01 day) PM10 exposure (IQR, 144 μg/m3) was significantly associated with 2.56% decrease in FVC, 5.46% in FEV1, 4.23% in PEF, and 7.35% in FEF25%, respectively. The effect estimates were stronger after adjusting for gaseous pollutants in particulate matter (PM) models. The strengths of these associations were stronger in girls than those in boys. ConclusionShort-term exposure to PM was associated with reduced lung function in healthy children. The estimated adverse effects were greater in girls than in boys.

Acute effects of air pollution on ischaemic stroke onset and deaths: a time-series study in Changzhou, China

ObjectiveTo investigate the acute effect of air pollutants on ischaemic stroke (IS) and IS-related death.SettingFive urban districts in Changzhou, China, between 9 January 2015 and 31 December 2016.ParticipantsA total of...

Distal fibula oblique fracture fixation using one-third tubular plate with and without lag screw – A biomechanical study of stability

This laboratory-based study compared distal fibula simple oblique fracture fixation with one-third tubular plate with and without a single lag screw to determine which was mechanically more stable. A control group fixed with a limited contact dynamic compression plate was also tested. Biomechanical testing of 30 osteotomised saw bones under lateral bending and torsional forces was performed. There was no significant difference between the mean lateral bending and mean torsional stiffness between the fixation with tubular plate and lag screw and tubular plate alone. Limited contact dynamic compression plate conferred the best stability in lateral bending and torsion, as expected.

Thermal wave propagation in blood perfused tissues under hyperthermia treatment for unique oscillatory heat flux at skin surface and appropriate initial condition

This paper aims to develop an analytical study of heat propagation in biological tissues for constant and variable heat flux at the skin surface correlated with Hyperthermia treatment. In the present research work we have attempted to impose two unique kind of oscillating boundary condition relevant to practical aspect of the biomedical engineering while the initial condition is constructed as spatially dependent according to a real life situation. We have implemented Laplace’s Transform method (LTM) and Green Function (GFs) method to solve single phase lag (SPL) thermal wave model of bioheat equation (TWMBHE). This research work strongly focuses upon the non-invasive therapy by employing oscillating heat flux. The heat flux at the skin surface is considered as constant, sinusoidal, and cosine forms. A comparative study of the impact of different kinds of heat flux on the temperature field in living tissue explored that sinusoidal heat flux will be more effective if the time of therapeutic heating is high. Cosine heating is also applicable in Hyperthermia treatment due to its precision in thermal waveform. The result also emphasizes that accurate observation must be required for the selection of phase angle and frequency of oscillating heat flux. By possible comparison with the published experimental research work and published mathematical study we have experienced a difference in temperature distribution as 5.33% and 4.73%, respectively. A parametric analysis has been devoted to suggest an appropriate procedure of the selection of important design variables in viewpoint of an effective heating in hyperthermia treatment.

About quasi-solutions of traveling wave type in models for organizing cargo transportation

Nerses K. Khachatryan - Senior Researcher, Laboratory of Dynamic Models of Economy and Optimization, Central Economics and Mathematics Institute, Russian Academy of Sciences; Associate Professor, Department of Business Analytics, National Research University Higher School of EconomicsAddress: 47, Nakhimovsky Prospect, Moscow, 117418, Russian FederationE-mail: nerses@cemi.rssi.ru; nkhachatryan@hse.ruAndranik S. Akopov - Professor, Department of Business Analytics, National Research University Higher School of Economics; Leading Researcher, Laboratory of Dynamic Models of Economy and Optimization, Central Economics and Mathematics Institute, Russian Academy of Sciences Address: 20, Myasnitskaya Street, Moscow, 101000, Russian FederationE-mail: aakopov@hse.ruFedor A. Belousov - Researcher, Laboratory of Dynamic Models of Economy and Optimization, Central Economics and Mathematics Institute, Russian Academy of Sciences; Associate Professor, Department of Business Analytics, National Research University Higher School of EconomicsAddress: 47, Nakhimovsky Prospect, Moscow, 117418, Russian FederationE-mail: sky_tt@list.ru; fbelousov@hse.ru This article is devoted to the construction and research of a model for organizing cargo transportation between two node stations connected by a railway line which contains a certain number of intermediate stations. The organization of freight traffic is facilitated by a number of technologies. These technologies determine the rules for taking on cargo at the initial node station, the rules of interaction between neighboring stations, as well as the rule of distribution of cargo to the final node stations. The process of cargo transportation is accompanied by the set rule of control consisting in measuring the volumes of goods transported at neighboring stations with a single time lag. For such a model, one must determine possible modes of cargo transportation and describe their properties. Traffic flow is described by a finite-difference analog of the nonlinear parabolic equation. The control system is set by nonlocal restrictions, which distinguishes the solutions of traveling wave type. The class of such solutions is extremely narrow. This results in the need for the “correct” extension of a class of solutions of the traveling wave type to a class of quasi-solutions of the traveling wave type. One type of expansion presupposes assumptions of discontinuous solutions of the traveling wave type; the second type allows for violations in a small control system. An essential lack of discontinuous solutions is their limitlessness. In this work, we investigate quasi-solutions obtained with the help of a second type of extension. The distinctive feature of such quasi-solutions is the assumption of feasibility of not local restrictions with the set error. The question of the limitation of such quasi-solutions is investigated. Using computer model implementation we investigate the dependence of the error in the performance of nonlocal restrictions on model parameters, which are the characteristics of the technologies used to carry out the cargo flow.This work was partially supported by the Russian Foundation for Basic Research (project No. 16-01-00110)

Lag time structure of cardiovascular deaths attributed to ambient air pollutants in Ahvaz, Iran, 2008-2015.

There are few studies about the association between breathing polluted air and increased risk of cardiovascular diseases and cardiac death in the Middle East. This study aimed to investigate the relation between air pollutants and cardiovascular mortality (based on ICD-10) in Ahvaz. In this ecological study, the data about cardiovascular disease mortality and air pollutants from March 2008 until March 2015 was inquired from the Ahvaz City Authority and the Khuzestan Province Environmental Protection Agency. The quasi-Poisson, second degree polynomial constrained, distributed lag model; using single and cumulative lag structures, adjusted by trend, seasonality, temperature, relative humidity, weekdays and holidays was used for the data analysis purposes. Findings indicated a direct significant relation between an interquartile range (IQR) increase in ozone and cardiovascular deaths among men after 3 days' lag. There was also a significant relation between an IQR increase in particulate matter below 10 μm and cardiovascular deaths for all people, over 60 years old and under 18 years old after 3 and 13 days' lags. There was a significant relation between an IQR increase in nitrogen dioxide and carbon monoxide, and cardiovascular deaths in the case of under 18-year-olds (in the lag 11) and over 60-year-olds (in the lag 9), respectively. We finally found a significant association between an IQR increase in sulfur dioxide and cardiovascular deaths in the case of men, under 18-year-olds and from 18- to 60-year-olds in the lag 9, 0, and 11, respectively (p-values < 0.05). It appears that air pollution is significantly associated with cardiovascular deaths in Ahvaz City. Int J Occup Med Environ Health 2018;31(4):459-473.

Inference with Cumulative Relative Risk in Environmental Epidemiology: Part III. Inference from Lag Variables

Background/Aim: A distributed lag model (DLM) including a single lag variable has been widely used in air pollution and temperature studies. Researchers have questioned which is the unbiased model among the variety of candidate models. Causal inference from a lag variable (e.g. lag1) may be doubtful if it is not consistent with a lag time implied in toxicological studies. Based upon reasoning in Part I and Part II, we aimed to prove that a coefficient of interest including a single and a sum (i.e. cumulative) of coefficients should be treated as a lower bound of a true (cumulative) coefficient. Methods: We simulated 5,000 runs of estimation of PM risk on all-cause mortality based upon real data. PM effect scenarios include 1) an effect on the same day, 2) effects upto the previous 2 days, 3) effects with exponential decay over time, 4) full harvesting, 5) limited harvesting with effects in longer lags. We compared candidate models in terms of bias, mean squared error (MSE), nominal coverage and probability of model selection by information criteria. Results: DLM with sufficient lags provided unbiased estimates while MSE tended to be compromised. In this regard, information criteria performed poorly in selecting an unbiased model. In a harvesting scenario, models with limited lags were bound to away-from-the null bias. DLM with sufficient lags only for harvesting yielded an estimate smaller than or equal to a true effect. We call these types of bias as insufficient lag bias. Conclusions: Inference based upon a face value of a lag variable should be disregarded if population dynamics cannot be ruled out. A coefficient/sum of coefficients of interest should be interpreted as a lower bound of a true cumulative coefficient. In epidemiologic studies, prior knowledge is crucial in order to reach an unbiased estimate.

Manufacturing and Agricultural Sector Synergies in Zimbabwe: Estimating the Unrestricted Bivariate Vector Auto Regressive Model

This paper investigates the nature of the linkage that exist between the agricultural sector and industrial sector in Zimbabwe using unrestricted bivariate Vector Autoregressive (VAR) model. Using annual time series macroeconomic data for the periods between 1990 and 2015, obtained from the WorldBank.org, we controlled for structural blips and mean-shifts by employing structural break dummies following suggestions by Zivot and Andrews (1992) and Perron (1997). Using a single lag length period obtained from Akaike’s information criterion, we performed the unit root test on the modified Augmented Dickey Fuller specifications, controlling for trend, in level and first difference. We observed that the series are weakly stationery integrated of order 1 [I(1)]. Results and post-estimation diagnostics from the VAR system including autocorrelation, residual normality and stability tests confirm the existence of a stable but weak relationship between industrial and agricultural activities in Zimbabwe. However, we found no evidence to suggest that industry depends on agriculture. To the contrary, Granger causality tests confirmed that the joint lag values of industry cause agriculture. Furthermore, innovations in industry had a relatively more positive shock impact in agriculture than the other way around suggesting that more responsive agriculture to impulse in industry.

A single phase lag model of heat mass transfer for different geometries of food during drying

A single phase lag model of heat mass transfer for different geometries of food during drying

Ensemble Learning Multiple LSSVR With Improved Harmony Search Algorithm for Short-Term Traffic Flow Forecasting

Short-term traffic flow forecasting plays an important role in current intelligent transportation system. For most models, the selection of time lag is a crucial factor affecting the forecasting performance. Instead of choosing a single time lag when constructing model, in this paper, we propose a novel approach attempting to construct multiple base forecasting models, each with different time lag and performance. Least squares support vector regression (LSSVR) with the Gaussian kernel function is adopted as the base model because of its nonlinear modeling capability, as well as empirical performance. Then, the outputs of these base models are integrated to produce final prediction through another LSSVR with the linear kernel function. This ensemble forecasting framework consists of many parameters that need to be adjusted. To address this issue, an improved harmony search algorithm tailored for our forecasting system is further developed for seeking the optimal parameters. The real-world traffic flow data are collected from several observation sites located around the intersection of Interstate 205 and Interstate 84 freeways in Portland, OR, USA. Experimental results verify that the proposed approach is able to provide better forecasting performance in comparison with other competing methods.

Outcomes of surgical treatment of posterior cruciate ligament tibial avulsion fractures through an open posterior approach

Background Avulsion of the tibial insertion of the posterior cruciate ligament (PCL) is believed to be an uncommon injury. A nondisplaced bony avulsion can be treated conservatively with a plaster cast, holding the knee flexed and the tibia pulled forward to diminish tension on the PCL. There is general consensus that a displaced bony PCL avulsion should be surgically reduced and fixed immediately to stabilize the knee joint and prevent nonunion. Hypothesis Our hypothesis was that surgically reduced and fixed displaced bony PCL avulsions stabilize the knee joint and prevent nonunion. Patients and methods This prospective study was performed between January 2010 and August 2013. A total of 11 patients (three females and eight males) with PCL avulsion fracture of the tibial attachment (six isolated and five associated with other ligamentous injuries, meniscal injuries or bony fractures) were treated surgically through a posterior approach at the trauma unit of our university hospital. The mean age of patients was 24.72 years (range, 18–33years). Fixation with a single screw and washer was used in nine cases with a large bony fragment and multiple screws in two cases with comminuted fragments. The operating time was 60 min (range, 45–70 min). All patients were followed for an average of 22 months (range, 19–26 months), and at the end of the follow-up period, patients were evaluated using and Lysholm scoring system. Results All 1-year postoperative radiographs demonstrated union at the fracture site. At the end of the follow-up period, the mean Lysholm score was 88.7 points (range, 70–100 points) with a good overall outcome. Conclusion Treatment of displaced large PCL avulsion injuries with a single lag screw and washer or multiple screws through the open posterior approach results in good clinical and radiographic outcomes.

A meta-analysis of integrated compression screw compared to single screw nails using a single lag screw or single helical blade screw for intertrochanteric hip fractures

A meta-analysis of integrated compression screw compared to single screw nails using a single lag screw or single helical blade screw for intertrochanteric hip fractures

Acute respiratory symptoms associated with short term fluctuations in ambient pollutants among schoolchildren in Durban, South Africa.

Ambient air pollution has been associated with adverse respiratory outcomes, especially among children with asthma. This study reports on associations between daily ambient air pollutant concentrations and the respiratory symptoms of schoolchildren living in Durban, South Africa. This city is Africa's busiest port and a key hub for imported crude oil and exported refined petroleum and petrochemical products, and it experiences a mixture of air pollutants that reflects emissions from industry, traffic and biomass burning. Children in four communities in the highly industrialized southern portion of the city were compared to children of similar socio-economic profiles living in the north of the city. One school was selected in each community. A total of 423 children were recruited. Symptom logs were completed every 1.5-2h over 3-week period in each of four seasons. Ambient concentrations of NO2, NO, SO2, CO, O3, PM2.5 and PM10 were measured throughout the study. Generalized estimating equation (GEE) models were used to estimate odds ratios (ORs) and assess lag effects (1-5 days) using single pollutant (single lags or distributed lags) models. Concentrations of SO2 and NOx were markedly higher in the south, while PM10 did not vary. Significant increase in the odds ratios of cough were identified for the various lags analyzed. The OR of symptoms was further increased among those living in the south compared to the north. In conclusion, in this analysis of over 70,000 observations, we provide further evidence that exposure to PM10, SO2, NO2 and NO is associated with significantly increased occurrence of respiratory symptoms among children. This was evident for cough, shortness of breath, and chest tightness, across the four pollutants and for different lags of exposure. This is the first study describing these changes in sub-Saharan Africa.