Optimization of the chin bar of a composite-shell helmet to mitigate the upper neck force

The chin bar of motorcycl e full - face helmets is the most likely region of the helmet to sustain impact s during accident s , with a large percentage of these impacts lead ing to basilar skull fracture . Currently, helmet chin bars are designed to mitigate the peak acceleration at the c entre o f g ravity of isolated headforms , as required by standards, but they are not designed to mitigate the neck force, which is probably the cau se of basilar skull fracture, a type of head injury that can lead to fatalities . Here we test whether it is possible to increase the protection of helmet chin bars while meeting standard requirements. Fibre - reinforced composite shells are commonly used in helmets due to their lightweight and energy absorption charac teristics. W e optimize the ply orientation of a chin bar made of fibre - reinforced composite layers for reduction of the neck force in a dummy model using a computational approach . We use the fini te element model of a human head/neck surrogate and measure the neck axial force, which has been shown to be correlated with the risk of basilar skull fracture. The results show t hat by varying the orientation of the chin bar plies , thus keeping the helmet mass constant, the neck axial force can be reduced by approximately 3 0 % while ensuring that the helmet complies with the impact attenuation requirements prescribed in helmet standards

A Simple Three-component Synthesis of 3-Amino-5-arylpyridazine-4-carbonitriles

New 3-amino-5-arylpyridazine-4-carbonitriles have been synthesized by a one-pot three-component reaction of malononitrile with arylglyoxals in the presence of hydrazine hydrate at room temperature in water and ethanol.KEYWORDS Arylglyoxals, arylpyridazines, hydrazine hydrate, one-pot, malononitrile

On the generalized vector F-implicit complementarity problems and vector F-implicit variational inequality problems

In this paper, we introduce and analyze some new classes of generalized vector-F implicit complementarity problems and the general mixed vector-F variational inequalities. Under suitable conditions, we prove the equivalences between these new problems. We establish several existence theorems for these classes of vector-F complementarity and general mixed vector-F variational inequalities using a new version of the Fan-KKM theorem in Hausdorff topological vector spaces, and without even using the classical assumptions in this context, like monotonicity or continuity. Results obtained in this paper represent significant improvement and refinement of the previously known results

THE EVALUATION OF GRAIN AND OIL PRODUCTION, SOME PHYSIOLOGICAL AND MORPHOLOGICAL TRAITS OF AMARANTH ‘CV. KONIZ’ AS INFLUENCED BY THE SALT STRESS IN HYDROPONIC CONDITIONS

The purpose of this study was investigation of salinity effect on some traits of Amaranth. A split plot designed with three replications with two factors: 5 salinity levels (control, 75, 150, 225, 300 mM NaCl) and applied time at 4 levels (plant establishment, branching, flowering, grain filling) in a greenhouse under hydroponic system. Application of 300 mM salinity after plant establishment led to death of amaranth. Salinity application after establishment decreased significantly plant height and number of branches as 44.9 and 31.8, respectively. Production of grain weight was not affected by 75 mM salinity, but at higher salinity showed significantly decrease. The highest decrease in grain weight obtained by applying 225 mM salt after the plant establishment and salinity at 300 mM after branching as 86.6 and 71.3 percent respectively, resulting in a decrease in both 1000 kernel weight and grain number, respectively. Salinity application increased H2O2, MDA and total phenolics contents, severely. Most of characteristics hadnot affect by 75 mM NaCl, but other concentrations had a negative effect on the growth and production of Amaranth and increasing salinity had more negative impact. In this study, the most sensitive to salinity was after plant establishment and grain filling stage was the most tolerant

The Association Between Obstructive Sleep Apnea and Depression in Older Adults

Background: Depression is the most frequent psychiatric disorder among the elderly. Obstructive sleep apnea (OSA) is a chronic and prevalent disease that has an ambiguous role in triggering depression. Several researches with contradictory findings have been performed about the association between OSA and depression. Objectives: This study aimed to investigate the association between OSA and depression among elderly. Patients and Methods: A total of 350 home residing elderly took part in this case-control study. The participants were selected using clustering method. All cases were divided into two groups of depressed and non-depressed using the geriatric depression scale (GDS). Then they were matched in age, gender, education and body mass index (BMI). Berlin questionnaire (BQ) was used to diagnose OSA. Data analysis was performed using Mann-Whitney U test, t-test, Chi-square and Fisher’s exact tests and odds ratio. Results: Totally, 60.6 % of depressed group and 18.9 % of non-depressed group were in high risk for OSA. A significant association was found between OSA and depression (P < 0.001, OR = 6.61, CI 95 % = 4.1 - 10.7). In addition, a significant association was found between gender and OSA (P = 0.008). Conclusions: OSA was associated with depression among the elderly patients. Given the high prevalence of OSA in older adults, implementation of screening methods is necessary to identify people at high risk of OSA

The Prevalence of Restless Legs Syndrome in Patients Undergoing Hemodialysis: A Systematic Review and Meta-analysis Study

Introduction: Restless legs syndrome is a sensory-motor disorder that causes sleep disorder. The syndrome in patients undergoing hemodialysis associates with depression, sleep deprivation, performance disorder, day fatigue, excessive daytime sleepiness, stress, anxiety, and higher risk of cardiovascular diseases. The objective of this systematic meta-analysis study was to estimate prevalence of restless legs syndrome in patients undergoing hemodialysis. Methods: Twenty-six relevant articles published between 2000 and 2015 indexed in Iranian (MagIran and IranMedex) and international databases (SID, Google Scholar, ScienceDirect, PubMed, Pre Quest, and Scopus) were selected. Data analysis was carried out through metaanalysis (random effect model) and heterogeneity of the studies was determined using I2 index. The obtained data were analyzed in STAT (11.2). Results: Prevalence of the syndrome according to the found articles was 50 (95 CI: 38-61) in Iranian and 30 (95 CI: 23-37) in international databases. There was an ascending trend of prevalence of the syndrome corresponding to the publication year of the articles (P= 0.419), while the trend based on age of the patients was descending (P= 0.604). However, the variations were not significant. Conclusion: Given the high prevalence and considerable effects of restless legs syndrome on patients undergoing hemodialysis, it is recommended that these patients be screened for the syndrome

Relationship between Obstructive Sleep Apnea (OSA) and Difficult Intubation

BACKGROUND AND OBJECTIVE: One of the challenges of patients who are candidates for anesthesia is difficult intubation, which leads to severe complications and even death after anesthesia. The aim of this study is to investigate the relationship between obstructive sleep apnea and difficult intubation through systematic review and meta-analysis. METHODS: In this review article, observational articles about the relationship between obstructive sleep apnea and difficult intubation were extracted without time limit by searching national and international databases and the keywords were: difficult intubation, problematic intubation, Intra tracheal-endotracheal, difficult airway OSA, OSAS, obstructive sleep apnea, sleep breathing disorder, anesthesia, and their Persian equivalents. Data were analyzed using meta-analysis and fixed effects model. In order to study the heterogeneity and contradictions in the studies, Q Cochrane and I2 indices were used, respectively. FINDINGS: Of the 72 found articles, 9 articles with a sample size of 1,126 and an average of 125 subjects were included in the study. The results of this study showed that the relationship between obstructive sleep apnea and difficult intubation is significant (OR = 3.88, CI95% = 2.69 – 5.61). In addition, the results of the analysis based on country showed that the highest and lowest odds ratios were observed in studies conducted in France and Canada, respectively. CONCLUSION: The results of this study showed that there is a correlation between obstructive sleep apnea and difficult intubation

The Stability of Gauss Model Having One-Prey and Two-Predators

The study of the dynamics of predator-prey interactions can be recognized as a major issue in mathematical biology. In the present paper, some Gauss predator-prey models in which three ecologically interacting species have been considered and the behavior of their solutions in the stability aspect have been investigated. The main aim of this paper is to consider the local and global stability properties of the equilibrium points for represented systems. Finally, stability of some examples of Gauss model with one prey and two predators is discussed

An evaluation model for the implementation of hospital information system in public hospitals using multi-criteria-decision-making (MCDM) approaches

Background: Hospital Information System (HIS) is implemented to provide high-quality patient care. The aim of this study is to identify significant dimensional factors that influence the hospital decision in adopting the HIS. Methods: This study designs the initial integrated model by taking the three main dimensions in adopting HIS technology. Accordingly, DEMATEL was utilized to test the strength of interdependencies among the dimensions and variables. Then ANP approach is adapted to determining how the factors are weighted and prioritized by professionals and main users working in the Iranian public hospitals, in-volved with the HIS system. Results: The results indicated that "Perceived Technical Competence" is a key factor in the Human dimension. The respondents also believed that "Relative Advantage," "Compatibility" and "Security Concern" of Technology dimension should be further assessed in relation to other factors. With respect to Organization dimension, "Top Management Support" and "Vendor Support" are considered more important than others. Conclusion: Applying the TOE and HOT-fit models as the pillar of our developed model with significant findings add to the growing literature on the factors associated with the adoption of HIS and also shed some light for managers of public hospitals in Iran to success-fully adopt the HIS. © 2018 Ali Aliakbar Esfahani et al