Investigating Effects of Clay and Carbonaceous Nanoparticles on Asphalt Degradation Aerobic Microorganisms

Background: Hot mix asphalt (HMA) is one of the most important structures to implement the road and street surfaces, which always exposed to destruction. Provide new solutions to reduce the destructive process of effective factors on asphalt destruction and increasing prolong of its lifetime is important for society of road engineers. Traffic loading and weather conditions are the major factors that have role on different asphalt destruction.Materials and Methods: In this study, three types of HMAs, which contain nanoclay, and carbon nanotubes were produced by Marshall method in Iran University of Science and Technology, and one type of aged HMA were also collected for further investigations. The HMA samples were transferred to microbiology laboratory of Shahid Beheshti University of Medical Sciences, and then suspensions were prepared from specimens and cultured on nutrient agar medium. After 24 hours’ incubation at 37 ̊C the bacteria that were grown on the plate were identified. At least the effect of clay and carbon nanoparticles on minimum inhibitory concentration (MIC) of bacteria, were determined by microdilution broth method.Results: A lot of bacterial colonies (Bacillus and Pseudomonas) were collected from the aged specimens. The asphalt, which contain nanoclay had more bacteria than the nanocarbon asphalt. The carbon and clay nanoparticles in 2% and 4% concentration prevented the growth of bacteria, respectively.Conclusion: The old asphalt had more bacteria than other samples, which shows bacteria are one of the main factors in decomposition of asphalt by applying corrosion to bituminous hydrocarbons. Presence of clay and carbon nanoparticles in asphalt structures could increase the durability of the HMAs and reduce the relevant economics costs

Nosocomial Infections Caused by Drug-Resistant Bacteria in a Referral University Hospital, Tehran, Iran

Background: The emergence of antimicrobial-resistant pathogens associated with hospital-acquired infections (HAIs) is a major public health problem worldwide. Although being drug resistance is common in some countries and rare in others, the extent of this condition is not precisely known in most parts of Iran.Materials and Methods: Clinical specimens from patients who had been in the hospital for at least 48 hours were included in this study. The pattern of antibiotic resistance was determined by disk diffusion method as recommended by the Clinical Laboratory and Standards Institute (CLSI).Results: Of 11164 patients that were investigated, 369 (3.3%) had nosocomial infections. The most frequently isolated organisms from all sites of infections were Acinetobacter species (14.2%), Escherichia coli (13.7%) and Pseudomonas aeruginosa (9.9%). Among the Gram-negative bacilli, Acinetobacter spp was mostly resistant to ciprofloxacin, ceftriaxon, co-trimoxazole and centamicin, while P. aeruginosa was frequently resistant to ampicillin/sulbactam (87%). Imipenem and piperacillin/tazobactam were the most active antimicrobials against gram-negative microorganisms whereas vancomycin was the antimicrobial agent most consistently active against the Gram-positive cocci.Conclusions: This study highlights the importance of antimicrobial-resistant pathogens associated with nosocomial infection in Tehran, Iran. Using proper diagnostic criteria as well as administering more effective treatment may limit the frequency of drug-resistant bacteria associated with HAIs.

An enriched mixed finite element model for the simulation of microseismic and acoustic emissions in fractured porous media with multi-phase flow and thermal coupling

A novel mixed enriched finite element model is developed for coupled non-linear thermo-hydro-mechanical simulation of fractured porous media with three-phase flow and thermal coupling. Simulation of induced acoustic emission (AE) and microseismic emission (ME) due to tensile fracturing and shear slip instability of pre-existing fracture interfaces is carried out and the numerical results of the emitted signals are analysed. The mathematical model is based on the generalized Biot's theory for coupled interaction of solid and fluid phases. A computationally robust non-linear solver is developed to handle the severe non-linearities arising from fluid saturations, relative permeabilities of fluids, constitutive models of interfaces and convective thermal coupling. To model pre-existing natural fractures and faults, discrete fracture propagation and nucleation of cracks (micro-cracking) independently of the original mesh topology, a local Partition-of-Unity (PU) finite element method, namely, the Phantom Node Method (PNM) is implemented. The cohesive fracture modelling scheme is implemented to account for the non-linear behaviour of fracturing and localization, and to rectify the non-physical stress singularity condition at the fracture tip. Effects of different system parameters on fracturing, shear-slip instability and the associated induced AEs and MEs are investigated through various numerical results

The Effect of Moral Hazards in the Health Insurance Industry in Iran in 2008-2010

Background: Health insurance is one of the most important financial resources for covering the growing costs of health care. Asymmetric information in the insurance market means that the insurer has less information about the health status of the insured person than the insured person him/herself and this leads to waste of treatment resources due to moral hazards. The aim of this study was to determine the effect of moral hazards in the health insurance industry. Methods: This study was a cross-sectional descriptive-analytic research. The study population was all households residing in Iran. For data collection, the questionnaire of urban and rural households Income and Expenditure Survey of Iran Statistics Center was used. For identification and estimation of utility function parameters , the generalized method of moments (GMM) and instrumental variables model were used. GAUSS and E-views software were used for data analysis. Results: According to the results, there were moral hazards in the basic health insurance organizations (medical service insurance organization and Social Security organization) and the complementary insurance. In addition, during these three years, individuals covered by the medical service insurance, with an average elasticity of -2.78, had the lowest moral hazards and those covered by the complementary insurance, with an average elasticity of -3.86, had the highest moral hazards. Conclusion: Insurance policy makers should control consumer's moral hazards

Clustering Elements of Truss Structures for Damage Identification by CBO

The number of structural elements plays a significant role in detecting damage location and severity; such methods have sometimes failed to provide correct solutions due to the entrapment of damage detection algorithms in the local optimum. To resolve this problem, this study proposed the simultaneous use of mathematical and statistical methods to narrow down the search space. To this end, a two-step damage detection method was proposed. In the first step, the structural elements were initially divided into different clusters using the k-means method. Subsequently, the possibly damaged elements of each cluster were identified. In the second step, the elements selected in the first step were placed in a new set, and a process was applied to identify their respective damage location and severity. Thus, the proposed method reduced the search space as well as the possibility of entrapment in the local optimum. Other advantages of the proposed method include the use of fewer dynamic properties. Accordingly, by narrowing down the search space and the dimensions of the system for governing equations, the proposed method could significantly increase the chance of obtaining favorable results in structures with many elements and those with few vibration modes. A meta-heuristic method, called the colliding bodies optimization (CBO), was used in the proposed damage detection optimization algorithm. The optimization problem was based on the modal strain energy equations. According to the results, the proposed method was able to detect the location and severity of damage, even at its slightest percentage

GeoStrain : an open source software for calculating crustal strain rates

We developed an open source software for crustal strain analysis using the least-squares collocation method based on the spherical model of the earth. The software is able to simultaneously determine the signal and noise of the velocities at the observation points with the best possible removal of the observational errors, or at any other position with no velocity observation. Furthermore, the software can calculate strain and rotation rate tensors at any points of interest, including observation points, grid points or points along a fault line. The advantage of the software is that the sphericity of the earth is considered in all the calculations. Moreover, it can optionally consider the effect of the vertical velocities on the strain rates that is principally important for regions where vertical deformation is the major geophysical signal compared to the horizontal deformation

Noise behavior in CGPS position time series : the eastern North America case study

We analyzed the noise characteristics of 112 continuously operating GPS stations in eastern North America using the Spectral Analysis and the Maximum Likelihood Estimation (MLE) methods. Results of both methods show that the combination ofwhite plus flicker noise is the best model for describing the stochastic part of the position time series. We explored this further using the MLE in the time domain by testing noise models of (a) powerlaw, (b)white, (c)white plus flicker, (d)white plus randomwalk, and (e) white plus flicker plus random-walk. The results show that amplitudes of all noise models are smallest in the north direction and largest in the vertical direction. While amplitudes of white noise model in (c–e) are almost equal across the study area, they are prevailed by the flicker and Random-walk noise for all directions. Assuming flicker noise model increases uncertainties of the estimated velocities by a factor of 5–38 compared to the white noise model

Distribution of Enterotoxigenic Escherichia coli among E. coli isolates from diarrheal samples referred to educational hospitals in Tehran-Iran

Background: Introduction: Enterotoxigenic Escherichia coli (ETEC) is the most important bacterial cause of watery  travelers' diarrhea  in  developing countries. Watery diarrhea is can cause serious life-threatening dehydration. ETEC was caused diarrhea by the secretion of two heat-labile enterotoxins (LTs) and the heat-stable enterotoxins (STs) which increase intestinal secretion. Routine laboratory methods are not appropriate to detect ETEC and other diarrheagenic E. coli pathotypes. The molecular techniques such as PCR are rapid and accurate methods that have been developed for detection of ETEC. We were recognized ETEC by PCR on lt and st genes from E. coli isolates from patients with diarrhea collected from selected Tehran educational hospitals.Materials and Methods: The E. coli isolates were collected from total 140 patients with diarrhea and 110 patients without diarrhea using culture and IMViC test. DNA was extracted by boiling method and the presence of the uidA, lt and st genes was detected by PCR.Results: Among 140 E. coli isolates from diarrheal stools 5 (3.6%) isolates were positive for, just lt gene, 3 (2.1%) co-amplified for both lt/st and 1 (0.7%) was positive for just the st gene which were considered as ETEC. In the E. coli isolates from non-diarrheal control samples just one (0.9%) isolate was positive for both lt and st genes.Conclusion: The results showed that the ETEC as a significant cause of diarrhea, usually ignored by laboratories using traditional methods. Sometimes the ETEC causes severe diarrhea and can threaten for patient's life. Thus a rapid diagnostic test such as PCR can be very helpful in the treatment of patients