132 research outputs found

    Domination Number of the Non-commuting Graph of Finite Groups

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    Let G be a non-abelian group. The non-commuting graph of group G, shown by ΓG, is a graph with the vertex set G \ Z(G), where Z(G) is the center of group G. Also two distinct vertices of a and b are adjacent whenever ab ≠ ba. A set S ⊆ V(Γ) of vertices in a graph Γ is a dominating set if every vertex v ∈ V(Γ) is an element of S or adjacent to an element of S. The domination number of a graph Γ denoted by γ(Γ), is the minimum size of a dominating set of Γ. </p><p>Here, we study some properties of the non-commuting graph of some finite groups. In this paper, we show that \gamma(\Gamma_G)<\frac{|G|-|Z(G)|}{2}. Also we charactrize all of groups G of order n with t = ∣Z(G)∣, in which $\gamma(\Gamma_{G})+\gamma(\overline{\Gamma}_{G})\in \{n-t+1,n-t,n-t-1,n-t-2\}.

    A novel phenomenological model for dynamic behavior of magnetorheological elastomers in tension-compression mode

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    Tension-compression operation in MR elastomers (MREs) offers both the most compact design and superior stiffness in many vertical load-bearing applications, such as MRE bearing isolators in bridges and buildings, suspension systems and engine mounts in cars, and vibration control equipment. It suffers, however, from lack of good computational models to predict device performance, and as a result shear-mode MREs are widely used in the industry, despite their low stiffness and load-bearing capacity. We start with a comprehensive review of modeling of MREs and their dynamic characteristics, showing previous studies have mostly focused on dynamic behavior of MREs in shear mode, though the MRE strength and MR effect are greatly decreased at high strain amplitudes, due to increasing distance between the magnetic particles. Moreover, the characteristic parameters of the current models assume either frequency, or strain, or magnetic field are constant; hence, new model parameters must be recalculated for new loading conditions. This is an experimentally time consuming and computationally expensive task, and no models capture the full dynamic behavior of the MREs at all loading conditions. In this study, we present an experimental setup to test MREs in a coupled tension-compression mode, as well as a novel phenomenological model which fully predicts the stress-strain material behavior as a function of magnetic flux density, loading frequency and strain. We use a training set of experiments to find the experimentally derived model parameters, from which can predict by interpolation the MRE behavior in a relatively large continuous range of frequency, strain and magnetic field. We also challenge the model to make extrapolating predictions and compare to additional experiments outside the training experimental data set with good agreement. Further development of this model would allow design and control of engineering structures equipped with tension-compression MREs and all the advantages they offer.We acknowledge funding from the European Research Council grant EMATTER 280078

    Study of nitrogen fertilizer and cycocel on FV/FM and dry matter mobilization to grain yield of wheat (Triticum aestivum L.)

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    In order to study of effects of nitrogen fertilizer and cycocel on yield, yield component and dry matter mobilization of wheat (Triticum aestivum L.) a factorial experiment was conducted based on randomized complete block design with three replications during 2014. Treatments were included nitrogen rates in four levels (without nitrogen application as control (N0) and application 80 (N1), 160 (N2) and 240 (N3) kg ha-1 urea) and four cycocel levels (without cycocel as control (C0), application of 500 (C1), 1000 (C2), 1500 (C3) ppm). Results showed that cycocel application increased chlorophyll index, photochemical efficiency of PSII (Fv/Fm) and dry matter mobilization from shoots and stem. Application of nitrogen and cycocel reduced dry matter mobilization from shoots and stem, contribution of remobilization from shoots to grain and stem reserve contribution in grain yield. Application of nitrogen and cycocel as N3C3 had 58.5% and 46.26% more dry matter mobilization from shoots and stem in comparison with N3C0. The highest 1000-grain weight by 28.90 and 28.54 g, respectively, belonged to application of cycocel as C2 and C3 and the lowest 1000-grain weight by 26.93 g belonged to the C0. The highest grain yield (1.068 g per plant), number of grains per ear (37.36) and 1000-grain weight (28.77 g) were obtained in application of 240 kg ha-1 urea. It seems that the increase of Fv/Fm ratio due to current photosynthesis in plants that were grown under cycocel and nitrogen treatments decreased mobilization of dry matter and stem reserves to grain yield. Generally, it was concluded that nitrogen and cycocel can be as a proper tool for increasing wheat yield

    Designing of a laboratory model for evaluation of the residual effects of deltamethrin (K-othrine WP 5%) on different surfaces against malaria vector, Anopheles stephensi (Diptera: Culicidae)

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    Background & objectives: Deltamethrin plays an important role in controlling malaria vectors,and is used in indoor residual spraying and manufacture of long-lasting insecticidal mosquitonets. The residual activity of deltamethrin (K-othrine WP 5%) @ 25 mg/m2 was studied in laboratoryconditions on different surfaces.Methods: The surfaces were made artificially with different building materials such as mud, plaster,cement and wood in the laboratory. The surfaces were mounted inside petri-dishes (diam: 20 cm)and wood surface was prepared separately. The prepared surfaces were attached to the walls anddeltamethrin was applied using standard Hudson pump sprayer with a discharge rate of 757 ml/min or 0.2 gal/min. The spraying was conducted at standard rhythm as recommended by WHO.After application all the sprayed surfaces were transferred into the special wooden boxes designedfor this purpose. The surfaces were maintained at laboratory conditions. The WHO’s recommendedbioassay kit and method was used during this study.Results: Bioassays on Anopheles stephensi Liston showed that the persistence of deltamethrin ondifferent surfaces (>70% mortality) was around 4 months on plaster (Mortality = 77±6.2%), 2months on mud (76.9±6.8%), 4.5 months on cement (79±3.2%), 4 months on wood (71.7±6.8%)and 4 months on filter papers (82.3±5.4%).Interpretation & conclusion: The results of this study on residual effects of deltamethrin WP 5%(25 mg/m2) are highly concordant with two field bioassays carried out in a malarious area atsouth-eastern Iran. This method can be replaced by the field bioassay tests which are time consumingand costlier

    Endoparasites of Rodents and Their Zoonotic Importance in Germi, Dashte–Mogan, Ardabil Province, Iran

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    Background: In order to verify the infectivity of rodents with endoparasites in Germi (Dashte-Mogan, Arda­bil Province) the current study was undertaken.Methods: Using live traps, 177 rodents were trapped during 2005-2007. In field laboratory, all rodents were bled prior to autopsy, frozen at -20°C, and shipped to the School of Public Health, Tehran University of Medical Sciences, Iran. In parasitological laboratory, every rodent was dissected and its different or­gans were examined for the presence of any parasite. Blood thick and thin smears as well as impression smears of liver and spleen were stained with Geimsa and examined microscopically.Results: Two species of rodents were trapped; Meriones persicus (90.4%) and Microtus socialis (9.6%). The species of parasites found in M. persicus and their prevalences were as follows: Hymenolepis di­minuta (38.8%), Hymenolepis nana (2.5%), Trichuris sp.(40.6), Mesocestoides larva (=tetrathyridium) (3.1%), Capil­laria hepatica (6.9%), Moniliformis moniliformis (11.3%), Syphacia obvelata (2.5%), Taenia endotho­racicus larva (0.6%), Physaloptera sp. (0.6%), Dentostomella translucida (0.6%), Heligmosomum mix­tum (0.6%), Strobilocercus fasciolaris (0.6%),and Aspiculuris tetraptera (0.6%). The species of para­sites found in M. socialis and their prevalences were as follows: H. diminuta (17.6%), Trichuris sp. (5.9%), Mesocestoides larva (5.9%), S. obvelata (11.8%), S. syphacia (11.8%), H. mixtum (17.6%), and Aspiculuris tetraptera (11.8%). There were no statistical differences between male and female for infectivity with parasites in either M. persicus or M. socialis. No blood or tissue protozoan parasite was found in any of the rodents examined. Conclusion: Among different species identified, some had zoonotic importance. Therefore, the potential health hazard of these species needs to be considered to prevent infectivity of humans

    Molecular assay on Crimean Congo Hemorrhagic Fever virus in ticks (Ixodidae) collected from Kermanshah Province, Western Iran

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    Background: Crimean-Congo Hemorrhagic Fever (CCHF) is a feverous and hemorrhagic disease endemic in some parts of Iran and caused by an arbovirus related to Bunyaviridae family and Nairovirusgenus. The main virus reservoir in the nature is ticks, however small vertebrates and a wide range of domestic and wild animals are regarded as reservoir hosts. This study was conducted to determine the infection rate of CCHF virus in hard ticks of Sarpole- Zahab County, Kermanshah province, west of Iran. Methods: From total number of 851 collected ticks from 8 villages, 131 ticks were selected randomlyand investigated for detection of CCHF virus using RT-PCR. Results: The virus was found in 3.8 of the tested ticks. Hyalommaanatolicum, H.asiaticum and Rhipicephalus sanguineus species were found to have viral infection, with the highest infection rate (11.11) in Rh. sanguineus. Conclusion: These findings provide epidemiological evidence for planning control strategies of the disease in the study area

    Tools for delivering entomopathogenic fungi to malaria mosquitoes: effects of delivery surfaces on fungal efficacy and persistence.

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    BACKGROUND\ud \ud Entomopathogenic fungi infection on malaria vectors increases daily mortality rates and thus represents a control measure that could be used in integrated programmes alongside insecticide-treated bed nets (ITNs) and indoor residual spraying (IRS). Before entomopathogenic fungi can be integrated into control programmes, an effective delivery system must be developed.\ud \ud METHODS\ud \ud The efficacy of Metarhizium anisopliae ICIPE-30 and Beauveria bassiana I93-825 (IMI 391510) (2 × 10(10) conidia m(-2)) applied on mud panels (simulating walls of traditional Tanzanian houses), black cotton cloth and polyester netting was evaluated against adult Anopheles gambiae sensu stricto. Mosquitoes were exposed to the treated surfaces 2, 14 and 28 d after conidia were applied. Survival of mosquitoes was monitored daily.\ud \ud RESULTS\ud \ud All fungal treatments caused a significantly increased mortality in the exposed mosquitoes, descending with time since fungal application. Mosquitoes exposed to M. anisopliae conidia on mud panels had a greater daily risk of dying compared to those exposed to conidia on either netting or cotton cloth (p < 0.001). Mosquitoes exposed to B. bassiana conidia on mud panels or cotton cloth had similar daily risk of death (p = 0.14), and a higher risk than those exposed to treated polyester netting (p < 0.001). Residual activity of fungi declined over time; however, conidia remained pathogenic at 28 d post application, and were able to infect and kill 73 - 82% of mosquitoes within 14 d.\ud \ud CONCLUSION\ud \ud Both fungal isolates reduced mosquito survival on immediate exposure and up to 28 d after application. Conidia were more effective when applied on mud panels and cotton cloth compared with polyester netting. Cotton cloth and mud, therefore, represent potential substrates for delivering fungi to mosquitoes in the field

    Hazardous element content and consumption risk of 9 apricot cultivars

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    The heavy metals pollution is one of the problems that arise due to the increased uses of fertilizers and other chemicals to meet the higher demands of food production for human consumption. In order to assess possible health risk of apricot (Prunus armeniaca L.) consumption, levels of Arsenic, Cadmium, Mercury and Lead were determined in fresh and dried samples of "Jumbo cot", "Tom cot", "Gold strike", "Gold bar", "Bergeron", "Bergarouge", "Sweet cot", "Yellow cot" and "Zebra" apricot cultivars. Wet digestion of samples with concentrate HNO3 – H2O2 digester mixture and inductively coupled plasma–atomic emission spectroscopy was used. Highest content of As, Cd, Hg and Pb among all cultivars, were 0.5, 0.04, 1.5 and 0.5mg/kg of dried apricot samples. Fresh fruit samples also contain 0.2, 0.016, 0.6 and 0.2 mg/kg of Arsenic, Cadmium, Mercury and Lead respectively. Daily intake of metals, hazard quotient and health risk index to reveal health risk possibility of dried and fresh fruits consumption were calculate and compared

    Hazardous element content and consumption risk of 9 apricot cultivars

    Get PDF
    The heavy metals pollution is one of the problems that arise due to the increased uses of fertilizers and other chemicals to meet thehigher demands of food production for human consumption. In order to assess possible health risk of apricot (Prunus armeniaca L.)consumption, levels of Arsenic, Cadmium, Mercury and Lead were determined in fresh and dried samples of "Jumbo cot", "Tom cot", "Goldstrike", "Gold bar", "Bergeron", "Bergarouge", "Sweet cot", "Yellow cot" and "Zebra" apricot cultivars. Wet digestion of samples withconcentrate HNO3 – H2O2 digester mixture and inductively coupled plasma–atomic emission spectroscopy was used. Highest content of As,Cd, Hg and Pb among all cultivars, were 0.5, 0.04, 1.5 and 0.5mg/kg of dried apricot samples. Fresh fruit samples also contain 0.2, 0.016, 0.6and 0.2 mg/kg of Arsenic, Cadmium, Mercury and Lead respectively. Daily intake of metals, hazard quotient and health risk index to revealhealth risk possibility of dried and fresh fruits consumption were calculate and compared
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