193 research outputs found

    On Strong Small Loop Transfer Spaces Relative to Subgroups of Fundamental Groups

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    Let HH be a subgroup of the fundamental group π1(X,x0)\pi_{1}(X,x_{0}). By extending the concept of strong SLT space to a relative version with respect to HH, strong HH-SLT space, first, we investigate the existence of a covering map for strong HH-SLT spaces. Moreover, we show that a semicovering map is a covering map in the presence of strong HH-SLT property. Second, we present conditions under which the whisker topology agrees with the lasso topology on X~H\widetilde{X}_{H}. Also, we study the relationship between open subsets of π1wh(X,x0)\pi_{1}^{wh}(X,x_{0}) and π1l(X,x0)\pi_{1}^{l}(X,x_{0}). Finally, we give some examples to justify the definition and study of strong HH-SLT spaces.Comment: 16 page

    Fuzzy AHP Method for Selection of a Suitable Seismic Retrofitting Alternative in Low-Rise Buildings

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    Decision making for selecting an appropriate alternative among nominated alternatives is still a problem among retrofit designers. It is clear that selected alternative should comply the current codes in terms of structural criteria, but the other criteria may not be considered. The main goal of this study is to introduce a suitable method for making a decision in order to find the best alternative considering the effective criteria in retrofitting of low-rise buildings. Analytic Hierarchy Process (AHP), as a technique of Multi-Criteria Decision Making (MCDM), is compatible to solve the problem. Effective criteria have been categorized to structural, operational, economic and functional criteria and sixteen sub-criteria considered as a pattern that satisfies the entire involved group including structural and architectural engineers, contractor, client, and authorities in retrofitting of low-rise buildings. Since most of the involved criteria such as aesthetic, durability, and compatibility have fuzzy nature and cannot be compared numerically, fuzzy AHP can be a compatible method for comparison different retrofitting alternatives among both fuzzy and non-fuzzy criteria. A matrix of pair-wise comparison (MPC) is used for determining the weight of criteria and also for scoring the alternatives respect to each criterion. A Fuzzy Importance scale with Triangular Fuzzy Numbers (TFN) is applied for comparing the criteria. The method is examined by a case study and the results show the used method can help designers for selecting the appropriate alternative

    Biological treatment of a synthetic dairy wastewater in a sequencing batch biofilm reactor: Statistical modeling using optimization using response surface methodology

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    In this study, the interactive effects of initial chemical oxygen demand (CODin), biomass concentration and aeration time on the performance of a lab-scale sequencing batch biofilm reactor (SBBR) treating a synthetic dairy wastewater were investigated. The experiments were conducted based on a central composite design (CCD) and analyzed using response surface methodology (RSM). The region of exploration for treatment of the synthetic dairy wastewater was taken as the area enclosed by the influent comical oxygen demand (CODin (1000, 3000 and 5000 mg/l)), biomass concentration (3000, 5000 and 7000 mg VSS/l) and aeration time (2, 8 and 18 h) boundaries. Two dependent parameters were measured or calculated as response. These parameters were total COD removal efficiency and sludge volume index (SVI). The maximum COD removal efficiencies (99.5%) were obtained at CODin, biomass concentration and aeration time of 5000 mg COD/l, 7000 mg VSS/l and 18 h, respectively. The present study provides valuable information about interrelations of quality and process parameters at different values of the operating variables

    Assessing breast cancer risk among Iranian women using the gail model

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    Background: Breast cancer risk assessment is a helpful method for estimating development of breast cancer at the population level. Materials and Methods: In this cross-sectional study, participants consisted of a group of 3,847 volunteers (mean ± SD age: 463 ± 7.59 years) in a convenience sample of women referred to health centers affiliated to Tehran University of Medical Sciences in Tehran, Iran. The risk of breast cancer was estimated by applying the National Cancer Institute's online version of the Gail Risk Assessment Tool. Results: Some 24.9 of women reported having one first-degree female relative with breast cancer, with 8.05 of them having two or more first-degree relatives with breast cancer. The mean five-year risk of breast cancer for all participants was 1.61±0.73, and 9.36 of them had a five-year risk of breast cancer > 1.66. The mean lifetime risk of breast cancer was 11.7±3.91. Conclusions: The Gail model is useful for assessing probability of breast cancer in Iranian women. Based on the their breast cancer risk, women may decide to accept further screening services

    Superradiance Emission and Its Thermal Decoherence in Lead Halide Perovskites Superlattices

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    Self-assembled nanocrystals (NCs) into superlattices (SLs) are alternative materials to polycrystalline films and single crystals, which can behave very differently from their constituents, especially when they interact coherently with each other. This work concentrates on the Superradiance (SR) emission observed in SLs formed by CsPbBr3 and CsPbBrI2 NCs. Micro-Photoluminescence spectra and transients in the temperature range 4–100 K are measured in SLs to extract information about the SR states and uncoupled domains of NCs. For CsPbBr3 SLs with mostly homogeneous SR lines (linewidth 1–5 meV), this work measures lifetimes as short as 160 ps, 10 times lower than the value measured in a thin film made with the same NCs, which is due to domains of near identical NCs formed by 1000 to 40 000 NCs coupled by dipole–dipole interaction. The thermal decoherence of the SR exciton state is evident above 25 K due to its coupling with an effective phonon energy of ≈8 meV. These findings are an important step toward understanding the SR emission enhancement factor and the thermal dephasing process in perovskite SLs.Financial support from the Spanish Ministry of Science (MICINN) through project no. PID2020- 120484RB-I00 is gratefully acknowledged. G.M.M. also thanks the support from the Spanish MICINN & AEI (project RTI2018-099015-J-I00). I.M.S. thanks the funding of MCIN/AEI/10.13039/501100011033 with the project STABLE PID2019-107314RB-I00. S.G. acknowledges her “Grisolia” grant from Generalitat Valenciana, and G.M.M. thanks the Ramon y Cajal programme (contract RYC2020-030099-I). Thanks are also due to Dr. Raúl Iván Sánchez Alarcón for his help with X-ray diffraction characterization of NC films and SLs

    Van Der Waals Heteroepitaxy of GaSe and InSe, Quantum Wells and Superlattices

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    Bandgap engineering and quantum confinement in semiconductor heterostructures provide the means to fine-tune material response to electromagnetic fields and light in a wide range of the spectrum. Nonetheless, forming semiconductor heterostructures on lattice-mismatched substrates has been a challenge for several decades, leading to restrictions for device integration and the lack of efficient devices in important wavelength bands. Here, we show that the van der Waals epitaxy of two-dimensional (2D) GaSe and InSe heterostructures occur on substrates with substantially different lattice parameters, namely silicon and sapphire. The GaSe/InSe heterostructures were applied in the growth of quantum wells and superlattices presenting photoluminescence and absorption related to interband transitions. Moreover, we demonstrate a self-powered photodetector based on this heterostructure on Si that works in the visible-NIR wavelength range. Fabricated at wafer-scale, these results pave the way for an easy integration of optoelectronics based on these layered 2D materials in current Si technology.Comment: 16 Pages, 5 figures. Supplementary Information included in the end (+10 pages, +10 Figures, + 2 Tables). Partially presented at 21st ICMBE - September 202

    Study of biological characteristics of jack knife clam Solen dactylus (Coscl, 1989) in Bandar Abbas coast

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    In this study, 945 Specimens of bivalve Solen dactylus were biometrically assessed from April 2007 to March 2008 in two transects of Golshahr coast in Bandar Abbas, Persian Gulf. Physical and chemical factors of water like temperature, pH, salinity, dissolved oxygen, coast's sediment, diversity and abundance of phytoplankton were studied monthly during the clam sampling. The mean clam length and total weight were 67.5 plus or minus 17.13mm and 6.3 plus or minus 4.04g, respectively. The relationship between clam length-width, total weight-dry weight and clam length-dry weight were significant (r^(2) = 0.91, r^(2) = 0.83 and r^(2) = 0.86, P0.05). The maximum value of Gonadosomatic Index (GSI) in the first and second transect were 11% and 16%, respectively in January (reproductive cycle). The minimum value of GSI in both transects was zero from April to September. Gonado Condition Index (GCI) was synchronous with the GSI during the year of study. GSI and GCI showed a negative relationship with temperature and a positive relationship with dissolved oxygen
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