787 research outputs found

    New Full-Diversity Space-Time-Frequency Block Codes with Simplified Decoders for MIMO-OFDM Systems

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    Multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) is known as a promising solution for wideband wireless communications. This is why it has been considered as a powerful candidate for IEEE 802.11n standard. Numerous space-frequency block codes (SFBCs) and space-time- frequency block codes (STFBCs) have been proposed so far for implementing MIMO-OFDM systems. In this paper, at first we propose new full-diversity STFBCs with high coding gain in time-varying channels; the construct method for this structure is using orthogonal space-time block code for any arbitrary number of transmit antenna and then we propose a decoder with linear complexity for our proposed coding scheme. Simulation results verify that the proposed STFBCs outperform other recently published STFBCs

    Synchronization in Networks of Identical Systems via Pinning: Application to Distributed Secondary Control of Microgrids

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    Motivated by the need for fast synchronized operation of power microgrids, we analyze the problem of single and multiple pinning in networked systems. We derive lower and upper bounds on the algebraic connectivity of the network with respect to the reference signal. These bounds are utilized to devise a suboptimal algorithm with polynomial complexity to find a suitable set of nodes to pin the network effectively and efficiently. The results are applied to secondary voltage pinning control design for a microgrid in islanded operation mode. Comparisons with existing single and multiple pinning strategies clearly demonstrates the efficacy of the obtained results.Comment: 11 pages, 9 figures, submitted to Transactions on Control Systems Technolog

    Polymeric Nanocomposite Structures Based on Functionalized Graphene with Tunable Properties for Nervous Tissue Replacement

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    Electroconductive scaffolds can be a promising approach to repair conductive tissues when natural healing fails. Recently, nerve tissue engineering constructs have been widely investigated due to the challenges in creating a structure with optimized physiochemical and mechanical properties close to the native tissue. The goal of the current study was to fabricate graphene-containing polycaprolactone/gelatin/polypyrrole (PCL/gelatin/PPy) and polycaprolactone/polyglycerol-sebacate/polypyrrole (PCL/PGS/PPy) with intrinsic electrical properties through an electrospinning process. The effect of graphene on the properties of PCL/gelatin/PPy and PCL/PGS/PPy were investigated. Results demonstrated that graphene incorporation remarkably modulated the physical and mechanical properties of the scaffolds such that the electrical conductivity increased from 0.1 to 3.9 ± 0.3 S m–1 (from 0 to 3 wt % graphene) and toughness was found to be 76 MPa (PCL/gelatin/PPy 3 wt % graphene) and 143.4 MPa (PCL/PGS/PPy 3 wt % graphene). Also, the elastic moduli of the scaffolds with 0, 1, and 2 wt % graphene were reported as 210, 300, and 340 kPa in the PCL/gelatin/PPy system and 72, 85, and 92 kPa for the PCL/PGS/PPy system. A cell viability study demonstrated the noncytotoxic nature of the resultant scaffolds. The sum of the results presented in this study suggests that both PCL/gelatin/PPy/graphene and PCL/PGS/PPy/graphene compositions could be promising biomaterials for a range of conductive tissue replacement or regeneration applications

    Características palinológicas de las subspecies de Linum mucronatum Bertol. con heterostilia

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    Linum mucronatum is a heterostylous species from sect. Syllinum with four subspecies in Iran. The present study examines palynological characteristics of the heterostylous subspecies of Linum mucronatum, pollen characters of brevistylous individuals (pins) as well as longistylous individuals (thrums) of these plants by scanning electron microscope and light microscope using the prolonged acetolysis procedure. Sixteen qualitative and quantitative characters were investigated. Pollen equatorial shapes varied between pin and thrum individuals of each subspecies with the exception of L. mucronatum subsp. assyriacum. Pollen sculptures varied between pin and thrum samples of each subspecies and were seen in the gemmate, clavate and baculate shapes. In addition, quantitative palynological characters differed between plants and ANOVA test showed significant variations for traits such as equatorial length, colpi width and apocolpium diameter. Hetrostylous individuals of each subspecies were separated from others in the UPGMA tree and also in the PCO and PCA plots. This study confirmed variations in pollen features between pin and thrum individuals of each subspecies.Linum mucronatum es una especie con heterostilia, que pertenece a la sección Syllinum del género Linum, y tiene cuatro subespecies en Irán. En el presente estudio se examinan las características palinológicas de las subespecies heterostilas de Linum mucronatum Bertol., así como los caracteres polínicos de individuos de los morfos brevistilo (pin) y longistilo (thrum) de estas plantas, mediante microscopía electrónica de scanning y microscopía óptica usando el método de acetolisis prolongada. Se estudiaron un total de 16 caracteres cualitativos y cuantitativos. La forma ecuatorial del polen varía entre los morfos pin y thrum en todas las subspecies, excepto en L. mucronatum subsp. assyriacum. La ornamentación también varía entre las muestras de morfos pin y thrum de cada subespecie, en los que se puede observar polen gemado, clavado y baculado. En algunos caracteres palinológicos cuantitativos, se encontraron también diferencias entre morfos y el test de ANOVA muestra que son significativas en cuanto a la longitud ecuatorial, la anchura de los colpos y el diámetro del apocolpio. Los individuos heterostilos de cada susbespecie aparecen separados en el árbol UPGMA y también en los gráficos de PCO y PCA. Este estudio confirma las diferencias en las características del polen entre individuos pin y thrum de cada una de las subespecies

    Ultrastructure of cytoplasmic fragments in human cleavage stage embryos

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    Purpose: The goal of this study was to evaluate the ultrastructure of cytoplasmic fragments along with the effect of cytoplasmic fragment and perivitelline space coarse granulation removal (cosmetic microsurgery) from embryos before embryo transfer on ART outcomes. Methods: One hundred and fifty intracytoplasmic sperm injection cycles with male factor infertility were included in this prospective study. Patients were divided into three groups of case (n = 50), sham (n = 50), and control (n = 50). Embryos with 10–50 % fragmentation were included in this study. Cosmetic microsurgery and zona assisted hatching were only performed in case and sham groups respectively. Extracted fragments were evaluated ultrastructurally by transmission electron microscopy (TEM). Rates of clinical pregnancy, live birth, miscarriage, multiple pregnancies, and congenital anomaly in the three groups were also compared. Results: Micrographs from TEM showed that mitochondria were the most abundant structures found in the fragments along with mitochondria-vesicle complexes, Golgi apparatus, primary lysosomes, and vacuoles. There were no significant differences in demographic characteristics, laboratory and clinical data, or embryo morphological features between the groups. The rate of clinical pregnancy in control, sham, and case groups had no significant differences (24, 18, and 18 %, respectively). The rates of live birth, miscarriage, multiple pregnancy, and congenital anomaly were also similar between the different groups. Conclusions: Our data demonstrated that cosmetic microsurgery on preimplantation embryos had no beneficial effect on ART outcomes in unselected groups of patients. As mitochondria are the most abundant organelles found in cytoplasmic fragments, fragment removal should be performed with more caution in embryos with moderate fragmentation

    Evaluation of diagnostic value of soluble urokinase-type plasminogen activator receptor in sepsis

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    Background: Sepsis is one of the most important causes of morbidity and mortality in the intensive care units (ICUs). It is difficult to accurately differentiate sepsis from similar diseases rapidly. Therefore, it becomes critical to identify any biomarker with the ability of differentiation between sepsis and nonsepsis conditions. The urokinase plasminogen activator receptor has been implicated as an important factor in regulation of leukocyte adhesion and migration. Objectives: In this study, we evaluated the value of soluble urokinase plasminogen activator receptor (suPAR), erythrocyte sedimentation (ESR), and C-reactive protein (CRP) serum levels in terms of their value for sepsis diagnosis in ICU patients. Patients and Methods: We enrolled 107 ICU patients; 40 with sepsis, 43 with systemic inflammatory response syndrome, and 24 as control group. Serum soluble urokinase plasminogen activator receptor, ESR, white blood cell (WBC), and CRP levels were measured on the day of admission. Results: The group with sepsis had higher suPAR, ESR, and CRP levels compared with the group with noninfectious systemic inflammatory response syndrome (SIRS) (P = 0.01, 0.00 and 0.00, respectively). CRP concentrations and ESR were higher in the sepsis group than in the non-SIRS group (P = 0.00 and 0.00, respectively). In a receiver-operating characteristic curve analysis, ESR, CRP and suPAR had an area under the curve larger than 0.65 (P = 0.00) in distinguishing between septic and noninfectious SIRS patients. CRP, ESR and suPAR had a sensitivity of 87, 71 and 66 and a specificity of 59, 76 and 74 respectively in diagnosing infection in SIRS. Conclusions: The diagnostic values of CRP and ESR were better than suPAR and WBC count in patients with sepsis. © 2015, Infectious Diseases and Tropical Medicine Research Center

    In vitro antifungal activity of various persian cultivars of Punica granatum L. Extracts against Candida species

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    Background: Resistance of Candida species to antifungal agents has potentially serious implications for management of infections. Candida species are now the fourth most common organisms isolated from hospitalized patients. Prevention and control of these infections will require new antimicrobial agents. Plant-derived antifungal agents have always been a source of novel therapeutics. Objectives: The aim of this study was to investigate the antifungal effect of pomegranate peel and pulp extracts against Candida species. Materials and Methods: Pomegranate pulp and peel were dried and powdered separately. The dried powders were extracted using a soxhlet extractor. The antifungal effect of pomegranate peel and pulp extracts were determined in vitro by using the minimum inhibitory concentration (MIC) against five standard species, including Candida albicans (ATCC 10231), Candida parapsilosis (ATCC 22019), Candida tropicalis (ATCC 750), Candida glabrata (PTCC 5297) and Candida krusei (PTCC 5295). Results: Maximum inhibitions were attributed to peel extract of the pomegranate cultivar against Candida species. The greatest antifungal inhibition among the eight different cultivars was observed for sour malas, sour white peel and sour summer extracts respectively, against the five Candida strains. The antifungal activity of pulp extracts against Candida species was somewhat negative. Conclusions: Our work suggested that pomegranate (Punica granatum L.) peel has potential antifungal activity against Candidiasis, and it is an attractive option for the development of new management strategies for candidiasis. � 2015, School of Pharmacy, Ahvaz Jundishapur University of Medical Sciences

    High resolution melting technique for molecular epidemiological studies of cystic echinococcosis: Differentiating G1, G3, and G6 genotypes of Echinococcus granulosus sensu lato

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    Reliable and rapid genotyping of large number of Echinococcus granulosus sensu lato isolates is crucial for understanding the epidemiology and transmission of cystic echinococcosis. We have developed a method for distinguishing and discriminating common genotypes of E. granulosus s.l. (G1, G3, and G6) in Iran. This method is based on polymerase chain reaction coupled with high resolution melting curve (HRM), ramping from 70 to 86 C with fluorescence data acquisition set at 0.1 C increments and continuous fluorescence monitoring. Consistency of this technique was assessed by inter- and intra-assays. Assessment of intra- and inter-assay variability showed low and acceptable coefficient of variations ranging from 0.09 to 0.17 %. Two hundred and eighty E. granulosus s.l. isolates from sheep, cattle, and camel were used to evaluate the applicability and accuracy of the method. The isolates were categorized as G1 (93, 94, and 25 %), G3 (7, 4, and 4 %), and G6 (0, 2, and 71 %) for sheep, cattle, and camel, respectively. HRM results were completely compatible with those obtained from sequencing and rostellar hook measurement. This method proved to be a valuable screening tool for large-scale molecular epidemiological studies. © 2013 Springer-Verlag Berlin Heidelberg

    Morphological and essential oil variations among Iranian populations of Salvia chloroleuca (Lamiaceae)

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    Salvia chloroleuca Rech. f. & Aell. is one of the perennial species of the Lamiaceae family in Iran, which has antimicrobial and antitumoural properties. In the current research, the morphological variables and hydrodistilled essential oils of two populations, from Polor and Neyshabur, of this species were evaluated. We studied 10 and 40 individuals for morphometrics and essential oils, respectively. Morphological data were analyzed using SPSS. Furthermore, the extracted oils were analysed using GC and GC/MS. The qualitative morphological characteristics were stable between the populations, while the quantitative ones highly varied. The one-sample variance test revealed significant differences for most of the studied features. The yielded oil highly differed between these populations. The first and second main groups of compounds were the same for both populations, but with different percentages. However, the third and fourth main groups of compounds were not similar. Furthermore, the main compounds of essential oil differed between the studied populations. The major compounds of the Polor population were: β-pinene (22.7%), α-pinene (18.3%), germacrene D (7.7%) and sabinene (6.6%). However, spathulenol (19.8%), bicyclogermacrene (11.4%), p-cymene (10.8%) and β-pinene (10.4%) constituted the major compounds of the Nyshabur population. In total, the Neyshabur population had higher amounts of sesquiterpene and oxygenated compounds than the other population. The results indicated that in this species the quantitative morphological characters and essential oils were strongly affected by environmental factors
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