744 research outputs found

    What could be learnt from Positronium for Quarkonium?

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    In order to fulfill Low's theorem requirements, a new lowest order basis for bound state decay computations is proposed, in which the binding energy is treated non-perturbatively. The properties of the method are sketched by reviewing standard positronium decay processes. Then, it is shown how applying the method to quarkonia sheds new light on some longstanding puzzles.Comment: 12 pages, 10 figures. Talk given at the ETH Workshop on Positronium Physics, May 30-31, 2003, Zurich, Switzerlan

    The supplementary irrigation effects on drought tolerance and ornamental characteristics of safflower varieties

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    Supplementary irrigation is a high-performance operation for increasing crop production and income of farmers in dryland conditions. In order to study the effect of supplementary irrigation on drought tolerance and ornamental characteristics of safflower genotypes an experiment was conducted in 2013-14 at North Khorasan Dryland Agricultural Research Station. The experimental design was split plot based on RCBD. Factors were included five levels of irrigation, i.e., no irrigation, irrigation at rosette stage, flowering stage, seed filling and irrigation in flowering + seed filling as the main factors, and sub factors were varieties in three levels included Feraman, Sina and Syrian. The effect of supplementary irrigation on harvest index, seed/main head, seed/sub head, thousand kernel weight and seed yield was significant. The effect of supplementary irrigation on traits: RGR, CGR, hollow seeds, number of flowers and flower size was not significant. The highest yield and harvest index were obtained with irrigation at flowering stage in "Feraman". Since the "Feraman" variety has shiny red flowers and spineless leaves, is a good plant for flower trade.Keywords: carthamus tinctorius; flower color; optimum irrigation; spineless leaf

    Characterization and Lytic Activity of Isolated Escherichia coli Bacteriophages against Escherichia coli in vitro.

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    Escherichia coli (E. coli) is the most common cause of urinary tract infection (UTI) and typically treated with antibiotics. Unrestricted use of antibiotics may lead to the emergence of antibiotic-resistant bacteria. The present study aimed to isolate and characterize phages against E. coli from infected urine samples and to determine the lytic activity of phages against E. coliin vitro. The present experimental study was conducted in the Laboratory of Bouali Sina Hospital (Sari, Iran) in May 2018. E. coli was identified from nine urine samples of patients with UTI using conventional microbiological methods. Bacteriophages were isolated from the infected urine specimens, and their lytic activity was determined using the spot test. The titer of the bacteriophages was measured using the double-layer agar technique. The morphology of the bacteriophages was revealed using transmission electron microscopy, and the latent time period and burst size were determined. Data were analyzed using the SPSS software package. E. coli was isolated from nine infected urine samples. The lytic activity of bacteriophages against E. coli was determined using the spot test by observing the formation of inhibition zones. Transmission electron microscopy showed E. coli phages belonging to the Myoviridae family. The latent time period was 20 minutes with a burst size of 1,200 plaque-forming unit (PFU) per infected cell. The results of the double-layer agar assay showed that the titer of bacteriophages was 20×10 <sup>8</sup> PFU/mL. The E. coli bacteriophage was isolated from infected urine samples and characterized, and their lytic activity against E. coli was determined in vitro

    A CFD Study of Industrial Double-Cyclone in HDPE Drying Process

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    Double-cyclone in fluidized bed drying is an important equipment which reflects the conditions of drying in HDPE slurry process. Cyclone is an important unite of fluidized bed drying in order to move the solid particles outward to its wall. Therefore, flow pattern created in fluidized bed will affect industrial cyclones installed in dryer for dust removing. Pressure drop of the cyclones is an effective parameter represents the drying behavior. Substantially, geometry of cyclone, inlet flow rate of gas, density and particle size distribution (PSD) can affect the pressure drop value. Fluidized bed hydrodynamic regime is very complex and must be understood to improve fluidized bed operations through theoretical, industrial and CFD study of double-cyclone. Pressure drop is introduced as parameter related to the cyclone efficiency can be calculated with ANSYS Fluent software in the Eulerian-Lagrangian framework with RNG k-ɛ turbulence model used as a mathematical method. Proper pressure drop concluded from industrial experiments and CFD calculation shows good fluidization of HDPE particles in the bed of nitrogen and powder  to reach the best fluidized bed situation and suitable quality of HDPE powdery product

    The Effect of Mulch, Pruning and Plant Density on Some Traits of Related to Production in Pepino

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    Pepino (Solanum muricatum) a new vegetable crops, is from Solanaceae family and cultivated as annual crops. In order to investigate the effects of mulch, pruning and plant density on some traits of related to production in Pepino, an experiment was conducted based on a randomized complete design with five replications at the Ferdowsi University of Mashhad greenhouse during 2009-2010. Traits such as leaf area, number of panicles per plant, number of fruits per plant, fruit length, fruit diameter and fruit weight. Treatment included: 3 levels of mulch (rice straw mulch, wood chips mulch and control), 3 levels of prune (two peduncular, 3 peduncular and controls) and 2 levels of plant density (3.3 and 4.3 plants per m2). The results indicated that the effect of mulch in all of the traits was significant (p≤0.01). Wood chips mulch in all of the traits was better than rice straw and control. Pruning was significant in all of the traits. The number of panicles and the number of fruits per plant were higher in tree peduncular but increasing the number of fruits was associated with a reduction in size. Interaction between mulch and pruning was significant in all of the traits. Plant density applied had significant effects on traits related to fruit

    A detector interferometric calibration experiment for high precision astrometry

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    Context: Exoplanet science has made staggering progress in the last two decades, due to the relentless exploration of new detection methods and refinement of existing ones. Yet astrometry offers a unique and untapped potential of discovery of habitable-zone low-mass planets around all the solar-like stars of the solar neighborhood. To fulfill this goal, astrometry must be paired with high precision calibration of the detector. Aims: We present a way to calibrate a detector for high accuracy astrometry. An experimental testbed combining an astrometric simulator and an interferometric calibration system is used to validate both the hardware needed for the calibration and the signal processing methods. The objective is an accuracy of 5e-6 pixel on the location of a Nyquist sampled polychromatic point spread function. Methods: The interferometric calibration system produced modulated Young fringes on the detector. The Young fringes were parametrized as products of time and space dependent functions, based on various pixel parameters. The minimization of func- tion parameters was done iteratively, until convergence was obtained, revealing the pixel information needed for the calibration of astrometric measurements. Results: The calibration system yielded the pixel positions to an accuracy estimated at 4e-4 pixel. After including the pixel position information, an astrometric accuracy of 6e-5 pixel was obtained, for a PSF motion over more than five pixels. In the static mode (small jitter motion of less than 1e-3 pixel), a photon noise limited precision of 3e-5 pixel was reached

    Comparison of normal values of Duplex indices of vertebral arteries in young and elderly adults

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    <p>Abstract</p> <p>Background</p> <p>Considering the role of aging in brain atrophy and cerebral vascular demand, we carried out this study to clarify the role of aging in duplex indices of vertebral arteries.</p> <p>Methods</p> <p>From June 2005 to June 2006, 96 volunteers with age range of 20 to 95 years, were evaluated with color doppler for duplex indices of vertebral arteries. Sever hemodynamic stenosis was excluded in all of these patients. These volunteers were subdivided in two groups: younger and older than 60 year old. In all of these patients we measured diameter, peak systolic velocity (PSV), resistive index (RI), and flow volume (FV) of vertebral arteries in right and left sides.</p> <p>Results</p> <p>There was no significant difference in diameter, PSV, RI and FV between two groups. We have clarified that in patients younger than 60 year old, comparing right and left vertebral arteries, PSV and FV were higher in left side.</p> <p>Conclusion</p> <p>Duplex indices of vertebral arteries are age independent in adults.</p

    Parthenolide: suggested drug for COVID-19

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    Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the 2019 novel coronavirus (2019-nCoV) that causes acute respiratory distress syndrome (ARDS) which is the main reason for patients mortality. One of the effective treatments to reduce the effects of this virus is parthenolide (PN). Parthenolide is a sesquiterpene lactone found in medicinal plants. It can inhibit several pro-inflammatory signaling pathways, in particular the ATPase activity of NLRP3. Based on its ability to suppress inflammatory signal transduction and elevated level of serum IL-1β (a surrogate marker for NLRP3 activation) in COVID-19 patients, we suggest that PN could be potentiallyeffective for the treatment of COVID-19

    Power counting and effective field theory for charmonium

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    We hypothesize that the correct power counting for charmonia is in the parameter Lambda_QCD/m_c, but is not based purely on dimensional analysis (as is HQET). This power counting leads to predictions which differ from those resulting from the usual velocity power counting rules of NRQCD. In particular, we show that while Lambda_QCD/m_c power counting preserves the empirically verified predictions of spin symmetry in decays, it also leads to new predictions which include: A hierarchy between spin singlet and triplet octet matrix elements in the J/psi system. A quenching of the net polarization in production at large transverse momentum. No end point enhancement in radiative decays. We discuss explicit tests which can differentiate between the traditional and new theories of NRQCD.Comment: 18 pages, 1 figure Replaced plot of the psi polarization parameter alpha as a function of transverse momentum. Alpha is now closer to zero for large transverse moment
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