81 research outputs found

    The Quantum McKay Correspondence for polyhedral singularities

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    Let G be a polyhedral group, namely a finite subgroup of SO(3). Nakamura's G-Hilbert scheme provides a preferred Calabi-Yau resolution Y of the polyhedral singularity C^3/G. The classical McKay correspondence describes the classical geometry of Y in terms of the representation theory of G. In this paper we describe the quantum geometry of Y in terms of R, an ADE root system associated to G. Namely, we give an explicit formula for the Gromov-Witten partition function of Y as a product over the positive roots of R. In terms of counts of BPS states (Gopakumar-Vafa invariants), our result can be stated as a correspondence: each positive root of R corresponds to one half of a genus zero BPS state. As an application, we use the crepant resolution conjecture to provide a full prediction for the orbifold Gromov-Witten invariants of [C^3/G].Comment: Introduction rewritten. Issue regarding non-uniqueness of conifold resolution clarified. Version to appear in Inventione

    ILSF, A THIRD GENERATION LIGHT SOURCE LABORATORY IN IRAN

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    Abstract The Iranian Light Source Facility (ILSF) project is a first large scale accelerator facility which is currently under planning in Iran. On the basis of the present design, circumference of the 3 GeV storage ring is 297.6 m. Beam current and natural beam emittance are 400 mA and 3.278 nm.rad respectively. The facility will be built on a land of 50 hectares area in the city of Qazvin, located 150 km West of Tehran. The city is surrounded by many universities, research centers and industrial companies. The design and construction of prototype items such as radio frequency solid state amplifier, dipole magnets, highly stable magnet power supplies and girders have already begun. Site selection studies, including geotechnical and seismological measurements are being performed. Conceptual Design Report, CDR, as the first milestone of the project was published in October 2012

    Nano reinforced cement paste composite with functionalized graphene and pristine graphene nanoplatelets

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    This study examines and compares the workability, hydration, mechanical, microstructure and transport properties of cement paste composites containing the three forms of graphene-based 2D nanomaterials synthesised from epigenetic graphite deposit, namely, graphene oxide (GO), reduced graphene oxide (rGO), and pristine graphene nanoplatelates (G). Graphene materials were used from 0.01% to 0.16% of cement weight. The rGO and G were treated with salt and surfactant, respectively during synthesis, to improve dispersion in water. Characteristics and physical strength vary among GO, rGO and G, which have influenced the properties of nano reinforced graphene-cement composites (GCCs). The 28-day compressive and flexural strength of graphene (GO, rGO and G) cement composite improved by 28% and 81%, 30% and 84%, and 39% and 38%, respectively, compared to the control mix (cement paste without graphene materials). Finally, microscopic analysis, dynamic vapour sorption (DVS), electrical resistivity and water sorptivity results suggested that graphene materials densify and reinforce the composite microstructure

    Application of weight functions in nonlinear analysis of structural dynamics problems

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    This paper presents a weighted residual method with several weight functions for solving differential equation of motion in nonlinear structural dynamics problems. Order of variation of acceleration is assumed to be quadratic in each time step in which polynomial of displacement would contain five unknown coefficients. Five equations are required for determination of these coefficients in each time step. These equations are obtained from initial conditions, satisfying equation of motions at both ends, and weighted residual integration. In this study, four procedures are considered for weight function to be used in the weighted residual integration as; unit weight function, Petrov–Galerkin's weight function, least square weight function, and collocation weight function. Due to higher order of acceleration in the proposed method, the results indicate better and more accurate responses. Among the tested functions, the unit weighted function method demonstrated to be non-dissipative and its numerical dispersion showed to be clearly less than the common Newmark's linear acceleration method. Also critical time step duration in stability investigation for weighted function procedure showed to be larger than the critical time step duration obtained by other methods used in the nonlinear structural dynamics problems.M. Ghassemieh, A. A. Gholampour, and S. R. Massa

    Aflatoxin M1 level in pasteurized and sterilized milk of Babol city

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    Background: Aflatoxins are severe toxic secondary metabolites found in most plant products. When animals consume contaminated feed stuff to Aflatoxin B1 (AFB1), the toxin is metabolized by liver and is excreted as Aflatoxin M1 (AFM1) via milk. Aflatoxins are acute toxic compounds, immunosuppressive, mutagen, tratogen and carcinogen."nMethods: During the winter of 2006, pasteurized and sterilized (ultra high temperature) (UHT) milk packages were collected from supermarkets in Babol city. 78 pasteurized and 33 sterilized milk, totally 111 samples were tested for AFM1 by competitive Enzyme Linked Immunosorbent Assay (ELISA). Solid phase in plastic micro wells coated whit anti-Aflatoxin M1 antibodies. We added 100 microliter skimmed milk and Aflatoxin M1 standard solutions in each well. In each plate, we appointed seven wells for standards. Plates were incubated at 20-25ď‚° centigrade for 45 min. Each well was washed four times by washing buffer 20X concentration. Then 100 micro liter conjugated solution (100X) was added to each well, and the plate was incubated at 20-25 centigrade for 15 min. After that, the wells were washed. After adding the substrates to wells, we incubated the plate at 20-25ď‚° centigrade in a dark place for 15 min. The reaction was stopped by stop solution. After one hour, light absorption was read at 450 nm by ELISA reader."nResults: AFM1 were detected in 100% of all samples. 100% of samples were above of European community regulations (50ng/l). AFM1 contamination mean levels pasteurized and sterilized milk were 230.5 and 221.66 respectively. Therefore more than four fold levels European community. There is not a significant relationship between AFM1 contamina-tion level and different months of winter applying statistical test."nConclusion: The results showed the need for introducing safety limits for AFM1 levels in child milk under Food Legislative liable of Iran. Aflatoxin M1 contamination is a serious problem for public health, and it is potentially hazardous for human health

    Mycological Survey and Total Aflatoxin Analyze in Silage from Qaemshahr City (Northern Iran)

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    In this study, 42 samples of silage were collected in Qaemshahr city in Iran during fall 2011. Samples were tested by competitive ELISA for total aflatoxins. Seven samples (16.7%) (Mean±se:1.24) from 42 silage samples were positive with total aflatoxin (1.1-27.3 ppb) in Nov., Dec. and Oct. The highest contamination was observed in Oct., three samples (21.4%) from 14 samples were contaminated with total aflatoxin by 22.2 ppb, 25.6 and 27.3 ppb. The culture results of samples showed that the most toxinigenic fungi among 57 colonies were<em> Aspergillus sp.</em> with fifteen (% 31.5), <em>Fusarium sp.</em> With thirteen (% 22.8), Alternaria<em> spp.</em> With twelve (21.05%), <em>Penicillium spp.</em> with nine (%15.78) and <em>Acremonium sp.</em> with five (8.77%) and also the most nontoxigenic fungi were <em>cladosporium spp.</em> with fifteen (% 37.5), <em>Rhizopus spp.</em> with nine (% 22.5), <em>Mucor spp. </em>with<em> </em>six (15%), <em>yeast</em> with six (15%) and <em>Scopulariopsis spp.</em> with four (10%) colonies isolated in culture medium among 40 colonies<em> </em>of nontoxigenic fungi

    Comparing the effect of low and high emittance on synchrotron radiation and beamline design

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    In this paper, we have discussed about the role of two emittance values suggested for Iranian Light Source Facility (ILSF) (3.278 and 0.476 nm.rad) on different radiation features of the synchrotron light sources (bending magnet, shaker and oscillator) such as spot size, divergence of the beam on light spot, brilliance and important quantities in beamline design such as photon cross-section, optical element sizes and energy resolution &nbsp

    Effects of Rosa canina L. on ischemia/ reperfusion injury in anesthetized rats

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    Background: Ischemia/reperfusion induced acute renal failure causes excretory functional disorders of nephrons. Ischemia/reperfusion injury is accompanied by generation of reactive oxygen species that leads to dysfunction, injury, and death of renal cells. Antioxidants of plant origin minimize the harmful effects of reactive oxygen species. The aim of this study was to determine the possible therapeutic potentials of Rosa canina L. in preventing renal functional disturbances during the post-ischemic reperfusion period. Methods: In this experimental study undertaken for evaluating renal excretory function in 30 male Wistar rats, renal ischemia was induced by occluding both renal arteries for 45 min, followed by 24 h of reperfusion. The rats received 2 ml of tap water or a hydroalcoholic extract of Rosa canina (500 mg/kg) orally for 7 days before induction of ischemia. In plasma samples, creatinine and urea nitrogen levels were measured, and in renal tissue samples, red blood cells were counted. The data were analyzed using ANOVA and Duncan tests. Results: Renal ischemia for 45 minutes increased plasma levels of creatinine (P<0.001) and nitrogen urea (P<0.01) while reducing red blood cell counts in renal glomeruli (P<0.001). Rosa canina administration diminished the increase in creatinine (P<0.001) and nitrogen urea concentrations (P<0.01), and prevented reductions in red blood cell counts in renal glomeruli (P<0.001). Conclusion: Rosa canina seems to be useful as a preventive agent against renal damages induced by ischemia/reperfusion injuries in rats
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