50,472 research outputs found

    Optical analogue of spontaneous symmetry breaking induced by tachyon condensation in amplifying plasmonic arrays

    Get PDF
    We study analytically and numerically an optical analogue of tachyon condensation in amplifying plasmonic arrays. Optical propagation is modeled through coupled-mode equations, which in the continuous limit can be converted into a nonlinear one-dimensional Dirac-like equation for fermionic particles with imaginary mass, i.e. fermionic tachyons. We demonstrate that the vacuum state is unstable and acquires an expectation value with broken chiral symmetry, corresponding to the homogeneous nonlinear stationary solution of the system. The quantum field theory analogue of this process is the condensation of unstable fermionic tachyons into massive particles. This paves the way for using amplifying plasmonic arrays as a classical laboratory for spontaneous symmetry breaking effects in quantum field theory.Comment: 5 pages, 5 figure

    The clathrin-binding domain of CALM-AF10 alters the phenotype of myeloid neoplasms in mice.

    Get PDF
    The PICALM (CALM) gene, whose product is involved in clathrin-mediated endocytosis, has been identified in two recurring chromosomal translocations, involving either MLL or MLLT10 (AF10). We developed a mouse model of CALM-AF10(+) leukemia to examine the hypothesis that disruption of endocytosis contributes to leukemogenesis. Exclusion of the C-terminal portion of CALM from the fusion protein, which is required for optimal binding to clathrin, resulted in the development of a myeloproliferative disease, whereas inclusion of this domain led to the development of acute myeloid leukemia and changes in gene expression of several cancer-related genes, notably Pim1 and Crebbp. Nonetheless, the development of leukemia could not be attributed directly to interference with endocytosis or consequential changes in proliferation and signaling. In leukemia cells, full-length CALM-AF10 localized to the nucleus with no consistent effect on growth factor endocyctosis, and suppressed histone H3 lysine 79 methylation regardless of the presence of clathrin. Using fluorescence resonance energy transfer analysis, we show that CALM-AF10 has a propensity to homo-oligomerize, raising the possibility that the function of endocytic proteins involved in chimeric fusions may be to provide dimerization properties, a recognized mechanism for unleashing oncogenic properties of chimeric transcription factors, rather than disrupting the internalization of growth factor receptors

    Cadaveric renal transplantation at the University of Pittsburgh: a two and one-half-year experience with the point system.

    Get PDF
    From January 1, 1986 to July 30, 1988, 530 consecutive cadaver kidney transplantations were performed with patient selection by a point system that took into account time awaiting an organ, donor-recipient matching, degree of presensitization, and some less important factors. The effect of the system was to diminish judgmental factors in case selection which in the past, had probably operated to the disadvantage of "undesirable" potential recipients, including older ones. Primary 1-year graft survival (74%) and graft survival after retransplantation (71%) were lower than in the earlier time. However, the results with triple-drug therapy using CsA, AZA and P demonstrated 88% 1-year graft survival for primary graft recipients and 74% in highly sensitized patients, with comparable patient mortality. These latter observations provide some assurance that the concepts of equitable access and efficient utilization of a scarce resource are not mutually exclusive

    Scope of using ICT for knowledge management on adaptation to climate change in agriculture

    Get PDF
    The char land of Bangladesh is vulnerable to climate change. There are changes in extreme weather events. Impact of climate change resulted feminization of agricultural practices. Number of development interventions have been taken to skill the rural community to take adaptation action on agriculture. Development interventions taken in the char land of Dimla, Nilphamari were studied from June 2018 to December 2019 to identify the capacity of climate change adaptation interventions using the information and communication technology to empower women. Mobile Phone Use Index study found that nearly three-fourth of rural female farmers were capable to manage knowledge on climate change adaptation if their access to device was ensured. Inclusion of women in the technology playing a very important role towards transformative leadership. Nearly 85% of the women farmers have high environmental awareness; likely to be contributory to adaptation knowledge management. Community themselves identified them more resilient comparing with areas where promotion of technology is not supported. Institutes with the capacity of information technology promotion could be the hub of resilience knowledge management for women, but external supports are required there. Self-motivation supported by project intervention has created notable capacity of a good number of women who could be the mentor of women transformative leadership towards resilience. Int. J. Agril. Res. Innov. Tech. 10(2): 1-6, December 202

    Studying the Lyman α optical depth fluctuations at z ∼ 5.5 using fast semi-numerical methods

    Get PDF
    We present a computationally efficient and fast semi-numerical technique for simulating the Lyman α (Ly α) absorption optical depth in presence of neutral hydrogen ‘islands’ left over from reionization at redshifts 5 ≲ z ≲ 6. The main inputs to the analysis are (i) a semi-numerical photon-conserving model of ionized regions during reionization (named script) along with a prescription for simulating the shadowing by neutral islands and (ii) the fluctuating Gunn–Peterson approximation to model the Ly α absorption. Our model is then used for simulating the large-scale fluctuations in the effective optical depth as observed along sightlines towards high-z quasars. Our model is fully described by five parameters. By setting two of them to default values and varying the other three, we obtain the constraints on reionization history at 5 ≲ z ≲ 6 as allowed by the data. We confirm that reionization is not complete before z ∼ 5.6 at ≳2σ confidence, with the exact confidence limits depending on how the non-detections of the flux in the data are treated. We also confirm that the completion of reionization can be as late as z ∼ 5.2. With further improvements in the model and with more sightlines at z ∼ 6, we can take advantage of the computational efficiency of our analysis to obtain more stringent constraints on the ionization fraction at the tail end of reionization

    Necromass in forests of Madre de Dios, Peru: a comparison between terra firme and lowland forests

    Get PDF
    Stocks of dead wood or necromass represent an important portion of biomass and nutrients in tropical forests. The objectives of this study were: 1) to evaluate and compare the necromass of "terra firme" and lowlands forests, (2) to study the relationship between necromass, above-ground biomass and wood density, and (3) to estimate the necromass of the department of Madre de Dios, Peru. Stocks of necromass and above-ground biomass were estimated at three different locations using permanent plots and line intercept transects. The average volume of necromass for the three sites was 72.9 m3 ha-1 with an average weight varying between 24.8 and 30.7 Mg ha-1, depending on the estimations of dead wood density used for the calculations. Terra firme forests had significantly higher stocks of necromass than lowland forests. The amount of necromass was 11% of the total above-ground biomass in Madre de Dios forests. The total stock of carbon stored in dead wood for the entire department of Madre de Dios was estimated to be approximately 100 mega tonnes of carbon. This is ten times more than the annual fossil fuel emissions of Peru between 2000 and 2008. The substantial stocks of necromass emphasize the importance of these types of field studies, considering that this component of tropical forest carbon cannot be detected using other methods such as satellite remote sensing

    Image intensifier distortion correction for fluoroscopic RSA: the need for independent accuracy assessment

    No full text
    Fluoroscopic images suffer from multiple modes of image distortion. Therefore, the purpose of this study was to compare the effects of correction using a range of two‐dimensional polynomials and a global approach. The primary measure of interest was the average error in the distances between four beads of an accuracy phantom, as measured using RSA. Secondary measures of interest were the root mean squared errors of the fit of the chosen polynomial to the grid of beads used for correction, and the errors in the corrected distances between the points of the grid in a second position. Based upon the two‐dimensional measures, a polynomial of order three in the axis of correction and two in the perpendicular axis was preferred. However, based upon the RSA reconstruction, a polynomial of order three in the axis of correction and one in the perpendicular axis was preferred. The use of a calibration frame for these three‐dimensional applications most likely tempers the effects of distortion. This study suggests that distortion correction should be validated for each of its applications with an independent “gold standard” phantom

    Necromass in forests of Madre de Dios, Peru: A comparison between terra firme and lowland forests

    Get PDF
    This is the final version of the article. Available from Universidad Nacional Mayor de San Marcos, Facultad de Ciencias Biológicas via the DOI in this record.Stocks of dead wood or necromass represent an important portion of biomass and nutrients in tropical forests. The objectives of this study were: 1) to evaluate and compare the necromass of “terra firme” and lowlands forests, (2) to study the relationship between necromass, above-ground biomass and wood density, and (3) to estimate the necromass of the department of Madre de Dios, Peru. Stocks of necromass and above-ground biomass were estimated at three different locations using permanent plots and line intercept transects. The average volume of necromass for the three sites was 72.9 m3 ha-1 with an average weight varying between 24.8 and 30.7 Mg ha-1, depending on the estimations of dead wood density used for the calculations. Terra firme forests had significantly higher stocks of necromass than lowland forests. The amount of necromass was 11% of the total above-ground biomass in Madre de Dios forests. The total stock of carbon stored in dead wood for the entire department of Madre de Dios was estimated to be approximately 100 mega tonnes of carbon. This is ten times more than the annual fossil fuel emissions of Peru between 2000 and 2008. The substantial stocks of necromass emphasize the importance of these types of field studies, considering that this component of tropical forest carbon cannot be detected using other methods such as satellite remote sensing
    corecore