1,119 research outputs found

    Unitarized Diffractive Scattering in QCD and Application to Virtual Photon Total Cross Sections

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    The problem of restoring Froissart bound to the BFKL-Pomeron is studied in an extended leading-log approximation of QCD. We consider parton-parton scattering amplitude and show that the sum of all Feynman-diagram contributions can be written in an eikonal form. In this form dynamics is determined by the phase shift, and subleading-logs of all orders needed to restore the Froissart bound are automatically provided. The main technical difficulty is to find a way to extract these subleading contributions without having to compute each Feynman diagram beyond the leading order. We solve that problem by using nonabelian cut diagrams introduced elsewhere. They can be considered as colour filters used to isolate the multi-Reggeon contributions that supply these subleading-log terms. Illustration of the formalism is given for amplitudes and phase shifts up to three loops. For diffractive scattering, only phase shifts governed by one and two Reggeon exchanges are needed. They can be computed from the leading-log-Reggeon and the BFKL-Pomeron amplitudes. In applications, we argue that the dependence of the energy-growth exponent on virtuality Q2Q^2 for γP\gamma^*P total cross section observed at HERA can be interpreted as the first sign of a slowdown of energy growth towards satisfying the Froissart bound. An attempt to understand these exponents with the present formalism is discussed.Comment: 41 pages in revtex preprint format, with 10 figure

    An Interactive Approach Based on Alternative Achievement Scale and Alternative Comprehensive Scale for Multiple Attribute Decision Making under Linguistic Environment

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    The aim of this paper is to develop an interactive approach for multiple attribute decision making with incomplete weight information under linguistic environment. Some of the concepts are defined, such as the distance between two 2-tuple linguistic variables, the expectation level of alternative, the achievement scale, the alternative comprehensive scale under linguistic environment. Based on these concepts, we establish some linear programming models, through which the decision maker interacts with the analyst. Furthermore, we establish a practical interactive approach for selecting the most desirable alternative(s). The interactive process can be realized by giving and revising the achievement scale and comprehensive scale of alternatives till the achievement scale and the comprehensive scale are achieved to the decision maker’s request. Finally, an illustrative example is also given.The author is very grateful to the associated editor and two anonymous referees for their insightful and constructive comments and suggestions that have led to an improved version of this paper. This work was partly supported by the National Natural Science Foundation of China (No. 90924027, No. 71101043), National Basic Research Program of China (973 Program, No. 2010C B951104), Key Program of National Social Science Foundation of China (No. 10AJY005), College Philosophy and Social Science Research Project of Jiangsu Province under Grant 2011SJD630007.Xu, Y.; Wang, H.; Palacios Marqués, D. (2013). An Interactive Approach Based on Alternative Achievement Scale and Alternative Comprehensive Scale for Multiple Attribute Decision Making under Linguistic Environment. International Journal of Computational Intelligence Systems. 6(1):87-95. https://doi.org/10.1080/18756891.2013.756226S87956

    Study on a Cracked Single-Layer 2D Woven Composite Plate: Fracture Mode and Damage Analysis

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    An experimental study and numerical calculation are conducted to investigate the crack propagation in a 2D woven composite. Crack propagation tests of single-layer composite plate specimens permit this process to be directly followed. Analysis of their fracture surfaces reveals crack propagation paths, fracture mode, and damage mechanisms. The load–deflection curve represents the crack propagation as a three-stage process. The stress intensity near the crack tip is evaluated with the critical stress intensity factor numerically calculated. The results demonstrate a good agreement between the calculations and experiment.Проведены экспериментальные исследования и численные расчеты для изучения распространения трещин плоского тканого композита. Благодаря испытанию на распространение трещин в однослойной композитной пластине можно непосредственно наблюдать процесс распространения трещин. Анализ поверхностей разрушенных образцов позволяет установить траекторию распространения трещин, характер разрушения и механизмы повреждения. Согласно кривой нагрузка–перемещение, процесс распространения трещин разделяется на три стадии. Для исследования интенсивности напряжений в вершине трещины образцов определяется критический коэффициент интенсивности напряжений путем численных расчетов. Полученные результаты демонстрируют хорошее соответствие расчетных данных с экспериментальными

    Understorey plant community and light availability in conifer plantations and natural hardwood forests in Taiwan

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    Questions: What are the effects of replacing mixed species natural forests with Cryptomeria japonica plantations on understorey plant functional and species diversity? What is the role of the understorey light environment in determining understorey diversity and community in the two types of forest? Location: Subtropical northeast Taiwan. Methods: We examined light environments using hemispherical photography, and diversity and composition of understorey plants of a 35‐yr C. japonica plantation and an adjacent natural hardwood forest. Results: Understorey plant species richness was similar in the two forests, but the communities were different; only 18 of the 91 recorded understorey plant species occurred in both forests. Relative abundance of plants among different functional groups differed between the two forests. Relative numbers of shade‐tolerant and shade‐intolerant seedling individuals were also different between the two forest types with only one shade‐intolerant seedling in the plantation compared to 23 seedlings belonging to two species in the natural forest. In the natural forest 11 species of tree seedling were found, while in the plantation only five were found, and the seedling density was only one third of that in the natural forest. Across plots in both forests, understorey plant richness and diversity were negatively correlated with direct sunlight but not indirect sunlight, possibly because direct light plays a more important role in understorey plant growth. Conclusions: We report lower species and functional diversity and higher light availability in a natural hardwood forest than an adjacent 30‐yr C. japonica plantation, possibly due to the increased dominance of shade‐intolerant species associated with higher light availability. To maintain plant diversity, management efforts must be made to prevent localized losses of shade‐adapted understorey plants

    BK1(1270)(ρK)+B \to K_1(1270) (\to \rho K) \ell^+ \ell^- in LEET

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    Flavour Changing Neutral Current decays of the BB-meson are a very useful tool for studying possible physics scenarios beyond the Standard Model (SM), where of the many FCNC modes radiative, purely leptonic and semi-leptonic decays of the BB-meson are relatively clean tests. Within this context the BELLE collaboration has searched for the BK1(1270)γB \to K_1(1270) \gamma process and provided an upper bound on this decay. In this work we have used this upper bound in studying the angular coorelations for the related semi-leptonic decay mode BK1(1270)(ρK)+B \to K_1(1270) (\to \rho K) \ell^+ \ell^-, where we have used the form factors that have already been estimated for the BK1(1270)γB \to K_1(1270) \gamma mode. Note that the additional form factors that are required were calculated using the Large Energy Effective Theory (LEET).Comment: 13 pages, 4 figure

    Long-distant contribution and χc1\chi_{c1} radiative decays to light vector meson

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    The discrepancy between the PQCD calculation and the CLEO data for χc1γV\chi_{c1}\to \gamma V (V=ρ0,ω,ϕV=\rho^0,\,\omega,\,\phi) stimulates our interest in exploring extra mechanism of χc1\chi_{c1} decay. In this work, we apply an important non-perturbative QCD effect, i.e., hadronic loop mechanism, to study χc1γV\chi_{c1}\to \gamma V radiative decay. Our numerical result shows that the theoretical results including the hadronic loop contribution and the PQCD calculation of χc1γV\chi_{c1}\to \gamma V are consistent with the corresponding CLEO data of χc1γV\chi_{c1}\to \gamma V. We expect further experimental measurement of χc1γV\chi_{c1}\to \gamma V at BES-III, which will be helpful to test the hadronic loop effect on χc1\chi_{c1} decay.Comment: 7 pages, 2 figures. Accepted for publication in Eur. Phys. J.

    Intestinal geotrichosis in a German shepherd

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    A 4-year-old sexually intact male German shepherd with a 3-month history of chronic watery diarrhea was referred to the Veterinary Medical Teaching Hospital. Dehydration and serum biochemistry revealed hypoalbuminemia, and fecal material contained a large quantity of round arthroconidia that were microscopically observed. A specimen was submitted for fungal culture and yielded a white to cream-colored subsurface colony. Microorganisms derived from the colony exhibited chains of smooth, septate hyaline hyphae that were producing 1-celled arthroconidia. Geotrichum candidum was thus identified. Colonoscopic features included erythema, edema, and loss of the usual fine vascular pattern, with granularity of the mucosa of the descending column. Treatment consisted of oral administration of ketoconazole and metronidazole for 3 weeks, while oral prednisolone was tapered after 1 week of therapy. The dog's feces gradually softened after the first treatment. Fecal smear examination revealed no trace of the yeast-like microbes 7 days after treatment was administered, and 2 weeks post-treatment the dog passed well-formed stools and had regained its normal body weight. The previously observed clinical signs did not reoccur, even after oral medication was withdrawn

    Another Two Dark Energy Models Motivated from Karolyhazy Uncertainty Relation

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    The Kaˊ\acute{\text{a}}rolyhaˊ\acute{\text{a}}zy uncertainty relation indicates that there exists the minimal detectable cell δt3\delta t^{3} over the region t3t^3 in Minkowski spacetime. Due to the energy-time uncertainty relation, the energy of the cell δt3\delta t^3 can not be less δt1\delta t^{-1}. Then we get a new energy density of metric fluctuations of Minkowski spacetime as δt4\delta t^{-4}. Motivated by the energy density, we propose two new dark energy models. One model is characterized by the age of the universe and the other is characterized by the conformal age of the universe. We find that in the two models, the dark energy mimics a cosmological constant in the late time.Comment: 10 pages, 5 figures, References are adde

    Development of a metal-free black phosphorus/graphitic carbon nitride heterostructure for visible-light-driven degradation of indomethacin

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    The development of affordable and efficient technologies for the removal of pharmaceuticals and personal care products (PPCPs) from water has recently been the subject of extensive attention. In this study, a black phosphorus/graphitic carbon nitride (BP-g-C3N4) heterostructure is fabricated as an extremely active metal-free photocatalyst via a newly-developed exfoliation strategy. The BP-g-C3N4 shows an 11 times better decomposition rate of a representative PPCPs-type pollutant, indomethacin (IDM), compared to the widely used P25 TiO2 under real-sunlight illumination. Also, its visible-light activity is even better than that of the best photocatalysts previously developed, but only consumes 1/10-1/4 of the catalyst. The results show that BP performs a cocatalyst-like behavior to catalyze the generation of reactive oxygen species, thus speeding up the decomposition of IDM. In addition, the BP-g-C3N4 photocatalyst also exhibits excellent IDM removal efficiency in authentic water matrices (tap water, surface water, and secondarily treated sewage effluent). Large-scale application demonstration under natural sunlight further reveals the practicality of BP-g-C3N4 for real-world water treatment operations. Our work will open up new possibilities in the development of purely metal-free photocatalysts for "green" environmental remediation applications. (C) 2021 Elsevier B.V. All rights reserved.Environmental Biolog
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