311 research outputs found
Thermal effects in perturbative noncommutative gauge theories
The thermodynamics of gauge theories on the noncommutative plane is studied
in perturbation theory. For U(1) noncommutative Yang-Mills we compute the first
quantum correction to the ideal gas free energy density and study their
behavior in the low and high temperature regimes. Since the noncommutativity
scale effectively cutoff interactions at large distances, the theory is regular
in the infrared. In the case of U(N) noncommutative Yang-Mills we evaluate the
two-loop free energy density and find that it depends on the noncommutativity
parameter through the contribution of non-planar diagrams.Comment: 15 pages, harvmac. Minor changes with respect to v2. Footnote
expanded, remark added in Section 3, typos corrected and references added.
Final version to be published in JHE
Accumulation of Mutated Maize Zeins in Transgenic Forage Legumes
Accumulation of zeins, the endosperm storage proteins of maize, in a heterologous plant expression system was attempted. Plants of birdsfoot trefoil (Lotus corniculatus) and alfalfa (Medicago sativa) were transformed by Agrobacterium with binary vectors harboring genes that code for γ-zein and β-zein, two proteins rich in sulphur amino acids. Adding the ER retention signal KDEL to the C-terminal domain modified zein polypeptides. Our long-term goal was to improve birdsfoot trefoil and alfalfa forage quality. Significant levels of γ- zein:KDEL and β-zein:KDEL were detected in primary transformants of birdsfoot trefoil. Moreover, alfalfa plants expressing γ-zein:KDEL in the leaves were obtained. γ-zein:KDEL accumulated in spherical or elliptical electron-dense bodies of birdsfoot trefoil leaves. The protein bodies were present in the cytoplasm of either mesophyll cells or epidermis cells
Implementing holographic projections in Ponzano--Regge gravity
We consider the path-sum of Ponzano-Regge with additional boundary
contributions in the context of the holographic principle of Quantum Gravity.
We calculate an holographic projection in which the bulk partition function
goes to a semi-classical limit while the boundary state functional remains
quantum-mechanical. The properties of the resulting boundary theory are
discussed.Comment: 20 pages, late
Boundary description of Planckian scattering in curved spacetimes
We show that for an eikonal limit of gravity in a space-time of any dimension with a non-vanishing cosmological constant, the Einstein -- Hilbert action reduces to a boundary action. This boundary action describes the interaction of shock-waves up to the point of evolution at which the forward light-cone of a collision meets the boundary of the space-time. The conclusions are quite general and in particular generalize the previous work of E. and H. Verlinde. The role of the off-diagonal Einstein action in removing the bulk part of the action is emphasised. We discuss the sense in which our result is a particular example of holography and also the relation of our solutions in to those of Horowitz and Itzhaki
Current and Future Research Trends in Substrate Integrated Waveguide Technology
Substrate Integrated Waveguide (SIW) technology is the most promising candidate for the implementation of millimeter-wave (mm-wave) integrated circuits and systems for the next decade. Based on planar dielectric substrates with top and bottom metal layers perforated with metalized holes, SIW structures offer a compact, low loss, flexible, and cost-effective solution for integrating active circuits, passive components and radiating elements on the same substrate. This paper presents an overview of the current status and future trends of academic and industrial research on SIW technology. The historical development of SIW components and circuits is briefly outlined, and the current research topics are discussed: they include the development of numerical techniques for the modeling and design of SIW components, the investigation of novel compact and broadband interconnects, the determination of design solutions for loss minimization. Future research trends are also discussed: they mainly aim at the implementation of SIW components at higher frequency (60-350 GHz) and the integration of complete Systems-on-Substrate (SoS)
Role of the BANYULS(BAN) Gene from Arabidopsis Thaliana in Transgenic Alfalfa Expression of Anthocyanins and Proanthocyanidins
Condensed tannins (CTs) are flavonoid oligomers, many of which have beneficial effects on animal (bloat safe) and human health. The BAN gene encodes anthocyanidin reductase (ANR), an enzyme proposed to convert anthocyanidins to their corresponding 2,3-cis-flavan-3-ols (Xie et al., 2003). Ectopic expression of BAN in Alfalfa transgenic foliage results in accumulation of CTs. Thus, it has been assumed that the BAN gene also acts in starter units for the condensation of tannins in Alfalfa
The boundary field theory induced by the Chern-Simons theory
The Chern-Simons theory defined on a 3-dimensional manifold with boundary is
written as a two-dimensional field theory defined only on the boundary of the
three-manifold. The resulting theory is, essentially, the pullback to the
boundary of a symplectic structure defined on the space of auxiliary fields in
terms of which the connection one-form of the Chern-Simons theory is expressed
when solving the condition of vanishing curvature. The counting of the physical
degrees of freedom living in the boundary associated to the model is performed
using Dirac's canonical analysis for the particular case of the gauge group
SU(2). The result is that the specific model has one physical local degree of
freedom. Moreover, the role of the boundary conditions on the original Chern-
Simons theory is displayed and clarified in an example, which shows how the
gauge content as well as the structure of the constraints of the induced
boundary theory is affected.Comment: 10 page
Feasibility study to realize an anaerobc digester fed with vegetables matrices in central Italy
In the present paper we have analysed the possibility to realize an anaerobic digester in a bio-Energy Park located in Città della Pieve, a small town in Central Italy. The use of anaerobic digesters is quite common in Europe for reducing the environmental impact of manure in a co-digestion procedure with vegetables materials. In addition, for several areas of Central Italy there is the need to find alternative productions to improve farmer's incomes, as traditional cropping systems are loosing convenience. An interesting alternative seems to be cultivation of energy crops because of the favourable conditions of the electric energy market. We are suggesting a low input cropping system to be implemented in areas where low input food/feed crops are no more profitable. In particular our case-study is an example based on the use of a forage legume, alfalfa (Medicago sativa L.), together with other crops, like sorghum, to realize small-size bio-digesters plants. Alfalfa: is a highly sustainable crop as it is able to fix nitrogen and therefore it does not require this fertilization with the consequence of avoiding underground water pollution. Moreover alfalfa residual products are nitrogen rich thus improving soil structure and fertility more than popular graminaceous energy crops such as corn. Beside, alfalfa mostly does not need irrigation in the typical Central Italy environment, all these traits make it one of the species with the lowest energy needs for growing. The aims of this feasibility study are: i) optimization of plant materials feeding the bio-digester, ii) typology of bio-digester, iii) size of bio-digester in relation with land availability for growing energetic cultures, iv) the utilization of bio-gas produced by bio-digester plant to produce electric and thermal energy using cogeneration engines, vi) disposal of waste-water produced according to regional and national laws. The final aim of this study is to verify the possibility to develop an alternative economical use of marginal soils in relatively dry areas of Central Italy that would be replicable in other European areas with a similar climatic situation
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