A functional variant in the Stearoyl-CoA desaturase gene promoter enhances fatty acid desaturation in pork

There is growing public concern about reducing saturated fat intake. Stearoyl-CoA desaturase (SCD) is the lipogenic enzyme responsible for the biosynthesis of oleic acid (18:1) by desaturating stearic acid (18:0). Here we describe a total of 18 mutations in the promoter and 3′ non-coding region of the pig SCD gene and provide evidence that allele T at AY487830:g.2228T>C in the promoter region enhances fat desaturation (the ratio 18:1/18:0 in muscle increases from 3.78 to 4.43 in opposite homozygotes) without affecting fat content (18:0+18:1, intramuscular fat content, and backfat thickness). No mutations that could affect the functionality of the protein were found in the coding region. First, we proved in a purebred Duroc line that the C-T-A haplotype of the 3 single nucleotide polymorphisms (SNPs) (g.2108C>T; g.2228T>C; g.2281A>G) of the promoter region was additively associated to enhanced 18:1/18:0 both in muscle and subcutaneous fat, but not in liver. We show that this association was consistent over a 10-year period of overlapping generations and, in line with these results, that the C-T-A haplotype displayed greater SCD mRNA expression in muscle. The effect of this haplotype was validated both internally, by comparing opposite homozygote siblings, and externally, by using experimental Duroc-based crossbreds. Second, the g.2281A>G and the g.2108C>T SNPs were excluded as causative mutations using new and previously published data, restricting the causality to g.2228T>C SNP, the last source of genetic variation within the haplotype. This mutation is positioned in the core sequence of several putative transcription factor binding sites, so that there are several plausible mechanisms by which allele T enhances 18:1/18:0 and, consequently, the proportion of monounsaturated to saturated fat.This research was supported by grants from the Spanish Ministry of Science and Innovation (AGL2009-09779 and AGL2012-33529). RRF is recipient of a PhD scholarship from the Spanish Ministry of Science and Innovation (BES-2010-034607). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of manuscript

The Diffraction of an Inhomogeneous Plane Wave by an Impedance Wedge in a Lossy Medium

The diffraction of an inhomogeneous plane wave by an impedance wedge embedded in a lossy medium is analyzed. The rigorous integral representation for the field is asymptotically evaluated in the context of the uniform geometrical theory of diffraction (UTD) so that the asymptotic expressions obtained can be employed in a ray analysis of the scattering from more complex edge geometries located in a dissipative medium. Surface wave excitations at the edge and their propagation along the wedge faces are discussed with particular emphasis on the effects of losses

HIGH-FREQUENCY ELECTROMAGNETIC SCATTERING OF PLANE-WAVES FROM DOUBLE WEDGES

The application of a high-frequency solution for the field doubly diffracted in the far zone from a pair of parallel wedges illuminated by a plane wave is described. It is shown how a spectral extension of the uniform geometrical theory of diffraction (GTD) is used to obtain closed-form expressions for the field that are valid at any incidence and observation aspects. These expressions exhibit the proper discontinuities and singularities so that they can be suitably combined with the other singly diffracted fields to provide a uniformly valid ray description of the scattering in the far zone by an obstacle which is illuminated by a plane wave. They smoothly reduce both to those derived by directly applying the uniform GTD solution for single diffraction augmented by slope diffraction and to those recently obtained for grazing illumination of the edges, in their respective regions of validity. The solutions to the scalar problems are then used to construct a dyadic diffraction coefficient for the doubly diffracted field in the ray-fixed coordinate system. Examples of triangular cylinders are considered, and numerical results are presented

DOUBLE DIFFRACTION BY WEDGES IN NONPERFECTLY CONDUCTING SURFACES

A high-frequency solution is obtained via an extended ray method for the field doubly diffracted in the far zone by a pair of parallel wedges with impedance faces, when they are illuminated by a plane wave perpendicularly incident on the edges. Except for a multiplying special function, this solution is expressed in closed form, which is valid for any incident and observation aspects

Wireless propagation modeling by using ray-tracing

The asymptotic high frequency techniques, based on the Geometrical Optics (GO), the Geometrical Theory of Diffraction (GTD), and its extension such as the Uniform Theory of Diffraction (UTD), can be used to study the propagation of wireless electromagnetic signals in complex environments. Indeed, at high frequencies, it is possible to use the ray concept to trace the paths followed by electromagnetic waves from the transmitting to the receiving antenna, and to calculate the attenuation suffered by virtue of its interaction with the obstacles present in its environment. After a brief overview of the evaluation of electromagnetic fields by using the GO and/or the GTD/UTD, the fundamental geometric concepts of the ray-tracing algorithms are presented. Next, some acceleration techniques, necessary to efficiently model wireless propagation in outdoor and indoor environments, are discussed. Furthermore, leveraging the fact that the ray-tracing algorithm provides all the data necessary for a complete characterization of wireless propagation, it is used to derive some important parameters such as Path Loss, Delay Spread, channel frequency and impulse response, Power Delay Profile and Spreading Function

High-Frequency Green's Function for an Infinite Periodic Line Array of Phased Electric Dipoles on an Infinite Stratified Grounded Dielectric Slab

This paper deals with the spatial domain parametrization and physical interpretationof the asymptotic high-frequency solution pertaining to the asymptotic Green’s functionfor an infinite periodic line array of phased parallel dipoles on an infinite stratified groundeddielectric slab. This Green’s function is the basic constituent for deriving the array Green’sfunction (AGF) for a semi-infinite array of dipoles, which is treated elsewhere. The lineararray is synthesized as a superposition of smoothly phased periodicity-matched line sources.Each smoothly phased line source excites surface and leaky conical waves and associatedcoupled space wave contributions, which exhibit a transitional behavior at their appropriateshadow boundaries. The spectral integral which represents this space wave contribution istreated asymptotically by the use of an appropriate transition function

High-Frequency Green’s function for an infinite periodic line array of phased electric dipoles on an infinite stratified grounded dielectric slab

This paper deals with the spatial domain parametrization and physical interpretation of the asymptotic high-frequency solution pertaining to the asymptotic Green's function for an infinite periodic line array of phased parallel dipoles on an infinite stratified grounded dielectric slab. This Green's function is the basic constituent for deriving the array Green's function (AGF) for a semi-infinite array of dipoles, which is treated elsewhere. The linear array is synthesized as a superposition of smoothly phased periodicity-matched line sources. Each smoothly phased line source excites surface and leaky conical waves and associated coupled space wave contributions, which exhibit a transitional behavior at their appropriate shadow boundaries. The spectral integral which represents this space wave contribution is treated asymptotically by the use of an appropriate transition function