611 research outputs found
Dual-Layer Corrugated Plate Antenna
This letter presents a subwavelength slot-fed high-gain dual-layer corrugated plate antenna for X-band applications. The antenna is realized by placing a second corrugated layer that has three radiating slots on top of the traditional corrugated plate antenna. The addition of the second layer improves the gain and bandwidth of the proposed antenna. Compared to a traditional single-layer corrugated plate antenna, the proposed dual-layer antenna has higher gain, lower sidelobe level, narrower half-power beamwidth, and better impedance bandwidth. A prototype of the proposed antenna is built and tested, and the measured results show that the antenna has a peak gain of 16.3 dBi at 11.3 GHz. The gain of the proposed antenna has been improved by more than 4 dBi due to coupling more energy to the second layer's three slots. Finally, the operating principles of the proposed antenna are also discussed and analyzed thoroughly
Compact and Low-Cost 3-D Printed Antennas Metalized Using Spray-Coating Technology for 5G mm-Wave Communication Systems
This letter presents a design of two compact, light, rigid, and low-cost three-dimensionally (3-D) printed millimeter-wave antennas for a fifth-generation (5G) communication system. The proposed antennas consist of a radiating slot that is surrounded by a rectangular cavity and corrugations, which boost the gain performance of the antennas. Furthermore, the proposed antennas are fabricated using 3-D printing technology, and they are metalized using novel, simple, and low-cost techniques, which utilize the commercial conducive spray-coating technology. The proposed antennas operate at a 28 GHz band, where the first design is fed by a waveguide to prove the performance, whereas the second design is fed by a microstrip line to demonstrate the ability to be integrated into a compact structure. Measurement results show a wide impedance bandwidth, which enables the proposed antenna design to be a strong candidate for 5G applications
The eigenvalue problem for the ∞-Bilaplacian
We consider the problem of finding and describing minimisers of the Rayleigh quotient
Λ∞:=infu∈W2,∞(Ω)∖{0}∥Δu∥L∞(Ω)∥u∥L∞(Ω),
Λ∞:=infu∈W2,∞(Ω)∖{0}‖Δu‖L∞(Ω)‖u‖L∞(Ω),
where Ω⊆RnΩ⊆Rn is a bounded C1,1C1,1 domain and W2,∞(Ω)W2,∞(Ω) is a class of weakly twice differentiable functions satisfying either u=0u=0 on ∂Ω∂Ω or u=|Du|=0u=|Du|=0 on ∂Ω∂Ω . Our first main result, obtained through approximation by LpLp -problems as p→∞p→∞ , is the existence of a minimiser u∞∈W2,∞(Ω)u∞∈W2,∞(Ω) satisfying
{Δu∞∈Λ∞Sgn(f∞)Δf∞=μ∞ a.e. in Ω, in D′(Ω),
{Δu∞∈Λ∞Sgn(f∞) a.e. in Ω,Δf∞=μ∞ in D′(Ω),
for some f∞∈L1(Ω)∩BVloc(Ω)f∞∈L1(Ω)∩BVloc(Ω) and a measure μ∞∈M(Ω)μ∞∈M(Ω) , for either choice of boundary conditions. Here Sgn is the multi-valued sign function. We also study the dependence of the eigenvalue Λ∞Λ∞ on the domain, establishing the validity of a Faber–Krahn type inequality: among all C1,1C1,1 domains with fixed measure, the ball is a strict minimiser of Ω↦Λ∞(Ω)Ω↦Λ∞(Ω) . This result is shown to hold true for either choice of boundary conditions and in every dimension
Modal analysis of holey fiber mode-selective couplers
Mode Division Multiplexing is currently investigated as a possible way to increase fiber system capacity. With this approach, different modes of the same fiber carry distinct information. One of the problems to be solved in these systems concerns coupling/decoupling of the various modes to/from the same fiber. In this presentation, the mode features of a mode mux/demux based on holey fibers are investigated, with particular emphasis on optimal device design. Some preliminary experimental results will also be presented
Molecular characterization of Bifidobacterium longum biovar longum NAL8 plasmids and construction of a novel replicon screening system
In this study, we performed molecular characterization and sequence analysis of three plasmids from the human intestinal isolate Bifidobacterium longum biovar longum NAL8 and developed a novel vector screening system. Plasmids pNAL8H (10 kb) and pNAL8M (4.9 kb) show close sequence similarity to and the same gene organization as the already characterized B. longum plasmids. The B. longum plasmid pNAC1 was identified as being most closely related to pNAL8L (3.5 kb). However, DNA sequence analysis suggested that direct repeat-rich sites could have promoted several recombination events to diversify the two plasmid molecules. We verified the likely rolling circle replication of plasmid pNAL8L and studied the phylogenetic relationship in all the Bifidobacterium plasmids fully sequenced to date based on in silico comparative sequence analysis of their replication proteins and iteron regions. Our transformation experiments confirmed that the ColE1 replication origin from high-copy-number pUC vectors could interfere with the replication apparatus of Bifidobacterium plasmids and give rise to false positive clones. As a result, we developed a system suitable for avoiding possible interference by other functional replication modules on the vector and for screening functional replicons from wild-type plasmids
Proteomic profile of maternal-aged blastocoel fluid suggests a novel role for ubiquitin system in blastocyst quality
Purpose: The etiology of maternal aging, a common cause of female factor infertility and a rate-limiting step in vitro fertilization (IVF) success, remains still unclear. Proteomic changes responsible for the impaired successful pregnancy outcome after IVF with aged blastocysts have not been yet evaluated. The objective of this prospective study was to employ proteomic techniques and bioinformatic tools to enlight differences at the protein level in blastocoel fluid of aged and younger woman. Methods: Protein composition of human blastocoel fluid isolated by micromanipulation from 46 blastocysts of women aged <37 years (group A) and 29 of women aged 6537 years (group B) have been identified by a shotgun proteomic approach based on high-resolution nano-liquid chromatography electrospray-ionization-tandem mass spectrometry (nLC-ESI-MS/MS) using label free for the relative quantification of their expression levels. Results: The proteomic analysis leads to the identification and quantification of 148 proteins; 132 and 116 proteins were identified in groups A and B, respectively. Interestingly, the identified proteins are mainly involved in processes aimed at fine tuning embryo implantation and development. Among the 100 proteins commonly expressed in both groups, 17 proteins are upregulated and 44 downregulated in group B compared to group A. Overall, the analysis identified 33 proteins, which were increased or present only in B while 76 were decreased in B or present only in A. Conclusions: Data revealed that maternal aging mainly affects blastocyst survival and implantation through unbalancing the equilibrium of the ubiquitin system known to play a crucial role in fine-tuning several aspects required to ensure successful pregnancy outcome
Phase field approach to optimal packing problems and related Cheeger clusters
In a fixed domain of we study the asymptotic behaviour of optimal
clusters associated to -Cheeger constants and natural energies like the
sum or maximum: we prove that, as the parameter converges to the
"critical" value , optimal Cheeger clusters
converge to solutions of different packing problems for balls, depending on the
energy under consideration. As well, we propose an efficient phase field
approach based on a multiphase Gamma convergence result of Modica-Mortola type,
in order to compute -Cheeger constants, optimal clusters and, as a
consequence of the asymptotic result, optimal packings. Numerical experiments
are carried over in two and three space dimensions
Analyticity and criticality results for the eigenvalues of the biharmonic operator
We consider the eigenvalues of the biharmonic operator subject to several
homogeneous boundary conditions (Dirichlet, Neumann, Navier, Steklov). We show
that simple eigenvalues and elementary symmetric functions of multiple
eigenvalues are real analytic, and provide Hadamard-type formulas for the
corresponding shape derivatives. After recalling the known results in shape
optimization, we prove that balls are always critical domains under volume
constraint.Comment: To appear on the proceedings of the conference "Geometric Properties
for Parabolic and Elliptic PDE's - 4th Italian-Japanese Workshop" held in
Palinuro (Italy), May 25-29, 201
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