DoA estimation in EM lens assisted massive antenna system using subsets based antenna selection and high resolution algorithms

In recent times, massive antenna array technology has captured significant attention among wireless communication researchers. This is a field with strong potential to increase rates of data transfer; mitigate interference and serve a large number of users simultaneously. To contribute further to this emerging technology, this paper presents an approach for the line-of-sight (LoS) based direction of arrival (DoA) estimation using the electromagnetic (EM) lens-focusing antenna concept. The EM lens focuses the received signal energy as a function of the angle of arrival (AoA) to a small subset/area of the antenna array. This is advantageous, as it helps to reduce both hardware implementation (RF chains) and the complexity of signal processing in the large number of antennas system. Furthermore, this focusing capability of the EM lens provides additional interference rejection gain which leads to estimate the DoA of user terminals precisely. Hence, in this work, subsets based antenna selection approach and subspace-based high resolution DoA estimation algorithms have been considered in combination with the EM lens assisted massive antenna system. In simulations where the DoA is estimated with the EM lens, the results are comparable with conventional methods of DoA estimation without an EM lens, despite the significantly reduced overall system complexity

Performance analysis of 180\ub0 HRR coupler used for direction finding with an antenna array

This paper presents the performance analysis of  hybrid rat race coupler, widely used in radio frequency (RF)/wireless communication systems to couple the power in the desired way. The  hybrid ring coupler consists of 4 ports, two for the input signals and two for the output signals, where sum and difference patterns of the applied two signals can be obtained at two output ports and usually called sum and difference ports. In this work, the couplers have been designed and simulated at central frequencies (fo) of 2.4 and 10 GHz using different types of substrates such as RT Duroid 5880 and FR4.  Furthermore, the coupler has been used for direction finding (angle-of-arrival estimation) application, where we combine the designed  hybrid rat race coupler with a simple two antenna elements array  (at fo=10GHz and RT Duroid =2.2) and fabricate the circuit in order to validate the performance of the coupler by measuring the direction of arrival (DoA) from  and  ports. The obtained results show that good performance can be achieved with the designs considered in this paper.

Interplay of Kerr and Raman beam cleaning with a multimode microstructure fiber

We experimentally study the competition between Kerr beam self-cleaning and Raman beam cleanup in a multimode air-silica microstructure optical fiber. Kerr beam self-cleaning of the pump is observed for a certain range of input powers only. Raman Stokes beam generation and cleanup lead to both depletion and degradation of beam quality for the pump. The interplay of modal four-wave mixing and Raman scattering in the infrared domain lead to the generation of a multimode supercontinuum ranging from 500 nm up to 1800 nm

Self-cleaning on a higher order mode in ytterbium-doped multimode fiber with parabolic profile

We experimentally demonstrate polarization-dependent Kerr spatial beam self-cleaning into the LP11 mode of an Ytterbium-doped multimode optical fiber with parabolic gain and refractive index profiles

Formaldehyde solutions in simulated sweat increase human melanoma but not normal human keratinocyte cells proliferation

Our skin is in close contact with clothes most of the time thus risking potentially noxious chemicals contact. One of the potentially harmful manufacturing by-products that can be released by textiles when sweating is formaldehyde, used as an anti-crease treatment. As it is known to be carcinogenic to humans and a potent skin sensitizer, the aim of this study was to investigate its effects on both normal human keratinocytes (HaCaT cells) and on a highly invasive malignant melanoma cell line (SK-MEL-28) in order to contribute to the definition of safety cut-off to be applied to the production processes. Formaldehyde concentrations below the commonly accepted limits (10\u201350 \u3bcM) were obtained by diluting formaldehyde in simulated sweat (UNI EN ISO 105-E04). The effects on cell proliferation were evaluated by cell counting, while ERK pathway activation was evaluated by western blot. Low concentrations of formaldehyde (10 \u3bcM) in both acidic and alkaline simulated sweat were able to increase malignant melanoma cell proliferation, while not affecting normal keratinocytes. Melanoma proliferation increase was greater in acidic (pH = 5.5) than in alkaline (pH = 8) conditions. Moreover, formaldehyde stimulation was able to induce ERK pathway activation. The data obtained suggest the need for an even increasing attention to the potentially harmful effects of textile manufacturing by-products

Caracterização das fases de desenvolvimento e aspectos da biologia do percevejo barriga-verde Dichelops melacanthus (Dallas, 1851).

bitstream/CNPT-2010/40579/1/p-co214.pd

Control of signal coherence in parametric frequency mixing with incoherent pumps: narrowband mid-infrared light generation by downconversion of broadband amplified spontaneous emission source at 1550 nm

We study, with numerical simulations using the generalized nonlinear envelope equation, the processes of optical parametric and difference- and sum-frequency generation (SFG) with incoherent pumps in optical media with both quadratic and third-order nonlinearity, such as periodically poled lithium niobate. With ultrabroadband amplified spontaneous emission pumps or continua (spectral widths >10 THz), group-velocity matching of a near-IR pump and a short-wavelength mid-IR (MIR) idler in optical parametric generation may lead to more than 15-fold relative spectral narrowing of the generated MIR signal. Moreover, the SFG process may also lead to 6-fold signal coherence improvements. When using relatively narrowband filtered noise pumps (e.g., spectral widths < 1 THz), the signal from optical parametric, sum-frequency, and difference-frequency generation has nearly the same spectral width as that of the incoherent pump

Pre-odontoblast proliferation induced by near-infrared laser stimulation

OBJECTIVE: Laser therapy is known to stimulate cell proliferation and differentiation, an effect called "biostimulation". Although many clinical applications of laser therapy take advantage from such positive effect, the underlying molecular mechanisms are not fully understood. The aim of this work was to investigate the effect of near-infrared laser stimulation on rat pre-odontoblast cells (MDPC-23 cells) and the molecular mechanism/s involved. MATERIALS AND METHODS: MDPC-23 cells were stimulated with a near-infrared (980 nm) laser source with different energy settings (1-50 J, corresponding to 0.65-32.47 J/cm2) and cell proliferation was evaluated by manual count. ERK 1/2 pathway activation was evaluated by Western blot analysis. RESULTS: 1-10 J stimulation (corresponding to 0.65-6.5 J/cm2) significantly increase MDPC-23 cell proliferation and such effect seems to be mediated by ERK 1/2 signalling pathway activation, showing a key role of ERK 1/2 pathway in mediating the proliferative response induced by laser stimulation. CONCLUSIONS: Near infrared laser stimulation with low energies (1-10 J) is able to increase cell proliferation through ERK 1/2 signalling pathway activation. At the same time, higher energy stimulation (25-50 J) induces an initial toxic effect, probably activating pro-apoptotic signalling molecules, downstream ERK 1/2 kinase. Such results foster the application of this therapeutic approach in different clinical settings in which a regenerative tissue response is needed

Epiregulin-loaded PLGA nanoparticles increase human keratinocytes proliferation: preliminary data

OBJECTIVE:Epiregulin is a member of the epidermal growth factor (EGF) family produced by keratinocytes: the aim of this study was to investigate the ability of biocompatible nanoparticles loaded with such growth factor to increase human keratinocytes proliferation. MATERIALS AND METHODS:Different PLGA (Poly-d,l-lactide-co-glycolide)-nanoparticles (NPs) formulations have been characterized in size and zeta potential by dynamic light scattering (DLS) analysis. The ability of the different PLGA-NPs formulations to adhere onto dental surfaces has been tested, and epiregulin-enriched PLGA-NPs has been produced. Epiregulin release from NPs has been tested by enzyme-linked immunosorbent (ELISA) assay and the proliferative effects of epiregulin-NPs on human keratinocytes have been evaluated. RESULTS:DLS analysis revealed a different size distribution depending on the PLA/PGA (poly lactic acid/poly glycolic acid) ratio used. 50:50 PLGA-NPs exhibited the smaller size and the best dental adhesive ability. Moreover, such epiregulin-loaded NPs was able to increase cell proliferation. CONCLUSIONS:Direct dental pocket drug delivery implies the NPs solution loading onto the dental surface at the cement-enamel junction level: 50:50 PLGA-NPs, with their small size and excellent adhesive ability, represent an interesting tool to deliver epiregulin directly where there is the need for epithelial proliferation. These results describe a possible strategy for periodontal pocket delivery of Epiregulin-loaded PLGA-NPs and might provide a new approach for the treatment of gingival recession, where gingival epithelium proliferation is needed