Regularity of viscosity solutions to fully nonlinear elliptic transmission problems

We develop the regularity theory of viscosity solutions to transmission problems for fully nonlinear second order uniformly elliptic equations. Our results give a complete theory of existence, uniqueness, comparison principle, and regularity of solutions to flat interface transmission problems; and the $C^{0,\alpha}$, $C^{1,\alpha}$ and $C^{2,\alpha}$ regularity of viscosity solutions up to the transmission surface for the case of curved interfaces.Comment: Improved presentation. 37 page

Transmission of preferences and beliefs about female labor market participation : direct evidence on the role of mothers

Recently, economists have established that culture—defined as a common set of preferences and beliefs —affects economic outcomes, including the levels of female labor force participation. Although this literature has argued that culture is transmitted from parents to children, it has also recognized the difficulty in empirically disentangling the parental transmission of preferences and/or beliefs from other confounding factors, such as technological change or investment in education. Using church registry data from the 18th and 19th centuries, our primary contribution is to interpret the effect of a mother’s labor participation status on that of her daughter as the mother-to-daughter transmission of preferences and/or beliefs that are isolated from confounding effects. Because our data are characterized by abundant non-ignorable missing information, we estimate the participation model and the missing process jointly by maximum likelihood. Our results reveal that the mother’s working status has a large and statistically significant positive effect on the daughter’s probability of working. These findings suggest that intergenerational family transmission of preferences and/or beliefs played a decisive role in the substantial increases in female labor force participation that occurred later.We acknowledge the financial support of the Ramón Areces Foundation (2007), and the Spanish Ministry of Science and Innovation through Grants SEJ2007-66268 (Machado), ECO2009-11165 (Carro and Mora), ECO2010- 20504 (Machado), and ECO2012-31358 (Carro and Mora)

The role of mothers on female labour force participation: an approach using historical parish records

Using Portuguese parish data from 1675 to 1925, we estimate the relationship between a mother’s participation in the labour force and that of her daughter. We adapt a methodology to prevent bias that originates from potentially non-random missing data. Ignoring the missingness process results in substantial downward-biased estimates of the relationship, even for a proportion of missing values as low as 20 per cent. In contrast, our methodology yields unbiased estimates regardless of the proportion of missing values. We document the existence of a strong, positive association between the mother’s participation and that of her daughter long before the twentieth century’s substantial changes in education and the labour marketThe authors acknowledge the financial support of the Ramón Areces Foundation, and the Spanish Ministry of Science and Innovation through Grants ECO2016-78652 (P. Machado), ECO2015-65204-P (Carro and Mora), RTI2018-095231-B-I00 (Carro), and PID2019-108576RB-I00 (P. Machado and Mora)

Triple-Band Concurrent Reconfigurable Matching Network

Reconfigurable Matching Networks (RMN) have found a wide range of applications, such as antenna impedance matching (Antenna Tuning Units -ATU-), the design of reconfigurable power amplifiers, applications in Magnetic Resonance Imaging (MRI), adjustable low noise amplifier design, etc. In this paper, we propose the experimental design and verification of a reconfigurable impedance synthesis network that can simultaneously work in three different bands and is completely independent so that the impedance variations in a frequency band are approximately transparent to the rest. The variable elements used in this paper are varactors. To verify its operation, it is applied to a process of matching a laser modulator in three different frequency bands for C-RAN (Cloud Radio Access Networks) applications. Experimental results demonstrate, as expected, that losses may depend on the state in which they are driven. Consequently, a state that can guarantee a good match could also imply greater losses, leading to a certain trade-off. The application of genetic algorithms in this context points out that it may be convenient to optimize the insertion losses of the complete chain instead of the return losses

Predistorsión Digital mediante Señales Enventanadas Tipo Chirp para la Linealización de Amplificadores de Potencia

Digital PreDistortion (DPD) is a well-known method to reduce nonlinear distortion in power amplifiers (PA). In a LTE uplink transmission, the modulation schemes are adaptive. Thus, the DPD function will have to be re-calibrated once the modulation changes. This fact increases the DPD computational cost and the required memory. If the DPD is not re-trained its linearity performance will decrease. This effect can be reduced using a suitable training signal. We propose several novel non-stationary calibration signals based on a windowed-chirp waveform. The envelope of these sequences is bounded by different windows used in signal processing such as Bartlett, Blackman, Hamming or Welch. Bartlett and Blackman windows generate calibration sequences with higher peak to average power ratio values than Welch. Welch envelope creates a signal with a more uniform probability density function (pdf) than the Hamming-window, whose pdf is similar to a Rayleigh distribution. The linearization strategy is based on capturing the described sequences at the PA input and output to extract the predistortion parameters. Once the predistorter functions are computed, we apply them on various LTE-transmissions and perform linearity measurements in terms of the adjacent channel leakage ratio to compare with the standard requirements. In all cases the maximum nonlinear distortion reduction is accomplished with the Chirp-Bartlett sequence (up to 37dBc when transmitting a QPSK-LTE-signal). Thus, good DPD performance is achieved when using the proposed Bartlett-Chirp in the DPD-training-stage. This avoids generating specific DPDs for each modulation scheme, saving computational cost, required memory, and increasing the system efficiency

Radio-over-fiber linearization with optimized genetic algorithm CPWL model

This article proposes an optimized version of a canonical piece-wise-linear (CPWL) digital predistorter in order to enhance the linearity of a radio-over-fiber (RoF) LTE mobile fronthaul. In this work, we propose a threshold allocation optimization process carried out by a genetic algorithm (GA) in order to optimize the CPWL model (GA-CPWL). Firstly, experiments show how the CPWL model outperforms the classical memory polynomial DPD in an intensity modulation/direct detection (IM/DD) RoF link. Then, the GA-CPWL predistorter is compared with the CPWL model in several scenarios, in order to verify that the proposed DPD offers better performance in different optical transmission conditions. Experimental results reveal that with a proper threshold allocation, the GA-CPWL predistorter offers very promising outcomes