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

DPD Linearization Complexity Reduction of Remote Radio Heads in C-RAN with Radio over Fiber Fronthaul

Radio-over-Fiber (RoF) is a suitable technology for efficiently developing the cloud-RAN concept in Fifth Generation (5G) deployments based on Long Term Evolution Advanced LTE-A. Distortion coming out from the radiofrequency (RF) power amplifier should be taken into account in order to achieve the desired performance at the base station. In this paper, a complexity reduction technique based on a variable degree polynomial predistorter is proposed. The obtained results show that it is possible to achieve a reduction of operations with a penalty of 1.6 dB in ACLR and negligible impact on the EVM

A hybrid method to face class overlap and class imbalance on neural networks and multi-class scenarios

Class imbalance and class overlap are two of the major problems in data mining and machine learning. Several studies have shown that these data complexities may affect the performance or behavior of artificial neural networks. Strategies proposed to face with both challenges have been separately applied. In this paper, we introduce a hybrid method for handling both class imbalance and class overlap simultaneously in multi-class learning problems. Experimental results on five remote sensing data show that the combined approach is a promising method

Low-cost test measurement setup for real IoT BLE sensor device characterization

The methodology presented in this paper aims to characterize impairments shown by real devices which are usually neglected on standardized tests but that become very important in massive IoT scenarios. For instance, we have measured that real BLE scanners are not able to scan continuously even though they are configured to do so. Besides, we have also found and demonstrated that some manufacturers seem not to apply any backoff mechanism although it is mandatory. These two unexpected behaviors have a significant impact on the performance of massive wireless sensor networks based on BLE. So, it becomes necessary to characterize these and other impairments. The proposed tests are based on device current consumption measurements and their association with the information obtained from upper layers. We describe a new low-cost generic measurement setup and provide all the necessary data (configuration parameters, scripts, etc.) for applying the proposed methodology. As an example, we use it to profile the behavior of Bluetooth Low Energy devices. Furthermore, the proposed setup can also inspire researchers to characterize other wireless technology devices, like Wi-Fi, Zigbee, LoRa, etc

Experimental Evaluation of Transmitted Signal Distortion Caused by Power Allocation in Inter-Cell Interference Coordination Techniques for LTE/LTE-A and 5G Systems

Error vector magnitude (EVM) and out-of-band emissions are key metrics for evaluating in-band and out-band distortions introduced by all potential non-idealities in the transmitters of wireless systems. As EVM is a measure of the quality of the modulated signal/symbols, LTE/LTE-A and 5G systems specify mandatory EVM requirements in transmission for each modulation scheme. This paper analyzes the influence of the mandatory satisfaction of EVM requirements on the design of radio resource management strategies (RRM) (link adaptation, inter-cell interference coordination), specifically in the downlink (DL). EVM depends on the non-idealities of the transmitter implementations, on the allocated power variations between the subcarriers and on the selected modulations. In the DL of LTE, link adaptation is usually executed by adaptive modulation and coding (AMC) instead of power control, but some flexibility in power allocation remains being used. LTE specifies some limits in the power dynamic ranges depending on the allocated modulation, which ensures the satisfaction of EVM requirements. However, the required recommendations concerning the allowed power dynamic range when inter-cell interference coordination (ICIC) and enhanced ICIC (eICIC) mechanisms (through power coordination) are out of specification, even though the EVM performance should be known to obtain the maximum benefit of these strategies. We perform an experimental characterization of the EVM in the DL under real and widely known ICIC implementation schemes. These studies demonstrate that an accurate analysis of EVM is required. It allows a better adjustment of the design parameters of these strategies, and also allows the redefinition of the main criteria to be considered in the implementation of the scheduler/link adaptation concerning the allocable modulation coding scheme (MCS) in each resource block. © 2013 IEEE

Síndrome de intestino corto en niños: actualidades en su diagnóstico y manejo

ResumenEl síndrome de intestino corto (SIC) se refiere a la suma de alteraciones funcionales que resultan de una reducción crítica en la longitud del intestino, y que en ausencia de un tratamiento adecuado se manifiestan con diarrea crónica, deshidratación crónica, desnutrición, pérdida de peso, deficiencia de nutrimentos y electrolitos, así como falla para crecer que se presenta con mayor frecuencia durante el periodo neonatal. El objetivo de este artículo es realizar una revisión de la literatura médica sobre la definición, las causas más frecuentes de SIC así como entender la fisiopatología, los factores pronósticos y tratamiento.Se realizó una búsqueda de artículos en PubMed, considerando la información existente en niños con SIC de 20 años hasta la fecha, utilizando las palabras clave “síndrome de intestino corto”. De un total de 784 artículos potenciales, se realizó una selección de 82 artículos donde realizamos la revisión de la literatura médica. Los pacientes con SIC son todo un reto para su tratamiento, por lo que se debe establecer un manejo multidisciplinario enfocado en mantener un soporte nutricional óptimo que cubra las necesidades para crecimiento, desarrollo y asimismo, disminuir al máximo la presencia de complicaciones a corto, mediano y largo plazo. El diagnóstico y manejo de un niño con SIC, implica un equipo de profesionales expertos en el manejo gastroenterológico, pediátrico y nutricional. El pronóstico del niño estará en función al manejo oportuno, así como longitud de la resección intestinal y presencia o no de válvula ileocecal.AbstractShort bowel syndrome (SBS) refers to the sum of the functional alterations that are the result of a critical reduction in the length of the intestine, which in the absence of adequate treatment, presents as chronic diarrhea, chronic dehydration, malnutrition, weight loss, nutriment and electrolyte deficiency, along with a failure to grow that is present with greater frequency during the neonatal period. The aim was to carry out a review of the literature encompassing the definition and the most frequent causes of SBS, together with an understanding of its physiopathology, prognostic factors, and treatment.An Internet search of PubMed articles was carried out for the existing information published over the last 20 years on SBS in children, using the keywords “short bowel syndrome”. From a total of 784 potential articles, 82 articles were chosen for the literature review. The treatment of patients presenting with SBS is quite a challenge and therefore it is necessary to establish multidisciplinary management with a focus on maintaining optimal nutritional support that covers the necessities of growth and development and at the same time provides a maximum reduction of short, medium, and long-term complications. The diagnosis and treatment of a child with SBS require a team of professionals that are experts in gastroenterologic, pediatric, and nutritional management. The outcome for the child will be directly related to opportune management, as well as to the length of the intestinal resection and the presence or absence of the ileocecal valve

A New Under-Sampling Method to Face Class Overlap and Imbalance

Class overlap and class imbalance are two data complexities that challenge the design of effective classifiers in Pattern Recognition and Data Mining as they may cause a significant loss in performance. Several solutions have been proposed to face both data difficulties, but most of these approaches tackle each problem separately. In this paper, we propose a two-stage under-sampling technique that combines the DBSCAN clustering algorithm to remove noisy samples and clean the decision boundary with a minimum spanning tree algorithm to face the class imbalance, thus handling class overlap and imbalance simultaneously with the aim of improving the performance of classifiers. An extensive experimental study shows a significantly better behavior of the new algorithm as compared to 12 state-of-the-art under-sampling methods using three standard classification models (nearest neighbor rule, J48 decision tree, and support vector machine with a linear kernel) on both real-life and synthetic databases

Epigenetic and phenotypic changes result from a continuous pre and post natal dietary exposure to phytoestrogens in an experimental population of mice

Background: Developmental effects of exposure to endocrine disruptors can influence adult characters in mammals, but could also have evolutionary consequences. The aim of this study was to simulate an environmental exposure of an experimental population of mice to high amounts of nutritional phytoestrogens and to evaluate parameters of relevance for evolutionary change in the offspring. The effect of a continuous pre- and post-natal exposure to high levels of dietary isoflavones was evaluated on sexual maturity, morphometric parameters and DNA methylation status in mice. Adult mice male/female couples were fed ad libitum either with control diet (standard laboratory chow) or ISF diet (control diet plus a soy isoflavone extract at 2% (w/w) that contained the phytoestrogens genistein and daidzein). In the offspring we measured: i) the onset of vaginal opening (sexual maturation) in females, ii) weight and size in all pups at 7, 14, 21 and 42 days post-natal (dpn) and iii) DNA methylation patterns in skeletal α-actin (Acta1), estrogen receptor- α and c-fos in adults (42 dpn). Results: Vaginal opening was advanced in female pups in the ISF group, from 31.6 ± 0.75 dpn to 25.7 ± 0.48. No differences in size or weight at ages 7, 14 or 21 dpn were detected between experimental groups. Nevertheless, at age 42 dpn reduced size and weight were observed in ISF pups, in addition to suppression of normal gender differences in weight seen in the control group (males heavier that females). Also, natural differences seen in DNA methylation at Acta1 promoter in the offspring originated in the control group were suppressed in the ISF group. Acta1 is known to be developmentally regulated and related to morphomotric features. Conclusion: This study demonstrates in mammals that individuals from a population subjected to a high consumption of isoflavones can show alterations in characters that may be of importance from an evolutionary perspective, such as epigenetic and morphometric characters or sexual maturation, a life history character.We greatly appreciate the linguistic revision of the manuscript by Renée Hill and critical review of the manuscript by Dr. Anders Lindroth. We are very thankful for funding by FONDECYT projects 1010647 to PS and 1030309 to LV, CONICYT fellowship for graduate studies and MECESUP grant for overseas training to CG, and NH&MRC project grant funding to SJC