Applications of Graphene at Microwave Frequencies

In view to the epochal scenarios that nanotechnology discloses, nano-electronics has the potential to introduce a paradigm shift in electronic systems design similar to that of the transition from vacuum tubes to semiconductor devices. Since low dimensional (1D and 2D) nano-structured materials exhibit unprecedented electro-mechanical properties in a wide frequency range, including radio-frequencies (RF), microwave nano-electronics provides an enormous and yet widely undiscovered opportunity for the engineering community. Carbon nano-electronics is one of the main research routes of RF/microwave nano-electronics. In particular, graphene has shown proven results as an emblematic protagonist, and a real solution for a wide variety of microwave electronic devices and circuits. This paper introduces graphene properties in the microwave range, and presents a paradigm of novel graphene-based devices and applications in the microwave/RF frequency range

Análise granulométrica: novo método para determinar a fração argila.

Os autores apresentam um novo método para determinar argila total, na qual essa determinação é feita no 200ml da parte superior do cilindro de Koettgen (acima da torneira superior), após uma sedimentação de 90 minutos, utilizando o hidrômetro de Bouyoucos. Também fica demonstrado que os resultados obtidos com a técnica e o tempo recomendados por Bouyoucos deixam muito a desejar, principalmente com amostras ricas em silte.bitstream/item/65520/1/Analise-granulometrica-novo-metodo-para-determinar-a-fracao-argila-1968.pdfTrabalho apresentado ao XI Congresso Brasileiro de Ciência do Solo

Current-Voltage Characterization of Multi-Port Graphene Based Geometric Diodes for High-Frequency Electromagnetic Harvesting

In this contribution, geometric diodes based on graphene patterned with spatial asymmetry have been studied, starting from tight-binding numerical approximation in a self-consistent framework, to verify their potential for electromagnetic (e. m.) harvesting. We report a detailed analysis of coherent charge transport and provide some figures of merit with respect to e. m. rectification, such as, for instance, the asymmetry of the dark current-voltage characteristics. The most important achievement of this work is given by the accurate analysis of the main key physical/geometric parameters that affect the nonlinear response of the diodes, for different configurations and geometries. Owing to the Scattering Matrix approach, introduced elsewhere for coherent transport calculation, it was possible to cascade asymmetric discontinuities and simulate large structures (more than 100K atoms) in a modular fashion. In this way, simulation at the atomistic level can be brought up to the device level to provide guidelines for design and fabrication, in view of practical applications related to clean-energy harvesting/rectification up to infrared and solar-light frequencies

Dirac-Based Quantum Admittance of 2D Nanomaterials at Radio Frequencies

Starting from a rigorous finite mass, Dirac equation-based model, we investigate the R.F. quantum admittance of a monolayer 2D material under the action of an electromagnetic (e.m.) wave with axially directed vector potential. With some reasonable approximations, the analysis yields a relatively simple RLC-equivalent circuit with frequency-independent elements depending on the bias, temperature, effective mass, Fermi velocity and effective e.m. index of the material, losses and other relevant parameters

Owner and animal factors predict the incidence of, and owner reaction towards, problem behaviors in companion dogs

Unwelcome behaviors in pet dogs may have serious implications for the quality of life of both the animals and their owners. We investigated owners\u2019 perceptions about their dogs\u2019 behavioral issues as well as other factors that might be predictive of potential canine problem behaviors. We distinguished between \u201cundesirable behaviors\u201d (behaviors that were unpleasant to the owners) and \u201cproblematic behaviors\u201d (behaviors that the owners found difficult to overcome). We designed an on-line survey eliciting information about owners, their dogs, their relationship with their dogs and whether the animals exhibited any of 15 potentially problematic behaviors. The largest proportion of respondents (65%) reported that their dogs exhibited undesirable, but not problematic, behaviors and were not interested in their modification. Only 32% of the respondents considered the behavior to be both undesirable and problematic and wished to change it. The owners\u2019 perception of a problem was associated with reports of fear- and anxiety-related behaviors. The owner\u2019s gender, marital status and attitude towards the dog as his/her child as well as the dog\u2019s age, size, age at acquisition and breed emerged as robust predictors. Compared to all other behavioral categories, reported aggressive canine behaviors were three times more likely to elicit an owner\u2019s wish to address them. This study revealed that the behaviors of dogs may be perceived differently by their owners and the type of perception may influence the owner\u2019s actual willingness to change those behaviors. Moreover, we identified the most robust set of factors that, either individually or combined, would help predict a dog\u2019s potential problem behaviors and an owner\u2019s attitude towards them, which will be useful in improving rational prevention and treatment strategies

Activity of a Pediatric Emergency Department of a Tertiary Center in Bologna, Italy, during SARS-CoV-2 Pandemic

During the SARS-CoV-2 pandemic, the pediatric emergency department (ED) of Bologna, Emilia-Romagna, Italy faced a reorganization to better deal with the new clinical needs. We herein describe the main changes in the organization and in the attendances to our pediatric ED. From the 1 March 2020 to the 31 January 2022, 796 children positive for SARS-CoV-2 presented to our pediatric ED, but only 26 required hospitalizations, of which only 9 for COVID-19 related reasons. During this period, we also registered a temporal correlation between multisystem inflammatory syndrome in children (MIS-C) admissions and the peaks of SARS-CoV-2 infection in the Italian population. Respiratory syncytial virus (RSV) remained during last year the viral infection with the highest hospitalization rate. The analysis and description of the changes in the activity of the pediatric ED during the SARS-CoV-2 pandemic may help to better understand the routinary activity and be prepared for any possible new challenge

Nano-antenna array for high efficiency sunlight harvesting

none5noSolar rectennas are promising devices for energy harvesting. Capability of rectennas to convert incident light into useful energy depends on the antenna efficiency, that is the ratio between the power transferred to the load vs the incoming power. In this work, we first emphasize that for the efficiency to be calculated accurately, antennas need to be treated as receiving devices, not as transmitting ones. Then, we propose an arrangement of antennas that differs from those published so far in three respects: (1) the proposed arrangement is formed by an array of nano-antennas with sub-wavelength inter-element spacing, (2) it comprises a reflecting mirror, and (3) it allows for dual polarization operation. Through numerical simulations, we show that the small lattice pitch we use is responsible for frequency flattening of the lattice impedance over the whole solar spectrum, eventually allowing for excellent matching with the antennas’ loads. Also, the small pitch allows for a smooth dependence of the receiving efficiency on the angle of incidence of sunlight. Finally, we show numerically that the reflecting mirror also allows for an almost complete cancellation of light scattered by the receiving antennas. The final result is a polarization insensitive receiving theoretical efficiency larger than 70% over the whole 300-3000 nm spectral range, with a less than 10% energy wasting due to back-scattering of sunlight.openMidrio M.; Pierantoni L.; Boscolo S.; Truccolo D.; Mencarelli D.Midrio, M.; Pierantoni, L.; Boscolo, S.; Truccolo, D.; Mencarelli, D

Accurate modeling of high frequency microelectromechanical systems (MEMS) switches in time- and frequency-domainc

Abstract. In this contribution we present an accurate investigation of three different techniques for the modeling of complex planar circuits. The em analysis is performed by means of different electromagnetic full-wave solvers in the timedomain and in the frequency-domain. The first one is the Transmission Line Matrix (TLM) method. In the second one the TLM method is combined with the Integral Equation (IE) method. The latter is based on the Generalized Transverse Resonance Diffraction (GTRD). In order to test the methods we model different structures and compare the calculated Sparameters to measured results, with good agreement

Professional evaluation systems and contracting of the management in Primary Health Care in Portugal

Apresenta-se um estudo de caso realizado em Portugal sobre sistemas de avaliação profissional para atenção primária. Os objetivos foram analisar a trajetória de implantação, a estrutura organizacional e as ferramentas de gestão utilizadas, bem como discutir sobre os processos que vêm sendo instituídos no Brasil com o Programa Nacional de Melhoria do Acesso e da Qualidade. Trata-se de estudo descritivo, com investigação bibliográfica de abordagem qualitativa. Os resultados indicam uma estrutura de coordenação, com descentralização dos serviços, que requer maior autonomia dos gestores de saúde e regulamentação do processo avaliativo, contribuindo para a obtenção de melhores resultados. It presents a case study performed in Portugal on professional evaluation systems in primary care. The objectives were to analyze the implanting trajectory, organizational structure and the management tools employed, as well as to discuss about the processes that have been instituted in Brazil along with National Program for Improving Access and Quality (PMAQ). It is about a descriptive study, with bibliographical investigation of qualitative approach. Results indicate a coordination structure with decentralization of services that requires greater autonomy of the health managers and regulation of the evaluation process, contributing for obtaining greater results.publishersversionpublishe

The Latin Owner: profiles, perceptions and attitudes of Italian cat and dog owners towards their pet

Introduction Nowadays animal companionship is an integral aspect of life in Europe, with approximately 81 million registered dogs and 99.2 million cats (1). This research aims to identify characteristics of dog and cat-owning households from a large cross-sectional web-based survey in Italy. Material and Methods Owners over 18 years old were asked information about themselves, their dogs, cats and their relationship with their pets. Data was analysed using Pearson\u2019s \u3c72 tests and logistic regressions (SPSS). Results 3,298 owners completed the survey, 31.8% and 40.3% of whom owned dogs and cats respectively, and 72.8% both. People aged 18 to 30 years were more likely to own a dog than older respondents. Compared to cat owners, dog owners were more likely to believe that their pets considered them to be conspecific group members, rather than \u201conly humans\u201d. Dogs were more likely to be purebreds adopted for companionship. Cats were significantly more likely to be mixed breeds adopted because they needed a home. Dog owners were significantly more likely to rate other owners as an important source of information regarding handling and training than cat owners. Despite a similarly high prevalence of reported intraspecific aggression and noise reactivity among dogs and cats, dog ownership significantly increased the likelihood of the owner\u2019s actual willingness to change a pet\u2019s behavior. Cat ownership increased the likelihood that owners would consider surgical sterilisation as an option to correct behaviour. Conclusion These results may be useful in helping behaviour practitioners address population changes in terms of human-pet bonds and plan prevention and treatment strategies. Reference: Statista 2015. Available a