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This paper examines advances in ultra-high concentration photovoltaics (UHCPV), focusing specifically on vertical multijunction (VMJ) solar cells. The use of gallium arsenide (GaAs) in these cells increases their efficiency in a range of applications, including terrestrial and space settings. Several multijunction structures are designed to maximize conversion efficiency, including a vertical tunnel junction, which minimizes resistive losses at high concentration levels compared with standard designs. Therefore, careful optimization of interconnect layers in terms of thickness and doping concentration is needed. Homo-multijunction GaAs solar cells have been simulated and analyzed by using ATLAS Silvaco 5.36 R, a sophisticated technology computer-aided design (TCAD) tool aimed to ensure the reliability of simulation by targeting a high conversion efficiency and a good fill factor for our proposed structure model. Several design parameters, such as the dimensional cell structure, doping density, and sun concentrations, have been analyzed to improve device performance under direct air mass conditions AM1.5D. The optimized conversion efficiency of 30.2% has been achieved with investigated GaAs solar cell configuration at maximum concentration levels.

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The performance and reliability of semiconductor devices scaled down to the sub-nanometer regime are being seriously affected by process-induced variability. To properly assess the impact of the different sources of fluctuations, such as line edge roughness (LER), statistical analyses involving large samples of device configurations are needed. The computational cost of such studies can be very high if 3D advanced simulation tools (TCAD) that include quantum effects are used. In this work, we present a machine learning approach to model the impact of LER on two gate-all-around nanowire FETs that is able to dramatically decrease the computational effort, thus reducing the carbon footprint of the study, while obtaining great accuracy. Finally, we demonstrate that transfer learning techniques can decrease the computing cost even further, being the carbon footprint of the study just 0.18 g of CO2 (whereas a single device TCAD study can produce up to 2.6 kg of CO2), while obtaining coefficient of determination values larger than 0.985 when using only a 10% of the input samples.

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This article proposes a study of the SARS-CoV-2 virus spread and the efficacy of public policies in Brazil. Using both aggregated (from large Internet companies) and fine-grained (from Departments of Motor Vehicles) mobility data sources, our work sheds light on the effect of mobility on the pandemic situation in the Brazilian territory. Our main contribution is to show how mobility data, particularly fine-grained ones, can offer valuable insights into virus propagation. For this, we propose a modification in the SENUR model to add mobility information, evaluating different data availability scenarios (different information granularities), and finally, we carry out simulations to evaluate possible public policies. In particular, we conduct a case study that shows, through simulations of hypothetical scenarios, that the contagion curve in several Brazilian cities could have been milder if the government had imposed mobility restrictions soon after reporting the first case. Our results also show that if the government had not taken any action and the only safety measure taken was the population's voluntary isolation (out of fear), the time until the contagion peak for the first wave would have been postponed, but its value would more than double.

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This work deals with the application of femtosecond-laser-inscribed fiber Bragg gratings (FsFBGs) for monitoring the internal high-temperature surface distribution (HTSD) in solar receivers of concentrating solar power (CSP) plants. The fiber-optic sensor system is composed of 12 FsFBGs measuring points distributed on an area of 0.4 m2, which leads to obtain the temperature map at the receiver by means of two-dimensional interpolation. An analysis of the FsFBG performance in harsh environment was also conducted. It describes the influence of calibration functions in high-temperature measurements, determines a required 10 nm spectral interval for measuring temperatures in the range from 0 to 700 °C, and reveals wavelength peak tolerances in the FsFBG fabrication process. Results demonstrate the viability and reliability of this measuring technique, with temperature measurements up to 566 °C.

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This Special Issue looks at recent developments in the research field of Nanowire Field-Effect Transistors (NW-FETs), covering different aspects of technology, physics, and modelling of these nanoscale devices. In this summary, we present seven outstanding articles on NW-FETs by providing a brief overview of the articles' content.

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An in-house-built three-dimensional multi-method semi-classical/classical toolbox has been developed to characterise the performance, scalability, and variability of state-of-the-art semiconductor devices. To demonstrate capabilities of the toolbox, a 10 nm gate length Si gate-all-around field-effect transistor is selected as a benchmark device. The device exhibits an off-current (I OFF) of 0 . 03 µA/µm, and an on-current (I ON) of 1770 µA/µm, with the I ON / I OFF ratio 6 . 63 × 10 4, a value 27 % larger than that of a 10 . 7 nm gate length Si FinFET. The device SS is 71 mV/dec, no far from the ideal limit of 60 mV/dec. The threshold voltage standard deviation due to statistical combination of four sources of variability (line- and gate-edge roughness, metal grain granularity, and random dopants) is 55 . 5 mV, a value noticeably larger than that of the equivalent FinFET (30 mV). Finally, using a fluctuation sensitivity map, we establish which regions of the device are the most sensitive to the line-edge roughness and the metal grain granularity variability effects. The on-current of the device is strongly affected by any line-edge roughness taking place near the source-gate junction or by metal grains localised between the middle of the gate and the proximity of the gate-source junction.

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Interface roughness scattering (IRS) is one of the major scattering mechanisms limiting the performance of non-planar multi-gate transistors, like Fin field-effect transistors (FETs). Here, two physical models (Ando's and multi-sub-band) of electron scattering with the interface roughness induced potential are investigated using an in-house built 3D finite element ensemble Monte Carlo simulation toolbox including parameter-free 2D Schrödinger equation quantum correction that handles all relevant scattering mechanisms within highly non-equilibrium carrier transport. Moreover, we predict the effect of IRS on performance of FinFETs with realistic channel cross-section shapes with respect to the IRS correlation length (Λ) and RMS height ([Formula: see text]). The simulations of the n-type SOI FinFETs with the multi-sub-band IRS model shows its very strong effect on electron transport in the device channel compared to the Ando's model. We have also found that the FinFETs are strongly affected by the IRS in the ON-region. The limiting effect of the IRS significantly increases as the Fin width is reduced. The FinFETs with [Formula: see text] channel orientation are affected more by the IRS than those with the [Formula: see text] crystal orientation. Finally, Λ and [Formula: see text] are shown to affect the device performance similarly. A change in values by 30% (Λ) or [Formula: see text] ([Formula: see text]) results in an increase (decrease) of up to [Formula: see text] in the drive current.

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A trombose do seio dural é uma situação clínica rara, que resulta normalmente da complicação de processos infecciosos dos seios perinasais. Os sintomas e sinais são extremamente variados e inespecíficos sendo o diagnóstico feito através da ressonância magnética nuclear. Esse trabalho relata a ocorrência de trombose do seio dural em um paciente com idade pediátrica. Paciente com 10 anos de idade, sexo masculino, foi enviado ao serviço de urgência devido à diplopia e endotropia no olho esquerdo. No exame oftalmológico foi detectado papiledema bilateral, diplopia binocular e endotropia do olho esquerdo. Apresentava acuidade visual de 10/10 bilateralmente. Diante da suspeita de lesão ocupando espaço do sistema nervoso central, foi realizada ressonância magnética nuclear que confirmou o diagnóstico de TSD. Para avaliar a pressão intracraniana foi efetuada uma punção lombar com manometria, e esta demonstrou uma pressão intracraniana de 20mmHg (normal: <15mmHg). Perante isto a criança ficou internada para tratamento médico (enoxaparina de baixo peso molecular 1,5 mg/kg/dia subcutâneo (60 mg/dia), prednisolona 35 mg/dia oral e acetazolamida 250 mg/dia oral) durante 10 dias. Após 1 mês de follow-up verificou-se agravamento oftalmológico. A realização de nova punção lombar apresentou uma pressão intracraniana de 40 mmHg que não cedia ao tratamento médico. Após discussão multidisciplinar do caso optou-se pela realização de derivação lombo-peritoneal. A necessidade de uma grande dose de suspeição clínica, tanto para o diagnóstico inicial quanto para a monitorização das complicações, tornam a abordagem da trombose do seio dural um processo singular.

Dural sinus thrombosis is a rare condition, usually results from a late complication of an infection of the paranasal sinuses. The signs and symptoms are extremely varied and nonspecific, being the diagnosis made through magnetic resonance imaging. Ten-year-old male patient that was sent to our emergency department with left endotropia and diplopia. Ophthalmic examination was performed and showed papilledema with margin blurred right and left eye, binocular diplopia and left eye endotropia. Visual acuity was 10/10 bilaterally. Given the suspected space occupying lesion of the central nervous system, the MRI was performed and confirmed the diagnosis of DST. For evaluating the intracranial pressure (IP), a lombar puncture (LP) with manometry was carried out and revealed IP of 20 mmHg (normal values: <15mmHg). Towards this, the child’s was admitted for medical treatment (low molecular weight enoxaparin subcutaneous 1,5 mg/kg/day (60 mg/day), prednisolone 35 mg/per day and acetazolamide 250 mg/per day) over 10 days. After 1 month of follow-up there was deterioration of the ophthalmologic condition. A new LP was made and showed IP of 40 mmHg resilient to medical treatment. After multidisciplinary discussion of the case, it was decided for conducting lumboperitoneal shunt. The need for a great deal of suspicion for both the initial diagnosis and for monitoring complications make DST approach a special process.

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We are entering a new era of computing technology, the era of Internet of Things (IoT). An important element for this popularization is the large use of off-the-shelf sensors. Most of those sensors will be deployed by different owners, generally common users, creating what we call the Collaborative IoT. This collaborative IoT helps to increase considerably the amount and availability of collected data for different purposes, creating new interesting opportunities, but also several challenges. For example, it is very challenging to search for and select a desired sensor or a group of sensors when there is no description about the provided sensed data or when it is imprecise. Given that, in this work we characterize the properties of the sensed data in the Internet of Things, mainly the sensed data contributed by several sources, including sensors from common users. We conclude that, in order to safely use data available in the IoT, we need a filtering process to increase the data reliability. In this direction, we propose a new simple and powerful approach that helps to select reliable sensors. We tested our method for different types of sensed data, and the results reveal the effectiveness in the correct selection of sensor data.

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A trombose do seio cavernoso (TSC) é uma situação clínica rara, resultando normalmente da complicação de um processo infeccioso dos seios paranasais. Outras causas incluem alterações pró-trombóticas, anemia e trauma. Os sinais e sintomas são extremamente variados e inespecíficos, sendo o seu diagnóstico efetuado através de ressonância magnética nuclear (RMN). Os autores apresentam um caso clínico de uma doente com 75 anos de idade, que recorre ao serviço de urgência devido à dor em olho direito vermelho associado à cefaléias frontais com quatro dias de evolução. Ao exame oftalmológico observou-se defeito pupilar aferente relativo no olho direito (OD); na biomicroscopia vasos episclerais dilatados, catarata nuclear e à fundoscopia um edema discreto da papila com apagamento do rebordo nasal, hemorragias punctiformes dispersas e tortuosidade vascular em OD. A realização de angio-RMN confirmou o diagnóstico tendo a doente sido tratada com enoxaparina. Apesar do tratamento da TSC ser um tratamento etiológico, foi demonstrado que a anticoagulação está associada à diminuição da taxa de mortalidade.

Cavernous sinus thrombosis (CST) is a rare condition, usually results from a late complication of an infection of the paranasal sinuses. Other causes include prothrombotic disorders, anemia and trauma. The signs and symptoms are extremely varied and nonspecific, being the diagnosis made through magnetic resonance imaging (MRI). The authors present a 75-year-old woman, admitted in the emergency room complaining of ocular pain in the right eye (RE), red eye and frontal headache. She presented on ophthalmic examination of the RE: dilated episcleral vessels, nuclear cataract and a relative afferent pupillary defect. Fundoscopy examination of the RE revealed disc edema with nasal disc margin blurred, small dot hemorrhages and vascular tortuosity. The MRI angiography confirmed the diagnosis and the patient was treated with low molecular weight heparin. Despite treatment of CST is directed to the causal situation, being shown that anticoagulation is associated with reduction in mortality.

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The Internet of Things (IoT) is attracting considerable attention from the universities, industries, citizens and governments for applications, such as healthcare, environmental monitoring and smart buildings. IoT enables network connectivity between smart devices at all times, everywhere, and about everything. In this context, Wireless Sensor Networks (WSNs) play an important role in increasing the ubiquity of networks with smart devices that are low-cost and easy to deploy. However, sensor nodes are restricted in terms of energy, processing and memory. Additionally, low-power radios are very sensitive to noise, interference and multipath distortions. In this context, this article proposes a routing protocol based on Routing by Energy and Link quality (REL) for IoT applications. To increase reliability and energy-efficiency, REL selects routes on the basis of a proposed end-to-end link quality estimator mechanism, residual energy and hop count. Furthermore, REL proposes an event-driven mechanism to provide load balancing and avoid the premature energy depletion of nodes/networks. Performance evaluations were carried out using simulation and testbed experiments to show the impact and benefits of REL in small and large-scale networks. The results show that REL increases the network lifetime and services availability, as well as the quality of service of IoT applications. It also provides an even distribution of scarce network resources and reduces the packet loss rate, compared with the performance of well-known protocols.

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O Hemangioma racemoso da retina é uma malformação congênita caracterizada por comunicações arteriovenovas (AV) retinianas. Em cerca de 30 por cento dos casos pode haver manifestações a nível do sistema nervoso central (SNC), denominando-se então por Síndrome de Wyburn-Mason. Os autores apresentam um caso clínico de um doente do sexo masculino de 39 anos que recorre ao serviço de Urgência devido a diminuição da acuidade visual do olho esquerdo (OE) com cerca de seis dias de evolução.Apresenta melhor acuidade visual corrigida olho direito (OD): 4/10 e olho esquerdo (OE): 2/10.À fundoscopia apresenta disco óptico com limites indefinidos, alguma palidez, dilatação e tortuosidade, AV marcada bilateralmente. O hemangioma racemoso da retina é um diagnóstico clínico raro, efectuado por meio do exame oftalmológico. É importante verificar o envolvimento do SNC por meio da realização de angiorressonância magnética nuclear. Atualmente não existe nenhum tratamento preconizado, sendo importante a realização de observações periódicas para averiguação de eventuais complicações.

Racemose Haemangioma (RH) is a congenital anomaly, characterized by retinal arteriovenous(AV) malformation. About 30 percent of patients have signs of central nervous system (CNS) involvement, which has been called the Wyburn-Mason syndrome. The authors present a 39-year-old male patient, who was admitted at the emergency room with decreased visual acuity of his left eye, for the last 6 days. Ophthalmic examination was performed and showed a visual acuity of 4/10 in his right eye and of 2/10 in the left eye. Fundoscopy examination revealed pallor of both optic discs, with blurred limits and a characteristic dilation and AV connections. RH of retina is a rare entity which can be diagnosed by ophthalmic examination. Once this diagnosis is established, involvement of CNS has to be rulled out performing an angioMRI. Currently, no specific treatment has been defined, except a periodic follow-up to prevent complications.

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Wireless Sensor Networks are presented as devices for signal sampling and reconstruction. Within this framework, the qualitative and quantitative influence of (i) signal granularity, (ii) spatial distribution of sensors, (iii) sensors clustering, and (iv) signal reconstruction procedure are assessed. This is done by defining an error metric and performing a Monte Carlo experiment. It is shown that all these factors have significant impact on the quality of the reconstructed signal. The extent of such impact is quantitatively assessed.

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Routing is a basic function in wireless sensor networks (WSNs). For these networks, routing algorithms depend on the characteristics of the applications and, consequently, there is no self-contained algorithm suitable for every case. In some scenarios, the network behavior (traffic load) may vary a lot, such as an event-driven application, favoring different algorithms at different instants. This work presents a hybrid and adaptive algorithm for routing in WSNs, called Multi-MAF, that adapts its behavior autonomously in response to the variation of network conditions. In particular, the proposed algorithm applies both reactive and proactive strategies for routing infrastructure creation, and uses an event-detection estimation model to change between the strategies and save energy. To show the advantages of the proposed approach, it is evaluated through simulations. Comparisons with independent reactive and proactive algorithms show improvements on energy consumption.

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Con el objeto de conocer los factores que llevan a la adolescente a embarazarse, se realizó un estudio descriptibo, prospectivo, en 191 adolescentes de 17 años o menos, que acudieron a la Consulta Prenatal del adolescente, del Departamento de Obstetrica y Ginecología del Hospital "Antonio María Pineda", en Barquisimeto, y cuyos partos fueron atendidos por nuestro servicio (GO2), desde enero 1993 a enero 1994. La mayoría correspondieron a edades entre 16 y 17 años: 136 (71,2 por ciento) y las restantes 55 (28,8 por ciento) entre 13 y 15 años, con un promedio general de edad de 16,04 años. Del total de adolescentes, 168 (87,9 por ciento) son primigestas; 22 (11,5 por ciento) segundas gestas y 1 (0,5 por ciento) tercera gesta. El embarazo fue expresamente buscado en 89 (46,6 por ciento) de las adolescentes, mientras que 100 (52,4 por ciento) refirieron no haberlo buscado y 2 no respondió a la pregunta. En los aspectos socio-educativos, 109 (57,1 por ciento) no estudiaban al momento de salir embarazadas por primera vez, mientras que 80 (41,9 por ciento) si lo hacían; de estas últimas, 66 dejaron los estudios por el ambarazo y 14 continuaron a pesar de él. De las 23 segundas y terceras gestas, 19 no estudiaban al embarazarse y 4 si lo hacían. Las principales causas de retiro de la escolaridad fueron la falta de motivación hacia los estudios y el rechazo de la autoridad escolar a recibir embarazadas en el aula. La mayoría, 111 (58,1 por ciento) conocían de algún método anticonceptivo. Las espectativas al egresar del hospital son cuidar al hijo: 92 (37,2 por ciento); estudiar: 69 (27,9 por ciento) y trabajar: 31 (12,5 por ciento). 45 desean planificarse (18,2 por ciento) y 3 (1,6 por ciento) quieren tener otro hijo. 7 no sabían que responder. Se concluye que para que una política de prevención del embarazo en adolescentes tenga éxito, debe tener en cuenta la visión que estás tienen del embarazo actuando en base a la misma

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