Study of a Synchronization System for Distributed Inverters Conceived for FPGA Devices

In a multiple parallel-connected inverters system, limiting the circulating current phenomenon is mandatory since it may influence efficiency and reliability. In this paper, a new control method aimed at this purpose and conceived to be implemented on a Field Programmable Gate Array (FPGA) device is presented. Each of the inverters, connected in parallel, is conceived to be equipped with an FPGA that controls the Pulse-Width Modulation (PWM) waveform without intercommunication with the others. The hardware implemented is the same for every inverter; therefore, the addition of a new module does not require redesign, enhancing system modularity. The system has been simulated in a Simulink environment. To study its behavior and to improve the control method, simulations with two parallel-connected inverters have been firstly conducted, then additional simulations have been performed with increasing complexity to demonstrate the quality of the algorithm. The results prove the ability of the method proposed to limit the circulating currents to negligible values

Histamine neurons in the tuberomamillary nucleus: a whole center or distinct subpopulations?

Histamine axons originate from a single source, the tuberomamillary nucleus (TMN) of the posterior hypothalamus, to innervate almost all central nervous system (CNS) regions. This feature, a compact cell group with widely distributed fibers, resembles that of other amine systems, such as noradrenaline or serotonin, and is consistent with a function for histamine over a host of physiological processes, including the regulation of the sleep-wake cycle, appetite, endocrine homeostasis, body temperature, pain perception, learning, memory, and emotion. An important question is whether these diverse physiological roles are served by different histamine neuronal subpopulation. While the histamine system is generally regarded as one single functional unit that provides histamine throughout the brain, evidence is beginning to accumulate in favor of heterogeneity of histamine neurons. The aim of this review is to summarize experimental evidence demonstrating that histamine neurons are heterogeneous, organized into functionally distinct circuits, impinging on different brain regions, and displaying selective control mechanisms. This could imply independent functions of subsets of histamine neurons according to their respective origin and terminal projections

Distributed Access by Multiple Sources for Age of Information Minimization Over a Finite Horizon

Age of information (AoI) quantifies the freshness of updates in real time applications, such as vehicular networking or road traffic monitoring and control. This study explores the optimization of AoI over a finite horizon for multiple IoT devices independently tracking the same process of interest and reporting status updates. In this setting, the efficiency of distributed policies where sources probabilistically report their measurements is not adequate. Even assuming pre-defined rendez-vous transmission instants, if the choice about which one to utilize is left to the individual source, lack of coordination may arise, causing simultaneous transmissions (redundant and therefore inefficient) at times, and, consequently, other intervals where no node transmits. We investigate practical solutions to this problem inspired by random medium access techniques. Firstly, we introduce a protocol where no transmission instant is deserted thanks to carrier sensing. If no nodes choose to transmit, they all sense the channel as idle, and randomly revise their decision until at least one transmits. Subsequently, we explore an uneven spread of the transmission instants to balance the resulting scheduling. We measure the effectiveness of these improvements compared to full coordination. These techniques are shown to improve distributed policies by more than 20%, and in general offer valuable insights for future research on sensing in multi-source autonomic environments

Impact of Transmission Delays Over Age of Information Under Finite Horizon Scheduling

Sensor communications in real-time systems may be required to report status updates to minimize the so-called age of information metric, which quantifies the freshness of exchanged data. This situation can be heavily impacted by the delays in data transmission, as some updates may reach the destination when their information content is already stale. In this paper, we consider the problem of scheduling sensing updates over a finite time horizon, and discuss the impact of their transmission delay on the resulting data freshness. We tackle the adjustments required for an offline schedule aimed at minimizing the average age of information which, as long as they do not cause the updates to go off the boundaries of the finite horizon, are only dependent on the average transmission delay. We derive a closed form expression for the average age of information, also verified through simulations, and the resulting performance is evaluated under different system conditions. This can be used to further explore the task of delivering timely system updates under general scenarios, e.g., when the statistics of the delay is not known a priori, or under other non idealities

UTILIZAÇÃO DE VERMICOMPOSTO NO CRESCIMENTO DE MUDAS DE Hovenia dulcis Thunberg

Apesar de bem-adaptada ao Sul do Brasil, a Hovenia dulcis é pouco conhecida em nossas condições, principalmente na fase de viveiro. O presente estudo teve como objetivo avaliar o crescimento de mudas de Hovenia dulcis Thunberg sob o efeito de diferentes doses de vermicomposto. O delineamento experimental utilizado foi o inteiramente casualizado com 5 tratamentos e 4 repetições. Os tratamentos foram: Testemunha com 0% de vermicompsto, 10% de vermicomposto, 20% de vermicomposto, 30% de vermicomposto, 40% de vermicomposto, do volume total do tubete de 185 cm3. Decorridos 90 dias da semeadura, foram avaliados os parâmetros: diâmetro do colo, altura da parte aérea, massa seca aérea, massa seca radicular e massa seca total. As plantas de Hovenia dulcis responderam, de forma positiva, em todos os parâmetroas avaliados, à aplicação de vermicomposto. A dose mais indicada para produção de mudas de Hovenia dulcis é a de 40% de vermicomposto

Move Away from Me! User Repulsion Under Proximity-Induced Interference in OWC Systems

As communication systems shift towards ever higher frequency bands, the propagation of signal between a user device and an infrastructure becomes more susceptible to nearby obstacles including other users. As an extreme case, we consider such proximity-induced channel impairments in indoor optical wireless communication (OWC) systems. We set up a model, where the achievable OWC data rate depends not only on the relative position between a user device and an infrastructure access point, but also on the location of other users modeled as proximal interferers. We use a reinforcement learning (RL) approach to enable users to find suitable positions, both relative to the access point and to each other, that maximise the sum- rate capacity of the system. Our initial results demonstrate a feasibility of RL-based approach that enables indoor OWC users to find suitable balance between establishing high-rate direct link while remaining distant from proximal interferers

Memory discrimination is promoted by the expression of the transcription repressor WT1 in the dentate gyrus

The hippocampus is critical for the precise formation of contextual memories. Overlapping inputs coming from the entorhinal cortex are processed by the trisynaptic pathway to form distinct memories. Disruption in any step of the circuit flow can lead to a lack of memory precision, and to memory interference. We have identified the transcriptional repressor Wilm’s Tumor 1 (WT1) as an important regulator of synaptic plasticity involved in memory discrimination in the hippocampus. In male mice, using viral and transgenic approaches, we showed that WT1 deletion in granule cells of the dentate gyrus (DG) disrupts memory discrimination. With electrophysiological methods, we then identified changes in granule cells’ excitability and DG synaptic transmission indicating that WT1 knockdown in DG granule cells disrupts the inhibitory feedforward input from mossy fibers to CA3 by decreasing mIPSCs and shifting the normal excitatory/inhibitory (E/I) balance in the DG → CA3 circuit in favor of excitation. Finally, using a chemogenetic approach, we established a causal link between granule cell hyperexcitability and memory discrimination impairments. Our results suggest that WT1 enables a circuit-level computation that drives pattern discrimination behavior

The Gaia mission

Gaia is a cornerstone mission in the science programme of the EuropeanSpace Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach. Both the spacecraft and the payload were built by European industry. The involvement of the scientific community focusses on data processing for which the international Gaia Data Processing and Analysis Consortium (DPAC) was selected in 2007. Gaia was launched on 19 December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. The commissioning of the spacecraft and payload was completed on 19 July 2014. The nominal five-year mission started with four weeks of special, ecliptic-pole scanning and subsequently transferred into full-sky scanning mode. We recall the scientific goals of Gaia and give a description of the as-built spacecraft that is currently (mid-2016) being operated to achieve these goals. We pay special attention to the payload module, the performance of which is closely related to the scientific performance of the mission. We provide a summary of the commissioning activities and findings, followed by a description of the routine operational mode. We summarise scientific performance estimates on the basis of in-orbit operations. Several intermediate Gaia data releases are planned and the data can be retrieved from the Gaia Archive, which is available through the Gaia home page. http://www.cosmos.esa.int/gai

Evaluation of the effect of Hypericum caprifoliatum Cham. & Schltdl lipophilic extract on the extracellular levels of dopamine and its metabolites by cerebral microdialysis in freely moving rats

OBJETIVO: Desenvolver e validar a técnica de CLAE-DE para o doseamento de dopamina (DA), ácido diidrofenilacético (DOPAC), ácido homovanílico (HVA) e 3-metoxitiramina (3-MT); validar a técnica de microdiálise (MD) cerebral em animais conscientes e avaliar o efeito do tratamento agudo com um extrato lipofílico das partes aéreas de Hypericum caprifoliatum (HCP) sobre os níveis cerebrais de DA e seus metabólitos. MATERIAIS E MÉTODOS: A validação analítica foi realizada conforme o preconizado pela ANVISA, com análise dos parâmetros linearidade, precisão, exatidão, especificidade e limite inferior de quantificação. A técnica de microdiálise foi realizada de forma clássica: guias de sonda foram implantadas nas regiões cerebrais de interesse por cirurgia estereotáxica; os dialisados foram obtidos, 48 horas após a cirurgia, através da perfusão da sonda com líquido cérebroespinhal artificial (1 μL/min) e coleta durante três horas, em intervalos de 20 min; as três primeiras coletas foram utilizadas para determinação da linha de base e só então foram administrados os tratamentos. Para a validação da MD a sonda foi implantada no estriado (A: -0,3; L: + 3,2; P: - 4,5) e o tratamento foi sulfato de anfetamina (2 mg/kg, s.c.). Para a avaliação do efeito de HCP, a sonda foi implantada no núcleo acumbens (A: +2,2; L: -1,5; P: -5,8) e o tratamento foi uma dose de 270 mg/kg do extrato (v.o.). RESULTADOS E DISCUSSÃO: Os parâmetros avaliados para validar o método analítico ficaram dentro dos limites especificados pela ANVISA. O sulfato de anfetamina produziu um aumento nos níveis extracelulares de DA em 160% e uma redução de DOPAC e de HVA em 80% e 50%, respectivamente. O extrato HCP não alterou o conteúdo intersticial de DA, DOPAC e HVA no núcleo acumbens. Os valores basais encontrados estão de acordo com dados relatados na literatura. Não foi possível quantificar 3-MT. CONCLUSÃO: A metodologia analítica e as condições experimentais de microdiálise utilizadas permitiram a mensuração de mudanças induzidas por anfetamina nos níveis extracelulares de DA e seus principais metabólitos demonstrando que os fundamentos da técnica estão estabelecidos em nossas condições. O regime de tratamento empregado com HCP não foi suficiente para alterar os níveis de DA e seus principais metabólitos no núcleo acumbens de ratos.OBJECTIVE: The objectives of this work were to validate the HLPC-ED technique for measuring dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 3- methoxytyramine (3-MT); to put into operation the brain microdialysis technique (MD) in freely moving rats; to evaluate, by using MD, the effect of a single treatment with lipophilic extract from aerial parts of Hypericum caprifoliatum (HCP) on DA, DOPAC, HVA and 3-MT brain levels. MATERIALS AND METHODS: In order to validate the analytical technique we followed the parameters established by ANVISA for bioanalytical samples. The parameters were: precision, accuracy, specificity and also the lower limit of quantitation. The microdialysis technique was carried out following classical procedures: male Wistar rats were submitted to stereotaxic surgery for the guide cannula implantation in the brain regions of interest; 48 hours later, the microdiaysis probe was inserted and perfused with cerebrospinal fluid (1 μL/min). After baseline samples collecting (1 h), the treatments were administrated and samples were collected every 20 min, during 2h. To accomplish MD technique validation the animals were treated with amphetamine sulfate (2 mg/kg, s.c.) and the extracellular levels of DA, DOPAC e HVA were measured in striatum (A: -0,3; L: + 3,2; P: - 4,5). The effect of HCP acute treatment (270 mg/kg, p.o.) was evaluated in nucleus accumbens (A: +2,2; L: -1,5; P: -5,8). RESULTS AND DISCUSSION: The analytical parameters values found were within the acceptable ranges for bio-analytical limits specified by ANVISA. As expected, amphetamine sulfate administration significantly increased DA (160%) extracellular levels and decreased DOPAC (80%) and HVA (50%) levels. The quantification of 3-MT was not possible. Acute HCP administration did not affected DA, DOPAC and HVA levels in the nucleus accumbens. CONCLUSION: The HPLC-ED methodology and microdialysis procedures employed allowed the detection of amphetamineinduced changes in extracellular levels of DA and its metabolites demonstrating that the technical starting point was acceptable. The acute administration of 270 mg/kg, p.o. of HCP to rats was not sufficient to modify the extracellular levels of DA, DOPAC and HVA in the nucleus accumbens