An easy procedure for calibrating data acquisition systems using interleaving

Interleaving data acquisition channels is a well-known and interesting technique to achieve higher acquisition rates. However, to obtain the expected benefits, a careful look at the interleaving technique and to mismatches that can lead to unwanted harmonic distortion and noise is essential. In this paper we discuss the methods used to interleave existing high-speed, 250 MSPS 8-bit acquisition channels, and the results obtained. The methods presented allowed a good relative channel calibration in amplitude (amplitude mismatch under 0.1 lsb) and in time (time mismatch between acquisition channels in the ps range, under the specified maximum jitter for the ADC used). A dynamic, by software, amplitude level signal-dependent adjustment procedure is also suggested for signals with rich frequency content that can substantially improve the quality of the acquired signal when using interleaved channels. The techniques presented provide good results even in the presence of noise.info:eu-repo/semantics/publishedVersio

Shintani descent for standard supercharacters of algebra groups

Let $\mathcal{A}(q)$ be a finite-dimensional nilpotent algebra over a finite field $\mathbb{F}_{q}$ with $q$ elements, and let $G(q) = 1+\mathcal{A}(q)$. On the other hand, let $\Bbbk$ denote the algebraic closure of $\mathbb{F}_{q}$, and let $\mathcal{A} = \mathcal{A}(q) \otimes_{\mathbb{F}_{q}} \Bbbk$. Then $G = 1+\mathcal{A}$ is an algebraic group over $\Bbbk$ equipped with an $\mathbb{F}_{q}$-rational structure given by the usual Frobenius map $F:G\to G$, and $G(q)$ can be regarded as the fixed point subgroup $G^{F}$. For every $n \in \mathbb{N}$, the $n$th power $F^{n}:G\to G$ is also a Frobenius map, and $G^{F^{n}}$ identifies with $G(q^{n}) = 1 + \mathcal{A}(q^{n})$. The Frobenius map restricts to a group automorphism $F:G(q^{n})\to G(q^{n})$, and hence it acts on the set of irreducible characters of $G(q^{n})$. Shintani descent provides a method to compare $F$-invariant irreducible characters of $G(q^{n})$ and irreducible characters of $G(q)$. In this paper, we show that it also provides a uniform way of studying supercharacters of $G(q^{n})$ for $n \in \mathbb{N}$. These groups form an inductive system with respect to the inclusion maps $G(q^{m}) \to G(q^{n})$ whenever $m \mid n$, and this fact allows us to study all supercharacter theories simultaneously, to establish connections between them, and to relate them to the algebraic group $G$. Indeed, we show that Shintani descent permits the definition of a certain ``superdual algebra'' which encodes information about the supercharacters of $G(q^{n})$ for $n \in \mathbb{N}$

Avaliação de serviços de ecossistema de conservação do solo associados a processos erosivos

Estudos recentes mostram a necessidade de incorporar os conceitos de serviços de ecossistema e de sistemas sócio-ecológicos nos processos de planeamento e gestão dos espaços naturais. Esta necessidade reflete não só a importância dos ecossistemas, e dos serviços que lhes estão associados, para o sucesso dos processos de planeamento, mas também a relevância da implementação de estudos interdisciplinares que acrescentem conhecimento na avaliação das interações entre Homem e Natureza. Neste contexto, foram desenvolvidos um conjunto de trabalhos que pretendem, em zonas bastante distintas em termos climáticos e de ocupação e gestão do solo (i.e. Alto‐Minho [NO de Portugal] e Portel [SE de Portugal]), mostrar a aplicação e a importância da avaliação de serviços de ecossistema para a condução dos processos de planeamento local, definição de estratégias de gestão da terra e definição de políticas de investimento e regulamentação das atividades em espaço rural. A utilização de técnicas de detecção remota, assim como de um modelo conceptual orientado à identificação e quantificação de serviços de ecossistema associados à proteção do solo,permitem-­‐nos inferir por um lado, quais as estratégias de gestão da terra mais adequadas à provisão deste serviço, identificando assim limiares de gestão adequados, e por outro, quais as necessidades de planeamento e regulamentação à escala regional. Sendo o solo o elemento central do desenvolvimento local e regional, os resultados obtidos evidenciam o valor dos serviços de ecossistema associados à proteção do solo e a necessidade de definir novos planos e estratégias de gestão da terra que contribuam para a mitigação dos riscos associados à erosão do solo não só à escala local, como à escala regional

The design of a digital coincidence-detection trigger system for a RPC-based pet

A complex task for PET cameras is the design of an appropriate coincidence-detection trigger as it usually encompasses coincidences in a large number of channels and tight time specifications. Those requirements are even greater for a resistive plate chamber (RPC)-based detector technology as the time window specification is quite small (in the order of a few hundred picoseconds) and the number of coincidence-channels can be quite large (more than 100 in a large camera). In this work we discuss on-going work aimed at implementing the coincidence-detection algorithm inside a FPGA along with the necessary TDCs. The use of the developed solution in a first prototype of an RPC-based small animal PET and its scalability to the case of a human, all-body, PET, is discussed.info:eu-repo/semantics/publishedVersio

Core and patch position optimizations for vibration control of piezolaminated structures

This paper deals with a finite formulation baserd on the classical laminated plate tehory, for active control of thin late laminated structures with integrated piezoelectric layers, acting as sensors and actuators. The control is initialized through a previuos optimization of the core of the laminated structure, in order to minimize the vibration amplitude. Also the optimization of the patches position in performed to maximize the piezoelectric actuator efficiency. the simulating annealing mthod is used for these purposes. The finite element model is a single layer triangular nonconforming plate/shell element with 18 degrees of fredom for the generalized displacements, and one electrical potential degree of freedom for each piezoelectric element layer, wich can be surface bonded or imbedded on the laminate. To achieve a mechanism of active control of the structure dynamic response, a feedback control algorirhm is used, coupling the sensor and active piezoelectric layers. To calculate the dynamic response of the laminated structures the Newmark method is considered. The model is applied in the solution of an illustrative case and the results are presented and discussed

A 2.4-GHz wireless sensor network for smart electronic shirts integration

A typical sensing module is composed of sensors, interface electronics, a radio-frequency (RF) CMOS transceiver and an associated antenna. A 2.4-GHz RF transceiver chip was fabricated in a UMC 0.18 μm CMOS process. The receiver has a sensibility of -60 dBm and consumes 6.3 mW from a 1.8 V supply. The transmitter delivers an output power of 0 dBm with a power consumption of 11.2 mW. Innovative topics concerning efficient power management was taken into account during the design of the transceiver. A solution of individual sensing modules allows a plug-and-play solution. The target application is the integration of a wireless sensor network in smart electronic shirts, for monitoring the cardio-respiratory function and posture

Effects of the ESD protections in the behavior of a 2.4 GHz RF transceiver: problems and solutions

This paper identifies the main problems related to the Electrostatic Discharge (ESD) in submicron CMOS processes. The mitigation of this problem is made with the use of protections, in order to avoid the destruction of the internal and input/output circuits connected to the bondingpads. In the 2.4 GHz ISM band, the parallel capacitance and the serial resistance of the ESD protections have effects in the behavior of RF transceivers. The major identified effect was the transmission range. It is proposed two strategies to solve the secondary effects, due to the protections. All the measurements and simulations were made for a 2.4 GHz RF CMOS transceiver, designed and fabricated using the UMC 0.18 μm RF CMOS process

Biochar and zeolites did not improve phosphorus uptake or crop productivity in a field trial performed in an irrigated intensive farming system

Soil conditioners, such as biochar and zeolites, may play an important role in agriculture if they increase nutrient use efficiency, in particular, that of phosphorus (P), due to the depletion of phosphate rocks from which P-fertilizers are manufactured. This study report results from a field trial, where maize was grown in summer and oats in winter, and from a pot experiment with maize. In the field, the use of biochar and zeolites, along with an untreated control in combination with various P rates (0, 50, 100 and 200 kg P2O5 ha−1), was tested. In the pot experiment, six treatments were included, biochar, zeolites and a non-amended control with and without P application. Soil conditioners did not significantly influence tissue elemental composition or the dry matter (DM) yield of maize and oats in the field trial, nor the DM yield of maize in the pots. In the field trial, average maize DM yields varied from 14.3 to 15.6 t ha−1 and 11.8 to 13.7 t ha−1 and average oats DM yields from 2.1 to 2.4 t ha−1 and 3.0 to 3.2 t ha−1, respectively, in 2018 and 2019. Biochar only significantly increased total organic carbon (C); and zeolites the levels of potassium (K) in the soil, a result of their initial composition. P application increased DM yield of maize in the second year and oats in the two years of the field trial and also the DM yield of potted maize. In the pots, P application also influenced the concentration of P and several other nutrients in plant tissues and increased the labile soil P fraction. This study showed that the biochar and zeolite soil conditioners applied may not be suitable for short-term increase of crop production in soil with high agricultural potential and under intensive irrigated farming systems.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and European Regional Development Fund (ERDF) under Programme PT2020 for financial support to Centro de Investigação de Montana (CIMO) (UID/AGR/00690/2015) and Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB) (UIDB/04033/2020).info:eu-repo/semantics/publishedVersio

Hepatocytes and IL-15: A Favorable Microenvironment for T Cell Survival and CD8+ T Cell Differentiation

Human intrahepatic lymphocytes are enriched in CD1d-unrestricted T cells coexpressing NKR. Although the origin of this population remains controversial, it is possible to speculate that the hepatic microenvironment, namely epithelial cells or the cytokine milieu, may play a role in its shaping. IL-15 is constitutively expressed in the liver and has a key role in activation and survival of innate and tissue-associated immune cells. In this in vitro study, we examined whether hepatocyte cell lines and/or IL-15 could play a role in the generation of NK-like T cells. The results show that both HepG2 cells and a human immortalized hepatocyte cell line increase survival and drive basal proliferation of T cells. In addition, IL-15 was capable of inducing Ag-independent up-regulation of NKR, including NKG2A, Ig-like receptors, and de novo expression of CD56 and NKp46 in CD8(+)CD56(-) T cells. In conclusion, our study suggests that hepatocytes and IL-15 create a favorable microenvironment for T cells to growth and survive. It can be proposed that the increased percentage of intrahepatic nonclassical NKT cells could be in part due to a local CD8(+) T cell differentiation.This work was supported by grants from the American Portuguese Biomedical Research Fund (Inova Grant) and from ISCSN-CESPU (Grants CESPU 1F/05/2005 and CESPU 2F/03/2006). M.P.C. was supported by a fellowship from Fundação para a Ciência e a Tecnologia (SFRH/BD/24396/2005)