Thermal Noise-Boosting Effects in Hot-Wire-Based Micro Sensors

This article proposes an original approach aimed at modelling the noise density in sensors based on a single hot wire or pairs of thermally coupled wires. The model consists in an original combination of a previous electrothermal model of the wire with well-established assumptions on the thermal noise in conductors that carry moderate current densities. A simple method for estimating the model parameters with simple impedance spectroscopy is suggested. The predicted power spectral densities of the wire thermal noise differ from the result of previously presented analytical models, stimulating further experimental studies. The effects of the electrothermal feedback of both hot wires and hot-wire pairs on flicker noise is also intrinsically covered by the proposed approach

Antioxidant and Mineral Composition of Three Wild Leafy Species : A Comparison Between Microgreens and Baby Greens

Wild plants may play an important role in human nutrition and health and, among them, many are the leafy species. We hypothesized that the wild greens could be profitably grown as microgreens and baby greens, specialty products whose market is increasing. We compared three wild leafy species (Sanguisorba minor Scop., Sinapis arvensis L., and Taraxacum officinale Weber ex F. H. Wigg.) harvested at the microgreen and baby green stages. Seedlings were grown hydroponically in a half-strength Hoagland nutrient solution under controlled climatic conditions. At harvest, the yield was assessed, and chlorophylls, carotenoids, anthocyanins, phenolic index, nitrate, and mineral elements were measured in the two types of product. The potential contribution to human mineral intake was calculated, and the possible risk due to the presence of metals potentially detrimental for health was estimated. Results showed that micro/baby greens of the studied wild plants achieved competitive yields and could contribute to the dietary intake of macroelements, microelements, and non-nutrient bioactive compounds. On the other hand, the wild greens showed high amounts of nitrate and traces of some metals potentially detrimental for health, suggesting the need for caution in the use of wild species for producing microgreens and baby leaves

Performance Analysis of a Compact UHF RFID Ceramic Tag in High-Temperature Environments

In this paper an experimental analysis of the effect of high temperature on the performance of a compact UHF RFID tag is described and discussed. The tag is designed to be integrated into small cavities carved out of metal objects to identify themselves during the entire fabrication and assembly line. Since the UHF RFID tag is applied just after the die casting operations needed to model the metal component, it must be robust to high temperature manufacturing environments and processes. Tests demonstrated a significant chip input impedance variation by increasing the surrounding temperature, with a consequent read-range reduction. However, the considered ceramic tag can be detected at a satisfactory distance of 30 cm when employed with temperatures so high as up to 120 degrees C

A two-stage switched-capacitor integrator for high gain inverter-like architectures

A discrete-time, switched capacitor integrator is presented. The integrator is based on a two-stage architecture where the first stage converts the input voltage into a charge that is accumulated into the second stage. The main strength of the proposed circuit is a higher dc gain with respect to previous solutions, making it optimal for low-voltage inverter-like integrators. A further advantage is the fact that, in contrast with existing solutions, the output voltage is valid across the whole clock cycle. Theoretical analysis of the circuit is performed to calculate the dependence of the integrator dc gain and input-referred offset voltage on the corresponding parameters of the constituting amplifiers. Discrete-time simulations are performed to estimate the gain and phase error with respect to an ideal integrator. The results of electrical simulations performed on an inverter-like prototype, designed with the UMC 0.18-μm CMOS process, are presented to show the impact of non-idealities from the amplifiers and switches

Performance analysis and design optimization of parallel-type slew-rate enhancers for switched-capacitor applications

The design of single-stage OTAs for accurate switched-capacitor circuits involves challenging trade-offs between speed and power consumption. The addition of a Slew-Rate Enhancer (SRE) circuit placed in parallel to the main OTA (parallel-type SRE) constitutes a viable solution to reduce the settling time, at the cost of low-power overhead and no modifications of the main OTA. In this work, a practical analytical model has been developed to predict the settling time reduction achievable with OTA/SRE systems and to show the effect of the various design parameters. The model has been applied to a real case, consisting of the combination of a standard folded-cascode OTA with an existing parallel-type SRE solution. Simulations performed on a circuit designed with a commercial 180-nm CMOS technology revealed that the actual settling-time reduction was significantly smaller than predicted by the model. This discrepancy was explained by taking into account the internal delays of the SRE, which is exacerbated when a high output current gain is combined with high power efficiency. To overcome this problem, we propose a simple modification of the original SRE circuit, consisting in the addition of a single capacitor which temporarily boosts the OTA/SRE currents reducing the internal turn-on delay. With the proposed approach a settling-time reduction of 57% has been demonstrated with an SRE that introduces only a 10% power-overhead with respect of the single OTA solution. The robustness of the results have been validated by means of Monte-Carlo simulations

Taxa de concepção de cabras inseminadas com sêmen caprino resfriado a 5°C, por 12 ou 24 horas, em meio diluidor à base de gema de ovo.

Avaliou-se a capacidade fecundante do sêmen caprino resfriado a 5°C, por 12 (TI) ou 24 horas (TII), em container especial. Para tanto, utilizaram-se 62 fêmeas e dois reprodutores (B1 e B2) da raça Toggenburg, distribuídos em um esquema fatorial 2x2 (dois reprodutores e dois períodos de estocagem do sêmen). Após a coleta, o sêmen foi diluído em Tris-frutose-gema de ovo a 2,5%, envasado em palhetas de 0,25mL, com 150x106 espermatozoides móveis e resfriado a 5oC. As fêmeas receberam duas doses de 22,5µg de PGF2a, em intervalos de 10 dias para a sincronização do estro. A partir da primeira aplicação de PGF2a, as fêmeas foram monitoradas para ocorrência de estro, três vezes ao dia. Realizou-se uma única inseminação, pela técnica de fixação da cérvice, 12 horas após o início do estro. A motilidade e o vigor, após 12 ou 24 horas de resfriamento, foram de 66,14±0,11% e 62,50±0,05%, e 3,46±0,61 e 3,27±0,50, respectivamente. Não houve influência (P>0,05) do reprodutor, nem do período de armazenamento do sêmen sobre a taxa de concepção das cabras, que foi de 49,1%. Conception rate of goats inseminated with semen cooled in egg yolk diluent at 5 degrees C, for 12 or 24 hours. Abstract: The fertilizing capacity of goat semen cooled in egg yolk diluent at 5 degrees C, for 12 or 24 hours was evaluated. Sixty-two Toggenburg does and two sexually mature Toggenburg bucks were used in a fatorial treatment combination (two bucks and two storage periods). The semen was diluted in 2.5% Tris-frutose-egg yolk; envased in 0.25mL plastic straws, with 150x10(6) mobile spermatozoa; and cooled at 5 degrees C for 12 or 24 hours. The females received two doses of 22.5 mu g of prostaglandine F2 alpha, at each 10-day intervals in order to synchronize the estrous. From the first PGF2 alpha injection, estrous occurrence was monitored three times per day. Only one insemination was used, using the cervix fixation method, 12 hours after the estrous onset. The means of motility and strength, 12 (TI) and 24 hours (TII) after semen cooling at 5 degrees C, were 66.14 +/- 0.11% and 62.50 +/- 0.05%, and 3.46 +/- 0.61 and 3.27 +/- 0.50, respectively. Neither the sire nor the period of semen influenced (P>0.05) the conception rate of the does, which was 49.1%

Progesterona plasmática e fertilidade de fêmeas caprinas submetidas à sincronização do estro com prostaglandina F2?.

Resumo: Avaliou-se a resposta ao protocolo de sincronização do estro com duas doses de prostaglandina F2 (22,5µg) intervaladas de 10 dias, por meio da mensuração da concentração de progesterona plasmática, bem como a taxa de concepção das cabras após a inseminação artificial, de acordo com as diferentes respostas obtidas. Utilizaram-se 23 fêmeas e dois reprodutores da raça Toggenburg. A mensuração da progesterona plasmática foi realizada no dia da primeira aplicação de PGF2? (D0), no D5, no dia da segunda aplicação de PGF2? (D10), no D15, no D20 e no D33. A resposta positiva à PGF2? foi determinada pela queda da concentração de progesterona a valores abaixo de 1,5ng/mL, mensurada nos dias cinco e 15. As fêmeas foram distribuídas em três grupos. O grupo I foi composto por fêmeas que responderam às duas aplicações; o grupo II por fêmeas que não responderam à primeira aplicação e responderam à segunda aplicação; e o grupo III por fêmeas que responderam à primeira aplicação e não responderam à segunda aplicação, foram inseminadas e não conceberam. A presença de um corpo lúteo funcional, no momento das aplicações, determinou a resposta ao protocolo. As diferentes respostas das fêmeas ao protocolo, grupo I e II, não influenciaram as taxas de concepção. Plasmatic progesterone and fertility of goats submitted at estrus synchronization with Prostaglandin F2?. Abstract: Plasmatic progesterone concentrations were evaluated during the synchronization protocol with two doses of 22.5µg of Prostaglandin F2?, 10-day interval, and the conception rate of females in accordance to the reply to the protocol. Twenty-three female goats and two sexually mature Toggenburg bucks were used. Blood was sampled on day 0 (1st PGF2? injection), and on the following days 5, 10 (2nd PGF2? injection), 15, 20, and 33. The positive reply to the PGF2? was determined when the progesterone concentrations fell to values below 1.5ng/mL at days 5 and 15. The females were divided in three groups: Group I: females that responded to the two PGF2? applications; Group II: females that responded only to the second application; Group III: females that responded the first application, did not respond to the second application, were inseminated but did not conceive. The presence of a functional corpus luteum at the moment of the applications determined the reply to the protocol. There was no difference in the conception rates between females that responded to the two PGF2? applications or responded only to the second application

Non-Local Matrix Generalizations of W-Algebras

There is a standard way to define two symplectic (hamiltonian) structures, the first and second Gelfand-Dikii brackets, on the space of ordinary linear differential operators of order $m$, $L = -d^m + U_1 d^{m-1} + U_2 d^{m-2} + \ldots + U_m$. In this paper, I consider in detail the case where the $U_k$ are $n\times n$-matrix-valued functions, with particular emphasis on the (more interesting) second Gelfand-Dikii bracket. Of particular interest is the reduction to the symplectic submanifold $U_1=0$. This reduction gives rise to matrix generalizations of (the classical version of) the {\it non-linear} $W_m$-algebras, called $V_{m,n}$-algebras. The non-commutativity of the matrices leads to {\it non-local} terms in these $V_{m,n}$-algebras. I show that these algebras contain a conformal Virasoro subalgebra and that combinations $W_k$ of the $U_k$ can be formed that are $n\times n$-matrices of conformally primary fields of spin $k$, in analogy with the scalar case $n=1$. In general however, the $V_{m,n}$-algebras have a much richer structure than the $W_m$-algebras as can be seen on the examples of the {\it non-linear} and {\it non-local} Poisson brackets of any two matrix elements of $U_2$ or $W_3$ which I work out explicitly for all $m$ and $n$. A matrix Miura transformation is derived, mapping these complicated second Gelfand-Dikii brackets of the $U_k$ to a set of much simpler Poisson brackets, providing the analogue of the free-field realization of the $W_m$-algebras.Comment: 43 pages, a reference and a remark on the conformal properties for $U_1\ne 0$ adde

Should "migralepsy" be considered an obsolete concept? A multicenter retrospective clinical/EEG study and review of the literature.

The few reports that have been published on the current International Classification of Headache Disorders, Second Edition (ICHD-II), criteria for migralepsy and hemicrania epileptica have highlighted the considerable confusion regarding this "hot topic" within both headache and epilepsy classifications (ICHD-II and International League Against Epilepsy [ILAE]). Indeed, the ICHD-II describes a migraine-triggered seizure as a rare event in which a seizure occurs during migraine aura; on the other hand, hemicrania epileptica is described as an "ictal headache" that occurs "synchronously" with a partial seizure. To confuse matters even further, neither the term migralepsy nor the term hemicrania epileptica is included in the currently used ILAE classification. On the basis of both a review of "migralepsy" cases in the literature and 16 additional retrospective multicenter cases, we suggest that the term migraine-triggered seizure or migralepsy be deleted from the ICHD-II classification until unequivocal evidence is provided of its existence, and that the term ictal epileptic headache be introduced into the ILAE classification