1,721,059 research outputs found
Sensors and Measurements Design Optimization: Revisiting Resolution from Information Theory Viewpoint
No full textThe concept of resolution is fundamental to any sensing or measurement system, as it establishes a reference for the intrinsic detection limit of any acquisition process. Although this concept originally emerged in the context of DC measurements, it should be more clearly defined in a generic acquisition system, where the signal is inherently stochastic. This article revisits the sensing and measurement process through the lens of information theory, where resolution is considered in relation to the distributions of random variables. In addition, it will introduce a new parameter, the "number of resolution levels (NL)," which is valuable because it encapsulates the amount of information conveyed by a measurement system. The results demonstrate that how this framework can address key design questions, such as determining the optimal discretization for an analog-to-digital (A/D) converter given input-referred noise from a transducer, and how to optimize the system from a resolution perspective. Theoretical results will be compared with numerical simulations of an analog noisy interface coupled with an A/D converter
Dehydroepiandrosterone decreases the age-related decline of the in vitro fertilization outcome in women younger than 40 years old
No full textWith infertility populations rapidly aging, treatments improving pregnancy chances assume increasing clinical importance. Dehydroepiandrosterone (DHEA) has been reported to improve pregnancy rates and lower miscarriage rates in women with diminished ovarian function. This study was planned to evaluate whether pretreatment with DHEA may improve in vitro fertilization (IVF) parameters and pregnancy outcomes in infertile women with advanced reproductive age and normal ovarian reserve. Methods: In this double-blind, randomized, placebo-controlled study, 109 infertile patients aging 36-40 years old were selected to undergo the long protocol IVF. Eight weeks before starting the IVF cycle and during treatment, patients in Group 1 received 75 mg of DHEA once a day; patients in control group (Group 2) received placebo. The primary endpoint of the study was number of clinical pregnancy, live birth and miscarriage rates; secondary endpoint was modification of standard IVF parameters, including stimulation duration (days of rhFSH administration), E2 on HCG-day, endometrial thickness, number of retrieved oocytes, metaphase II oocytes, number of transferred embryos and score of leading embryos transferred. Results: Patients in the DHEA group had a significantly higher live birth rate compared with controls (P < 0.05). Conversely, miscarriage rate was higher for patients in the control group (P < 0.05). Conclusions: DHEA supplementation may significantly improve IVF outcomes in infertile women with advanced reproductive age and normal ovarian reserve
Novel Measurement Method for Air-Data System Based on Strip Sensors: Experimental Results
No full textWe report the first experiments performed in a wind tunnel to validate a novel measurement equipment, meant to be used in the air-data system of small aircrafts. The apparatus does not rely on conventional probes, but takes advantage of capacitive, strip pressure sensors that enable a survey of the pressure gradients on portions of the aircraft surfaces. Sensors are built by printed circuit board (PCB) technologies as conformable film-like structures that can be directly applied on the aircraft skin. They can read gradients thanks to the many elementary units present in each strip. The measurement equipment employs pressure-gradient information to indirectly infer the aircraft air speed and angle of attack. In the experiments, measurements are taken in a wind tunnel using a NACA0015 model airfoil hosting a single sensor and results confirm the ability of the system to correctly detect the target quantities
Antimicrobial prophylaxis for vaginal hysterectomy: comparison of two regimens.
No full textA randomized trial has been performed to evaluate the efficacy of two antibiotic regimens as a prophylaxis for vaginal hysterectomy. The results, especially in terms of microbiological characteristics of the local population, are then discussed
Non-Destructive Assessment of Kiwifruit Flesh Firmness by a Contactless Waveguide Device and Multivariate Regression Analyses
Full text linkNon-destructive and cheap methods to evaluate the slow ripening process with possible on-line applications are highly required by the industry to enhance critical post-harvest management. After a brief review of the literature, we present the potentiality of an electronic contactless device for the non-destructive assessment of the Magness-Taylor flesh firmness (Mtf) of Hayward kiwifruits. The technique combines spectral information acquired in the microwave range by an open-ended aluminum waveguide containing TX and RX antennas, placed above the sample, with the features of the multivariate analysis. The electronic controller comprises a VCO, a low noise amplifier, a gain-phase comparator, and a serial interface governed by an MCU. Partial Least Squares regression analysis (PLS) was used to build predictive models starting from gain and phase waveforms raw data in the 947-1900 MHz frequency range. The main results evidenced that explored spectra variability is related to changes occurring in the fruit during the maturity process and particularly to the cell wall degradation. PLS regression models show, in prediction, R2 values of 0.726 (RMSE = 5 N) for the estimation of the Mtf starting from gain waveforms. A lower accuracy was observed for the model setup by considering phase waveforms. These results demonstrate that the proposed non-invasive solution combined with the PLS is a grounded starting point for estimating kiwifruit firmness with an acceptable level of accuracy
Relationship between some maternal haemato-clinical parameters and low neonatal weight. Preliminary study
No full textIn a selected group of pregnant women we studied the influence of specific haematoclinical maternal factors (age, pre-pregnancy weight, pregnancy weight gain, blood pressure, haematocrit (HTC), haemoglobinaemia (Hb), platelets (PTL), uricaemia) on neonatal weight. The results show an association among pre-pregnancy low maternal weight, hypertension and low neonatal weight. The uricaemia behaviour and the role of PTL, Hb, HCT are uncertain
Kiwifruit flesh firmness determination by a NIR sensitive device and image multivariate data analyses
No full textA prototype based on a NIR sensitive camera and a Xenon lamp was set up and used to capture 8 bit gray scale (from 0 = black to 255 = white) image of the radiation that passes through the fruit. The count of the pixels with different gray tone was used to build statistical-mathematical models to correlate and predict the kiwifruit flesh firmness. One hundred sixteen fruits conveniently stored to obtain firmness within a range of penetrometric force from 0.8 N to 87 N, were submitted to the optical measurements. Simple regression between the gray tone having the maximum number of pixels and the firmness showed an exponential correlation with R2 values of 0.717. On the contrary, the tone uniformity (maximum number of pixels with the same gray tone) resulted linearly correlated with hardness (R2 = 0.687). PLS algorithm allowed prediction of the flesh firmness with R2 of 0.777 (RMSE = 13 N). Artificial neural networks produced similar results. Although the current technique does not fully satisfies the need of an accurate selection, it could be considered for on-line applications by improving performances (e.g. acting on lamp spectral emissions and camera detection) and with easy mechanical modifications of the sorting lines
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