30 research outputs found

    Hingeless arm for space robotics actuated through shape memory alloys

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    Operating outside the spacecraft via remotely controlled structures is an important opportunity in different space applications. The research in this area is focused on designing robots that are sufficiently flexible to allow inspection in locations where access is difficult or impossible for astronauts, while minimizing weight and bulk. The purpose of the research is to design a borescope for space applications with no hinges or other mechanisms, exploiting biomimetic design concepts. This is pursued by giving to the borescope a backbone exoskeleton provided by a continuous structure made of fibre reinforced composite material and using NiTi wires as tendons, taking advantage of their low weight and dimensions, which allow them to be embedded between the composite layers during the lamination process. After a study of the state of the art of flexible structures, concentrated in the medical and robotic fields, the research work unfolded in two phases. In the first design phase, several composite layup solutions were considered and analysed using finite element models, leading to the definition of the borescope geometrical parameters and to an initial estimate of the displacements that can be achieved. In the second experimental phase, seven prototypes were produced and tested, with one or more wires, to validate the design and to search for a configuration that can be actuated in different directions. The borescope prototypes resulted flexible enough to achieve an extended degree of bending and at the same time sufficiently rigid to allow complete rearm of the NiTi wires. The numerical and experimental study led to the definition of the design parameters, the number of wires, and the manufacturing technique to integrate NiTi actuators

    Intrapartum fetal heart rate between 150 and 160 bpm at or after 40 weeks and labor outcome

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    INTRODUCTION: A baseline fetal heart rate between 110 and 160 bpm is considered normal. However among normal fetuses the average baseline heart rate has been shown to diminish progressively and the 90th centile of the fetal heart rate at 40 weeks of gestation has been consistently found at around 150 bpm. The aim of our study was to assess the labor and neonatal outcome of fetuses at 40 gestational weeks or beyond, whose intrapartum baseline fetal heart rate was between 150 and 160 bpm.MATERIAL AND METHODS: Retrospective cohort study including singleton pregnancies with spontaneous onset of labor, gestational age between 40+0 and 42+0 , category I CTG trace according to the FIGO guidelines 2015 with baseline fetal heart rate between 110-160 bpm during the first 60 minutes of the active labor. Exclusion criteria were maternal hyperpyrexia at admission, fetal arrhythmias, maternal tachycardia (>110 bpm) and uterine tachysystole (>5 contractions/10 minutes). The following outcomes were compared between fetuses with a baseline ranging between 110-149 bpm and those with a baseline ranging between 150-160 bpm: incidence of meconium-stained amniotic fluid, intrapartum hyperpyrexia, mode of delivery, Apgar at 5th minute<7, arterial pH<7.1 and Neonatal Intensive Care Unit admission, incidence of a composite adverse neonatal outcome.RESULTS: One-thousand and four CTG traces were included in the analysis, 860 in Group 110-149 bpm and 144 in Group 150-160. Group 150-160 bpm had a significantly higher incidence of meconium-stained amniotic fluid (OR 2.6; 95%CI 1.8-3.8), maternal intrapartum hyperpyrexia (OR 4.7; 95%CI 1.1-14.6), urgent/emergent cesarean section for suspected fetal distress (OR 13.4; 95% CI 3.3-54.3), Apgar <7 at 5th min (OR 9.13; 95%CI 1.5-55.1) and neonatal acidemia (OR 3.5; 95%CI 1.5-55.1). Logistic regression including adjusted for potential confounders showed that fetal heart rate between 150-160 bpm is an independent predictor of meconium-stained amniotic fluid (aOR 2.2; 95% CI 1.5-3.3), cesarean section during labor for fetal distress (aOR 10.7; 95%CI 2.9-44.6), neonatal acidemia (aOR 2.6; 95%CI 1.1-6.7) and adverse composite neonatal outcome (aOR 2.6; 95% CI 1.2-5.6).CONCLUSIONS: In fetuses at 40 weeks or beyond, an intrapartum fetal heart rate baseline ranging between 150 and 160 bpm seems associated with a higher incidence of labor complications

    Cash holding and firm value: a meta-analysis

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    Il paper presenta una meta-analisi fra cash holding e valore. Facendo riferimento a un campione di 290 studi, i risultati mostrano che la detenzione di liquidità genera un aumento del valore delle imprese. Inoltre, dall’analisi dei fattori di moderazione si evince la presenza di alcuni fattori che condizionano significativamente la relazione oggetto di studio. In particolare, l’effetto positivo delle riserve di cassa è amplificato quando il valore delle imprese è misurato da una variabile di mercato, quando gli studi si riferiscono agli anni 2000 e in particolari contesti istituzionali. Al contrario, l’effetto si riduce nelle imprese con scarse opportunità di sviluppo e negli studi che risultano essere pubblicati e in quelli che impiegano tecniche econometriche che controllano i problemi di endogeneità
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