Geometry-aware Compensation Scheme for Morphing Drones

Morphing multirotors, such as the Foldable Drone , can increase the versatility of drones employing in-flight-adaptive-morphology. To further increase precision in their tasks, recent works have investigated stable flight in asymmetric morphologies mainly leveraging the low-level controller. However, the aerodynamic effects embedded in multirotors are only analyzed in fixed shape aerial vehicles and are completely ignored in morphing drones. In this paper, we investigate the effects of the partial overlap between the propellers and the main body of a morphing quadrotor. We perform experiments to characterize such effects and design a morphology-aware control scheme to account for them. To guarantee the right trade-off between efficiency and compactness of the vehicle, we propose a simple geometry-aware compensation scheme based on the results of these experiments. We demonstrate the effectiveness of our approach by deploying the compensation scheme on the Foldable Drone, a quadrotor that can fold its arms around the main body. The same set of experiments are performed and compared against one another by activating and deactivating the compensation scheme offline or during the flight. To the best of our knowledge, this is the first work counteracting the aerodynamic effects of a morphing quadrotor during flight and showing the effects of partial overlap between a propeller and the central body of the drone.Comment: Submitted to IEEE Conference on Intelligent Robots and Systems (IROS) 202

Single-shot implementation of dispersion-scan for the characterization of ultrashort laser pulses

We demonstrate a novel, single-shot ultrafast diagnostic, based on the dispersion-scan (d-scan) technique. In this implementation, rather than scanning wedges to vary the dispersion as in standard d-scan, the pulse to be measured experiences a spatially varying amount of dispersion in a Littrow prism. The resulting beam is then imaged into a second-harmonic generation crystal and an imaging spectrometer is used to measure the two-dimensional trace, which is analyzed using the d-scan retrieval algorithm. We compare the single-shot implementation with the standard d-scan for the measurement of sub-3.5-fs pulses from a hollow core fiber pulse compressor. We show that the retrieval algorithm used to extract amplitude and phase of the pulse provides comparable results, proving the validity of the new single-shot implementation down to near single-cycle durations.Comment: 6 pages, 4 figure

Vitamin D deficiency and HCV chronic infection: What comes first?

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The representation of bullying in Italian primary school children: A mixed-method study comparing drawing and interview data and their association with self-report involvement in bullying events

Bullying continues to be a social issue affecting millions of students of all ages worldwide. Research on bullying seems to be dominated by quantitative research approaches employed standardized categories and measures, ultimately limiting our knowledge about children’s own view on bullying. Our research follows another direction, aiming to explore the representation of bullying in a sample of Italian primary school children by using and comparing the functioning of two qualitative research instruments: interviews, and children’s drawings. In addition, aided by quantitative analyses, we aimed to investigate whether students’ involvement in different bullying roles (as bullies, victims, or defenders), as measured by self-assessment, correlated with different characteristics of the representation of bullying emerging from children’s drawings and interviews. We recruited a convenient sample of 640 primary school students (mean age = 9.44; SD = 0.67), 53.3% of whom were male. The results showed that all forms of bullying, i.e., physical, verbal, and social bullying, could be identified in interview and drawing data, although references to all types of bullying were more frequent in interview data. In terms of bullying criteria, the presence of a power imbalance between the bully and the victim was most frequently detected in both the interview data and the drawing data, while repetition was more easily detected in the interview data. The interview data showed that sadness was the most frequently reported victim emotions, followed by fear, anger, and lack of emotion. The drawing data showed a similar pattern, although victims were more frequently described as lacking emotions compared to the interview data. In both interview and drawing data, age and female gender were positively associated with references to verbal bullying, and negatively associated with references to physical bullying. Additionally, bully/victim children were more likely than uninvolved children to depict physical bullying in the drawings, while this association was not detected in interview data. In summary, our study shows that, compared with drawings, interviews tend to provide a more comprehensive view of children’s own representation of bullying, while drawing data tend to show stronger connections with children’s current personal experiences of bullying

Algorithms for Vision-Based Quality Control of Circularly Symmetric Components

Quality inspection in the industrial production field is experiencing a strong technological development that benefits from the combination of vision-based techniques with artificial intelligence algorithms. This paper initially addresses the problem of defect identification for circularly symmetric mechanical components, characterized by the presence of periodic elements. In the specific case of knurled washers, we compare the performances of a standard algorithm for the analysis of grey-scale image with a Deep Learning (DL) approach. The standard algorithm is based on the extraction of pseudo-signals derived from the conversion of the grey scale image of concentric annuli. In the DL approach, the component inspection is shifted from the entire sample to specific areas repeated along the object profile where the defect may occur. The standard algorithm provides better results in terms of accuracy and computational time with respect to the DL approach. Nevertheless, DL reaches accuracy higher than 99% when performance is evaluated targeting the identification of damaged teeth. The possibility of extending the methods and the results to other circularly symmetrical components is analyzed and discussed

Antiviral treatment in patients with hepatitis C virus-related cirrhosis awaiting liver transplantation

End stage liver disease due to hepatitis C virus (HCV) infection is the most common indication for liver transplantation (LT) worldwide. Regretfully, infection of the graft by HCV occurs almost universally after LT, causing chronic hepatitis and early progression to cirrhosis in a significant proportion of recipients. Moreover, graft and patient survival are significantly worse in patients undergoing LT for HCV-related cirrhosis than in those transplanted for other indications. Therefore, many LT centers consider antiviral treatment with interferon and ribavirin the mainstay of managing recurrent HCV disease in LT recipients. The optimal time to start treatment is unclear. In most instances, treatment is initiated when histological evidence of disease recurrence, either at protocol or on-demand liver biopsies, is observed after LT. However, antiviral treatment initiated before LT is a potential option for some patients for two reasons: first, clearing or suppressing HCV before LT may reduce or eliminate the risk of recurrent hepatitis C in the transplanted liver and thereby improve survival; second, clearing HCV in cirrhotic patient may halt disease progression and avoid the need for transplantation. In this article, the results obtained by pre-transplant antiviral regimens administered to HCV-positive cirrhotic patients awaiting LT are discussed

Carrier-envelope phase stability of hollow-fibers used for high-energy, few-cycle pulse generation

We investigated the carrier-envelope phase (CEP) stability of a hollow-fiber setup used for high-energy, few-cycle pulse generation. Saturation of the output pulse energy is observed at 0.6 mJ for a 260 um inner-diameter, 1 m long fiber, statically filled with neon, with the pressure adjusted to achieve an output spectrum capable of supporting sub-4fs pulses. The maximum output pulse energy can be increased to 0.8mJ by using either differential pumping, or circularly polarized input pulses. We observe the onset of an ionization-induced CEP instability, which does not increase beyond an input pulse energy of 1.25 mJ due to losses in the fiber caused by ionization. There is no significant difference in the CEP stability with differential pumping compared to static-fill, demonstrating that gas flow in differentially pumped fibers does not degrade the CEP stabilization.Comment: 4 pages, 4 figure

Prediction of attosecond light pulses in the VUV range in a high-order-harmonic-generation regime

Attosecond light pulses within the vacuum ultraviolet (VUV) energy range are predicted by solving the time-dependent Schrödinger equation (TDSE) for a model neon atom in short laser pulses of different field polarization states. We compare high-order harmonic generation in linearly polarized laser pulses to the method of polarization gating and find attosecond pulses that approach the Fourier limit of 700 as given by an indium filter, spectrally centered at 15 eV. At such low energies, harmonic generation has low sensitivity to ellipticity, which enables the generation of elliptically polarized attosecond pulses. We also show that emission at the atomic transition energies is strongly damped by including intensity averaging. © 2013 American Physical Society.EPSRC/EP/I032517/1EU Marie Curie Initial Training Network/FASTQUASTDF

Students’ Psychological Adjustment in Normative School Transitions From Kindergarten to High School: Investigating the Role of Teacher-Student Relationship Quality

School transitions require students to adapt to new challenges and situations and can increase the risk of externalizing and internalizing psychological symptoms. The teacher-student relationship seems to be a protective factor for the risk of developing psychological symptoms during school transitions. The aim of the present study is to investigate whether the quality of the teacher-student relationship predicts the decrease of internalizing and externalizing symptoms during three school transitions, namely: from kindergarten to primary school (T1), from primary to middle school (T2), and from middle to high school (T3). We recruited 127 kindergarten students (mean age = 5.40, SD = 0.49), 113 fifth grade primary school students (mean age = 10.64, SD = 0.54), and 240 eighth grade students (mean age = 13.88, SD = 0.37) and their teachers (response rate = 95%). Data were collected from 2016 to 2018. Teachers filled out an anonymous survey, acting as informants for the students, reporting demographic details (age, gender), psychological symptoms, and quality of the teacher-student relationship. The data show that a positive teacher-student relationship quality tends to be associated with a reduction of psychological symptoms. A stable, low-conflict teacher-student relationship was confirmed as a protective factor from increased internalizing and externalizing symptoms during all normative school transitions. Furthermore, we see that an increase in teacher-student conflict during the transitions from primary to middle school, and from middle to high school is linked to an exacerbation in students’ externalizing symptoms during the first year of attendance of the new school. Our study confirms the importance of the teacher-student relationship in reducing psychological symptoms associated with school transitions, in every type of transition, favoring an improved psychological adjustment to the new environment. A positive teacher-student relationship represents a protective factor for the development of students. Study limitations are discussed

Is there a place for nutritional supplements in the treatment of idiopathic male infertility?

Objective: Infertility affects 15% of couples in fertile age. Male factor is a cause of infertility in almost half of cases, mainly due to oligoasthenoteratozoospermia (OAT). The purpose of this study is to review the effects of nutritional supplements as medical treatment for idiopathic male infertility. Material and methods: A Pub Med and Medline review of the published studies utilizing nutritional supplements for the treatment of male infertility has been performed. Results: Clinical trials on Vitamin E, Vitamin A, Vitamin C. Arginine, Carnitine, N-Acetyl-Carnitine, Glutathione, Coenzyme Q10, Selenium and Zinc were reviewed. Although there is a wide variability in selected population, dose regimen and final outcomes, nutritional supplements both alone and in combination seems to be able to improve semen parameters (sperm count, sperm motility and morphology) and pregnancy rate in infertile men. Conclusions: There are rising evidences from published randomized trials and systematic review suggesting that nutritional supplementation may improve semen parameters and the likelihood of pregnancy in men affected by OAT. This improvement, however, is not consistent and there is a wide variation in the treatment regimens used. Well designed and adequately powered RCTs are needed to better clarify the role of nutritional supplements as treatment for male infertility