Modeling and Control of a novel Variable Stiffness three DoF Wrist

This paper presents a novel design for a Variable Stiffness 3 DoF actuated wrist to improve task adaptability and safety during interactions with people and objects. The proposed design employs a hybrid serial-parallel configuration to achieve a 3 DoF wrist joint which can actively and continuously vary its overall stiffness thanks to the redundant elastic actuation system, using only four motors. Its stiffness control principle is similar to human muscular impedance regulation, with the shape of the stiffness ellipsoid mostly depending on posture, while the elastic cocontraction modulates its overall size. The employed mechanical configuration achieves a compact and lightweight device that, thanks to its anthropomorphous characteristics, could be suitable for prostheses and humanoid robots. After introducing the design concept of the device, this work provides methods to estimate the posture of the wrist by using joint angle measurements and to modulate its stiffness. Thereafter, this paper describes the first physical implementation of the presented design, detailing the mechanical prototype and electronic hardware, the control architecture, and the associated firmware. The reported experimental results show the potential of the proposed device while highlighting some limitations. To conclude, we show the motion and stiffness behavior of the device with some qualitative experiments.Comment: 13 pages + appendix (2 pages), 19 figures, submitted to IJR

A new method of stellar spectra extraction from MUSE data cube in an high sky emission region: the complex case of Trumpler 14

Understanding how planets form is linked to knowing what the origins of Solar System are and the study of protoplanetary discs (PPD) is fundamental. Studies on PPDs have focused on nearby star-forming regions, they are not representative of the environment where stars and planets form. Stars form in star clusters and the environment has an effect on the disc. It is important to study how discs evolve in young clusters. Many factors take part in the discs evolution and the most important is the external photoevaportation, which is due to the presence of hot stars emitting energetic photons. This radiation evaporates the discs of the nearby stars. It means there are regions in which planets formation is dependent on the presence of hot stars. This work aims to study the external photoevaporation. The studied object is the open cluster Trumpler14 located in the Carina star forming region. The observations are made with MUSE an instrument of the VLT. It is essential for the study because the goal is to extract stars spectra and emission lines originated from disc-star interaction and photoevaporation. The problem is the behavior of the background because the sky around observed stars is emitting in a non homogeneous way and it cannot be easily subtracted from stars spectra. The contribution to the sky emission comes from radiation of massive stars. These create a region of ionized gas emitting in the lines also used as diagnostics for star-disc interaction and photoevaporation. This work also aims to find a method to extract stars spectra in this hostile situation. The interest of producing those spectra is to provide a robust estimate of their emission lines. We were able to detect [OI]line of some stars. Few flux are uncertain due to the sky subtraction. By comparing with external photoevaporation models fluxes from these stars are consistent with large discs. Finding an effective method to extract spectra plays an important role for the future analysis of PPDs in similar regions

A scoring system for biliary atresia: Is this the right one?

A clinical diagnostic score for biliary atresia in discusse

Audita: A Blockchain-based Auditing Framework for Off-chain Storage

The cloud changed the way we manage and store data. Today, cloud storage services offer clients an infrastructure that allows them a convenient source to store, replicate, and secure data online. However, with these new capabilities also come limitations, such as lack of transparency, limited decentralization, and challenges with privacy and security. And, as the need for more agile, private and secure data solutions continues to grow exponentially, rethinking the current structure of cloud storage is mission-critical for enterprises. By leveraging and building upon blockchain's unique attributes, including immutability, security to the data element level, distributed (no single point of failure), we have developed a solution prototype that allows data to be reliably stored while simultaneously being secured, with tamper-evident auditability, via blockchain. The result, Audita, is a flexible solution that assures data protection and solves challenges such as scalability and privacy. Audita works via an augmented blockchain network of participants that include storage-nodes and block-creators. In addition, it provides an automatic and fair challenge system to assure that data is distributed and reliably and provably stored. While the prototype is built on Quorum, the solution framework can be used with any blockchain platform. The benefit is a system that is built to grow along with the data needs of enterprises, while continuing to build the network via incentives and solving for issues such as auditing and outsourcing

Volcanogenic particulates and gases from Etna volcano (Italy)

Volcanic emissions represent one of the most relevant natural sources of trace elements to the troposphere. Due to their potential toxicity they may have important environmental impacts from the local to the global scale and they can severely affect the atmospheric and terrestrial environment also at timescales ranging from a few to million years. Etna volcano is known as one of the largest global contributors of magmatic gases (CO2, SO2, and halogens) and particulate matter, including some toxic trace elements. The aim of this study was to characterize the chemical composition and the mineralogical features of the volcanogenic aerosol passively emitted from Mt. Etna. Nine samples were collected by using the filtration technique at different sites on summer 2010 and 2011. Chemical and mineralogical analyses allowed to discriminate two main constituents: the first is mainly referable to the silicate component in the volcanic plume, like lithic and juvenile fragments, crystals (e.g., plagioclases, pyroxenes, oxides) and shards of volcanic glass; the second one is linked to the soluble components like sulfosalts or halide minerals (sulfates, chlorides and fluorides). These investigations are especially important in the study area because the summit of Mt. Etna is yearly visited by nearly one hundred thousand tourists that are exposed to potentially harmful compounds

The cortico-pallidal projection in the human: a tracking study with DT I technique

We investigated the globus pallidus starting from basal ganglia circuits scheme based on cortico-basal ganglia-thalamo-cortical loop. Globus pallidus represents the exit module from previous cited loop and having the role of locking or unlocking the motor gesture through its inhibition state. Such activities are regulated by direct, indirect and hyperdirect ways. Some studies demonstrated an immediate globus pallidus activation after cortex stimulation; another one provided the existence of a bundle of cortico-pallidal fibers, not crossing the neostriatum, in laboratory animals. Existence of such pathways is not demonstrated in human beings. Using DTI tecnique in this study we found an ipsilateral fiber bundle starting from prefrontal cortex and clearly directed to the globus pallidus. The existence of such direct cortico-pallidal projection, not crossing the neostriatum, was suggested by Testut and Latarjet and following asserted anatomically and by neuronography. Furthermore the presence of glutamatergic and dopaminergic receptors in the animal globus pallidus, already demonstrated in other studies, reinforces the validity of the results obtained in the present one also if should be important to demonstrate the presence of such receptors in humans