Neurosurgical systematic reviews and meta-analyses for a daily practice

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Quasi-static and low-velocity impact behavior of intraply hybrid flax/basalt composites

In an attempt to increase the low-velocity impact response of natural fiber composites, a new hybrid intraply woven fabric based on flax and basalt fibers has been used to manufacture laminates with both thermoplastic and thermoset matrices. The matrix type (epoxy or polypropylene (PP) with or without a maleated coupling agent) significantly affected the absorbed energy and the damage mechanisms. The absorbed energy at perforation for PP-based composites was 90% and 50% higher than that of epoxy and compatibilized PP composites, respectively. The hybrid fiber architecture counteracted the influence of low transverse strength of flax fibers on impact response, irrespective of the matrix type. In thermoplastic laminates, the matrix plasticization delayed the onset of major damage during impact and allowed a better balance of quasi-static properties, energy absorption, peak force, and perforation energy compared to epoxy-based composites

Recommended implementation of electrical resistance tomography for conductivity mapping of metallic nanowire networks using voltage excitation

open6noThe knowledge of the spatial distribution of the electrical conductivity of metallic nanowire networks (NWN) is important for tailoring the performance in applications. This work focuses on Electrical Resistance Tomography (ERT), a technique that maps the electrical conductivity of a sample from several resistance measurements performed on its border. We show that ERT can be successfully employed for NWN characterisation if a dedicated measurement protocol is employed. When applied to other materials, ERT measurements are typically performed with a constant current excitation; we show that, because of the peculiar microscopic structure and behaviour of metallic NWN, a constant voltage excitation protocols is preferable. This protocol maximises the signal to noise ratio in the resistance measurements-and thus the accuracy of ERT maps-while preventing the onset of sample alterations.openCultrera, Alessandro; Milano, Gianluca; De Leo, Natascia; Ricciardi, Carlo; Boarino, Luca; Callegaro, LucaCultrera, Alessandro; Milano, Gianluca; De Leo, Natascia; Ricciardi, Carlo; Boarino, Luca; Callegaro, Luc

Mapping Time-Dependent Conductivity of Metallic Nanowire Networks by Electrical Resistance Tomography toward Transparent Conductive Materials

partially_open7Metallic nanowire (NW) networks have attracted great attention as promising transparent conductive materials thanks to the low sheet resistance, high transparency, low cost production, and compatibility with flexible substrates. Despite many efforts having been devoted to investigating the conduction mechanism, a quantitative characterization of local electrical properties of nanowire networks at the macroscale still represents a challenge. In this work, we report on the investigation of local electrical properties and their evolution over time of Ag NW networks by means of electrical resistance tomography (ERT). Spatial correlation of local conductivity properties and optical transparency revealed that the nonscanning and rapid ERT technique allows to probe local electrical inhomogeneities in the NW network, differently from conventional measurement techniques such as van der Pauw and the four-point probe. In addition, ERT mapping over time was employed for in situ monitoring the evolution of Ag NW networks conductivity, elucidating the dependence of the degradation of local electrical properties under ambient exposure on the initial conductivity. Our results shed light on the importance of the characterization of local electrical properties of NW networks where uniformity and stability represent the main challenges to overcome for their use as transparent conductive materials.openGianluca Milano; Alessandro Cultrera; Katarzyna Bejtka; Natascia De Leo; Luca Callegaro; Carlo Ricciardi; Luca BoarinoMilano, Gianluca; Cultrera, Alessandro; Bejtka, Katarzyna; DE LEO, Maria; Callegaro, Luca; Ricciardi, Carlo; Boarino, Luc

Percutaneous instrumentation with cement augmentation for traumatic hyperextension thoracic and lumbar fractures in ankylosing spondylitis: a single-institution experience

The typical traumatic thoracolumbar (TL) fracture in patients with ankylosing spondylitis (AS) is a hyperextension injury involving all three spinal columns, which is associated with unfavorable outcomes. Although a consensus on the management of these highly unstable injuries is missing, minimally invasive surgery (MIS) has been progressively accepted as a treatment option, since it is related to lower morbidity and mortality rates. This study aimed to evaluate clinical and radiological outcomes after percutaneous instrumentation with cement augmentation for hyperextension TL fractures in patients with AS at a single institution

Foreground Enhancement and Background Suppression in Human Early Visual System During Passive Perception of Natural Images

One of the major challenges in visual neuroscience is represented by foreground-background segmentation, a process that is supposed to rely on computations in cortical modules, as information progresses from V1 to V4. Data from nonhuman primates (Poort et al., 2016) showed that segmentation leads to two distinct, but associated processes: the enhancement of cortical activity associated to figure processing (i.e., foreground enhancement) and the suppression of ground-related cortical activity (i.e., background suppression). To characterize foreground-background segmentation of natural stimuli in humans, we parametrically modulated low-level properties of 334 images and their behaviorally segmented counterparts. A model based on simple visual features was then adopted to describe the filtered and intact images, and to evaluate their resemblance with fMRI activity in different visual cortices (V1, V2, V3, V3A, V3B, V4, LOC). Results from representational similarity analysis (Kriegeskorte et al., 2008) showed that the correspondence between behaviorally segmented natural images and brain activity increases throughout the visual processing stream. We found evidence of foreground enhancement for all the tested visual regions, while background suppression occurs in V3B, V4 and LOC. Our results suggest that foreground-background segmentation is an automatic process that occurs during natural viewing, and cannot be merely ascribed to differences in objects size or location. Finally, neural images reconstructed from V4 and LOC fMRI activity revealed a preserved spatial resolution of foreground textures, indicating a richer representation of the salient part of natural images, rather than a simplistic model of objects shape

Spontaneous vertebral aspergillosis, the state of art: a systematic literature review

Objective: Vertebral aspergillosis are quite rare conditions, often misdiagnosed, that requires long-term antibiotic therapy and, sometimes, surgical treatments. The present investigations was aimed to investigate epidemiology, clinical-radiological aspects, treatment protocols, and outcomes of Aspergillus-mediated vertebral osteomyelitis. Methods: A systematic review of the pertinent English Literature according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed. The research was conducted on Cochrane library, MEDLINE, PubMed and Scopus using as search-terms “Aspergillus”, “vertebral osteomyelitis”, “spondylodiscitis”, “spine infection”. A case of vertebral apsergillosis conservatively managed was also reported. Results: Eighty-nine articles were included in our systematic review. Including the reported case, our analysis covered 112 cases of vertebral aspergillosis. Aspergillus fumigatus was isolated in 68 cases (61.2%), Aspergillus flavus in 14 (12.6%), Aspergillus terreus in 4 (3.6%), Aspergillus nidulans in 2 (1.8%). Seventy-three patients (65.7%) completely recovered at last follow-up evaluation; in 7 (6.3%) patients radiological signs of chronic infection were reported, whereas 32 (28.8%) patients died during the follow-up. Conclusion: This systematic review summarized the state of the art on vertebral aspergillosis, retrieving data on clinical features, diagnostic criteria and current limitations, treatment alternatives and their outcomes