Moving mass over a viscoelastic system: asymptotic behaviours and insights into nonlinear dynamics

Moving masses are of interest in many applications of structural dynamics, soliciting in the last decades a vast debate in the scientific literature. However, despite the attention devoted to the subject, to the best of the authors’ knowledge, there is a lack of analysis about the fate of a movable mass when it rolls or slips with friction on a structure. With the aim of elucidating the dynamics of the simplest paradigm of this system and to investigate its asymptotic response, we make reference to a two-degree-of-freedom model made of an elastically vibrating carriage surmounted by a spherical mass, facing the problem both theoretically and experimentally. In case of linear systems, the analytical solutions and the laboratory tests performed on ad hoc constructed prototypes highlighted a counterintuitive asymptotic dynamics, here called binary: in the absence of friction at the interface of the bodies’ system, the mass holds its initial position or, if nonzero damping acts, at the end of the motion it is in a position that exactly recovers the initial relative distance carriage–sphere. While the first result might be somewhat obvious, the second appears rather surprising. Such a binary behaviour is also confirmed for a Duffing-like system, equipped with cubic springs, while it can be lost when non-smooth friction phenomena occur, as well as in the case of elastic springs restraining the motion of the sphere. The obtained analytical results and the numerical findings, also confirmed by experimental evidences, contribute to the basic understanding of the role played by the damping parameters governing the systems’ dynamics with respect to its asymptotic behaviour and could pave the way for designing active or passive vibration controllers of interest in engineering

Biofilms: Novel strategies based on antimicrobial peptides

The problem of drug resistance is very worrying and ever increasing. Resistance is due not only to the reckless use of antibiotics but also to the fact that pathogens are able to adapt to different conditions and develop self-defense mechanisms such as living in biofilms; altogether these issues make the search for alternative drugs a real challenge. Antimicrobial peptides appear as promising alternatives but they have disadvantages that do not make them easily applicable in the medical field; thus many researches look for solutions to overcome the disadvantages and ensure that the advantages can be exploited. This review describes the biofilm characteristics and identifies the key features that antimicrobial peptides should have. Recalcitrant bacterial infections caused by the most obstinate bacterial species should be treated with a strategy to combine conventional peptides functionalized with nano-tools. This approach could effectively disrupt high density infections caused by biofilms. Moreover, the importance of using in vivo non mammalian models for biofilm studies is described. In particular, here we analyze the use of amphibians as a model to substitute the rodent model

New fluorescent polymeric nanocomposites synthesized by antimony dodecyl-mercaptide thermolysis in polymer

In this work, the formation of semiconductive Sb2S3 nanoparticles inside amorphous polystyrene has been achieved by thermal degradation of the corresponding antimony dodecyl-mercaptide, Sb(SC12H25)3. The thermolysis of the dodecyl-mercaptide precursor was studied as both pure phase and mercaptide solution in polystyrene. The thermal decom- position of the antimony mercaptide precursor at 350°C, under vacuum, showed the formation of a mixture of antimony trisulfide (stibnite, Sb2S3) and zero-valent antimony (Sb) phase. X-ray Powder Diffraction (XRD) and Rietveld analysis carried out on the obtained nanostructured powder confirmed the presence of Sb and Sb2S3 phases in 10.4 wt% and 89.6 wt% amount, respectively. The same pyrolysis reaction was carried out in the polymer and the resulting nanocompos- ite material was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-VIS spec- troscopy, and fluorescence spectroscopy. The nanocomposite structural characterization indicated the presence of well-dispersed nanoclusters of antimony and stibnite (15-30 nm in size) inside the amorphous polymeric phase. Optical measurements on the obtained nanocomposite films showed a strong emission at 432 nm upon excitation at 371 nm, prob- ably related to the presence of Sb2S3 nanoclusters

Optical fiber technology enables smart needles for epidurals. An in-vivo swine study

Nowadays, epidural space identification is made by using subjective and manual techniques characterized by failure rates up to 7%. In this work, we propose a fiber optic sensor technology based needle guidance system, that is directly inspired by the most common technique currently used for epidurals; through real-time strain measurements, the fiber Bragg grating integrated inside the needle lumen is able to effectively perceive the typical force drop occurring when the needle enters the epidural space. An in vivo swine study demonstrates the validity of our approach, paving the way for the development of lab-in-a-needle systems

Emotional rational education training associated with mindfulness for managing anxiety within adolescents affected by high-functioning autism: A descriptive study

Background: Autism spectrum disorder (ASD) is a chronic and persistent pervasive developmental disorder (PDD) whose characteristic deficit is represented by social difficulties, semantic–pragmatic alterations and a limited, unusual and repetitive pattern of interests and be-haviors. Specifically, individuals with high-functioning autism (HFA) frequently exhibit associated internalizing symptoms that are not part of the diagnostic criteria but which, nonetheless, tend to impair daily functioning. In this study, we investigated how some forms of treatment could be useful in subjects with HFA who display internalizing symptoms. Theoretical background relates to standard cognitive therapy (SCT) and rational education training with mindfulness (M-ERE). Methods: In this study, we investigated how some forms of treatment could be useful in subjects with HFA and internalizing symptoms, focusing on standard cognitive therapy (SCT) and mindfulness associated with emotional rational education training (M-ERE). We selected two groups of HFA patients with significant internalizing symptoms and performed two different forms of treatment for six months: SCT and M-ERE. The aim of the study was to verify the effectiveness of an M-ERE protocol with respect to anxious and depressive symptoms in subjects with HFA. Furthermore, we wanted to compare the results obtained with this combined treatment with those obtained in HFA subjects treated with SCT. Results: Our analyses showed an improvement in the internalizing symptoms (especially those related to the anxiety dimension) of the group that followed a treatment based on mindfulness and rational emotional education for 6 months compared to the group that had instead performed a 6-month treatment based on the SCT. Conclusions: Our hypotheses were supported by the results, which highlighted the efficacy of mindfulness-based interventions in the treatment of internalizing symptoms in adolescents with HFA, and specifically showed that an M-ERE intervention appears more effective in managing anxiety compared to treatment with SCT and appears to be equally effective in the management of depressive symptoms. Not only was the M-ERE treatment effective for the management of anxious and depressive symptoms in subjects with HFA, but the efficacy for the management of anxious symptoms was greater than the SCT treatment

Maternal reflexive functions and parent training in children with oppositional defiant disorder

Oppositional Defiant Disorder (ODD) is one of the most common neuropsychiatric disorders in preschool children. Parental self-regulation is critical for maintaining positive parenting practices. However, to the best of our knowledge, existing parental trainings for ODD do not focus on the enhancement of parental reflective functions. In the present study, we compare two models of behavioral Parent Training (PT) for duration of six months: one, already consolidated, is based on the principles of Applied Behavioral Analysis (ABA), the other, innovative, integrates with the model of the regulatory and reflective parental function of Fonagy. Outcomes revealed that the innovative training was more effective as compared to the ABA training shopping that an improvement into the ability of parents to imagine the subjective experience of their developing children increases the development of children's self-regulation

Polymicrobial antibiofilm activity of the membranotropic peptide gH625 and its analogue

Abstract This work illustrates a new role for the membranotropic peptide gH625 and its derivative gH625-GCGKKK in impairing formation of polymicrobial biofilms. Mixed biofilms composed of Candida and bacterial species cause frequently infections and failure of medical silicone devices and also show a major drug resistance than single-species biofilms. Inhibition and eradication of biofilms were evaluated by complementary methods: XTT-reduction, and crystal violet staining (CV). Our results indicate that gH625-GCGKKKK, better than the native peptide, strongly inhibited formation of mixed biofilms of clinical isolates of C. tropicalis/S. marcescens and C. tropicalis/S. aureus and reduced the biofilm architecture, interfering with cell adhesion and polymeric matrix, as well as eradicated the long-term polymicrobial biofilms on silicone surface

Sleep Macrostructure and NREM Sleep Instability Analysis in Pediatric Developmental Coordination Disorder

Developmental Coordination Disorder (DCD) is considered to be abnormal motor skills learning, identified by clumsiness, slowness, and/or motor inaccuracy impairing the daily-life activities in all ages of life, in the absence of sensory, cognitive, or neurological deficits impairment. The present research focuses on studying DCD sleep structure and Cyclic Alternating Pattern (CAP) parameters with a full overnight polysomnography and to study the putative correlations between sleep architecture and CAP parameters with motor coordination skills. The study was a cross-sectional design involving 42 children (26M/16F; mean age 10.12 ± 1.98) selected as a DCD group compared with 79 children (49M/30F; mean age 9.94 ± 2.84) identified as typical (no-DCD) for motor ability and sleep macrostructural parameters according to the MABC-2 and polysomnographic (PSG) evaluations. The two groups (DCD and non-DCD) were similar for age (p = 0.715) and gender (p = 0.854). More significant differences in sleep architecture and CAP parameters were found between two groups and significant correlations were identified between sleep parameters and motor coordination skills in the study population. In conclusion, our data show relevant abnormalities in sleep structure of DCD children and suggest a role for rapid components of A phases on motor coordination development

Children on the Autism Spectrum and the Use of Virtual Reality for Supporting Social Skills

Background: Autism spectrum disorders (ASDs) are characterized by differences in socio-pragmatic communication. These conditions are allocated within a “spectrum” of phenotypic variability. Virtual reality (VR) is a useful tool for healthcare intervention and particularly safely advancing social abilities in children with ASD. Methods: In our study two types of intervention for improving social skills were compared: (i) emotional training obtained by the use of virtual reality (Gr1), (ii) traditional emotional training performed individually with a therapist (Gr2). We aimed to identify the intervention with the shortest acquisition time for the proposed social tasks. Results: Our findings show that both types of intervention had the same acquisition time for the recognition of primary emotions. However, for the use of primary and secondary emotions, the group using VR showed shorter acquisition times. Conclusions: These findings together with previous preliminary datasuggest that VR can be a promising, dynamic and effective practice for the support of basic and complex social skills of these individuals