Waves in elastic metamaterials

Wave propagation in long-range elastic metamaterials produces important propagation phenomena, such as wave stopping, negative and supersonic group velocities. Metamaterials are particular materials that gain peculiar properties not because of the material itself, but thanks to the realization of periodic sub-structures, capable of modifying the behavior of the macro-structure. The advances in technological machining, especially in the field of additive manufacturing techniques, give the possibility to realize complex elastic connections between different cellular elements; the presence of micro- and nano-scale connected structures changes the dynamic response of materials composed by the aggregation of these lattices. Such solids are clustered as elastic metamaterials. In homogeneous elastic materials, each elementary cell is connected to its first neighbors, constituting short-range interactions; on the other hand, when the range of connections spreads, interesting phenomena in terms of mechanical wave propagation appear. The chance of controlling wave propagation by simply changing the topology of the elastic connections is an important achievement; for instance, such designed materials can manipulate the mechanical energy flow, by isolating a vibration sensitive area at the cost of routing the energy into less sensitive regions, or better the energy can be focused to be harvested and converted. A physical mathematical model has been constructed starting from some of the long-range interactions that can be found in nature, such as the presence in classical discrete system (Mass-Spring) of magnetostatic or electrostatic elements. The main feature of these interactions is the dependency on the absolute distance and not on the relative displacement; each element, indeed, exchange forces with all the elements of the system, not only with its close neighbors. Several approaches to the problem have been adopted to model long-range interaction metamaterials. The expertise in the homogenization of discrete problems involving complex structure has been the theoretical basis for building up a continuous model capable of describing long-range interactive metamaterials. Two opposite approaches have been adopted to describe the phenomenon: (i) a differential approach and (ii) an integral approach. The differential approach needs some assumptions and approximations, especially in the interaction range that needs to be limited in space, while the integral approach use some of the same assumptions and approximations but works with a full interaction range. For this reason, most of the mathematical efforts in modeling such materials has been dedicated to the development of the integral approach-based model. To better describe the system, the interaction model is based on two prototype forces: the Gauss-like and the Laplace-like. Technically speaking, these interactions, as the ones from which they come from, decay with the distance and respect the action-reaction principle holds. In addition, they have a known Fourier transform; it is not the case with magnetostatic and electrostatic forces, generally power-law based. The principal result of the investigation consists in finding some properties of phase and group velocities for one-dimensional infinite waveguides, where several unusual phenomena emerge. Namely we show and demonstrate in a close analytical form the following phenomena: wave-stopping, eigenstate migration, negative group velocity, leading to supersonic propagation. An analogous approach is used to evaluate wave propagation in long-range beams (Euler-Bernoulli), and in two dimensional membranes with circle-step long-range interaction, with the borne of analogous phenomena. The investigation includes also a huge experimental campaign, set in cooperation with Technion, Israel Institute of technology. An experimental setup for the testing of single and coupled long-range magnetic waveguide has been built, demonstrating interesting phenomena in terms of magnetically coupled waveguides that reproduce some of the results the theoretical investigation predicts

A multisensing setup for the intelligent tire monitoring

The present paper offers the chance to experimentally measure, for the first time, the internal tire strain by optical fiber sensors during the tire rolling in real operating conditions. The phenomena that take place during the tire rolling are in fact far from being completely understood. Despite several models available in the technical literature, there is not a correspondently large set of experimental observations. The paper includes the detailed description of the new multi-sensing technology for an ongoing vehicle measurement, which the research group has developed in the context of the project OPTYRE. The experimental apparatus is mainly based on the use of optical fibers with embedded Fiber Bragg Gratings sensors for the acquisition of the circumferential tire strain. Other sensors are also installed on the tire, such as a phonic wheel, a uniaxial accelerometer, and a dynamic temperature sensor. The acquired information is used as input variables in dedicated algorithms that allow the identification of key parameters, such as the dynamic contact patch, instantaneous dissipation and instantaneous grip. The OPTYRE project brings a contribution into the field of experimental grip monitoring of wheeled vehicles, with implications both on passive and active safety characteristics of cars and motorbikes

Feasibility and usefulness of ultrasonography in idiopathic intracranial hypertension or secondary intracranial hypertension

Transorbital sonography (TOS) has been proven to be able to non-invasively detect elevated intracranial pressure. In this condition TOS shows an increase in optic nerve sheath diameter (ONSD). It has been suggested that internal jugular vein valve insufficiency (IJVVI) may represent a factor contributing to the pathogenesis of idiopathic intracranial hypertension (IIH). The aim of this study was to investigate whether patients with IIH or secondary IH have higher ONSD values and higher frequency of IJVVI compared to subjects without IH

outcome of childhood onset full house nephropathy

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Risk factors for infections due to carbapenem-resistant Klebsiella pneumoniae after open heart surgery

OBJECTIVES Patients undergoing major surgery are at increased risk of developing infections due to resistant organisms, including carbapenem-resistant Klebsiella pneumoniae (CR-Kp). In this study, we assessed risk factors for CR-Kp infections after open heart surgery in a teaching hospital in northern Italy. METHODS A retrospective study was conducted from January to December 2014. The primary outcome measure was postoperative CR-Kp infection, defined as a time-to-event end-point. The effect of potentially related variables was assessed by univariable and multivariable analyses. Secondary end-points were in-hospital mortality and 180-day postoperative mortality. RESULTS Among 553 patients undergoing open heart surgery, 32 developed CR-Kp infections (6%). In the final multivariable model, CR-Kp colonization [hazard ratio (HR) 227.45, 95% confidence intervals (CI) 67.13-1225.20, P < 0.001], cardiopulmonary bypass time in minutes (HR 1.01, 95% CI 1.01-1.02, P < 0.001), chronic obstructive pulmonary disease (HR 3.99, 95% CI 1.61-9.45, P = 0.004), SOFA score (HR 1.29, 95% CI 1.08-1.53, P = 0.007), preoperative mechanical ventilation (HR 8.10, 95% CI 1.31-48.57, P = 0.026), prolonged mechanical ventilation (HR 2.48, 95% CI 1.08-6.15, P = 0.032) and female sex (HR 2.08, 95% CI 1.00-4.36, P = 0.049) were associated with the development of CR-Kp infection. Increased in-hospital mortality and 180-day mortality were observed in patients who developed CR-Kp infections in comparison with those who did not. CONCLUSIONS In our cohort, CR-Kp colonization was an important predictor of CR-Kp infection after open heart surgery. CR-Kp infection after surgery significantly affected survival. Preventing colonization is conceivably the most effective current strategy to reduce the impact of CR-Kp

Longitudinal assessment of transorbital sonography, visual acuity, and biomarkers for inflammation and axonal injury in optic neuritis

BACKGROUND AND OBJECTIVE: To investigate the relationship between optic nerve sheath diameter, optic nerve diameter, visual acuity and osteopontin, and neurofilament heavy chain in patients with acute optic neuritis. PATIENTS AND METHODS: Sonographic and visual acuity assessment and biomarker measurements were executed in 23 patients with unilateral optic neuritis and in 19 sex- and age-matched healthy controls. RESULTS: ONSD was thicker on the affected side at symptom onset (median 6.3\u2009mm; interquartile range 6.0-6.5) than after 12 months (5.3\u2009mm; 4.9-5.6; p < 0.001) or than in controls (5.2\u2009mm; 4.8-5.5; p < 0.001). OND was significantly increased in the affected side (3.4\u2009mm; 2.9-3.8) compared to healthy controls (2.7\u2009mm; 2.5-2.9; p < 0.001) and was thicker at baseline than after 12 months (2.8\u2009mm; 2.7-3.0; p < 0.01). Visual acuity improved significantly after 12 months (1.00; 0.90-1.00) compared to onset of symptoms (0.80; 0.40-1.00; p < 0.001). OPN levels were significantly higher in patients at presentation (median 6.44\u2009ng/ml; 2.05-10.06) compared to healthy controls (3.21\u2009ng/ml, 1.34-4.34; p < 0.03). Concentrations of NfH were significantly higher in patients than in controls. CONCLUSION: ONSD and OND are increased in the affected eye. OPN and NfH are elevated in patients, confirming the presence of any underlying inflammation and axonal injury

Targeted-release budesonide versus placebo in patients with IgA nephropathy (NEFIGAN) : a double-blind, randomised, placebo-controlled phase 2b trial

Background IgA nephropathy is thought to be associated with mucosal immune system dysfunction, which manifests as renal IgA deposition that leads to impairment and end-stage renal disease in 20-40% of patients within 10-20 years. In this trial (NEFIGAN) we aimed to assess safety and efficacy of a novel targeted-release formulation of budesonide (TRF-budesonide), designed to deliver the drug to the distal ileum in patients with IgA nephropathy. Methods We did a randomised, double-blind, placebo-controlled phase 2b trial, comprised of 6-month run-in, 9-month treatment, and 3-month follow-up phases at 62 nephrology clinics across ten European countries. We recruited patients aged at least 18 years with biopsy-confirmed primary IgA nephropathy and persistent proteinuria despite optimised renin-angiotensin system (RAS) blockade. We randomly allocated patients with a computer algorithm, with a fixed block size of three, in a 1:1:1 ratio to 16 mg/day TRF-budesonide, 8 mg/day TRF-budesonide, or placebo, stratified by baseline urine protein creatinine ratio (UPCR). Patients self-administered masked capsules, once daily, 1 h before breakfast during the treatment phase. All patients continued optimised RAS blockade treatment throughout the trial. Our primary outcome was mean change from baseline in UPCR for the 9-month treatment phase, which was assessed in the full analysis set, defined as all randomised patients who took at least one dose of trial medication and had at least one post-dose efficacy measurement. Safety was assessed in all patients who received the intervention. This trial is registered with ClinicalTrials.gov, number NCT01738035. Findings Between Dec 11, 2012, and June 25, 2015, 150 randomised patients were treated (safety set) and 149 patients were eligible for the full analysis set. Overall, at 9 months TRF-budesonide (16 mg/day plus 8 mg/day) was associated with a 24.4% (SEM 7.7%) decrease from baseline in mean UPCR (change in UPCR vs placebo 0.74; 95% CI 0.59-0.94; p=0.0066). At 9 months, mean UPCR had decreased by 27.3% in 48 patients who received 16 mg/day (0.71; 0.53-0.94; p=0.0092) and 21.5% in the 51 patients who received 8 mg/day (0.76; 0.58-1.01; p=0.0290); 50 patients who received placebo had an increase in mean UPCR of 2.7%. The effect was sustained throughout followup. Incidence of adverse events was similar in all groups (43 [88%] of 49 in the TRF-budesonide 16 mg/day group, 48 [94%] of 51 in the TRF-budesonide 8 mg/day, and 42 [84%] of 50 controls). Two of 13 serious adverse events were possibly associated with TRF-budesonide-deep vein thrombosis (16 mg/day) and unexplained deterioration in renal function in follow-up (patients were tapered from 16 mg/day to 8 mg/day over 2 weeks and follow-up was assessed 4 weeks later). Interpretation TRF-budesonide 16 mg/day, added to optimised RAS blockade, reduced proteinuria in patients with IgA nephropathy. This effect is indicative of a reduced risk of future progression to end-stage renal disease. TRF-budesonide could become the first specific treatment for IgA nephropathy targeting intestinal mucosal immunity upstream of disease manifestation.Peer reviewe