Controllo reattivo delle forze di presa durante il trasferimento di un oggetto in uno scenario di manipolazione bimanuale

Il presente lavoro di tesi parte dall’analisi di un modello quasi-statico per la manipolazione robotica, passando in rassegna le equazioni che regolano la presa di un oggetto. Lo studio è condotto a livello del tutto generale e include il caso di power grasping e la possibilità di avere sottoattuazione nel sistema di manipolazione. Si passa poi alla simulazione dinamica del trasferimento di un oggetto da una mano all’altra in uno scenario di manipolazione bimanuale. In particolare, si prende in esame un semplice modello bidimensionale e si utilizza un algoritmo di ottimizzazione per ottenere una distribuzione pianificata delle forze di contatto che sposti gradualmente l’onere della presa dalla mano sinistra a quella destra, tenendo conto anche della eventuale presenza di un disturbo esterno. Alla pianificazione si affianca poi un sistema di controllo reattivo che permette di agire sulla posizione e sulla velocità delle dita, alla luce delle informazioni ricavabili da opportuni sensori tattili

Dynamic Morphological Computation Through Damping Design of Soft Continuum Robots

Inspired by nature, soft robotics aims at enhancing robots capabilities through the use of soft materials. This article presents the study of soft continuum robots which can change their dynamic behavior thanks to a proper design of their damping properties. It enables an under-actuated dynamic strategy to control multi-chamber pneumatic systems using a reduced number of feeding lines. The present work starts from the conceptual investigation of a way to tune the damping properties of soft continuum robots, and leverages on the introduction of viscous fluid within the soft chamber wall to produce dissipative actions. Several solutions are analyzed in simulations and the most promising one is tested experimentally. The proposed approach employs a layer of granular material immersed in viscous silicone oil to increase the damping effect. After validation and experimental characterization, the method is employed to build soft continuum actuators with different deformation patterns, i.e., extending, contracting and bending. Experimental results show the dynamic behavior of the presented actuators. Finally, the work reports information on how the actuators are designed and builded, together with a discussion about possible applications and uses

Second harmonic generation in reverse proton exchanged Lithium Niobate waveguides.

We investigate efficient second harmonic generation in reverse proton exchanged Lithium Niobate waveguides. In z-cut crystals, the resulting buried and surface guides support TM and TE polarizations, respectively, and are coupled through the d 31 nonlinear element. Numerically estimated conversion efficiencies in planar structures operating at 1.32microm reach 90% in 2cm or a normalized 14% microm/Wcm

Species diversity, spatial distribution, and virulence associated genes of culturable vibrios in a brackish coastal Mediterranean environment

The Vibrio genus is widespread in marine and brackish environments, and several species are human and animal pathogens of global importance. Vibrios adapt rapidly to many environmental stresses, so that brackish environments can be both a suitable niche and a possible reservoir for them. To test the occurrence of culturable vibrios and their possible correlation with environmental factors in a temperate brackish environment, a 1year sampling study was performed in three brackish ponds located along the Central Thyrrenian coast in the Macchiatonda Nature Reserve (Santa Marinella, district of Rome, Italy). Molecular methods were used to detect Vibrio cholerae, Vibrio arahaemolyticus, and Vibrio vulnificus pathogenicity associated genes among the Vibrio isolates. Out of 130 Vibrio isolates identified by sequencing a recA fragment, 70 harbored virulence associated genes including ctx, ace, tcpA, tdh, trh, vvhA, vllY, and toxRS, so confirming the spread of virulence determinants across the environmental isolates. Ecological analysis showed that, although the water temperature is known to be a strong predictor of abundance and distribution of vibrios, its influence accounts for 27 % of the observed variance in the Macchiatonda samples, increasing to 40 % when combined with salinity

Incidence and risk factors of hospitalization for bronchiolitis in preterm children: a retrospective longitudinal study in Italy

<p>Abstract</p> <p>Background</p> <p>Bronchiolitis is a distressing, potentially life-threatening respiratory condition that affects infants. We evaluated the incidence and risk factors of hospitalization for broncholitis in preterm infants (i.e., a gestational age of <36 weeks) born between 2000 and 2006, and the use and impact of Palivizumab, a monoclonal antibody that in randomized clinical trials has been shown to lessen the severity of RSV-related bronchiolitis.</p> <p>Methods</p> <p>Retrospective cohort study that linked data from four health administrative databases in the Lazio region (a region of central Italy): the birth register, the hospital discharge register, and two ad-hoc databases that record the doses of Palivizumab administered at two local health units.</p> <p>Results</p> <p>Among 2407 preterm infants, 137 had at least one hospitalization for bronchiolitis in the first 18 months of life, an overall incidence rate of 4.70 per 100 person-years (95%CI: 3.98-5.56); similar incidence rates were observed by calendar year. A multiple Poisson model showed that the following characteristics were associated with higher incidence: younger age of the infant, the period between October-April, male gender, low Apgar score at birth, low birth weight, and low maternal educational level. At least one dose of Palivizumab was administered to 324 (13.5%) children; a dramatic increase from 2000 (2.8%) to 2006 (19.1%) (p < 0.01) was observed. Other factors independently associated with more frequent Palivizumab use were older maternal age, Italian-born mothers, female gender, low Apgar score, low birth weight, shorter gestational age, a diagnosis of broncho-dysplasia, and the month of birth. It is of note that none of the 34 children with congenital heart disease were prescribed Palivizumab. Performing several multiple Poisson models that also considered Palivizumab use as covariate, although the point estimates were in agreement with previous clinical trial results, we did not find in most of them a significant reduction for immunized children to be hospitalized for bronchiolitis.</p> <p>Conclusion</p> <p>In Italy the incidence of hospitalization for bronchiolitis, and its associated risk factors, are similar to that found in other countries. Although Palivizumab use is associated with the most important characteristics of severe prematurity, other aspects of its non-use in children with congenital heart disease, the age and the birth country of the mother suggest the need for public health measures that can reduce these health disparities. Finally, the estimated effectiveness of Palivizumab in routine practice, although not significant, confirms the results of previous clinical trials, but its impact on modifying the temporal trend in this population is still negligible.</p

Analysis of Four New Enterococcus faecalis Phages and Modeling of a Hyaluronidase Catalytic Domain from Saphexavirus

Background: Phage therapy (PT), as a method to treat bacterial infections, needs identification of bacteriophages targeting specific pathogenic host. Enterococcus faecalis, a Gram-positive coccus resident in the human gastrointestinal tract, may become pathogenic in hospitalized patients showing acquired resistance to vancomycin and thus representing a possible target for PT. Materials and Methods: We isolated four phages that infect E. faecalis and characterized them by host range screening, transmission electron microscopy, and genome sequencing. We also identified and three-dimensional modeled a new hyaluronidase enzyme. Results: The four phages belong to Siphoviridae family: three Efquatrovirus (namely vB_EfaS_TV51, vB_EfaS_TV54, and vB_EfaS_TV217) and one Saphexavirus (vB_EfaS_TV16). All of them are compatible with lytic cycle. vB_EfaS_TV16 moreover presents a gene encoding for a hyaluronidase enzyme. Conclusions: The identified phages show features suggesting their useful application in PT, particularly the Saphexavirus that may be of enhanced relevance in PT because of its potential biofilm-digestion capability

Early and late mortality in elderly patients after hip fracture: a cohort study using administrative health databases in the Lazio region, Italy

<p>Abstract</p> <p>Background</p> <p>Hip fractures represent one of the most important causes of morbidity and mortality in elderly people. We evaluated the risk and the potential determinants of early, mid and long term mortality, in a population-based cohort of subjects aged ≥ 65 years old.</p> <p>Methods</p> <p>Using hospital discharge database we identified all hospitalized hip fracture cases of 2006, among residents in Lazio Region aged ≥ 65 years old. The mortality follow-up was performed through a deterministic record-linkage between the cohort and the death registry for the years 2006 and 2007.</p> <p>Kaplan-Meier method was used to calculate cumulative survival probability after admission. Shared frailties Cox regression model was used to estimate adjusted hazard ratios (HRs) for early (within 1 month), mid (1-6 months) and long term (6-24 months) mortality. As possible cofactors we considered age, gender, marital status, education degree, comorbidities, surgical intervention, and hospital volume of surgical treatment for hip fracture.</p> <p>Results</p> <p>We identified 6,896 patients; 78% were females, median age was 83 and 9% had two or more comorbidities. Five percent died during hospital stay; the cumulative probability of dying at 30, 180 days, and at 2 years was 7%, 18% and 30%. In the first month following admission, we found a significantly increased HR with older age, male sex, not married status, history of hearth disease, chronic pulmonary and renal disease; for those who had surgery there was a significantly increased HR within two days after surgical intervention and a significantly decreased HR thereafter compared to those who received a conservative management. Between 1 and 6 months significantly increased HRs were for older age, male sex and higher hospital volume of surgical treatment. After six months, significantly increased HRs were for older age, male sex, presence of dementia and other low prevalence diseases.</p> <p>Conclusion</p> <p>In Lazio region the risk of dying after hip fracture is similar to that found in high-income countries. Both clinical and organizational factors of acute care are associated with the risk of early mortality. As time passes, some of these factors tend to become less important while older age, male gender, the presence of cognitive problems and the presence of other comorbidities remain significant.</p

Evidence of another anthropic impact on iguana delicatissima from the lesser Antilles: the presence of antibiotic resistant enterobacteria

The improper use of antibiotics by humans may promote the dissemination of resistance in wildlife. The persistence and spread of acquired antibiotic resistance and human-associated bacteria in the environment, while representing a threat to wildlife, can also be exploited as a tool to monitor the extent of human impact, particularly on endangered animal species. Hence, we investigated both the associated enterobacterial species and the presence of acquired resistance traits in the cloacal microbiota of the critically endangered lesser Antillean iguana (Iguana delicatissima), by comparing two separate populations living in similar climatic conditions but exposed to different anthropic pressures. A combination of techniques, including direct plating, DNA sequencing and antimicrobial susceptibility testing allowed us to characterize the dominant enterobacterial populations, the an- tibiotic resistant strains and their profiles. A higher frequency of Escherichia coli was found in the samples from the more anthropized site, where multi-drug resistant strains were also isolated. These results confirm how human-associated bacteria as well as their antibiotic-resistance determinants may be transferred to wildlife, which, in turn, may act as a reservoir of antibiotic resistance

Range resolution improvement in passive bistatic radars using nested FM channels and least squares approach

One of the main disadvantages of using commercial broadcasts in a Passive Bistatic Radar (PBR) system is the range resolution. Using multiple broadcast channels to improve the radar performance is offered as a solution to this problem. However, it suffers from detection performance due to the side-lobes that matched filter creates for using multiple channels. In this article, we introduce a deconvolution algorithm to suppress the side-lobes. The two-dimensional matched filter output of a PBR is further analyzed as a deconvolution problem. The deconvolution algorithm is based on making successive projections onto the hyperplanes representing the time delay of a target. Resulting iterative deconvolution algorithm is globally convergent because all constraint sets are closed and convex. Simulation results in an FM based PBR system are presented. © 2015 SPIE