Influence of Structural Stiffness on Ratcheting Convection Cells of Granular Soil under Cyclic Lateral Loading

In granular soils, long-term cyclically loaded structures can lead to an accumulation of irreversible strain by forming closed convective cells in the upper layer of the bedding. The size of the convective cell, its formation and grain migration inside this closed volume have been studied with reference to different stiffness of the embedded structure and different maximum force amplitudes applied at the head of the structure. This relation was experimentally investigated by applying a cyclic lateral force to a scaled flexible vertical element embedded in a dry granular soil. The model was monitored with a camera in order to derive the displacement field by means of the PIV technique. Furthermore, the ratcheting convective cell was also simulated with DEM with the aim of extracting some micromechanical information. The main results regarded the different development, shape and size of the convection cell and the surface settlements

Experiments and DEM Simulations of Granular Ratcheting

In this work we studied the effect of cyclic loading on a granular packing by means of numerical simulations and experiments. A confined packing of glass beads was prepared and one of the walls was moved cyclically with a prescribed amplitude of the order of the particle diameter. Different amplitudes were tested, and their effect on the free surface evolution, the force transmitted to the moving wall and the displacement patterns in the material was characterized. Discrete numerical simulations were also carried out with the specific purpose of evaluating the effect of the particle shape on the dynamics of the system. The displacement amplitude of the moving wall was shown to increase the maximum force experienced at the end of the compressive phase of the wall movement; the angularity of the particles had a similar effect. Force-wall displacement curves displayed a peculiar hysteretic behavior. The evolution of the system towards an asymptotic state was shown to be faster for spheres than for angular particles; the latter displayed an interesting long-time evolution of the force-displacement paths which deserves deeper investigations

Analysis of the role of MTP1, NRAMP4 and ZNT1 metal transporters in Ni hypertolerance and hyperaccumulation in Noccaea caerulescens and Identification of miRNAs involved in response to Zn excess in Arabidopsis species

Among hyperaccumulators, i.e. plants able to accumulate extremely high concentrations of heavy metals (HMs) in shoots, the Brassicaceae Arabidopsis halleri and Noccaea caerulescens, zinc (Zn)/cadmium (Cd) and Zn/Cd/nickel (Ni) hyperaccumulators respectively, represent two of the most interesting species, due to the huge variability between different ecotypes and populations in metal tolerance and accumulation. In this PhD work, two independent approaches were used aiming for a deeper understanding of metal hypertolerance and hyperaccumulation. The first approach exploits N. caerulescens ecotype Monte Prinzera (MP, Italy), native of a serpentine soil, that is able to hypertolerate and hyperaccumulate Ni in addition to Zn. Molecular mechanisms responsible for Ni tolerance and accumulation are still mostly unknown, although several studies suggested that metal transporters, also essential for metal homeostasis, have a fundamental role in HM tolerance and accumulation. Therefore, the vacuolar transporters MTP1 and NRAMP4 and of plasma membrane transporter ZNT1 were taken in consideration, thanks to their proposed role in Ni tolerance and accumulation in N. caerulescens MP (Visioli et al., 2014). At first, the expression of all three genes in N. caerulescens MP exposed to different Ni concentrations was analysed and compared with those of T. arvense (non-accumulator) and N. caerulescens ecotype Ganges (GA, Zn/Cd hyperaccumulator). Higher expression levels of all genes were found in N. caerulescens MP under normal and Ni excess conditions, confirming the different regulation of metal transporter proteins in hyperaccumulator plants and suggesting their role in Ni tolerance. The Ni transport properties of both NcNRAMP4 and NcZNT1 was tested by yeast complementation assays, using a WT strain of S. cerevisiae; according to the results previously found for the other Ni hyperaccumulator plant N. japonica (Mizuno et al., 2005), NcNRAMP4 reduced recombinant yeast survival under Ni treatment and the opposite result was found for NcZNT1, indicating a possible direct involvement of both proteins in Ni transport. To better understand the role of NcNRAMP4 and NcZNT1 in Ni tolerance and accumulation, plants of Arabidopsis thaliana were transformed with constructs carrying CaMV35S::NRAMP4 and CaMV35S::ZNT1 and the transgenic lines were crossed to obtain plants overexpressing both genes. Single 35S::NRAMP4 and double 35S::NRAMP4/35S::ZNT1 lines displayed bigger shoot compared to WT plants and the same results were also found for two of the three lines overexpressing ZNT1, although with a minor impact compared to the other gene. The impact of both genes on Ni tolerance and accumulation in planta was also elucidated by in vivo and in vitro analysis. Compared to WT plants, transgenic lines of A. thaliana expressing NcNRAMP4, NcZNT1 or NcNRAMP4/NcZNT1 in combination showed higher tolerance to Ni excess in vivo, thanks to a reduction of Ni accumulation in shoots. In addition, single 35S::NcNRAMP4 and double 35S::NcNRAMP4/35S::ZNT1 transgenic lines displayed longer roots in vitro, under standard and Ni excess condition compared to the WT, although no significative differences were found regarding 35S::ZNT1 overexpressing lines. These data may suggest that NRAMP4 and ZNT1 could participate in the transport and accumulation of Ni in N. caerulescens MP, although probably these proteins are more associated with the transport of other micronutrients than Ni itself. The possible involvement of the vacuolar transporter MTP1 in Ni hyperaccumulation and hypertolerance in N. caerulescens MP was also investigated. Gene expression analysis have initially confirmed the high constitutive levels of MTP1 expression previously found in different hyperaccumulator-hypertolerant plants belonging to Noccaea genus (Assun\ue7\ue3o et al., 2001; van de Mortel et al., 2006) under normal and stressful conditions, although in N. caerulescens MP this gene seem to be downregulate upon Ni treatment. In both N. caerulescens GA and MP two different CDSs of MTP1 gene, characterized by different length, were found in cDNA and genomic DNA; these proteins, called MTP1-long and MTP1-short, based on the presence or absence of the conserved His-loop region, are localized in the vacuolar compartment, as confirmed by subcellular localization experiments, suggesting their role in metal detoxification. The metal binding properties of both NcMTP1-long and NcMTP1-short were tested by yeast complementation assays using zrc1cot1 double mutant yeast of S. cerevisiae, which lacks these two vacuolar proteins, and WT strain of S. cerevisiae considering AtMTP1 as control for Zn transport ability (Desbrosses-Fonrouge et al., 2005). The two MTP1 forms displayed different metal specificity regarding Zn, Ni and Co, suggesting their possible different involvement in detoxification of metal excess in N. caerulescens MP. Therefore, A. thaliana mtp1+/+ homozigous mutants were transformed with constructs carrying CaMV35S::MTP1-long and CaMV35S::MTP1-short and also CaMV35S::AtMTP1 as control to elucidate their different metal binding specificity in planta. The transgenic lines were selected and the biological effect of MTP1 in planta will be investigated. With the second approach the attention is focused on the identification of miRNAs involved in the response to Zn excess. In eukaryotes, these small non-coding RNAs are essential for the regulation of gene expression during development and stress response, as well as nutrient homeostasis. miRNAs are small regulatory RNAs (20-24 nt length), with important role in plant development and response to many abiotic and biotic stress in Arabidopsis and other plant species. Moreover, several works have led the attention on metal -responsive miRNAs, which are responsible for the morphological and metabolical adaptation of environmental cues in plants, representing an interesting starting point for further analysis. To identify miRNAs putatively involved in response to Zn excess in Arabidopsis, miRNA-seq analysis was performed on miRNAs extracted from shoots of A. thaliana, treated and not treated with an excess of Zn for one week, and from untreated A. halleri. This hyperaccumulator plants was used in order to evaluate the existence of a possible different regulation mechanisms which regulates miRNA-target interaction compared to the non-hyperaccumulator A. thaliana. 100 miRNAs resulted to be differentially modulated in A. halleri compared to A. thaliana, including metal responsive miRNAs. Some of them were experimentally validated by Northern Blot Analysis and Real Time RT-PCR, in particular miRNAs with a role in plant development (miR157, miR159, miR390) and in nutrient homeostasis regulation (miR395, miR398, miR408), confirming the data obtained by miRNA-seq analysis and suggesting that some miRNAs could have an important role in metal hypertolerance and hyperaccumulation. Then, the attention was focuses on miR398b and miR408, two conserved miRNAs principally involved in the regulation of copper homeostasis in A. thaliana and other plant species; several works have elucidated their role in response to many abiotic stresses, including oxidative stress and heavy metals (Yamasaki et al., 2009; Ma et al. 2015; Pilon et al., 2017; Jalmi et al., 2018); moreover, the coordinate action of both miRNAs in planta have been suggested to be required for Cd basal tolerance in Arabidopsis (Gayomba et al., 2013; Gielen et al., 2016), representing an interesting starting point for further analysis. In order to investigate the possible involvement of both miR398b and miR408 in response to Zn excess, the promoter sequence of both miRNAs was amplified from genomic DNA of A. thaliana and A. halleri and fused to GUS reporter gene. A bioinformatic analysis was initially done comparing the entire sequences obtained by A. thaliana and A. halleri, and several DNA motifs involved in response to abiotic stresses were identified. GUS assay on A. thaliana transgenic lines expressing pAtMIR398::GUS, pAhMIR398b::GUS, pAtMIR408::GUS, pAhMIR408::GUS have shown that both miRNAs are expressed in roots and shoots of Arabidopsis, particularly in the vasculature tissues, suggesting their mobility into the whole plant. In addition, GUS expression was also evaluated on transgenic plants grown under Zn and Cu treatment, to better elucidate a possible competition between Cu and Zn, as previously proposed (Remans et al., 2012), and study the response of these two miRNAs under metal exposure. Both miRNAs resulted to be modulated by high concentration of these two micronutrients, suggesting a competition between Zn and Cu as previously proposed (Remans et a., 2012). Finally, the effect of the overexpression of pre-miR408 of A. halleri upon Zn treatment was investigated, since it is known its fundamental role for the adaptation to environmental cues in plants as demonstrated for the homologous of A. thaliana (Ma et al., 2015; Zhang and Li, 2013; Song et al., 2018). Compared to WT plants, transgenic lines overexpressing the precursor sequence of miR408 of A. halleri displayed higher shoot biomass and a significative reduction of root length, suggesting that high expression of miR408 could modify Zn tolerance in planta. Further investigations will be also required to better elucidate the possible role of miRNAs in response to Zn excess in Arabidopsis

Train vs. play: Evaluating the effects of gamified and non-gamified wheelchair skills training using virtual reality

This study compares the influence of a gamified and a non-gamified virtual reality (VR) environment on wheelchair skills training. In specific, the study explores the integration of gamification elements and their influence on wheelchair driving performance in VR-based training. Twenty-two non-disabled participants volunteered for the study, of whom eleven undertook the gamified VR training, and eleven engaged in the non-gamified VR training. To measure the efficacy of the VR-based wheelchair skills training, we captured the heart rate (HR), number of joystick movements, completion time, and number of collisions. In addition, an adapted version of the Wheelchair Skills Training Program Questionnaire (WSTP-Q), the Igroup Presence Questionnaire (IPQ), and the Simulator Sickness Questionnaire (SSQ) questionnaires were administered after the VR training. The results showed no differences in wheelchair driving performance, the level of involvement, or the ratings of presence between the two environments. In contrast, the perceived cybersickness was statistically higher for the group of participants who trained in the non-gamified VR environment. Remarkably, heightened cybersickness symptoms aligned with increased HR, suggesting physiological connections. As such, while direct gamification effects on the efficacy of VR-based wheelchair skills training were not statistically significant, its potential to amplify user engagement and reduce cybersickness is evident

Long-term cyclic triaxial tests with DEM simulations

Modeling the long-term performance of granular materials under cyclic loading conditions is still a challenge and a better understanding could provide a large benefit for the design of foundations. One typical application example are the foundations of wind turbines, for which the evolution of the soil mechanical behavior could lead to irreversible strain accumulation (with tilting and settlement) and dynamic resonance problems [1]. In this framework the Discrete Element Method [2] can provide useful information starting from a micromechanical point of view: it may allow engineers to increase their knowledge on the evolution of the mechanical behavior and to optimize the long-term design of these structures [3]. The present paper presents the capability of DEM to simulate a long-term cyclic drained triaxial test (up to 100,000 cycles). The results regard the progressive accumulation of plastic strain as function of the number of particles and the initial particles rearrangement. The influence of densification and contact orientation (anisotropy) in the evolution of the strength of the soil during the cyclic loading history is investigated

Untargeted Metabolomics Analysis of the Orchid Species Oncidium sotoanum Reveals the Presence of Rare Bioactive C-Diglycosylated Chrysin Derivatives

Plants are valuable sources of secondary metabolites with pharmaceutical properties, but only a small proportion of plant life has been actively exploited for medicinal purposes to date. Underexplored plant species are therefore likely to contain novel bioactive compounds. In this study, we investigated the content of secondary metabolites in the flowers, leaves and pseudobulbs of the orchid Oncidium sotoanum using an untargeted metabolomics approach. We observed the strong accumulation of C-diglycosylated chrysin derivatives, which are rarely found in nature. Further characterization revealed evidence of antioxidant activity (FRAP and DPPH assays) and potential activity against neurodegenerative disorders (MAO-B inhibition assay) depending on the specific molecular structure of the metabolites. Natural product bioprospecting in underexplored plant species based on untargeted metabolomics can therefore help to identify novel chemical structures with diverse pharmaceutical properties

Train vs. Play: Evaluating the Effects of Gamified and Non-Gamified Wheelchair Skills Training Using Virtual Reality

This study compares the influence of a gamified and a non-gamified virtual reality (VR) environment on wheelchair skills training. In specific, the study explores the integration of gamification elements and their influence on wheelchair driving performance in VR-based training. Twenty-two non-disabled participants volunteered for the study, of whom eleven undertook the gamified VR training, and eleven engaged in the non-gamified VR training. To measure the efficacy of the VR-based wheelchair skills training, we captured the heart rate (HR), number of joystick movements, completion time, and number of collisions. In addition, an adapted version of the Wheelchair Skills Training Program Questionnaire (WSTP-Q), the Igroup Presence Questionnaire (IPQ), and the Simulator Sickness Questionnaire (SSQ) questionnaires were administered after the VR training. The results showed no differences in wheelchair driving performance, the level of involvement, or the ratings of presence between the two environments. In contrast, the perceived cybersickness was statistically higher for the group of participants who trained in the non-gamified VR environment. Remarkably, heightened cybersickness symptoms aligned with increased HR, suggesting physiological connections. As such, while direct gamification effects on the efficacy of VR-based wheelchair skills training were not statistically significant, its potential to amplify user engagement and reduce cybersickness is evident

A standardised and cost-effective VR approach for powered wheelchair training

Mastering wheelchair driving skills is essential for the safety of wheelchair users (WUs), yet the acquisition of these skills can be challenging, and training resources can be costly or not available. Technologies such as virtual reality (VR) have grown in popularity as they can provide a motivating training environment without the risks found in real-life training. However, these approaches often deploy navigation controllers which are different from the ones WUs utilise, and do not use a standardised approach in assessing the acquisition of skills. We propose a VR training system based on the wheelchair skills training program (WSTP) and utilizing a sensor device that can be retrofitted to any joystick and communicates wirelessly with a Head-Mounted Display. In this paper, we present a first-validation study with fourteen able-bodied participants, split between a VR test group and a non-VR control group. To determine the acquisition of skills, participants complete tasks in real-life before and after the VR training, where completion time and length of joystick movements are measured. We also assess our system using heart rate measurements, the WSTP questionnaire, the simulator sickness questionnaire and the igroup presence questionnaire. We found that the VR training facilitates the acquisition of skills for more challenging tasks; thus, our system has the potential of being used for training skills of powered wheelchair users, with the benefit of conducting the training in safely and in a low-cost setup

Renin-Angiotensin-Aldosterone System Inhibitors and Risk of Death in Patients Hospitalised with COVID-19: A Retrospective Italian Cohort Study of 43,000 Patients

Introduction The epidemic due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been spreading globally, raising increasing concerns. There are several controversial hypotheses on the potentially harmful or beneficial effects of antihypertensive drugs acting on the renin-angiotensin-aldosterone system (RAAS) in coronavirus disease 2019 (COVID-19). Furthermore, there is accumulating evidence, based on several observational studies, that angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) do not increase the risk of contracting SARS-CoV-2 infection. On the other hand, conflicting findings regarding the role of ACEIs/ARBs as prognosis modifiers in COVID-19 hospitalised patients have been reported. Objective The aim of this large-scale, retrospective cohort study was to investigate whether prior exposure to ACEIs and/or ARBs was associated with all-cause mortality among over 40,000 hospitalised COVID-19 patients compared with calcium channel blockers (CCBs), a potential therapeutic alternative. Methods This study was conducted using COVID-19 registries linked to claims databases from Lombardy, Veneto and Reggio Emilia (overall, 25% of Italian population). Overall, 42,926 patients hospitalised between 21 February and 21 April 2020 with a diagnosis of COVID-19 confirmed by real-time polymerase chain reaction tests were included in this study. All-cause mortality occurring in or out of hospital, as reported in the COVID-19 registry, was estimated. Using Cox models, adjusted hazard ratios (HRs) of all-cause mortality (along with 95% confidence intervals [CIs]) were estimated separately for ACEIs/ARBs and other antihypertensives versus CCBs and non-use. Results Overall, 11,205 in- and out-of-hospital deaths occurred over a median of 24 days of follow-up after hospital admission due to COVID-19. Compared with CCBs, adjusted analyses showed no difference in the risk of death among ACEI (HR 0.97, 95% CI 0.89-1.06) or ARB (HR 0.98, 95% CI 0.89-1.06) users. When non-use of antihypertensives was considered as a comparator, a modest statistically significant increase in mortality risk was observed for any antihypertensive use. However, when restricting to drugs with antihypertensive indications only, these marginal increases disappeared. Sensitivity and subgroup analyses confirmed our main findings. Conclusions ACEI/ARB use is not associated with either an increased or decreased risk of all-cause mortality, compared with CCB use, in the largest cohort of hospitalised COVID-19 patients exposed to these drugs studied to date. The use of these drugs therefore does not affect the prognosis of COVID-19. This finding strengthens recommendations of international regulatory agencies about not withdrawing/switching ACEI/ARB treatments to modify COVID-19 prognosis

Epidermal Growth Factor Receptor (EGFR) gene copy number (GCN) correlates with clinical activity of irinotecan-cetuximab in K-RAS wild-type colorectal cancer: a fluorescence in situ (FISH) and chromogenic in situ hybridization (CISH) analysis

<p>Abstract</p> <p>Background</p> <p>K-RAS wild type colorectal tumors show an improved response rate to anti-EGFR monoclonal antibodies. Nevertheless 70% to 40% of these patients still does not seem to benefit from this therapeutic approach. FISH EGFR GCN has been previously demonstrated to correlate with clinical outcome of colorectal cancer treated with anti-EGFR monoclonal antibodies. CISH also seemed able to provide accurate EGFR GCN information with the advantage of a simpler and reproducible technique involving immunohistochemistry and light microscopy. Based on these findings we investigated the correlation between both FISH and CISH EGFR GCN and clinical outcome in K-RAS wild-type colorectal cancer treated with irinotecan-cetuximab.</p> <p>Methods</p> <p>Patients with advanced K-RAS wild-type, colorectal cancer receiving irinotecan-cetuximab after failure of irinotecan-based chemotherapy were eligible.</p> <p>A cut-off value for EGFR GCN of 2.6 and 2.12 for FISH and CISH respectively was derived from ROC curve analysis.</p> <p>Results</p> <p>Forty-four patients were available for analysis. We observed a partial remission in 9 (60%) and 2 (9%) cases with a FISH EGFR GCN ≥ 2.6 and < 2.6 respectively (p = 0.002) and in 10 (36%) and 1 (6%) cases with a CISH EGFR GCN ≥ 2.12 and < 2.12 respectively (p = 0.03). Median TTP was 7.7 and 6.4 months in patients showing increased FISH and CISH EGFR GCN whereas it was 2.9 and 3.1 months in those with low FISH and CISH EGFR GCN (p = 0.04 and 0.02 respectively).</p> <p>Conclusion</p> <p>FISH and CISH EGFR GCN may both represent effective tools for a further patients selection in K-RAS wild-type colorectal cancer treated with cetuximab.</p