The isotropic-nematic phase transition in hard, slightly curved, lens-like particles.

Monte Carlo numerical simulations are used to study in detail how the characteristics of the isotropic-nematic phase transition change as infinitely thin hard platelets are bent into shallow lens-like particles. First, this phase transition in the former reference model system is re-examined and more accurately located. Then, it is shown quantitatively that this already quite weak but distinctly first-order phase transition weakens further upon curving the platelets to such an extent that, thanks to the thinness of these particles that does not favor its pre-emptying by a transition to a (partially) positionally ordered phase, an isotropic-nematic tricritical point limit can be arbitrarily closely approached

Stokes-Einstein relation of the liquid metal rubidium and its relationship to changes in the microscopic dynamics with increasing temperature

For liquid rubidium the Stokes-Einstein (SE) relation is well fulfilled near the melting point with an effective hydrodynamic diameter, which agrees well with a value from structural investigations. A wealth of thermodynamic and microscopic data exists for a wide range of temperatures for liquid rubidium and hence it represents a good test bed to challenge the SE relation with rising temperature from an experimental point of view. We performed classical molecular dynamics simulations to complement the existing experimental data using a pseudopotential, which describes perfectly the structure and dynamics of liquid rubidium. The derived SE relation from combining experimental shear viscosity data with simulated diffusion coefficients reveals a weak violation at about 1.3Tmelting ≈ 400 K. The microscopic relaxation dynamics on nearest neighbor distances from neutron spectroscopy demonstrate distinct changes in the amplitude with rising temperature. The derived average relaxation time for density fluctuations on this length scale shows a non-Arrhenius behavior, with a slope change around 1.5Tmelting ≈ 450 K. Combining the simulated macroscopic self-diffusion coefficient with that microscopic average relaxation time, a distinct violation of the SE relation in the same temperature range can be demonstrated. One can conclude that the changes in the collective dynamics, a mirror of the correlated movements of the particles, are at the origin for the violation of the SE relation. The changes in the dynamics can be understood as a transition from a more viscous liquid metal to a more fluid-like liquid above the crossover temperature range of 1.3–1.5 Tmelting. The decay of the amplitude of density fluctuations in liquid aluminium, lead, and rubidium demonstrates a remarkable agreement and points to a universal thermal crossover in the dynamics of liquid metals

The study of demonstration in motor learning: state of the art, challenges, and perspectives

O objetivo deste artigo é realizar uma revisão de literatura sobre a demonstração, uma importante fonte de informação no processo de aquisição de habilidades motoras, buscando apresentar o estado da arte, os principais desafios e algumas perspectivas de pesquisa. A demonstração tem sido investigada sob diferentes bases teóricas. A primeira delas é a teoria de aprendizagem social de Bandura, na qual foram apresentadas proposições acerca de como a informação observada é processada pelo aprendiz. As pesquisas mais recentes têm procurado elucidar a natureza da informação observada e se fundamentam em duas abordagens teóricas: a motora e a da ação. Os resultados de pesquisas com base na teoria de Bandura mostram que, no ato da aprendizagem por observação, as características do modelo, do aprendiz, da demonstração e da habilidade motora potencializam diferentemente os subprocessos relacionados à formação de referência da ação. Já os estudos que têm investigado a natureza da informação apresentam avanços em ambas as abordagens teóricas, porém em ritmo lento. Para que novos avanços ocorram, sugere-se um intercâmbio metodológico entre as abordagens e a realização de investigações em que o aprendiz tenha maior controle sobre a solicitação e o uso da demonstração.The aim of this study was to review the literature regarding demonstration as an important information source for the acquisition of motor skills. State of the art, main research challenges and some research perspectives are presented. Different theoretical bases have been used for the investigation of demonstration. The first is Bandura's social learning theory, in which proposals of how the observed information is processed by the learner are presented. Recent studies have tried to identify the nature of the observed information based on two theoretical models: motor and action approaches. Research findings based on Bandura's theory show that, during the process of observational learning, factors such as characteristics of the model, learner, demonstration, and motor skill differently affect the sub-processes related to the formation of the guide of action. On the other hand, studies investigating the nature of the information have shown advances in both theoretical approaches, but at a slower pace. For further developments to occur, we suggest a methodological exchange between the two theoretical approaches and investigations in which the learner has greater control over the request and use of demonstration

Large Attractive Depletion Interactions in Soft Repulsive-Sphere Binary Mixtures

We consider binary mixtures of soft repulsive spherical particles and calculate the depletion interaction between two big spheres mediated by the fluid of small spheres, using different theoretical and simulation methods. The validity of the theoretical approach, a virial expansion in terms of the density of the small spheres, is checked against simulation results. Attention is given to the approach toward the hard-sphere limit, and to the effect of density and temperature on the strength of the depletion potential. Our results indicate, surprisingly, that even a modest degree of softness in the pair potential governing the direct interactions between the particles may lead to a significantly more attractive total effective potential for the big spheres than in the hard-sphere case. This might lead to significant differences in phase behavior, structure and dynamics of a binary mixture of soft repulsive spheres. In particular, a perturbative scheme is applied to predict the phase diagram of an effective system of big spheres interacting via depletion forces for a size ratio of small and big spheres of 0.2; this diagram includes the usual fluid-solid transition but, in the soft-sphere case, the metastable fluid-fluid transition, which is probably absent in hard-sphere mixtures, is close to being stable with respect to direct fluid-solid coexistence. From these results the interesting possibility arises that, for sufficiently soft repulsive particles, this phase transition could become stable. Possible implications for the phase behavior of real colloidal dispersions are discussed.Comment: 31 pages, 8 figures; version accepted for publication in the Journal of Chemical Physic

Autonomous IoT Monitoring Matching Spectral Artificial Light Manipulation for Horticulture

This paper aims at demonstrating the energy self-sufficiency of a LoRaWAN-based sensor node for monitoring environmental parameters exploiting energy harvesting directly coming from the artificial light used in indoor horticulture. A portable polycrystalline silicon module is used to charge a Li-Po battery, employed as the power reserve of a wireless sensor node able to accurately monitor, with a 1-h period, both the physical quantities most relevant for the application, i.e., humidity, temperature and pressure, and the chemical quantities, i.e., O(2) and CO(2) concentrations. To this aim, the node also hosts a power-hungry NDIR sensor. Two programmable light sources were used to emulate the actual lighting conditions of greenhouses, and to prove the effectiveness of the designed autonomous system: a LED-based custom designed solar simulator and a commercial LED light especially thought for plant cultivation purposes in greenhouses. Different lighting conditions used in indoor horticulture to enhance different plant growth phases, obtained as combinations of blue, red, far-red and white spectra, were tested by field tests of the sensor node. The energy self-sufficiency of the system was demonstrated by monitoring the charging/discharging trend of the Li-Po battery. Best results are obtained when white artificial light is mixed with the far-red component, closest to the polycrystalline silicon spectral response peak

Relaxin prevents cardiac fibroblast-myofibroblast transition via Notch-1-mediated Inhibition of TGF-β/Smad3 signaling

The hormone relaxin (RLX) is produced by the heart and has beneficial actions on the cardiovascular system. We previously demonstrated that RLX stimulates mouse neonatal cardiomyocyte growth, suggesting its involvement in endogenous mechanisms of myocardial histogenesis and regeneration. In the present study, we extended the experimentation by evaluating the effects of RLX on primary cultures of neonatal cardiac stromal cells. RLX inhibited TGF-β1-induced fibroblast-myofibroblast transition, as judged by its ability to down-regulate α-smooth muscle actin and type I collagen expression. We also found that the hormone up-regulated metalloprotease (MMP)-2 and MMP-9 expression and downregulated the tissue inhibitor of metalloproteinases (TIMP)-2 in TGF-β1-stimulated cells. Interestingly, the effects of RLX on cardiac fibroblasts involved the activation of Notch-1 pathway. Indeed, Notch-1 expression was significantly decreased in TGF-β1-stimulatedfibroblasts as compared to the unstimulated controls; this reduction was prevented by the addition of RLX to TGF-β1-stimulated cells. Moreover, pharmacological inhibition of endogenous Notch-1 signaling by N-3,5-difluorophenyl acetyl-L-alanyl-2-phenylglycine-1,1-dimethylethyl ester (DAPT), a γ-secretase specific inhibitor, as well as the silencing of Notch-1 ligand, Jagged-1, potentiated TGF-β1-induced myofibroblast differentiation and abrogated the inhibitory effects of RLX. Interestingly, RLX and Notch-1 exerted their inhibitory effects by interfering with TGF-β1 signaling, since the addition of RLX to TGF-β1-stimulated cells caused a significant decrease in Smad3 phosphorylation, a typical downstream event of TGF-β1 receptor activation, while the treatment with a prevented this effect. These data suggest that Notch signaling can down-regulate TGF-β1/Smad3-induced fibroblast-myofibroblast transition and that RLX could exert its well known anti-fibrotic action through the up-regulation of this pathway. In conclusion, the results of the present study beside supporting the role of RLX in the field of cardiac fibrosis, provide novel experimental evidence on the molecular mechanisms underlying its effects

Integra® dermal matrix bioengineered with platelet rich plasma (PRP) and mesenchymal stromal cells to serve as niche for skin regeneration

Regenerative medicine strategies represent one of the main challenges to improve tissue healing and repair after damage or chronic pathologies. In this perspective, the setting of bioengineered scaffolds, namely synthetic matrices enriched with growth factors and stem cells, is considered a hot issue by numerous research groups. In a previous “in vitro” study we have demonstrated that rat bone marrow-derived mesenchymal stem cells (MSCs) seeded on an artificial dermal matrix Integra®, enriched with platelet-rich plasma (PRP) displayed enhanced proliferative attitude as compared with those cultured in the presence of PRP or on the scaffold alone. To this purpose, in this study we wanted to extend the experimentation by evaluating the efficacy of the bioengineered Integra® in an in vivo model of skin damage in rats. In particular, we used MSC derived from genetically modified rats overexpressing green fluorescent protein (GFP). Rats were divided into different groups: those receiving Integra® or PRP alone, Integra® plus PRP, Integra® plus PRP and MSC, and injured and untreated rats. Skin biopsies, obtained at different times from the injury and the implant, were examined to evaluate the regeneration process and neovascularization pattern of the substrate at light an confocal immunofluorescence microscopy. In parallel experiments we evaluated the ability of MSC to release growth factors, namely VEGF and FGF, and immunomodulatory cytokines, to underscore the paracrine effects of these cells on the surrounding host tissue

The predictive and prognostic potential of plasma telomerase reverse transcriptase (TERT) RNA in rectal cancer patients

Background: Preoperative chemoradiotherapy (CRT) followed by surgery is the standard care for locally advanced rectal cancer, but tumour response to CRT and disease outcome are variable. The current study aimed to investigate the effectiveness of plasma telomerase reverse transcriptase (TERT) levels in predicting tumour response and clinical outcome. Methods: 176 rectal cancer patients were included. Plasma samples were collected at baseline (before CRT\ubcT0), 2 weeks after CRT was initiated (T1), post-CRT and before surgery (T2), and 4\u20138 months after surgery (T3) time points. Plasma TERT mRNA levels and total cell-free RNA were determined using real-time PCR. Results: Plasma levels of TERT were significantly lower at T2 (Po0.0001) in responders than in non-responders. Post-CRT TERT levels and the differences between pre- and post-CRT TERT levels independently predicted tumour response, and the prediction model had an area under curve of 0.80 (95% confidence interval (CI) 0.73\u20130.87). Multiple analysis demonstrated that patients with detectable TERT levels at T2 and T3 time points had a risk of disease progression 2.13 (95% CI 1.10\u20134.11)-fold and 4.55 (95% CI 1.48\u201313.95)-fold higher, respectively, than those with undetectable plasma TERT levels. Conclusions: Plasma TERT levels are independent markers of tumour response and are prognostic of disease progression in rectal cancer patients who undergo neoadjuvant therapy

The physics potential of proton-nucleus collisions at the TeV scale

The LHC brings nuclear collisions to the TeV scale for the first time and the first data show the qualitative differences of this new regime. The corresponding phase-space available encompasses completely uncharted regions of QCD in which high-density or high-temperature domains can be identified. Proton-nucleus runs are essential for a complete interpretation of the data and for the study of new regimes dominated by large occupation numbers in the hadronic wave function. I comment here the physics opportunities for p+Pb runs at the LHC and d+Au runs at RHIC and the corresponding needs in view of the new Pb+Pb data from the LHC.Comment: Proceedings of the conference Quark Matter 2011, Annecy (France) May 201

Lenalidomide in Pretreated Mantle Cell Lymphoma Patients: An Italian Observational Multicenter Retrospective Study in Daily Clinical Practice (the Lenamant Study)

Background: Mantle cell lymphoma (MCL) has the worst prognosis of B-cell subtypes owing to its aggressive clinical disease course and incurability with standard chemo-immunotherapy. Options for relapsed MCL are limited, although several single agents have been studied. Lenalidomide is available in Italy for patients with MCL based on a local disposition of the Italian Drug Agency. Subjects, Materials, and Methods: An observational retrospective study was conducted in 24 Italian hematology centers with the aim to improve information on effectiveness and safety of lenalidomide use in real practice. Results: Seventy patients received lenalidomide for 21/28 days with a median of eight cycles. At the end of therapy, there were 22 complete responses (31.4%), 11 partial responses, 6 stable diseases, and 31 progressions, with an overall response rate of 47.1%. Eighteen patients (22.9%) received lenalidomide in combination with either dexamethasone (n = 13) or rituximab (n = 5). Median overall survival (OS) was reached at 33 months and median disease-free survival (DFS) at 20 months: 14/22 patients are in continuous complete response with a median of 26 months. Patients who received lenalidomide alone were compared with patients who received lenalidomide in combination: OS and DFS did not differ. Progression-free survivals are significantly different: at 56 months, 36% in the combination group versus 13% in patients who received lenalidomide alone. Toxicities were manageable, even if 17 of them led to an early drug discontinuation. Conclusion: Lenalidomide therapy for relapsed MCL patients is effective and tolerable even in a real-life context. Implication for Practice: Several factors influence treatment choice in relapsed/refractory mantle cell lymphoma (rrMCL), and the therapeutic scenario is continuously evolving. In fact, rrMCL became the first lymphoma for which four novel agents have been approved: temsirolimus, lenalidomide, ibrutinib, and bortezomib. The rrMCL therapeutic algorithm is not so well established because data in the everyday clinical practice are still poor. Lenalidomide for rrMCL patients is effective and tolerable even in a real-life context