Avalanche statistics during coarsening dynamics

We study the coarsening dynamics of a two dimensional system via lattice Boltzmann numerical simulations. The system under consideration is a biphasic system consisting of domains of a dispersed phase closely packed together in a continuous phase and separated by thin interfaces. Such system is elastic and typically out of equilibrium. The equilibrium state is attained via the coarsening dynamics, wherein the dispersed phase slowly diffuses through the interfaces, causing domains to change in size and eventually rearrange abruptly. The effect of rearrangements is propagated throughout the system via the intrinsic elastic interactions and may cause rearrangements elsewhere, resulting in intermittent bursts of activity and avalanche behaviour. Here we aim at quantitatively characterizing the corresponding avalanche statistics (i.e. size, duration, inter-avalanche time). Despite the coarsening dynamics is triggered by an internal driving mechanism, we find quantitative indications that such avalanche statistics displays scaling-laws very similar to those observed in the response of disordered materials to external loads

Broadband stimulated four-wave parametric conversion on a tantalum pentoxide photonic chip

We exploit the large third order nonlinear susceptibility (?(3) or “Chi 3”) of tantalum pentoxide (Ta2O5) planar waveguides and realize broadband optical parametric conversion on-chip. We use a co-linear pump-probe configuration and observe stimulated four wave parametric conversion when seeding either in the visible or the infrared. Pumping at 800 nm we observe parametric conversion over a broad spectral range with the parametric idler output spanning from 1200 nm to 1600 nm in infrared wavelengths and from 555 nm to 600 nm in visible wavelengths. Our demonstration of on-chip stimulated four wave parametric conversion introduces Ta2O5 as a novel material for broadband integrated nonlinear photonic circuit applications

Cues Triggering Formation and Germination of Resting Stages in Marine Diatoms

The project of my PhD thesis was focused on understanding the factors that induce spore formation and germination in the marine planktonic diatom Chaetoceros socialis. Among the candidate triggers of spore formation, nitrogen depletion is the most common while light is the principal trigger of spore germination. The link between spore formation and nitrogen starvation in the natural environment is however elusive and this lead me to test other factors, such as cell crowding and viral infections, which were never tested before. The results of my experimental work show that nitrogen depletion is not the only factor that induces the formation of resting spores, even though it remains the most effective in laboratory experiments. Spore formation was in fact induced when nitrogen and other nutrients were still available; it was induced by culture medium conditioned by the presence of high cell density, by culture medium obtained after killing cells by sonication. This is evidence for the presence of chemical compound/s that induced the formation of spores. Moreover, spores were produced in nutrient replete cultures infected by a species-specific virus. A transcriptomic approach in which the differential expression of genes in key time points during spore formation versus the control (exponentially growing cells), provided insights on the molecular mechanisms involved in this life cycle transition. I evaluated the role of blue, red and white light at very low intensity (1.2 μmol m2 sec -1) below the threshold for photosynthesis and slight higher white light (20 μmol m2 sec -1) in inducing spore germination. Results showed significantly higher germination rates only at higher light levels, while low and similar germination rates although germination occurred in other conditions including the controls in the dark. This study adds new and relevant information for understanding how and why spores are formed, underlying their potential importance in population dynamics and, in turn, in the ecosystem functioning

The Effects of the New Therapeutic Treatments for Diabetes Mellitus on the Male Reproductive Axis

One of the complications of chronic hyperglycemia and insulin resistance due to type 2 diabetes mellitus (T2DM) on the hypothalamic-pituitary-gonadal axis in men, is the high prevalence of hypogonadotropic hypogonadism, which has been recently defined as functional hypogonadism, characterized by low testosterone associated with inappropriately normal gonadotropin levels. Although the pathophysiology of this hormonal imbalance may be related to several factors, including glycemic control, concomitant sleep apnea, insulin resistance, the main role is determined by the degree of central or visceral obesity and the consequent inflammatory state. Several drugs have been developed to treat T2DM such as glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase 4 inhibitors, and sodium-glucose co-transporter 2 inhibitors. All appear to be effective in ameliorating blood glucose control, by lowering inflammation and body weight, and most seem to reduce the risk of micro- and macrovascular damage as a consequence of uncontrolled diabetes. A few studies have evaluated the impact of these drugs on gonadal function in T2DM patients with hypogonadism, with promising results. This review summarizes the main current knowledge of the effects of these new antidiabetic drugs on the hypothalamus-pituitary-gonadal axis, showing their potential future application in addition to glucose control in dysmetabolic male patients

On the impact of controlled wall roughness shape on the flow of a soft-material

We explore the impact of geometrical corrugations on the near-wall flow properties of a soft-material driven in a confined rough microchannel. By means of numerical simulations, we perform a quantitative analysis of the relation between the flow rate $\Phi$ and the wall stress $\sigma_w$ for a number of setups, by changing both the roughness values as well as the roughness shape. Roughness suppresses the flow, with the existence of a characteristic value of $\sigma_w$ at which flow sets in. Just above the onset of flow, we quantitatively analyze the relation between $\Phi$ and $\sigma_w$. While for smooth walls a linear dependency is observed, steeper behaviours are found to set in by increasing wall roughness. The variation of the steepness, in turn, depends on the shape of the wall roughness, wherein gentle steepness changes are promoted by a variable space localization of the roughness

Portfolio implementation risk management using evolutionary multiobjective optimization

Portfoliomanagementbasedonmean-varianceportfoliooptimizationissubjecttodifferent sources of uncertainty. In addition to those related to the quality of parameter estimates used in the optimization process, investors face a portfolio implementation risk. The potential temporary discrepancybetweentargetandpresentportfolios,causedbytradingstrategies,mayexposeinvestors to undesired risks. This study proposes an evolutionary multiobjective optimization algorithm aiming at regions with solutions more tolerant to these deviations and, therefore, more reliable. The proposed approach incorporates a user’s preference and seeks a fine-grained approximation of the most relevant efficient region. The computational experiments performed in this study are based on a cardinality-constrained problem with investment limits for eight broad-category indexes and 15 years of data. The obtained results show the ability of the proposed approach to address the robustness issue and to support decision making by providing a preferred part of the efficient set. The results reveal that the obtained solutions also exhibit a higher tolerance to prediction errors in asset returns and variance–covariance matrix.Sandra Garcia-Rodriguez and David Quintana acknowledge financial support granted by the Spanish Ministry of Economy and Competitivity under grant ENE2014-56126-C2-2-R. Roman Denysiuk and Antonio Gaspar-Cunha were supported by the Portuguese Foundation for Science and Technology under grant PEst-C/CTM/LA0025/2013 (Projecto Estratégico-LA 25-2013-2014-Strategic Project-LA 25-2013-2014).info:eu-repo/semantics/publishedVersio

Optimised design of fibre-based pulse compressor for gain-switched DFB laser pulses at 1.5 µm

An optical-fibre based pulse compressor for gain-switched DFB laser pulses has been optimised using a systematic procedure based on the initial complete characterisation of the laser pulses, followed by numerical simulations of the pulse propagation in different types of fibre to determine the required lengths for optimum compression. Using both linear and nonlinear compression techniques, an optimum compression factor of 12 is achieved

Research of current postgraduate nursing training courses in ICU: a systematic review.

INTRODUCTION Critical care nurses need the ability to integrate advanced theoretical knowledge and practical skills to meet the needs of critical patient care. OBJECTIVE The study presented in this paper wants to research the postgraduate training courses for critical care nurses the techniques that improve more their knowledge and skills. METHODS The authors conducted a systematic review lasting 7 months on three different databases. A search string was placed, based on the selected PICO. A PRISMA flow chart was drawn up. The inclusion and exclusion criteria were established. Several quality assessment tools were used. Results: the search string yielded 506 articles. After the removal of duplicates, the selection with the inclusion and exclusion criteria and the qualitative evaluation; the review included 41 studies. DISCUSSION AND CONCLUSIONS The survey affirms the importance to continuously update the knowledge and skills of the staff who give assistance in high care complexity situations. A lack of uniformity in the definition of standardized training courses emerged from the study. Australian research has given the possibility to develop a tool to evaluate the expected practice level after a training program. Simulation is identified as the best teaching strategy for postgraduate courses in the critical area