276 research outputs found
The Naples Systematic Series – Second part: Irregular waves, seakeeping in head sea
Abstract The main aim of this study is to characterize the dynamic behavior of the Naples Systematic Series (NSS) in irregular head sea. A further aim of the study is to provide data to detect the influence of hull form on the sea-keeping performances in the planing and semi-planing speed range. The NSS derives from a parent hull that has shown to behave well in rough seas, characterized by high deadrise angles of the bottom at the bow, to reduce acceleration. All the models of NSS were tested in three different sea states and in Fr range from 0.515 to 1.197. The relatively high Froude numbers associated with the forms of the series make inappropriate the statistical analysis usually carried out to describe the behavior of the displacement ships. To overcome these unsuitableness, Cartwright Lounguet Higgins, extreme value and normal distribution fittings have been furnished for heave and pitch maxima and minima; gamma and extreme value have been furnished to represent acceleration in the centre of gravity and bow. Finally, a case study is presented to show a useful procedure for designer evaluation
Flettner Rotor Concept for Marine Applications: A Systematic Study
The concept of Flettner rotor, a rotating cylinder immersed in a fluid current, with a top-mounted disk, has been analyzed by means of unsteady Reynolds averaged Navier-Stokes simulations, with the aim of creating a suitable tool for the preliminary design of the Flettner rotor as a ship's auxiliary propulsion system. The simulation has been executed to evaluate the performance sensitivity of the Flettner rotor with respect to systematic variations of several parameters, that is, the spin ratio, the rotor aspect ratio, the effect of the end plates, and their dimensions. The Flettner rotor device has been characterized in terms of lift and drag coefficients, and these data were compared with experimental trends available in literature. A verification study has been conducted in order to evaluate the accuracy of the simulation results and the main sources of numerical uncertainty. All the simulation results were used to achieve a surrogate model of lift and drag coefficients. This model is an effective mathematical tool for the preliminary design of Flettner rotor. Finally, an example of assessment of the Flettner rotor performance as an auxiliary propulsion device on a real tanker ship is reported
A Framework for Recommending Multimedia Cultural Visiting Paths
In this work, we present a general framework for Cultural Heritage applications able to uniformly manage heterogeneous multimedia data coming from several web repositories and to provide context- Aware recommendation services in order to generate dynamic multimedia visiting paths useful for the users during the exploration of different kinds of cultural sites. A specific application of our system within the cultural heritage domain is proposed together with some experimental results
The Role of a Double Molecular Anchor on the Mobility and Self-Assembly of Thiols on Au(111): The Case of Mercaptobenzoic Acid
The dynamics of the self-assembly process of thiol molecules on Au(111) is affected by the interplay between molecule–substrate and molecule–molecule interactions. Therefore, it is interesting to explore the effect of a second anchor to the gold surface, in addition to the S atom, on both the order and the feasibility of phase transitions in self-assembled monolayers. To assess the role of an additional O anchor, we have compared the adsorption of two mercaptobenzoic acid isomers, 2-mercaptobenzoic acid (2-MBA) and 4-mercaptobenzoic acid (4-MBA), on Au(111). Results from scanning tunneling microscopy, X-ray photoelectron spectroscopy, electrochemical techniques, and density functional theory calculations show that the additional O anchor in 2-MBA hinders surface mobility, reducing domain size and impeding the molecular reorganization involved in phase transition to denser phases on the Au(111) substrates. This knowledge can help to predict the range order and molecular density of the thiol SAM depending on the chemical structure of the adsorbate.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada
Zinc inhibits calcium-mediated and nitric oxide-mediated ion secretion in human enterocytes
Zn2+ is effective in the treatment of acute diarrhea, but its mechanisms are not completely understood. We previously demonstrated that Zn2+ inhibits the secretory effect of cyclic adenosine monophosphate but not of cyclic guanosine monophosphate in human enterocytes. The aim of the present study was to investigate whether Zn2+ inhibits intestinal ion secretion mediated by the Ca2+ or nitric oxide pathways. To investigate ion transport we evaluated the effect of Zn2+ (35 μM) on electrical parameters of human intestinal epithelial cell monolayers (Caco2 cells) mounted in Ussing chambers and exposed to ligands that selectively increased intracellular Ca2+ (carbachol 10− 6 M) or nitric oxide (interferon-γ 300 UI/ml) concentrations. We also measured intracellular Ca2+ and nitric oxide concentrations. Zn2+ significantly reduced ion secretion elicited by carbachol (− 87%) or by interferon-γ (− 100%), and inhibited the increase of intracellular Ca2+ and nitric oxide concentrations. These data indicate that Zn2+ inhibits ion secretion elicited by Ca2+ and nitric oxide by directly interacting with the enterocyte. They also suggest that Zn2+ interferes with three of the four main intracellular pathways of intestinal ion secretion that are involved in acute diarrhe
Differentiation dynamics of mammary epithelial cells revealed by single-cell RNA sequencing.
Characterising the hierarchy of mammary epithelial cells (MECs) and how they are regulated during adult development is important for understanding how breast cancer arises. Here we report the use of single-cell RNA sequencing to determine the gene expression profile of MECs across four developmental stages; nulliparous, mid gestation, lactation and post involution. Our analysis of 23,184 cells identifies 15 clusters, few of which could be fully characterised by a single marker gene. We argue instead that the epithelial cells-especially in the luminal compartment-should rather be conceptualised as being part of a continuous spectrum of differentiation. Furthermore, our data support the existence of a common luminal progenitor cell giving rise to intermediate, restricted alveolar and hormone-sensing progenitors. This luminal progenitor compartment undergoes transcriptional changes in response to a full pregnancy, lactation and involution. In summary, our results provide a global, unbiased view of adult mammary gland development
A single-cell atlas enables mapping of homeostatic cellular shifts in the adult human breast
A.D.R. performed the majority of the bioinformatic analysis and interpretation of the data. S.P. contributed to the study design, sample processing, analysis and interpretation of the data. J.S. contributed to the sample processing. D.J.K. and P.H. contributed to the data processing, batch correction and cell cluster identification. A.S. contributed to the design of the sample batches and contributed to the analysis of the raw data. A.J.T. contributed to the analysis of the data and Figure design. L.J.P. performed the immune histochemistry validations. K.H. assisted A.D.R. with the inferCNV analysis and interpretation. P.H. assisted with the subclustering of immune cells and scVI integration analysis. A.Q.S. performed the immunofluorescence quantification. K.K. performed all the scRNA-seq library preparation and sequencing. R.B.M., I.G., J.J.G., V.S. and J.L.J. provided the human tissues and the metadata from the 55 donors. A.D.R., S.P., J.C.M. and W.T.K. wrote the paper. J.C.M. and W.T.K. conceptualized and supervised the study.Peer reviewe
Analysis and Practical Guideline of Constraint-Based Boolean Method in Genetic Network Inference
Boolean-based method, despite of its simplicity, would be a more attractive approach for inferring a network from high-throughput expression data if its effectiveness has not been limited by high false positive prediction. In this study, we explored factors that could simply be adjusted to improve the accuracy of inferring networks. Our work focused on the analysis of the effects of discretisation methods, biological constraints, and stringency of Boolean function assignment on the performance of Boolean network, including accuracy, precision, specificity and sensitivity, using three sets of microarray time-series data. The study showed that biological constraints have pivotal influence on the network performance over the other factors. It can reduce the variation in network performance resulting from the arbitrary selection of discretisation methods and stringency settings. We also presented the master Boolean network as an approach to establish the unique solution for Boolean analysis. The information acquired from the analysis was summarised and deployed as a general guideline for an efficient use of Boolean-based method in the network inference. In the end, we provided an example of the use of such a guideline in the study of Arabidopsis circadian clock genetic network from which much interesting biological information can be inferred
Conditional Wwox Deletion in Mouse Mammary Gland by Means of Two Cre Recombinase Approaches
Loss of WWOX expression has been reported in many different cancers including breast cancer. Elucidating the function of this gene in adult tissues has not been possible with full Wwox knockout models. Here we characterize the first conditional models of Wwox ablation in mouse mammary epithelium utilizing two transgenic lines expressing Cre recombinase, keratin 5-Cre (BK5-Cre) and MMTV-Cre. In the BK5-Cre model we observed very efficient Wwox ablation in KO mammary glands. However, BK5-Cre Wwox KO animals die prematurely for unknown reasons. In the MMTV-Cre model we observed significant ablation of Wwox in mammary epithelium with no effect on survival. In both of these models we found that Wwox deletion resulted in impaired mammary branching morphogenesis. We demonstrate that loss of Wwox is not carcinogenic in our KO models. Furthermore, no evidence of increase proliferation or development of premalignant lesions was observed. In none of the models did loss of a single Wwox allele (i.e. haploinsufficiency) have any observable phenotypic effect in mammary gland. To better understand the function of Wwox in the mammary gland, transcriptome profiling was performed. We observed that Wwox ablation results in the deregulation of genes involved in various cellular processes. We found that expression of the non-canonical Wnt ligand, Wnt5a, was significantly upregulated in Wwox KO mammary epithelium. Interestingly, we also determined that components of the Jak/Stat3 signaling pathway were upregulated in KO mice and this correlated with a very robust increase in phospho-Stat3 signaling, which warrants further testing. Even though the loss of Wwox expression in breast and other cancers is very well documented, our findings suggest that Wwox does not act as a classical tumor suppressor as previously thought
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