Automatic Extraction of Planetary Image Features

With the launch of several Lunar missions such as the Lunar Reconnaissance Orbiter (LRO) and Chandrayaan-1, a large amount of Lunar images will be acquired and will need to be analyzed. Although many automatic feature extraction methods have been proposed and utilized for Earth remote sensing images, these methods are not always applicable to Lunar data that often present low contrast and uneven illumination characteristics. In this paper, we propose a new method for the extraction of Lunar features (that can be generalized to other planetary images), based on the combination of several image processing techniques, a watershed segmentation and the generalized Hough Transform. This feature extraction has many applications, among which image registration

Unsupervised Detection of Planetary Craters by a Marked Point Process

With the launch of several planetary missions in the last decade, a large amount of planetary images is being acquired. Preferably, automatic and robust processing techniques need to be used for data analysis because of the huge amount of the acquired data. Here, the aim is to achieve a robust and general methodology for crater detection. A novel technique based on a marked point process is proposed. First, the contours in the image are extracted. The object boundaries are modeled as a configuration of an unknown number of random ellipses, i.e., the contour image is considered as a realization of a marked point process. Then, an energy function is defined, containing both an a priori energy and a likelihood term. The global minimum of this function is estimated by using reversible jump Monte-Carlo Markov chain dynamics and a simulated annealing scheme. The main idea behind marked point processes is to model objects within a stochastic framework: Marked point processes represent a very promising current approach in the stochastic image modeling and provide a powerful and methodologically rigorous framework to efficiently map and detect objects and structures in an image with an excellent robustness to noise. The proposed method for crater detection has several feasible applications. One such application area is image registration by matching the extracted features

Interventi funzionali dedicati alla modifica della superficie degli ingranaggi: la cementazione e la nitrurazione come pretrattamento di rivestimenti PVD

Per contrastare i meccanismi di danneggiamento degli ingranaggi (usura, fatica da contatto e fatica) èprassi comune intervenire con trattamenti a carico della superficie in grado, non solo di aumentare ladurezza superficiale, ma, anche, di indurre uno stato di compressione in corrispondenza della dentatura.Oltre ai tradizionali trattamenti di cementazione e di nitrurazione sono sempre più frequenti lesperimentazioni dedicate all’analisi degli effetti di rivestimenti sottili quali quelli ottenuti con tecniche PVD.Partendo da questi presupposti, nel presente lavoro è stata valutata la resistenza a fatica di un rivestimentodi nitruro di cromo depositato rispettivamente su di un acciaio da cementazione (16MnCrS5) e su di unacciaio da nitrurazione (42CrMo4) entrambi sottoposti a trattamento termochimico prima del rivestimento.La caratterizzazione delle modifiche superficiali è stata effettuata mediante analisi al SEM, misure dimicrodurezza e di nanoindentazione oltre che di stato tensionale residuo

The CDC42-Interacting Protein 4 Controls Epithelial Cell Cohesion and Tumor Dissemination

SummaryThe role of endocytic proteins and the molecular mechanisms underlying epithelial cell cohesion and tumor dissemination are not well understood. Here, we report that the endocytic F-BAR-containing CDC42-interacting protein 4 (CIP4) is required for ERBB2- and TGF-β1-induced cell scattering, breast cancer (BC) cell motility and invasion into 3D matrices, and conversion from ductal breast carcinoma in situ to invasive carcinoma in mouse xenograft models. CIP4 promotes the formation of an E-cadherin-CIP4-SRC complex that controls SRC activation, E-cadherin endocytosis, and localized phosphorylation of the myosin light chain kinase, thereby impinging on the actomyosin contractility required to generate tangential forces to break cell-cell junctions. CIP4 is upregulated in ERBB2-positive human BC, correlates with increased distant metastasis, and is an independent predictor of poor disease outcome in subsets of BC patients. Thus, it critically controls cell-cell cohesion and is required for the acquisition of an invasive phenotype in breast tumors

Human cortical organoids expose a differential function of GSK3 on cortical neurogenesis

The regulation of the proliferation and polarity of neural progenitors is crucial for the development of the brain cortex. Animal studies have implicated glycogen synthase kinase 3 (GSK3) as a pivotal regulator of both proliferation and polarity, yet the functional relevance of its signaling for the unique features of human corticogenesis remains to be elucidated. We harnessed human cortical brain organoids to probe the longitudinal impact of GSK3 inhibition through multiple developmental stages. Chronic GSK3 inhibition increased the proliferation of neural progenitors and caused massive derangement of cortical tissue architecture. Single-cell transcriptome profiling revealed a direct impact on early neurogenesis and uncovered a selective role of GSK3 in the regulation of glutamatergic lineages and outer radial glia output. Our dissection of the GSK3-dependent transcriptional network in human corticogenesis underscores the robustness of the programs determining neuronal identity independent of tissue architecture

DEVELOPMENT AND CHARACTERIZATION OF TIO2 COATINGS PREPARED BY ELECTRIC ARC-PHYSICAL VAPOUR DEPOSITION SYSTEM

TiO2 thin coatings were prepared, on various substrates, through evaporation of metallic titanium in an oxidizing atmosphere by modified electric arc physical vapor deposition (EA-PVD). The coatings were characterized chemically (by means of XPS and SIMS) and from the structural point of view (by means of XRD and Raman spectroscopy), in order to understand the factors which lead to homoge-neous coatings with high anatase content. The type of substrate is the main parameter that influence the crystal structure of the coatings: when stainless steel is used as substrate the coatings consist es-sentially of rutile, while on glass substrates coatings containing mainly anatase are obtained. The photocatalytic activity of the samples upon UVA irradiation was tested by using phenol as the target molecule. Phenol in the solution can be photocatalytically and rapidly degraded through the EA-PVD anatase TiO2 coatings

Neurosphere-Derived Cells Exert a Neuroprotective Action by Changing the Ischemic Microenvironment

BACKGROUND: Neurosphere-derived cells (NC), containing neural stem cells, various progenitors and more differentiated cells, were obtained from newborn C57/BL6 mice and infused in a murine model of focal ischemia with reperfusion to investigate if: 1) they decreased ischemic injury and restored brain function; 2) they induced changes in the environment in which they are infused; 3) changes in brain environment consequent to transient ischemia were relevant for NC action. METHODOLOGY/PRINCIPAL FINDINGS: NC were infused intracerebroventricularly 4 h or 7 d after 30 min middle cerebral artery occlusion. In ischemic mice receiving cells at 4 h, impairment of open field performance was significantly improved and neuronal loss significantly reduced 7–14 d after ischemia compared to controls and to ischemic mice receiving cells at 7 d. Infusion of murine foetal fibroblast in the same experimental conditions was not effective. Assessment of infused cell distribution revealed that they migrated from the ventricle to the parenchyma, progressively decreased in number but they were observable up to 14 d. In mice receiving NC at 7 d and in sham-operated mice, few cells could be observed only at 24 h, indicating that the survival of these cells in brain tissue relates to the ischemic environment. The mRNA expression of trophic factors such as Insulin Growth Factor-1, Vascular Endothelial Growth Factor-A, Transforming Growth Factor-β1, Brain Derived Neurotrophic Factor and Stromal Derived Factor−1α, as well as microglia/macrophage activation, increased 24 h after NC infusion in ischemic mice treated at 4 h compared to sham-operated and to mice receiving cells at 7 d. CONCLUSIONS/SIGNIFICANCE: NC reduce functional impairment and neuronal damage after ischemia/reperfusion injury. Several lines of evidence indicate that the reciprocal interaction between NC and the ischemic environment is crucial for NC protective actions. Based on these results we propose that a bystander control of the ischemic environment may be the mechanism used by NC to rapidly restore acutely injured brain function

Requirements for F-BAR Proteins TOCA-1 and TOCA-2 in Actin Dynamics and Membrane Trafficking during Caenorhabditis elegans Oocyte Growth and Embryonic Epidermal Morphogenesis

The TOCA family of F-BAR–containing proteins bind to and remodel lipid bilayers via their conserved F-BAR domains, and regulate actin dynamics via their N-Wasp binding SH3 domains. Thus, these proteins are predicted to play a pivotal role in coordinating membrane traffic with actin dynamics during cell migration and tissue morphogenesis. By combining genetic analysis in Caenorhabditis elegans with cellular biochemical experiments in mammalian cells, we showed that: i) loss of CeTOCA proteins reduced the efficiency of Clathrin-mediated endocytosis (CME) in oocytes. Genetic interference with CeTOCAs interacting proteins WSP-1 and WVE-1, and other components of the WVE-1 complex, produced a similar effect. Oocyte endocytosis defects correlated well with reduced egg production in these mutants. ii) CeTOCA proteins localize to cell–cell junctions and are required for proper embryonic morphogenesis, to position hypodermal cells and to organize junctional actin and the junction-associated protein AJM-1. iii) Double mutant analysis indicated that the toca genes act in the same pathway as the nematode homologue of N-WASP/WASP, wsp-1. Furthermore, mammalian TOCA-1 and C. elegans CeTOCAs physically associated with N-WASP and WSP-1 directly, or WAVE2 indirectly via ABI-1. Thus, we propose that TOCA proteins control tissues morphogenesis by coordinating Clathrin-dependent membrane trafficking with WAVE and N-WASP–dependent actin-dynamics

Carburizing and nitriding as surface pre-treatment of PVD coating for gears application

Among the different treatments that can be carried out to locally improve the mechanical behaviour of gears a combination of case hardening followed by PVD coatings (duplex treatment) seems to give promising results in terms of surface hardness, residual stress profile and fatigue resistance. In particular considering the carburizing and the nitriding treatments they can be both aimed, in the same way than the surface coatings, to introduce a different mechanical behaviour between surface and core in order to improve life, reliability and load capacity of the treated component. This is fundamental for gears whose damage is mainly related to contact fatigue, fatigue at the tooth root and pitting on the tooth flank [1-3]. The need of optimising the surface material in order to delay the progressive deterioration of the components due to wear, fatigue or contact fatigue mechanisms, often worsened by the presence of hostile environments, explains the increasing attention on different coating technologies [5-7], In particular, considering the PVD coatings, chemical composition of the surface deposited film, coating thickness, hardness, adhesion with the substrate material and plastic deformation of the substrate material have an important influence on the damage mechanism affecting the coated component. Although hard PVD coatings are well known for improving friction and resistance to wear and corrosion, their tribological performance is often limited by elastic and plastic deformation of the substrate, which can allow to coating failures [12]. The emergence of the duplex treatments, consisting in the sequential application of two o more established surface technologies, has represented a novel approach to the achievement of enhancing coating properties. Duplex treatments, comprising a nitriding treatment followed by the deposition of a hard PVD coating, have been proven to be successful in increasing wear, thermal fatigue and corrosion resistance and the load carrying capability of different steel substrates [13-16]. By increasing the hardness of the substrate, for instance using a nitriding case, often provides a suitable load support for PVD coatings so that superior wear resistance can be achieved. The high values of hardness related to the thermochemical treatment, further enhanced by the introduction of the ceramic coating characterized by a strong difference in coefficient of thermal expansion with respect to the substrate material, affects the surface level of compression residual stress data [21-23], Therefore the residual stress gradient must be evaluated when a prediction of the gear life is requested: in fact the residual stress distribution affecting the nucleation of the fatigue cracks is a factor able to control the gear performance. Starting from such considerations, this work is focused on the microstructural (fig.2, fig. 4) and mechanical characterization (nanohardness and fatigue behaviour) of a CrN coating, about 5 μm thick, deposed by PVD technique on two different steels: a carburizing 16MnCrS5 steel grade and a nitriding 42CrMo4 steel grade (Table I). CrN films were deposited by means of the standard cathodic. arc using an industrial devices. Before coating the fatigue specimens (Fig. 1) were polished with a 3 μm diamond suspension and then ultrasonically cleaned. On the basis of published works [11] it is known that, in the case of nitrided substrates, the adhesion with the PVD coating is enhanced by the presence of Feα(N) structure while ε-Fe2-3N or γprime;-Fe 4N ones are detrimental. For such a reason a NITREG treatment was executed on the 42NiCrMo4 steel grade with the purpose of producing a low white layer, further reduced, before the coating deposition step, by means of a mechanical samples polishing targeted to remove the superficial brittle and porous layers. A short ion cleaning executed with Ar was carried out before the beginning of the coating deposition phase. The steel temperature was kept constant at 180°C with an initial peak of 210°C acting for about 2 minutes, independently from the type of substrate considered. Microhardness profiles were measured both on uncoated and on coated samples in order to determine both the thickness of the carburized and nitrided layers and the effect of the thin film deposition process (fig. 3). The coating nanohardness data were also measured by the depth sensing technique using a Fisherscope H100 nanoindenter operating by a computer controlled stress limited device and equipped with a Vickers indenter. X-ray diffractometry (XRD) was used to identify the chemical coating composition (fig. 2) and to measure the residual stresses induced from the sample's process route including the coating step. XRD with Bragg Brentano geometry were performed with a Philips PW 1830 instrument with a goniometer PW 3020 and a control unit Philips PW 3710 (Cu K α radiation, scan rate 1° /min). Surface residual stresses were detected using Cu Kα radiation by means of a Italstructure Stress X3000 diffractometer. The stresses (-120±25 MPa after carburizing; -580±40 MPa after nitriding; -1870±87 MPa after carburizing + PVD and -2350±114 MPa after nitriding + PVD) were calculated using the sinj2 method and adapting the elastic modulus value obtained by nanoindentation measurements and assuming a Poisson ratio of 0.2, value usually taken as a reference when ceramic CrN or Cr(C,N) thin films are considered. Using a rotating bending machine fatigue tests were carried out both on case hardened samples and nitrided plus PVD coated specimens (fig. 1). Experiments were executed at room temperature, in air, at a test frequency of 33 Hz using a sinusoidal load wave form and a load ratio (minimum to maximum load) of R=0. The stress level at which specimens can run without occurrence of failure after 3 · 106 stress cycles was chosen as the fatigue limit. Results of the fatigue tests were analysed according to the stair-case up and down method (Table II). The presence of the PVD film is responsible for a light increase in the fatigue resistance both for the carburized samples and for the nitrided ones. Fatigue nucleation sites resulted affected from the presence of PVD coating only in the case of carburized substrate: the high residual stress level characterizing the ceramic coating excludes the surface as nucleation zone and moves it at the interface with the steel material (fig. 5). No change in the nucleation areas were observed in the nitrided specimens or in the nitrided and coated samples (fig. 6) where the weak points resulted the non metallic inclusions inside the substrate material