Nontrivial classes in H∗(Imb(S1,Rn))H^*(Imb(S^1,\R^n)) from nontrivalent graph cocycles

We construct nontrivial cohomology classes of the space $Imb(S^1,\R^n)$ of imbeddings of the circle into $\R^n$, by means of Feynman diagrams. More precisely, starting from a suitable linear combination of nontrivalent diagrams, we construct, for every even number $n\geq 4$, a de Rham cohomology class on $Imb(S^1,\R^n)$. We prove nontriviality of these classes by evaluation on the dual cycles.Comment: 10 pages, 11 figures. V2: minor changes, typos correcte

Determinants of fibrinogen in an Italian population suffering from claudication. Lower fibrinogen in the south compared to middle and north of Italy. The ADEP Group.

Prospective studies have shown that high plasma levels of fibrinogen are independently associated with the risk of cardiovascular complications. In patients suffering from peripheral vascular disease (PVD) fibrinogen has been shown to be an independent predictor of cardiovascular disease but its determinants have never been examined in this clinical setting. DESIGN AND METHODS: Fibrinogen levels were related to clinical and laboratory variables in 2,111 patients suffering from PVD. We also analyzed whether there was a regional distribution of risk factors. RESULTS: The median values of fibrinogen was 312 mg/dL. The clinical variables examined did not differentiate patients with elevated or normal fibrinogen levels. In particular, patients with ankle/arm pressure ratio < 0.8 did not show a higher prevalence of fibrinogen > 312 mg/dL. Conversely, white blood cell (WBC) count and serum cholesterol levels were significantly associated with high fibrinogen levels (p < 0.0001). Multiple logistic regression analysis demonstrated that areas of Italy were differently associated with high plasma fibrinogen levels (p < 0.03): subjects in the north and middle of Italy having significantly higher values of fibrinogen than subjects in the south of Italy (p < 0.01). A similar regional distribution was observed for WBC count and serum cholesterol levels. INTERPRETATION AND CONCLUSIONS: The regional distribution of risk factors raises the question as to whether the already reported large variability of cardiovascular events so in PVD may be attributed to a non homogeneous distribution of risk factors

BANK EROSION AND INSTABILITY MONITORING WITH A LOW COST TERRESTRIAL LASER SCANNER

ABSTRACT: Among the dominant processes taking place in a river basin, especially mountain ones, sediments creation and transport play a key role in morphological processes. Studies usually focus on big mass movements, such as landslides and debris flows, or on wide spread slope erosion due to rainfalls, while bank erosion is neglected or not considered essential for sediment budget at basin scale. Nevertheless, authors consider bank erosion a process that deserve more careful studies; not only the sediment share from bank erosion is not negligible in steep mountain rivers, but also the process can threat structures on river sides due the possibility to have limited, but still significant, mass collapse of bank sections during intense events. The paper present an attempt to monitor bank erosion in a section of a river in Northern Italy Alps and to put it in relation with weather and water discharge. Survey campaign was set up at regular time intervals, or after particularly intense rainfalls, and uses a Terrestrial Laser Scanner (TLS) to acquire the bank surface. The tool was developed internally, at Politecnico di Milano, to meet requirements about low cost level and good accuracy. Successive acquisitions of point clouds were elaborated, via an ad-hoc MatLab code, to determine erosion, or deposition, volumes of sediments. These volumetric results have been evaluated in relation with rainfalls and freeze-thaw cycles looking for a relationship between environmental conditions and bank failures. Some interesting results are shown, such as a relation between erosion rates and temperature or water flow in the river. The path to a complete process understanding and modelling is long, however the results reported can be considered a first step towards objective

Orographic Precipitation Extremes: An Application of LUME (Linear Upslope Model Extension) over the Alps and Apennines in Italy

Critical hydrometeorological events are generally triggered by heavy precipitation. In complex terrain, precipitation may be perturbed by the upslope raising of the incoming humid airflow, causing in some cases extreme rainfall. In this work, the application of LUME-Linear Upslope Model Extension-to a group of extreme events that occurred across mountainous areas of the Central Alps and Apennines in Italy is presented. Based on the previous version, the model has been "extended" in some aspects, proposing a methodology for physically estimating the time-delay coefficients as a function of precipitation efficiency. The outcomes of LUME are encouraging for the cases studied, revealing the intensification of precipitation due to the orographic effect. A comparison between the reference rain gauge data and the results of the simulations showed good agreement. Since extreme precipitation is expected to increase due to climate change, especially across the Mediterranean region, LUME represents an effective tool to investigate more closely how these extreme phenomena originate and evolve in mountainous areas that are subject to potential hydrometeorological risks

IMAGE-BASED RECONSTRUCTION AND ANALYSIS OF DYNAMIC SCENES IN A LANDSLIDE SIMULATION FACILITY

The application of image processing and photogrammetric techniques to dynamic reconstruction of landslide simulations in a scaled-down facility is described. Simulations are also used here for active-learning purpose: students are helped understand how physical processes happen and which kinds of observations may be obtained from a sensor network. In particular, the use of digital images to obtain multi-temporal information is presented. On one side, using a multi-view sensor set up based on four synchronized GoPro 4 Black® cameras, a 4D (3D spatial position and time) reconstruction of the dynamic scene is obtained through the composition of several 3D models obtained from dense image matching. The final textured 4D model allows one to revisit in dynamic and interactive mode a completed experiment at any time. On the other side, a digital image correlation (DIC) technique has been used to track surface point displacements from the image sequence obtained from the camera in front of the simulation facility. While the 4D model may provide a qualitative description and documentation of the experiment running, DIC analysis output quantitative information such as local point displacements and velocities, to be related to physical processes and to other observations. All the hardware and software equipment adopted for the photogrammetric reconstruction has been based on low-cost and open-source solutions

TEACHING GEOMATICS FOR GEOHAZARD MITIGATION AND MANAGEMENT IN THE COVID-19 TIME

Abstract. Starting from the Academic Year 2018–2019, Politecnico di Milano university has established a BSc programme on "Civil Engineering for Risk Mitigation" (ICMR). This course is aimed at training students to cope with issues related to different types of natural and anthropogenic hazards, among which Geohazards are paid a primary attention. A "Workshop on Monitoring Techniques for Geohazards" is included to present different Geological, Geophysical and Geodetic techniques to be applied to landslides within an integrated approach. The use of active and problem-based learning techniques was one of the basic principles in the design of ICMR programme. This resulted in planning some visits and field campaigns to allow students to directly work on real case studies. The course has been scheduled for the first time in the second term of A.Y. 2019–2020, when the COVID-19 pandemics developed and prevented the lab activities in the field to be implemented as planned. The paper presents how the content and the organization of the course have been revised to try to reach the same learning objectives notwithstanding the limitations on the activities "in presence"

Phenotypical and Functional Characterization of Mesenchymal Stem Cells Derived From Patients Affected by Schwachman-Diamond Syndrome

n/

APPLICATION OF LUCAS-KANADE DENSE FLOW FOR TERRAIN MOTION IN LANDSLIDE MONITORING APPLICATION

Landslides are natural hazards that can cause severe damage and loss of life. Optical cameras are a low-cost and high-resolution alternative among many monitoring systems, as their size and capabilities can vary, allowing for flexible implementation and location. Computer vision is a branch of artificial intelligence that can analyze and understand optical images, using techniques such as optical flow, image correlation and machine learning. The application of such techniques can estimate the motion vectors, displacement fields, providing valuable information for landslide detection, monitoring and prediction. However, computer vision also faces some challenges such as illumination changes, occlusions, image quality, and computational complexity. In this work, a computer vision approach based on Lucas-Kanade optical dense flow was applied to estimate the motion vectors between consecutive images obtained during landslide simulations in a laboratory environment. The approach is applied to two experiments that vary in their illumination and setup parameters to test its applicability. We also discuss the application of this methodology to images from Sentinel-2 satellite optical sensors for landslide monitoring in real-world scenarios