On the Multi-Instanton Measure for Super Yang--Mills Theories

In this paper we revisit the arguments that have led to the proposal of a multi-instanton measure for supersymmetric Yang-Mills theories. We then recall how the moduli space of gauge connections on $\real^4$ can be built from a hyperk\"ahler quotient construction which we generalize to supermanifolds. The measure we are looking for is given by the supermetric of the supermoduli space thus introduced. To elucidate the construction we carry out explicit computations in the case of N=2 supersymmetric Yang-Mills theories.Comment: 28 pages, latex fil

Instanton Calculus, Topological Field Theories and N=2 Super Yang-Mills Theories

The results obtained by Seiberg and Witten for the low-energy Wilsonian effective actions of N=2 supersymmetric theories with gauge group SU(2) are in agreement with instanton computations carried out for winding numbers one and two. This suggests that the instanton saddle point saturates the non-perturbative contribution to the functional integral. A natural framework in which corrections to this approximation are absent is given by the topological field theory built out of the N=2 Super Yang-Mills theory. After extending the standard construction of the Topological Yang-Mills theory to encompass the case of a non-vanishing vacuum expectation value for the scalar field, a BRST transformation is defined (as a supersymmetry plus a gauge variation), which on the instanton moduli space is the exterior derivative. The topological field theory approach makes the so-called "constrained instanton" configurations and the instanton measure arise in a natural way. As a consequence, instanton-dominated Green's functions in N=2 Super Yang-Mills can be equivalently computed either using the constrained instanton method or making reference to the topological twisted version of the theory. We explicitly compute the instanton measure and the contribution to u=<\Tr \phi^2> for winding numbers one and two. We then show that each non-perturbative contribution to the N=2 low-energy effective action can be written as the integral of a total derivative of a function of the instanton moduli. Only instanton configurations of zero conformal size contribute to this result. Finally, the 8k-dimensional instanton moduli space is built using the hyperkahler quotient procedure, which clarifies the geometrical meaning of our approach.Comment: latex, 66 page

General purpose readout board {\pi} LUP: overview and results

This work gives an overview of the PCI-Express board $\pi$LUP, focusing on the motivation that led to its development, the technological choices adopted and its performance. The $\pi$LUP card was designed by INFN and University of Bologna as a readout interface candidate to be used after the Phase-II upgrade of the Pixel Detector of the ATLAS and CMS experiments at LHC. The same team in Bologna is also responsible for the design and commissioning of the ReadOut Driver (ROD) board - currently implemented in all the four layers of the ATLAS Pixel Detector (Insertable B-Layer, B-Layer, Layer-1 and Layer-2) - and acquired in the past years expertise on the ATLAS readout chain and the problematics arising in such experiments. Although the $\pi$LUP was designed to fulfill a specific task, it is highly versatile and might fit a wide variety of applications, some of which will be discussed in this work. Two 7$^{th}$-generation Xilinx FPGAs are mounted on the board: a Zynq-7 with an embedded dual core ARM Processor and a Kintex-7. The latter features sixteen 12.5$\,$Gbps transceivers, allowing the board to interface easily to any other electronic board, either electrically and/or optically, at the current bandwidth of the experiments for LHC. Many data-transmission protocols have been tested at different speeds, results will be discussed later in this work. Two batches of $\pi$LUP boards have been fabricated and tested, two boards in the first batch (version 1.0) and four boards in the second batch (version 1.1), encapsulating all the patches and improvements required by the first version.Comment: 6 pages, 10 figures, 21th Real Time Conference, winner of "2018 NPSS Student Paper Award Second Prize

K-NN FOREST: a software for the non-parametric prediction and mapping of environmental variables by the k-Nearest Neighbors algorithm

In the last decades researchers investigated the possibility of extending the information collected in sampling units during a field survey to wider geographical areas through the use of remotely sensed images. One of the most widely adopted approaches is based on the non-parametric k-Nearest Neighbors (k-NN) algorithm. This contribution describes the software K-NN FOREST we developed to provide a complete tool for the implementation of the k-NN technique to generate spatially explicit estimations (maps) of a response variable acquired in the field by sampling units through the use of remotely sensed data or other ancillary variables. K-NN FOREST is designed to guide the user through a graphic user interface in the different phases of the process. K-NN FOREST is freely available for download and it is designed to run under Windows environment in conjunction with the GIS software IDRISI

K-NN FOREST: a software for the non-parametric prediction and mapping of environmental variables by the k-Nearest Neighbors algorithm

In the last decades researchers investigated the possibility of extending the information collected in sampling units during a field survey to wider geographical areas through the use of remotely sensed images. One of the most widely adopted approaches is based on the non-parametric k-Nearest Neighbors (k-NN) algorithm. This contribution describes the software K-NN FOREST we developed to provide a complete tool for the implementation of the k-NN technique to generate spatially explicit estimations (maps) of a response variable acquired in the field by sampling units through the use of remotely sensed data or other ancillary variables. K-NN FOREST is designed to guide the user through a graphic user interface in the different phases of the process. K-NN FOREST is freely available for download and it is designed to run under Windows environment in conjunction with the GIS software IDRISI

Sviluppo di una procedura innovativa per la cubatura del volume della massa legnosa di fustaie di latifoglie mediante LiDAR

La tecnica di scansione aerea con strumentazione LiDAR (Light Detection and Ranging) è sempre più presa in considerazione ai fini di analisi e monitoraggio degli attributi dendrometrici dei popolamenti forestali, ma anche per stimare attributi complessi quali il volume della massa legnosa e la biomassa legnosa. Il presente contributo propone una procedura innovativa per la stima del volume di massa legnosa di soprassuoli forestali mediante elaborazione di dati LiDAR in ambiente GIS, in particolare per i popolamenti a prevalenza di latifoglie dove i convenzionali metodi di stima basati sulle misurazioni LiDAR dell’altezza dei singoli fusti arborei conducono in genere a risultati relativamente insoddisfacenti.L'articolo è disponibile sul sito dell'editore http://www.asita.i

Bleeding risk evaluation in cerebral cavernous malformation, the role of medications, and hemorrhagic factors: a case-control study

Objective: Cerebral cavernous malformations (CCMs) are vascular lesions with an overall risk of rupture from 2% to 6% per year, which is associated with significant morbidity and mortality. The diagnostic incidence is increasing, so it is of paramount importance to stratify patients based on their risk of rupture. Data in the literature seem to suggest that specific medications, particularly antithrombotic and cardiovascular agents, are associated with a reduced risk of bleeding. However, the effect of the patient coagulative status on the cumulative bleeding risk remains unclear. The aim of this study was to assess the impact of different radiological, clinical, and pharmacological factors on the bleeding risk of CCMs and to assess the predictive power of an already validated scale for general bleeding risk, the HAS-BLED (hypertension, abnormal renal/liver function, stroke, bleeding history or predisposition, labile international normalized ratio, elderly, drugs/alcohol concomitantly). Method: This was a multicenter retrospective observational study. The authors collected imaging, clinical status, and therapy data on patients with bleeding and nonbleeding CCMs. Univariate analysis and subsequent multivariate logistic regression were performed between the considered variables and bleeding or nonbleeding status to identify potential independent predictors of bleeding. Results: The authors collected data on 257 patients (46.7% male, 25.3% with bleeding CCMs). Compared with patients with nonbleeding lesions, those with bleeding CCMs were younger, less frequently had hypertension, and less frequently required antiplatelet drugs and beta-blockers (all p &lt; 0.05). Bleeding lesions, however, had significantly higher median volumes (1050 mm3 vs 523 mm3 , p &lt; 0.001). On multivariate analyses, after adjusting for age, history of hypertension and diabetes, and use of antiplatelet drugs or beta-blockers, lesion volume ≥ 300 mm3 was the only significant predictor of bleeding (adjusted OR 3.11, 95% CI 1.09-8.86). When the diagnostic accuracy of different volume thresholds was explored, volume ≥ 300 mm3 showed a limited sensitivity (36.7%, 95% CI 24.6%-50.0%), but a high specificity 78.2% (95% CI 71.3%-84.2%), with an area under the curve of 0.57 (95% CI 0.51-0.64). Conclusions: This study supports previous findings that the CCM volume is the only factor influencing the bleeding risk. Antithrombotic agents and propranolol seem to have a protective role against the bleeding events. A high HAS-BLED score was not associated with an increased bleeding risk. Further studies are needed to confirm these results