Symmetry breaking in a constrained cheeger type isoperimetric inequality

The study of the optimal constant Kq(Ω) in the Sobolev inequality ∥u∥Lq(Ω) ≤ 1/Kq(Ω)∥Du∥(double-struck Rn), 1 ≤ q < 1∗, for BV functions which are zero outside Ω and with zero mean value inside Ω, leads to the definition of a Cheeger type constant. We are interested in finding the best possible embedding constant in terms of the measure of Ω alone. We set up an optimal shape problem and we completely characterize, on varying the exponent q, the behaviour of optimal domains. Among other things we establish the existence of a threshold value 1 ≤ q < 1∗ above which the symmetry of optimal domains is broken. Several differences between the cases n = 2 and n ≥ 3 are emphasized

Total pancreatectomy for ampullary adenocarcinoma in a 74-year-old patient. Case report and literature review

Primary ampullary neoplasms have origin in the ampulla of Vater, an anatomical structure where the common bile duct and the pancreatic duct join together as a common channel. It represents <0.5% of all gastrointestinal cancers and approximately 7% of all periampullary cancers. The adenocarcinomas arising in this region originate from different epithelial cellular constituents present at the site, the histopathological classification encompass: intestinal type, pancreaticobiliary type, and mixed type. Pancreaticoduodenectomy is the treatment of choice when there is an overt or highly suspicious malignant behaviour. We present here the case of a 74-year-old male patient who presented to our department for further investigation of obstructive jaundice and a pancreatic mass associated with a six-month history of significant weight loss and mild epigastric pain. Eventually, a total splenopancreatectomy was performed given the extension of structural anomalies of the organ secondary to an ampullary adenocarcinoma

The ATLAS RPC ROD for Super LHC

The number of interactions per bunch crossing for the upgrade of the Large Hadron Collider is expected to be ten times greater than the actual one. As a consequence, the ATLAS detector for SLHC foresees the use of a larger number of readout channels and also a new trigger level is under development. In order to face with such issue, we developed a new architecture for the Read Out Driver (ROD) for the ATLAS RPC Muon Spectrometer in the barrel region. Presently, each ROD board receives ATLAS RPC Muon readout data and arranges all the data fragments of a sector of the spectrometer in a unique event, sending it to the next acquisition systems. Our new design is based on the new generation Xilinx Virtex5 FPGA and it works with a clock frequency six times greater than the actual bunch crossing rate of the LHC. We also implemented the output channel of the ROD, presently based on S-Link protocol, by using the GTP transceivers inside the FPGA. We present an overview of our design, focusing on the newly added hardware features

Analysing the performance of MCECs over a wide range of operating temperatures

Hydrogen production through water electrolysis has gained significant attention in the past years as a means of tackling the problem of the imbalance between the intermittent rate of electricity production from renewable sources and the continuous electricity demand from end users. Recently, much of the effort has been shifted toward the electrolysis of steam rather than water, for example in solid oxide cells, which operate at temperatures around 800°C. In this manner, part of the energy required for the conversion to hydrogen is provided as heat rather than electricity. At the same time, the high temperature levels require the use of highly resistant materials, which increase the overall cost of the process. An interesting alternative is represented by molten carbonate electrolysis cells (MCECs), operating at temperatures well below 700°C. In the present work, a molten carbonate cell was operated in a lower temperature range (490-550°C) by changing the composition of the electrolyte mixture. The data obtained, along with experimental results at higher temperature (570-650°C) available in the literature, was analyzed using a 0D model accounting for Ohmic and activation overpotentials to determine the correlation between current and potential. It was found that, while the dependence of Ohmic losses on temperatures is discontinuous when cell operation is switched from the lower to the higher temperature range, activation losses vary with continuity. This result provides important insight on the performance of MCECs that can serve as a basis for future studies

The IBMAP approach for Markov networks structure learning

In this work we consider the problem of learning the structure of Markov networks from data. We present an approach for tackling this problem called IBMAP, together with an efficient instantiation of the approach: the IBMAP-HC algorithm, designed for avoiding important limitations of existing independence-based algorithms. These algorithms proceed by performing statistical independence tests on data, trusting completely the outcome of each test. In practice tests may be incorrect, resulting in potential cascading errors and the consequent reduction in the quality of the structures learned. IBMAP contemplates this uncertainty in the outcome of the tests through a probabilistic maximum-a-posteriori approach. The approach is instantiated in the IBMAP-HC algorithm, a structure selection strategy that performs a polynomial heuristic local search in the space of possible structures. We present an extensive empirical evaluation on synthetic and real data, showing that our algorithm outperforms significantly the current independence-based algorithms, in terms of data efficiency and quality of learned structures, with equivalent computational complexities. We also show the performance of IBMAP-HC in a real-world application of knowledge discovery: EDAs, which are evolutionary algorithms that use structure learning on each generation for modeling the distribution of populations. The experiments show that when IBMAP-HC is used to learn the structure, EDAs improve the convergence to the optimum

GNAM and OHP: Monitoring Tools for ATLAS experiment at LHC.

ATLAS is one of the four experiments under construction along the Large Hadron Collider (LHC) ring at CERN. The LHC will produce interactions at a center-of-mass energy equal to âs = 14 TeV at 40 MHz rate. The detector consists of more than 140 million electronic channels. The challenging experimental environment and the extreme detector complexity impose the necessity of a common scalable distributed monitoring framework, which can be tuned for the optimal use by different ATLAS sub-detectors at the various levels of the ATLAS data flow. This note presents two monitoring tools that have been developed for this aim within the architecture ATLAS Monitoring Framework and the Data Acquisition System: GNAM and OHP. The first one is a framework for online histogram production; the second one is graphical application for histogram presentation. This tools are now widely used during the ATLAS commissioning and their performances are reported in this not

Study of Chinese Insurance Company’s Risk Estimation Index System

自从1990年以来，日本多家保险公司因资不抵债相继破产，不仅在国际社会造成了极大的震动，也给我国保险业敲响了警钟：保险公司在经营风险产品的同时，应加强对自身风险的评估。自从我国加入WTO后，保险业受到了巨大的冲击，加强对我国保险公司风险评估指标体系的研究便具有十分重要的意义。首先，对保险公司风险评估指标体系的研究，能为量化保险公司经营风险提供依据。其次，对保险公司风险评估指标体系的研究，有利于保险公司加强风险管理。 本文选择保险公司风险评估指标作为研究的重点，详细介绍了保险公司风险评估指标体系的内容、评价及在我国保险市场上的应用，并选取了四家保险公司近年来的数据，用IRIS指标体系做实证研究...Since 1990, some insurance companies of Japanese have been bankrupted. It made a big ring to the international financial market and Chinese insurance market: Insurance companies should pay more attention to its risk evaluation. After China’s entry into the WTO, some industries fell under big impact, especially the insurance industry. So the study of risk evaluation became more and more important t...学位：经济学硕士院系专业：经济学院财政金融系_金融学(含保险学)学号：20044202

Ageing test of the ATLAS RPCs at X5-GIF

An ageing test of three ATLAS production RPC stations is in course at X5-GIF, the CERN irradiation facility. The chamber efficiencies are monitored using cosmic rays triggered by a scintillator hodoscope. Higher statistics measurements are made when the X5 muon beam is available. We report here the measurements of the efficiency versus operating voltage at different source intensities, up to a maximum counting rate of about 700Hz/cm^2. We describe the performance of the chambers during the test up to an overall ageing of 4 ATLAS equivalent years corresponding to an integrated charge of 0.12C/cm^2, including a safety factor of 5.Comment: 4 pages. Presented at the VII Workshop on Resistive Plate Chambers and Related Detectors; Clermont-Ferrand October 20th-22nd, 200

System Test of the ATLAS Muon Spectrometer in the H8 Beam at the CERN SPS

An extensive system test of the ATLAS muon spectrometer has been performed in the H8 beam line at the CERN SPS during the last four years. This spectrometer will use pressurized Monitored Drift Tube (MDT) chambers and Cathode Strip Chambers (CSC) for precision tracking, Resistive Plate Chambers (RPCs) for triggering in the barrel and Thin Gap Chambers (TGCs) for triggering in the end-cap region. The test set-up emulates one projective tower of the barrel (six MDT chambers and six RPCs) and one end-cap octant (six MDT chambers, A CSC and three TGCs). The barrel and end-cap stands have also been equipped with optical alignment systems, aiming at a relative positioning of the precision chambers in each tower to 30-40 micrometers. In addition to the performance of the detectors and the alignment scheme, many other systems aspects of the ATLAS muon spectrometer have been tested and validated with this setup, such as the mechanical detector integration and installation, the detector control system, the data acquisition, high level trigger software and off-line event reconstruction. Measurements with muon energies ranging from 20 to 300 GeV have allowed measuring the trigger and tracking performance of this set-up, in a configuration very similar to the final spectrometer. A special bunched muon beam with 25 ns bunch spacing, emulating the LHC bunch structure, has been used to study the timing resolution and bunch identification performance of the trigger chambers. The ATLAS first-level trigger chain has been operated with muon trigger signals for the first time

A survey on independence-based Markov networks learning

This work reports the most relevant technical aspects in the problem of learning the \emph{Markov network structure} from data. Such problem has become increasingly important in machine learning, and many other application fields of machine learning. Markov networks, together with Bayesian networks, are probabilistic graphical models, a widely used formalism for handling probability distributions in intelligent systems. Learning graphical models from data have been extensively applied for the case of Bayesian networks, but for Markov networks learning it is not tractable in practice. However, this situation is changing with time, given the exponential growth of computers capacity, the plethora of available digital data, and the researching on new learning technologies. This work stresses on a technology called independence-based learning, which allows the learning of the independence structure of those networks from data in an efficient and sound manner, whenever the dataset is sufficiently large, and data is a representative sampling of the target distribution. In the analysis of such technology, this work surveys the current state-of-the-art algorithms for learning Markov networks structure, discussing its current limitations, and proposing a series of open problems where future works may produce some advances in the area in terms of quality and efficiency. The paper concludes by opening a discussion about how to develop a general formalism for improving the quality of the structures learned, when data is scarce.Comment: 35 pages, 1 figur