374 research outputs found

    Engaging Empirical Dynamic Modeling to Detect Intrusions in Cyber-Physical Systems

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    Modern cyber-physical systems require effective intrusion detection systems to ensure adequate critical infrastructure protection. Developing an intrusion detection capability requires an understanding of the behavior of a cyber-physical system and causality of its components. Such an understanding enables the characterization of normal behavior and the identification and reporting of anomalous behavior. This chapter explores a relatively new time series analysis technique, empirical dynamic modeling, that can contribute to system understanding. Specifically, it examines if the technique can adequately describe causality in cyber-physical systems and provides insights into it serving as a foundation for intrusion detection

    Risk-shifting Through Issuer Liability and Corporate Monitoring

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    This article explores how issuer liability re-allocates fraud risk and how risk allocation may reduce the incidence of fraud. In the US, the apparent absence of individual liability of officeholders and insufficient monitoring by insurers under-mine the potential deterrent effect of securities litigation. The underlying reasons why both mechanisms remain ineffective are collective action problems under the prevailing dispersed ownership structure, which eliminates the incentives to moni-tor set by issuer liability. This article suggests that issuer liability could potentially have a stronger deterrent effect when it shifts risk to individuals or entities holding a larger financial stake. Thus, it would enlist large shareholders in monitoring in much of Europe. The same risk-shifting effect also has implications for the debate about the relationship between securities litigation and creditor interests. Credi-tors’ claims should not be given precedence over claims of defrauded investors (e.g., because of the capital maintenance principle), since bearing some of the fraud risk will more strongly incentivise large creditors, such as banks, to monitor the firm in jurisdictions where corporate debt is relatively concentrated

    Molecular dynamics simulations of oxide memristors: thermal effects

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    We have extended our recent molecular-dynamic simulations of memristors to include the effect of thermal inhomogeneities on mobile ionic species appearing during operation of the device. Simulations show a competition between an attractive short-ranged interaction between oxygen vacancies and an enhanced local temperature in creating/destroying the conducting oxygen channels. Such a competition would strongly affect the performance of the memristive devices.Comment: submit/0169777; 6 pages, 4 figure

    Ultra Compact and Low-power TDC and TAC Architectures for Highly-Parallel Implementation in Time-Resolved Image Sensors

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    We report on the design and characterization of three different architectures, namely two Time-to- Digital Converters (TDCs) and a Time-to-Amplitude Converter (TAC) with embedded analog-to-digital conversion, implemented in a 130-nm CMOS imaging technology. The proposed circuit solutions are conceived for implementation at pixel-level, in image sensors exploiting Single-Photon Avalanche Diodes as photodetectors. The fabricated 32x32 TDCs/TACs arrays have a pitch of 50μm in both directions while the average power consumption is between 28mW and 300mW depending on the architectural choice. The TAC achieves a time resolution of 160ps on a 20-ns time range with a differential and integral non-linearity (DNL, INL) of 0.7LSB and 1.9LSB, respectively. The two TDCs have a 10-bit resolution with a minimum time resolution between 50ps and 119ps and a worst-case accuracy of ±0.5 LSB DNL and 2.4 LSB INL. An overview of the performance is given together with the analysis of the pros and cons for each architecture

    Paired comparisons of carbon exchange between undisturbed and regenerating stands in four managed forests in Europe

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    The effects of harvest on European forest net ecosystem exchange (NEE) of carbon and its photosynthetic and respiratory components (GPP (gross primary production) and TER (total ecosystem respiration)) were examined by comparing four pairs of mature/harvested sites in Europe via a combination of eddy covariance measurements and empirical modeling. Three of the comparisons represented high coniferous forestry (spruce in Britain, and pines in Finland and France), while a coppice-with-standard oak plantation was examined in Italy. While every comparison revealed that harvesting converted a mature forest carbon sink into a carbon source of similar magnitude, the mechanisms by which this occurred were very different according to species or management practice. In Britain, Finland, and France the annual sink (source) strength for mature (clear-cut) stands was estimated at 496 (112), 138 (239), and 222 (225) g C m−2, respectively, with 381 (427) g C m−2 for the mature (coppiced) stand in Italy. In all three cases of high forestry in Britain, Finland, and France, clear-cutting crippled the photosynthetic capacity of the ecosystem – with mature (clear-cut) GPP of 1970 (988), 1010 (363), and 1600 (602) g C m−2– and also reduced ecosystem respiration to a lesser degree – TER of 1385 (1100), 839 (603), and 1415 (878) g C m−2, respectively. By contrast, harvesting of the coppice oak system provoked a burst in respiration – with mature (clear-cut) TER estimated at 1160 (2220) gC m−2– which endured for the 3 years sampled postharvest. The harvest disturbance also reduced GPP in the coppice system – with mature (clear-cut) GPP of 1600 (1420) g C m−2– but to a lesser extent than in the coniferous forests, and with near-complete recovery within a few years. Understanding the effects of harvest on the carbon balance of European forest systems is a necessary step towards characterizing carbon exchange for timberlands on large scales

    Improved identification of viable myocardium using second harmonic imaging during dobutamine stress echocardiography

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    OBJECTIVE: To determine whether, compared with fundamental imaging, second harmonic imaging can improve the accuracy of dobutamine stress echocardiography for identifying viable myocardium, using nuclear imaging as a reference. PATIENTS: 30 patients with chronic left ventricular dysfunction (mean (SD) age, 60 (8) years; 22 men). METHODS: Dobutamine stress echocardiography was carried out in all patients using both fundamental and second harmonic imaging. All patients underwent dual isotope simultaneous acquisition single photon emission computed tomography (DISA-SPECT) with (99m)technetium-tetrofosmin/(18)F-fluorodeoxyglucose on a separate day. Myocardial viability was considered present by dobutamine stress echocardiography when segments with severe dysfunction showed a biphasic sustained improvement or an ischaemic response. Viability criteria on DISA-SPECT were normal or mildly reduced perfusion and metabolism, or perfusion/metabolism mismatch. RESULTS: Using fundamental imaging, 330 segments showed severe dysfunction at baseline; 144 (44%) were considered viable. The agreement between dobutamine stress echocardiography by fundamental imaging and DISA-SPECT was 78%, kappa = 0.56. Using second harmonic imaging, 288 segments showed severe dysfunction; 138 (48%) were viable. The agreement between dobutamine stress echocardiography and DISA-SPECT was significantly better when second harmonic imaging was used (89%, kappa = 0.77, p = 0.001 v fundamental imaging). CONCLUSIONS: Second harmonic imaging applied during dobutamine stress echocardiography increases the agreement with DISA-SPECT for detecting myocardial viability

    Differential Diagnosis and Clinical Management of a Case of COVID-19 in a Patient With Stage III Lung Cancer Treated With Radio-chemotherapy and Durvalumab

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    none14nononeGuerini A.E.; Borghetti P.; Filippi A.R.; Bonu M.L.; Tomasini D.; Greco D.; Imbrescia J.; Volpi G.; Triggiani L.; Borghesi A.; Maroldi R.; Pasinetti N.; Buglione M.; Magrini S.M.Guerini, A. E.; Borghetti, P.; Filippi, A. R.; Bonu, M. L.; Tomasini, D.; Greco, D.; Imbrescia, J.; Volpi, G.; Triggiani, L.; Borghesi, A.; Maroldi, R.; Pasinetti, N.; Buglione, M.; Magrini, S. M
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