Measuring the propagation of financial distress with Granger-causality tail risk networks

Using the test of Granger-causality in tail of Hong et al. (2009), we define and construct Granger-causality tail risk networks between 33 systemically important banks (G-SIBs) and 36 sovereign bonds worldwide. Our purpose is to exploit the structure of the Granger-causality tail risk networks to identify periods of distress in financial markets and possible channels of systemic risk propagation. Combining measures of connectedness of these networks with the ratings of the sovereign bonds, we propose a flight-to-quality indicator to identify periods of turbulence in the market. Our measure clearly peaks at the onset of the European sovereign debt crisis, signaling the instability of the financial system. Finally, we use the connectedness measures of the networks to forecast the quality of sovereign bonds. We find that connectedness is a significant predictor of the cross-section of bond quality

Sinonasal angioleiomyoma with adipocyte differentiation: clinicopathologic study of 2 cases and review of the literature

Angioleiomyoma (ALM) is a benign tumor of the skin and soft tissues composed of well differentiated smooth muscle cells arranged around and among many vascular channels. Few cases have been reported in the sinonasal region, where ALM may show a variable amount of mature adipose tissue that may make hard the distinction from angiomyolipoma. We report here two cases that presented with a three- and six-month history of left nasal obstruction respectively. In both patients, clinical examination and imaging studies failed to reveal features of tuberous sclerosis complex and demonstrated a mass obliterating the nasal cavity arising from the inferior turbinate. Both masses were endoscopically excised. Pathologic analysis revealed highly vascularized tumors composed of well differentiated smooth muscle cells intermingled with a variable number of mature adipocytes. Immunostaining for melanocytic markers was negative. Based on these findings, both tumors were diagnosed as sinonasal-ALM with adipocytic differentiation. These two cases indicate that both clinical data (i.e. absence of features of tuberous sclerosis complex) and immunohistochemistry (i.e. absence of melanocytic markers) are mandatory for the recognition of sinonasal-ALM with adipocytic differentiation. The term angiomyolipoma to identify these lesions is confusing and should be abandoned

Studying the WHIM with Gamma Ray Bursts

We assess the possibility to detect and characterize the physical state of the missing baryons at low redshift by analyzing the X-ray absorption spectra of the Gamma Ray Burst [GRB] afterglows, measured by a micro calorimeters-based detector with 3 eV resolution and 1000 cm2 effective area and capable of fast re-pointing, similar to that on board of the recently proposed X-ray satellites EDGE and XENIA. For this purpose we have analyzed mock absorption spectra extracted from different hydrodynamical simulations used to model the properties of the Warm Hot Intergalactic Medium [WHIM]. These models predict the correct abundance of OVI absorption lines observed in UV and satisfy current X-ray constraints. According to these models space missions like EDGE and XENIA should be able to detect about 60 WHIM absorbers per year through the OVII line. About 45 % of these have at least two more detectable lines in addition to OVII that can be used to determine the density and the temperature of the gas. Systematic errors in the estimates of the gas density and temperature can be corrected for in a robust, largely model-independent fashion. The analysis of the GRB absorption spectra collected in three years would also allow to measure the cosmic mass density of the WHIM with about 15 % accuracy, although this estimate depends on the WHIM model. Our results suggest that GRBs represent a valid, if not preferable, alternative to Active Galactic Nuclei to study the WHIM in absorption. The analysis of the absorption spectra nicely complements the study of the WHIM in emission that the spectrometer proposed for EDGE and XENIA would be able to carry out thanks to its high sensitivity and large field of view.Comment: 16 pages, 16 figures, accepted for publication by Ap

Study of Packaging and Installation of FBG Sensors for Monitoring of Aircraft Systems

Next generation aircraft systems will feature an ever increasing complexity. In this context, advanced health monitoring strategies will be required to ensure a high level of operations safety as well as a good reliability. Hence, Prognostics and Health Management (PHM) is emerging as an enabling discipline for future advanced aircraft design and operations, with a particular application to Flight Control System (FCS) monitoring. One of the most critical issues for real-time Fault Detection and Identification (FDI) of aircraft FCS is the availability of actuator load measurements. The aerodynamic load on flight control actuators has a significant influence on their dynamic response, and can easily hide the effect of incipient failure precursors. For this reason, real-time monitoring FDI algorithms relying on the comparison between the actual system response and that of a digital twin require either a measure or an estimation of aerodynamic loads. Usually, this quantity is not monitored by a dedicated sensor, since it is not required as a feedback signal by most control logics. A dedicated load sensor for PHM with traditional technologies is not easily feasible: for example, a load cell would be mechanically connected in series with the actuator, adding a potential single failure point and affecting the overall system safety; the use of strain gages on the structure is less accurate, and requires several sensors with individual wiring and complex signal conditioning circuitry. Optical strain sensors based on Fiber Bragg Gratings (FBG) allow indirect load measurement combined with real-time structural monitoring, combining an acceptable increase in complexity and costs with a high robustness. In this preliminary study, we installed an FBG monitoring system on a UAV to assess the feasibility of such technology. Measures of structure deflection were correlated to actuator position and IMU data, to estimate aerodynamic loads

Involved margins after lumpectomy for breast cancer: Always to be re-excised?

Background: The oncologic benefit of upfront re-excision of involved margins after breast-conserving surgery in the context of current multimodal clinical management of breast cancer is unclear. The aim of the present study was to assess the 5-years locoregional recurrence (LRR)-free and distant metastases (DM)-free survival probabilities in patients not undergoing re-excision of positive margins after lumpectomy for breast cancer. Methods: A cohort of 104 patients with positive margins not undergoing re-excision was matched by propensity score with a cohort of 2006 control patients with clear margins after breast-conserving surgery, treated between 2008 and 2018. A multivariate survival analysis was performed accounting for all variables related to LRR and DM, including adjuvant treatments. Results: After adjusting for potential confounders, avoiding to re-excise a positive margin after lumpectomy had no effect on 5-years LRR-free survival probability (HR 0.98, 95%CI 0.36-2.67, p = 0.96) or 5-years DM-free survival probability (HR 0.37, 95%CI 0.08-1.61, p = 0.18). No correlation was found between occurrence of LRR and number of involved margins (HR 1.28, 95%CI 0.10-12.4, Log-rank p = 0.83), or extension of infiltrating disease (HR 1.21, 95%CI 0.20-7.40, Log-rank p = 0.83), but a trend toward higher LRR probability was found for invasive ductal (HR 6.92, 95%CI 0.7-68.8, Log-rank p = 0.10) and invasive lobular cancer (HR 12.95, 95%CI 0.79-213.6, Log-rank p = 0.07) on positive margins. Conclusions: In the era of multimodal treatment of breast cancer and accurate strategies to reduce the probability of residual disease in the post-lumpectomy cavity, re-excision of positive margins might be omitted in selected patients with low-risk breast cancers

Star Counts in the Globular Cluster Omega Centauri. I. Bright Stellar Components

We present an extensive photometry on HB, RGB, and MSTO stars in Omega Cen. The central regions of the cluster were covered with a mosaic of F435W, F625W, and F658N-band data collected with ACS/HST. The outer reaches were covered with a large set of U,B,V,I-band data collected with the [email protected] ESO/MPI telescope. The final catalogue includes ~1.7 million stars. We identified ~3,200 likely HB stars and ~12,500 stars brighter than the subgiant branch and fainter than the RGB bumps. The HB morphology changes with the radial distance. The relative number of extreme HB stars decreases from ~30% to ~21% when moving from the center toward the outer regions of the cluster, while the fraction of less hot HB stars increases from ~62% to ~72%. We performed a detailed comparison between observed ratios of different stellar tracers and predictions based on canonical evolutionary models with a primordial helium (Y=0.23) content and metal abundances (Z=0.0002,0.001) that bracket the observed spread in metallicity of Omega Cen stars. We found that the empirical star counts of HB stars are on average larger (30%-40%) than predicted. Moreover, the rate of HB stars is 43% larger than the MSTO rate. The discrepancy between the rate of HB compared with the rate of RG and MSTO stars supports the evidence that we are facing a true excess of HB stars. The same comparison was performed by assuming a mix of stellar populations made with 70% of canonical stars and 30% of He-enhanced stars. The discrepancy between theory and observations decreases by a factor of two when compared with rates predicted by canonical He content models, but still 15%-25% (Y=0.42) and 15%-20% (Y=0.33) higher than observed. Furthermore, the ratio between HB and MSTO star counts are ~24% (Y=0.42) and 30% (Y=0.33) larger than predicted lifetime ratios.Comment: 54 pages, 17 figures,to be published in ApJ, see link at http://stellari.wiki.zoho.co