88 research outputs found
A Bayesian Networks Approach to Operational Risk
A system for Operational Risk management based on the computational paradigm
of Bayesian Networks is presented. The algorithm allows the construction of a
Bayesian Network targeted for each bank using only internal loss data, and
takes into account in a simple and realistic way the correlations among
different processes of the bank. The internal losses are averaged over a
variable time horizon, so that the correlations at different times are removed,
while the correlations at the same time are kept: the averaged losses are thus
suitable to perform the learning of the network topology and parameters. The
algorithm has been validated on synthetic time series. It should be stressed
that the practical implementation of the proposed algorithm has a small impact
on the organizational structure of a bank and requires an investment in human
resources limited to the computational area
Financial instability from local market measures
We study the emergence of instabilities in a stylized model of a financial
market, when different market actors calculate prices according to different
(local) market measures. We derive typical properties for ensembles of large
random markets using techniques borrowed from statistical mechanics of
disordered systems. We show that, depending on the number of financial
instruments available and on the heterogeneity of local measures, the market
moves from an arbitrage-free phase to an unstable one, where the complexity of
the market - as measured by the diversity of financial instruments - increases,
and arbitrage opportunities arise. A sharp transition separates the two phases.
Focusing on two different classes of local measures inspired by real markets
strategies, we are able to analytically compute the critical lines,
corroborating our findings with numerical simulations.Comment: 17 pages, 4 figure
The Role of Multiparametric Magnetic Resonance in Volumetric Modulated Arc Radiation Therapy Planning for Prostate Cancer Recurrence After Radical Prostatectomy: A Pilot Study
Background and Purpose: Volumetric modulated arc radiotherapy (RT) has become pivotal in the treatment of prostate cancer recurrence (RPC) to optimize dose distribution and minimize toxicity, thanks to the high-precision delineation of prostate bed contours and organs at risk (OARs) under multiparametric magnetic resonance (mpMRI) guidance. We aimed to assess the role of pre-treatment mpMRI in ensuring target volume coverage and normal tissue sparing.
Material and Methods: Patients with post-prostatectomy RPC eligible for salvage RT were prospectively recruited to this pilot study. Image registration between planning CT scan and T2w pre-treatment mpMRI was performed. Two sets of volumes were outlined, and DWI images/ADC maps were used to facilitate precise gross tumor volume (GTV) delineation on morphological MRI scans. Two rival plans (mpMRI-based or not) were drawn up.
Results: Ten patients with evidence of RPC after prostatectomy were eligible. Preliminary data showed lower mpMRI-based clinical target volumes than CT-based RT planning (p = 0.0003): median volume difference 17.5 cm3. There were no differences in the boost volume coverage nor the dose delivered to the femoral heads and penile bulb, but median rectal and bladder V70Gy was 4% less (p = 0.005 and p = 0.210, respectively) for mpMRI-based segmentation.
Conclusions: mpMRI provides high-precision target delineation and improves the accuracy of RT planning for post-prostatectomy RPC, ensures better volume coverage with better OARs sparing and allows non-homogeneous dose distribution, with an aggressive dose escalation to the GTV. Randomized phase III trials and wider datasets are needed to fully assess the role of mpMRI in optimizing therapeutic strategies
Dyspnea in Patients Receiving Radical Radiotherapy for Non-Small Cell Lung Cancer: A Prospective Study
Background and Purpose: Dyspnea is an important symptomatic endpoint for
assessment of radiation-induced lung injury (RILI) following radical radiotherapy in
locally advanced disease, which remains the mainstay of treatment at the time of
significant advances in therapy including combination treatments with immunotherapy
and chemotherapy and the use of local ablative radiotherapy techniques. We investigated
the relationship between dose-volume parameters and subjective changes in dyspnea as
a measure of RILI and the relationship to spirometry.
Material and Methods: Eighty patients receiving radical radiotherapy for non-small cell
lung cancer were prospectively assessed for dyspnea using two patient-completed tools:
EORTC QLQ-LC13 dyspnea quality of life assessment and dyspnea visual analogue scale
(VAS). Global quality of life, spirometry and radiation pneumonitis grade were also
assessed. Comparisons were made with lung dose-volume parameters.
Results: The median survival of the cohort was 26 months. In the evaluable group of 59
patients there were positive correlations between lung dose-volume parameters and a
change in dyspnea quality of life scale at 3 months (V30 p=0.017; V40 p=0.026; V50
p=0.049; mean lung dose p=0.05), and a change in dyspnea VAS at 6 months (V30
p=0.05; V40 p=0.026; V50 p=0.028) after radiotherapy. Lung dose-volume parameters
predicted a 10% increase in dyspnea quality of life score at 3 months (V40; p=0.041, V50;
p=0.037) and dyspnea VAS score at 6 months (V40; p=0.027) post-treatment.
Conclusions: Worsening of dyspnea is an important symptom of RILI. We demonstrate a
relationship between lung dose-volume parameters and a 10% worsening of subjectiv
The Social Climbing Game
The structure of a society depends, to some extent, on the incentives of the
individuals they are composed of. We study a stylized model of this interplay,
that suggests that the more individuals aim at climbing the social hierarchy,
the more society's hierarchy gets strong. Such a dependence is sharp, in the
sense that a persistent hierarchical order emerges abruptly when the preference
for social status gets larger than a threshold. This phase transition has its
origin in the fact that the presence of a well defined hierarchy allows agents
to climb it, thus reinforcing it, whereas in a "disordered" society it is
harder for agents to find out whom they should connect to in order to become
more central. Interestingly, a social order emerges when agents strive harder
to climb society and it results in a state of reduced social mobility, as a
consequence of ergodicity breaking, where climbing is more difficult.Comment: 14 pages, 9 figure
Ductal prostate cancer: Clinical features and outcomes from a multicenter retrospective analysis and overview of the current literature
Impact of gastrointestinal side effects on patients’ reported quality of life trajectories after radiotherapy for prostate cancer: Data from the prospective, observational pros-it CNR study
Radiotherapy (RT) represents an important therapeutic option for the treatment of localized prostate cancer. The aim of the current study is to examine trajectories in patients’ reported quality of life (QoL) aspects related to bowel function and bother, considering data from the PROState cancer monitoring in ITaly from the National Research Council (Pros-IT CNR) study, analyzed with growth mixture models. Data for patients who underwent RT, either associated or not associated with androgen deprivation therapy, were considered. QoL outcomes were assessed over a 2-year period from the diagnosis, using the Italian version of the University of California Los Angeles-Prostate Cancer Index (Italian-UCLA-PCI). Three trajectories were identified for the bowel function; having three or more comorbidities and the use of 3D-CRT technique for RT were associated with the worst trajectory (OR = 3.80, 95% CI 2.04–7.08; OR = 2.17, 95% CI 1.22–3.87, respectively). Two trajectories were identified for the bowel bother scores; diabetes and the non-Image guided RT method were associated with being in the worst bowel bother trajectory group (OR = 1.69, 95% CI 1.06–2.67; OR = 2.57, 95% CI 1.70–3.86, respectively). The findings from this study suggest that the absence of comorbidities and the use of intensity modulated RT techniques with image guidance are related with a better tolerance to RT in terms of bowel side effects
Disease-specific and general health-related quality of life in newly diagnosed prostate cancer patients: The Pros-IT CNR study
Background: The National Research Council (CNR) prostate cancer monitoring project in Italy (Pros-IT CNR) is an observational, prospective, ongoing, multicentre study aiming to monitor a sample of Italian males diagnosed as new cases of prostate cancer. The present study aims to present data on the quality of life at time prostate cancer is diagnosed. Methods: One thousand seven hundred five patients were enrolled. Quality of life is evaluated at the time cancer was diagnosed and at subsequent assessments via the Italian version of the University of California Los Angeles-Prostate Cancer Index (UCLA-PCI) and the Short Form Health Survey (SF-12). Results: At diagnosis, lower scores on the physical component of the SF-12 were associated to older ages, obesity and the presence of 3+ moderate/severe comorbidities. Lower scores on the mental component were associated to younger ages, the presence of 3+ moderate/severe comorbidities and a T-score higher than one. Urinary and bowel functions according to UCLA-PCI were generally good. Almost 5% of the sample reported using at least one safety pad daily to control urinary loss; less than 3% reported moderate/severe problems attributable to bowel functions, and sexual function was a moderate/severe problem for 26.7%. Diabetes, 3+ moderate/severe comorbidities, T2 or T3-T4 categories and a Gleason score of eight or more were significantly associated with lower sexual function scores at diagnosis. Conclusions: Data collected by the Pros-IT CNR study have clarified the baseline status of newly diagnosed prostate cancer patients. A comprehensive assessment of quality of life will allow to objectively evaluate outcomes of different profile of care
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