Purpose
To compare the interpretive performance of synthetic mammography (SM), reconstructed from digital breast tomosynthesis (DBT), and full-field digital mammography (FFDM) in a diagnostic ...setting, covering different conditions of breast density and mammographic signs.
Methods
A retrospective analysis was conducted on 231 patients, who underwent FFDM and DBT (from which SM images were reconstructed) between September 2014–September 2015. The study included 250 suspicious breast lesions, all biopsy proven: 148 (59.2%) malignant and 13 (5.2%) high-risk lesions were confirmed by surgery, 89 (35.6%) benign lesions had radiological follow-up. Two breast radiologists, blinded to histology, independently reviewed all cases. Readings were performed with SM alone, then with FFDM, collecting data on: probability of malignancy for each finding, lesion conspicuity, mammographic features and dimensions of detected lesions.
Results
Agreement between readers was good for BI-RADS classification (Cohen’s k-coefficient = 0.93 ± 0.02) and for lesion dimension (Wilcoxon’s
p
= 0.76). Visibility scores assigned to SM and FFDM for each lesion were similar for non-dense and dense breasts, however, there were significant differences (
p
= 0.0009) in distribution of mammographic features subgroups. SM and FFDM had similar sensitivities in non-dense (respectively 94 vs. 91%) and dense breasts (88 vs. 80%) and for all mammographic signs (93 vs. 87% for asymmetric densities, 96 vs. 75% for distortion, 92 vs. 85% for microcalcifications, and both 94% for masses). Based on all data, there was a significant difference in sensitivity for SM (92%) vs. FFDM (87%),
p
= 0.02, whereas the two modalities yielded similar results for specificity (SM: 60%, FFDM: 62%,
p
= 0.21).
Conclusions
SM alone showed similar interpretive performance to FFDM, confirming its potential role as an alternative to FFDM in women having tomosynthesis, with the added advantage of halving the patient’s dose exposure.
La rappresentazione di Santiago nella sua eccezione di matamoros, ovvero di sterminatore di mori quale difensore della cristianità, tema ricorrente nell'iconografia iacopea in ambito ispanico perché ...legato all'epopea della Reconquista, si è diffuso anche nell'arte italiana. Identificato dagli studiosi in alcuni affreschi, il repertorio si potrebbe arricchire di statue, formelle, bassorilievi e altorilievi, lamine d'argento, arazzi, casse e mazze processionale, stendardi, stemmi, pendenti, etc. Le ho cercate nelle chiese, nelle collezioni private, nei musei e in altri luoghi deputati ad accoglierle. Probabilmente ci sono altre rappresentazioni, ma queste sono quelle che ho trovato al momento. In Sicilia Santiago matamoros è rappresentato ben 25 volte in 11 località diverse.
•Our work highlights some of the complex factors underlying BC surgical treatment.•The addition of more breast imaging appears to be driving more radical surgery.•Several factors (such as larger ...tumors, invasive cancer with in-situ component) were associated with selection to mastectomy.
To compare the rates of mastectomy and re-operation after breast-conserving surgery (BCS) among patients who had different pre-operative multi-modality imaging, hence identifying significant predictors of mastectomy and re-operations within each group.
Retrospective study of consecutive patients with primary breast cancer treated January 2010 – December 2016, divided in 3 groups, undergoing pre-operative local staging respectively with conventional imaging modalities only (2D mammography, ultrasound (US)), conventional imaging and tomosynthesis (DBT) and/or MRI. The primary outcome was identification of significant predictors of surgical outcomes, within each group. Study variables examined in univariate analysis were age, lesion dimension, breast density, multifocality, tumor size, histology, and if associated with outcomes they were included in binary logistic regression analysis.
Amongst 1547 patients, patient and tumor characteristics differed across the three groups, as did mastectomy rates which were 18 % (102/562) for 2D + US, 36 % (154/428) for 2D + DBT + US, 45 % (250/557) for 2D+/-DBT + US + MRI(p < 0.001). Variables strongly associated with mastectomy were larger lesions and multifocality (as was multi-modality group). Re-operation rate showed an opposite trend: 12.2 % (56/459) for 2D + US, 8 % (22/272) for 2D + DBT + US, 6.5 % (20/306) for 2D+/-DBT + US + MRI. Re-operation rate for 2D+/-DBT + US + MRI was lower than for 2D + US (p = 0.01) but similar to 2D + DBT + US (p = 0.58). Patients who had 2D + US and re-operations had significantly larger lesions, more underestimation, higher proportion of invasive carcinoma with in-situ component than those who did not require re-operation.
Patients who had larger tumors and multifocal disease were more frequently staged by adding DBT and/or MRI to conventional imaging (mammography and US) which was associated with more extensive surgical treatment but lower reoperation rates.
Purpose
Accurate measurement of breast tumour size is fundamental for treatment planning. We compared the accuracy of digital mammography (DM), digital breast tomosynthesis (DBT), ultrasound (US) and ...magnetic resonance imaging (MRI) for the preoperative evaluation of breast cancer size.
Materials and methods
We retrospectively reviewed 149 breast cancers in 110 patients who underwent DM, DBT, US and MRI between January 2010 and December 2011, before definitive surgery. The lesions were measured by two radiologists, without knowledge of the final histological examination, considered the gold standard. For each imaging modality, the maximum tumour size was measured to the nearest millimetre; the measurements were considered concordant if they were within ±5 mm. Pearson’s correlation coefficient was calculated for each imaging modality.
Results
The median pathological tumour size was 22.3 mm. MRI and DBT had a level of concordance with pathology of 70% and 66%, respectively, which was higher than that of DM (54%). DBT and MRI measurements had a better correlation with pathological tumour size (R:0.89 and R:0.92, respectively) compared to DM (R:0.83) and US (R:0.77).
Conclusions
DBT and MRI are superior to DM and US in the preoperative assessment of breast tumour size. DBT seems to improve the accuracy of DM, although MRI remains the most accurate imaging modality for breast cancer extension.
We study effort provision and incentivisation in a Tullock group-contest with m ≥ 2 groups that differ in size. A novel algorithmic procedure is presented that, under a symmetry assumption, ...explicitly characterises the equilibrium. Endogenous, optimal incentivisation schemes are then determined. Four results ensue. First, strategic interactions endogenously come in mean-field form: individual effort provision responds to the aggregate effort and average egalitarianism across groups. Therefore, the game is aggregative. Second, individuals endlessly cycle between zero and positive effort provision at some incentivisation schemes: no pure-strategy equilibria exist in these cases. Third, group size determines whether the egalitarianism of endogenous schemes increases or decreases in the average egalitarianism across groups. Fourth, all groups provide effort at the endogenous schemes if incentivisation is properly restricted.
This paper presents a stylised social-interaction game where the implementation of a lockdown policy is delegated to the decentralised, uncoordinated decision-making of a large population of ...atomistic agents – assumed risk-neutral and demographically heterogeneous. Compliance with policy prescriptions is socially beneficial but individually costly. In the static, it determines the individual risk of contagion in social interactions (at the micro-level) and the number of new infections (at the macro-). Over time, it affects the peak prevalence of the disease and the duration of the epidemic. Albeit atomistic, agents act strategically, for they rationally anticipate others’ behaviour when deciding (not) to comply. Three are the key results of our analysis. First, the strategic incentives faced by the agents co-evolve with the epidemic. When prevalence is low, compliance is a dominated strategy. When prevalence is high, individual decisions to comply are strategic substitutes: older/weaker agents self-protect by implementing social distancing and younger/healthier ones free-ride. Second, the strategic incentives faced by the agents co-evolve, too, with their beliefs about susceptibility. When they disregard any information about their past behaviour and use the aggregates to estimate susceptibility, strategic substitutability prevails. When beliefs are path-dependent, both complementarity and substitutability may arise. Third, we show that SIR-based models that fail to account for the endogenous response to policy prescriptions may substantially overestimate the effectiveness of lockdowns. Incidentally, we highlight that myopic behaviour may cease to be rational in a dynamic setting where agents’ beliefs about susceptibility are path-dependent.
Questa tesi si compone di due capitoli indipendenti, ciascuno dei quali analizza il ruolo giocato dall’informazione pubblica endogenamente determinata in situazioni caratterizzate da decision-making ...decentralizzato e da complementarietà strategica. Il primo capitolo analizza un regime-change game, in cui un governo autoritario può influenzare il consenso popolare attraverso l’implementazione di uno strumento di policy. A policy implementata, i cittadini possono tentare di destituire il governo in carica attraverso una rivolta popolare, la cui probabilità di successo è proporzionale al numero di partecipanti, quest’ultimo proporzionale al livello medio di malcontento. Per migliorare l’efficacia del policy-making, il governo necessita di informazioni affidabili sul consenso popolare, tipicamente difficili da reperire. Tali informazioni sono potenzialmente destabilizzanti, poiché aiutano i cittadini a coordinare meglio la loro azione collettiva. I risultati suggeriscono che maggiore trasparenza è desiderabile ex ante per quei regimi che, in equilibrio, hanno maggiore probabilità di implementare delle politiche di consensus-building. Maggiori livelli di libertà di informazione dovrebbero quindi essere osservati in regimi né troppo deboli, né troppo forti. Il secondo capitolo propone un modello di bank run, in cui la presenza di un mercato secondario efficiente dal punto di vista informativo destabilizza una istituzione a priori solida, tramutando uno shock temporaneo di liquidità in una spirale di fire-sales. Gli investitori di un fondo open-ended posso richiedere la liquidazione anticipata delle proprie quote dopo aver ricevuto informazioni private riguardo alla qualità degli asset in portafogli. Per rimborsare le quote, il fund manager vende una quota di asset sul mercato secondario. I potenziali acquirenti estraggono informazione dall’osservazione dell’offerta aggregata: maggiori volumi d’offerta corrispondono ad un maggior numero di investitori pessimisti, e suggeriscono quindi che gli asset potrebbero essere di scarsa qualità. Temendo una spirale discendente dei prezzi, anche gli investitori meno pessimisti sono indotti, ex ante, a liquidare le proprie quote, ulteriormente sostenendo il feedback negativo. Quando l’informazione privata è sufficientemente imprecisa, complementarietà strategica nelle azioni degli investitori del fondo emerge endogenamente.
This dissertation consists of two essays, aimed at providing a sound theoretical investigation of the signaling role of (observed) collective behavior in environments characterized by incomplete information and strategic complementarity. The effects of both endogenous signaling and (the disclosure of) exogenous public information on the degree of coordination failure that arises from decentralized decision-making are analyzed in-depth. In the first chapter I analyze a regime-change game, where an authoritarian government can influence popular support via the implementation of costly policies. Citizens can challenge the government via a riot, whose chances to succeed increase with the unknown average popular discontent. In order to fine-tune its policy-making, the regime needs reliable information about popular consensus. Such information, however, improves the ability of citizens to coordinate their revolt. I show that public information is ex ante beneficial for those regimes which are more likely to build consensus via policy-making in equilibrium. Higher levels of media freedom should therefore be observed in regimes that are neither too weak, nor too strong. In the second chapter I study a bank run model, where the informational efficiency of a (secondary) financial market pushes into insolvency an a priori solvent institution after a temporary, non-fundamental liquidity shock. The most pessimistic investors of an open-ended fund are allowed to ask for the early liquidation of their share after receiving private information about the economic fundamentals of the fund’s portfolio of assets. Some of the assets in portfolio are sold in the secondary market to meet those investors’ requests. Higher volumes of early redemptions decrease both the current price, via a standard law-of-demand effect, and the future price, by signaling bad news to the market. Anticipating such effect, less pessimistic investors, too, opt for early liquidation, thus further exacerbating the price spiral. Strategic complementarity arises endogenously when investors’ private information is sufficiently poor. In this case, a spiral of fire sales is observed in equilibrium.
The Laser Interferometer Space Antenna (LISA) will be the first gravitational wave detector in space. The European Space Agency has selected LISA as a large mission scheduled to launch in the ...mid-2030s. The sensitivity of LISA to gravitational waves is limited at low frequencies by force disturbances acting on the otherwise free-falling test masses. Among the stray forces relevant to the LISA noise budget, we find the ones that arise from the electrostatic interaction between the test masses and the surrounding capacitive sensor. Most of such electrostatic forces scale with the electric charge deposited on the test masses. This problem is aggravated by the fact that isolated objects in space, such as the floating LISA test masses, accumulate electric charge due to the constant bombardment of cosmic rays and solar energetic particles. We, therefore, understand that if the test masses were not discharged, the electrostatic disturbances could spoil the performance of the whole mission at low frequency. The precursor LISA Pathfinder (LPF) mission proved that the test mass charge could be successfully managed with a contactless system based on photoelectric charge transfer. The light sources required for photoemission in LISA Pathfinder were mercury-vapor lamps emitting photons in the UV range. In this thesis, we will present our on-ground testing campaign of a prototype Charge Management System for LISA, which relies on UV-LEDs as light sources. LEDs, compared to mercury-vapor lamps, can emit short pulses of UV light (~10 ns), which can be synchronized with the time-varying electrostatic fields around the test mass. For this reason, we studied new discharge strategies made possible by adopting UV-LEDs characterized by pulsed illumination synced with the capacitive sensing injection bias. Our measurements indicate that UV-LEDs offer significant advantages regarding the flexibility and robustness of the Charge Management System. Moreover, the new illumination patterns offered by UV-LEDs allow fine-tuning the TM equilibrium potential without introducing local DC fields, easing the implementation of the continuous discharge mode to manage the TM potential. Finally, we investigated the charge noise introduced by the continuous discharge mode and verified that it could be kept within the LISA requirements. We will present hereafter the outline of the thesis. In the first chapter, we present a mandatory introduction to gravitational waves and the LISA mission. In the second chapter, we present the instrument used for our experimental campaign, namely the four-test-masses torsion pendulum at the University of Trento. We also present the electrostatic model and the measurement techniques used to evaluate the electric charge on the pendulum test mass.;
In the third chapter, we introduce the concept of apparent yield, which is a figure of merit of the charge management system performance. We also present our experimental measurement, which encompasses tests on several UV-LEDs in different illumination patterns. In the fourth chapter, we derive a simple photoemission model, which is useful for interpreting the apparent yield data acquired. We will also use the model to fit the experimental data and extract estimates of the microscopic parameters that affect the photoemission from metallic surfaces, e.g. work function or quantum yield. In the fifth chapter, we present a model and our torsion pendulum measurements for the charge noise induced on the test masses when continuously illuminated with UV light. Such noise arises from the discrete and intrinsically stochastic nature of photoelectric charge transfer. Finally, in the last chapter, we will wrap up by presenting the problems encountered and the "lessons learned" during the years-long experimental endeavor.
Citrus limon (L.) Burm. F. is an important evergreen fruit crop whose rhizosphere and phyllosphere microbiota have been characterized, while seed microbiota is still unknown. Bacterial and fungal ...endophytes were isolated from C. limon surface-sterilized seeds. The isolated fungi-belonging to Aspergillus, Quambalaria and Bjerkandera genera-and bacteria-belonging to Staphylococcus genus-were characterized for indoleacetic acid production and phosphate solubilization. Next Generation Sequencing based approaches were then used to characterize the endophytic bacterial and fungal microbiota structures of surface-sterilized C. limon seeds and of shoots obtained under aseptic conditions from in vitro growing seedlings regenerated from surface-sterilized seeds. This analysis highlighted that Cutibacterium and Acinetobacter were the most abundant bacterial genera in both seeds and shoots, while Cladosporium and Debaryomyces were the most abundant fungal genera in seeds and shoots, respectively. The localization of bacterial endophytes in seed and shoot tissues was revealed by Fluorescence In Situ Hybridization coupled with Confocal Laser Scanning Microscopy revealing vascular bundle colonization. Thus, these results highlighted for the first time the structures of endophytic microbiota of C. limon seeds and the transmission to shoots, corroborating the idea of a vertical transmission of plant microbiota and suggesting its crucial role in seed germination and plant development.
PDF