A METHODOLOGY FOR THE PREDICTION AND ANALYSIS OF PRECURSORS TO FLIGHT ADVERSE EVENTS

Air transportation is known to be the safest mean of transportation nowadays. The drastic improvements in aviation safety since its gain in popularity are undeniably a factor in the industry's growth over the last several decades. This growth brought social and economic benefits throughout the world and was expected to keep its momentum pre-COVID-19. Stakeholders such as the National Aeronautics and Space Administration (NASA), the Federal Aviation Administration (FAA), the National Transportation Safety Board (NTSB), aircraft manufactures, and airlines have developed systems, techniques, and technologies that are to thank for today's overall safety improvements and the reduction of accidents. The industry's maintained growth is welcomed, but current safety performances have been observed to stagnate instead of declining. With safety initiatives such as the Flight Operational Quality Assurance (FOQA) program and the growing number of aviation data, many of the previous techniques used to understand the causes of accidents are not scalable. These reasons led to the development of novel methods leveraging advanced analytical tools such as machine learning and deep learning. However, current use cases have focused mainly on anomaly detection and system health monitoring, which does not bring enough reaction time to deal with an imminent event. This research proposes the improvement of aviation safety through precursor mining. Precursors are defined as events that are highly correlated to the adverse event that they precede. Therefore, they provide predictive capabilities and can be used to explain pre-defined events. This thesis uses publicly available flight data to 1) develop a novel deep learning method to identify and rank precursors of multiple adverse events, 2) use unsupervised learning algorithms to group flights based on their precursors to identify potential causes for these events at a fleet-level, and finally 3) detect novelty to ensure that the developed precursor models operate within their limits and that new non pre-defined adverse events could be detected.M.S

Adaptive spatial-temporal filtering applied to x-ray fluoroscopy angiography

Adaptive filtering of temporally varying X-ray image sequences acquired during endovascular interventions can improve the visual tracking of catheters by radiologists. Existing techniques blur the important parts of image sequences, such as catheter tips, anatomical structures and organs; and they may introduce trailing artifacts. To address this concern, an adaptive filtering process is presented to apply temporal filtering in regions without motion and spatial filtering in regions with motion. The adaptive filtering process is a multi-step procedure. First a normalized motion mask that describes the differences between two successive frames is generated. Secondly each frame is spatially filtered using the specific motion mask to specify different types of filtering in each region. Third an IIR filter is then used to combine the spatially filtered image with the previous output image; the motion mask thus serves as a weighted input mask to determine how much spatial and temporal filtering should be applied. This method results in improving both the stationary and moving fields. The visibility of static anatomical structures and organs increases, while the motion of the catheter tip and motion of anatomical structures and organs remain unblurred and visible during interventional procedures

Evaluation of a multi-scale enhancement protocol for digital mammography

We have carried out a receiver operating characteristics (ROC) study for the enhancement of mammographic features in digitized mammograms. The study evaluated the benefits of multi-scale enhancement methods in terms of diagnostic performance of radiologists. The enhancement protocol relied on multi-scale expansions and non-linear enhancement functions. Dyadic spline wavelet functions were used together with a sigmoidal non-linear enhancement function. We designed a computer interface ona softcopy display and performed an ROC study with three radiologists, who specialized in mammography. Clinical cases were obtained from a national mammography database of digitized radiographs prepared by the University of South Florida and Harvard Medical School. Our study focused on dense mammograms, i.e. mammograms of density 3 and 4 on the American College of Radiology breast density rating, which are the most difficult cases in screening, were selected. To compare the performance of radiologists with an without using multi-scale enhancement, two groups of 30 cases each were diagnosed. Each group contained 15 cases of cancerous and 15 cases of normal mammograms. Conventional ROC analysis was applied, and the resulting ROC curves indicated improved diagnostic performance when radiologists used multi-scale non-linear enhancement

Selection of the spraying technologies for over-coating of metal-stampings with thermo-plastics for use in direct-adhesion polymer metal hybrid load-bearing components

The suitability of various polymer-powder spraying technologies for coating of metal-stampings used in polymer metal hybrid (PMH) load-bearing automotive-component applications is considered. The suitability of the spraying technologies is assessed with respect to a need for metal-stamping surface preparation/treatment, their ability to deposit the polymeric material without significant material degradation, the ability to selectively overcoat the metal-stamping, the resulting magnitude of the polymer-to-metal adhesion strength, durability of the polymer/metal bond with respect to prolonged exposure to high-temperature/high-humidity and mechanical/thermal fatigue service conditions, and compatibility with the automotive body-in-white (BIW) manufacturing process chain. The analysis revealed that while each of the spraying technologies has some limitations, the cold-gas dynamic-spray process appears to be the leading candidate technology for the indicated applications

Clinical presentation of simple and combined or syndromic arteriovenous malformations.

OBJECTIVES Arteriovenous malformations of the lower extremities (AVMLE) can present as simple or complex combined or syndromic forms (e.g. Parkes Weber Syndrome). We aimed to characterize the differences in clinical presentation and natural history of these potentially life and limb threatening congenital vascular malformations. METHODS We conducted a retrospective analysis of a consecutive series of patients with AVMLE, who presented to a tertiary referral center in Switzerland between 2008 and 2018. Clinical baseline characteristics, D-dimer level and course were summarized and differences between simple, non-syndromic and combined or syndromic AVMLE determined. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression models. RESULTS Overall, 506 patients were prospectively enrolled in the Bernese Congenital Vascular Malformation Registry, 31 (6%) with AVMLE. There were 16 women and 15 men with a mean age of 18 years at first diagnosis (1 month - 72 years). Simple AVMLE was present in 22 (71%), combined or syndromic AVMLE with limb overgrowth in 9 patients (29%), respectively. Common symptoms and signs were pain 25 (81%), swelling 21 (68%) and soft tissue hypertrophy 13 (42%). Among combined or syndromic patients, 3 patients died from wound infection with sepsis or disseminated intravascular coagulation with bleeding complications (intracranial hemorrhage and bleeding from extensive leg ulcers). Combined or syndromic patients presented more often with bleeding (67% vs. 5%; p<0.001), malformation related infection (44% vs. 5%; p=0,017) and leg length difference (56% vs. 14%; p=0.049). D-dimer levels were elevated (mean 17256 μg/L, range 1557 μg/L to 80000 μg/L) and angiographic appearance showed complex, mixed type of AVMs, including interstitial type IV, in all patients with combined or syndromic AVMLE. CONCLUSION Patients with congenital simple AVMLE most often present with benign clinical features and rarely complications related to hemodynamic changes. Patients with combined or syndromic AVMLE often face serious outcomesdominated by complications other than direct high flow related heart failure

056: Biological efficacy of a 600mg loading dose of clopidogrel in ST-elevation myocardial infarction

BackgroundOptimal platelet reactivity (PR) inhibition is critical to prevent thrombotic events in primary percutaneous coronary intervention (PCI). We aimed to determine the relationship between high on-treatment platelet reactivity (HTPR) and ST-elevation myocardial infarction (STEMI) following a 600mg loading dose (LD) of clopidogrel.Methods and resultsWe performed a prospective monocentre study enrolling patients on clopidogrel undergoing PCI. The VASP index was used to assess PR inhibition after clopidogrel LD. HTPR was defined according to the consensus as a VASP index ≥50%. The present study included 833 patients undergoing PCI. Most patients had PCI for an acute coronary syndrome (58.7%). The mean VASP index was 50±23% with a large inter-individual variability (range: 1–94%). Patients with a VASP index ≥50% were significantly older (p=0.03), with a higher BMI (p<0.001), more often diabetic (p=0.03), taking omeprazole (p=0.03), admitted for an ACS and with a high fibrinogen level compared to good responders (VASP<50%). In multivariate analysis BMI, omeprazole use, acute coronary syndrome and high fibrinogen level (p<0.001) remained significantly associated with HTPR. Of importance, in this analysis STEMI was independently associated with HTPR when compared with the other forms of ACS (NSTEMI and unstable angina) with an odd ratio of 2.14 (95% CI: 1.3 –3.5; p=0.003).ConclusionSTEMI is associated with high on-treatment platelet reactivity following 600mg of clopidogrel. The present results suggest that 600mg of clopidogrel may not be able to achieve an optimal PR inhibition in STEMI patients undergoing PCI and more potent drugs may be preferred

039: Platelet reactivity predicts both ischemic and bleeding events at one year follow-up in acute coronary syndome patients receiving prasugrel

There are evidences of a link between platelet reactivity inhibition and thrombotic and bleeding events. We have previously demonstrated that PR after prasugrel loading dose (LD) predicts short-term thrombotic events. We aimed to further investigate the relationship between PR under prasugrel and one-year thrombotic and bleeding events.MethodPatients were prospectively included in this multicentre study if they had a successful PCI for an acute coronary syndrome (ACS) and received prasugrel. Vasodilator-Stimulated Phosphoprotein (VASP index) was measured after prasugrel LD. Endpoint included the rate of thrombotic events (cardiovascular death, myocardial infarction and stent thrombosis) and bleeding events (TIMI) at one year.ResultsThree hundreds and one patients were enrolled. Nine patients (3%) were lost to follow-up at one year. The rates of thrombotic and bleeding events at one year were 7.5 and 6.8% respectively. The mean VASP index after a 60mg LD of prasugrel was 34}23% and 76 patients (25%) were considered as having high on-treatment platelet reactivity (HTPR). Patients with HTPR had a higher rate of thrombotic events compared to good responders (19.7 vs 3.1%;p<0.001). Patients with a minor or major non-CABG related TIMI bleeding had lower PR compared to patients with no bleeding events (21}18 vs 35}23%;p=0.008). In multivariate analysis, the VASP index predicted both thrombotic and bleeding events (OR: 1.44 (95% CI: 1.2–1.72; p<0.001 and 0.75 (95% CI: 0.59–0.96;p=0.024 (respectively, per 10% increase)).ConclusionPlatelet reactivity measurement after prasugrel LD predicts both ischemic and bleedings events at one year follow-up for ACS patients undergoing PCI

The effect of starting point placement technique on thoracic transverse process strength: an ex vivo biomechanical study

<p>Abstract</p> <p>Background</p> <p>The use of thoracic pedicle screws in spinal deformity, trauma, and tumor reconstruction is becoming more common. Unsuccessful screw placement may require salvage techniques utilizing transverse process hooks. The effect of different starting point placement techniques on the strength of the transverse process has not previously been reported. The purpose of this paper is to determine the biomechanical properties of the thoracic transverse process following various pedicle screw starting point placement techniques.</p> <p>Methods</p> <p>Forty-seven fresh-frozen human cadaveric thoracic vertebrae from T2 to T9 were disarticulated and matched by bone mineral density (BMD) and transverse process (TP) cross-sectional area. Specimens were randomized to one of four groups: A, control, and three others based on thoracic pedicle screw placement technique; B, straightforward; C, funnel; and D, in-out-in. Initial cortical bone removal for pedicle screw placement was made using a burr at the location on the transverse process or transverse process-laminar junction as published in the original description of each technique. The transverse process was tested measuring load-to-failure simulating a hook in compression mode. Analysis of covariance and Pearson correlation coefficients were used to examine the data.</p> <p>Results</p> <p>Technique was a significant predictor of load-to-failure (<it>P </it>= 0.0007). The least squares mean (LS mean) load-to-failure of group A (control) was 377 N, group B (straightforward) 355 N, group C (funnel) 229 N, and group D (in-out-in) 301 N. Significant differences were noted between groups A and C, A and D, B and C, and C and D. BMD (0.925 g/cm²[range, 0.624-1.301 g/cm²]) was also a significant predictor of load-to-failure, for all specimens grouped together (<it>P </it>< 0.0001) and for each technique (<it>P <</it>0.05). Level and side tested were not found to significantly correlate with load-to-failure.</p> <p>Conclusions</p> <p>The residual coronal plane compressive strength of the thoracic transverse process is dependent upon the screw starting point placement technique. The funnel technique significantly weakens transverse processes as compared to the straightforward technique, which does not significantly weaken the transverse process. It is also dependent upon bone mineral density, and low failure loads even in some control specimens suggest limited usefulness of the transverse process for axial compression loading in the osteoporotic thoracic spine.</p

Hubble Space Telescope Imaging of Brightest Cluster Galaxies

We used the HST WFPC2 to obtain I-band images of the centers of 81 brightest cluster galaxies (BCGs), drawn from a volume-limited sample of nearby BCGs. The images show a rich variety of morphological features, including multiple or double nuclei, dust, stellar disks, point source nuclei, and central surface brightness depressions. High resolution surface brightness profiles could be inferred for 60 galaxies. Of those, 88% have well-resolved cores. Twelve percent of the BCG sample lacks a well-resolved core; all but one of these BCGs have ``power-law'' profiles. Some of these galaxies have higher luminosities than any power-law galaxy identified by Faber et al. (1997), and have physical upper limits on the break radius well below the values observed for core galaxies of the same luminosity. These results support the idea that the central structure of early-type galaxies is bimodal in its physical properties, but also suggest that there exist high luminosity galaxies with power-law profiles (or unusually small cores). The BCGs in the latter category tend to fall at the low end of the BCG luminosity function and tend to have low values of the quantity alpha (the logarithmic slope of the metric luminosity as a function of radius, at 10 kpc). Since theoretical calculations have shown that the luminosities and alpha values of BCGs grow with time as a result of accretion, this suggests a scenario in which elliptical galaxies evolve from power-law profiles to core profiles through accretion and merging. This is consistent with theoretical scenarios that invoke the formation of massive black hole binaries during merger events (Abridged).Comment: Accepted for publication in AJ. Postscript file with high resolution figures (1 and 3) is available at http://spider.ipac.caltech.edu/staff/seppo/bcgfig

The nature of late-type spiral galaxies: structural parameters, optical and near-infrared colour profiles, and dust extinction

We analyse V and H-band surface photometry of a sample of 18 Sb-Sd galaxies. Combining high resolution HST images with ground-based NIR observations, we extract photometric profiles, which cover the whole disk and provide the highest possible resolution. This is the first photometric study of late-type spirals for which the stellar kinematics have been measured. For 10 out of the 18 galaxies, HST data in both F160W (H) and F606W (V) are available, and, for those, we present colour maps and radial colour profiles at the resolution of the Hubble Space Telescope. Colours vary significantly from galaxy to galaxy, but tend to be highly homogeneous within each galaxy, with smooth and flat colour profiles. Some of the colour maps show jumps in the inner regions, likely due to dust. We determine extinction-maps in an almost model-independent way using the V-H colour map and the SAURON Mg b absorption line map of Ganda et al. (2007). The maps show that A_V ranges from 0 to 2 mag, in the center from 0 to 1.5 mag, in agreement with the models of Tuffs et al. (2004). We describe the surface brightness profiles as the superposition of an exponential disk and a Sersic bulge. The bulges are small (0.1-2.5 kpc), and show a shape parameter n ranging from ~ 0.7 to 3, with a mean value smaller than two: well below the value for the 'classical' de Vaucouleurs bulges. Most galaxies (16 out of 18) show a central light excess above the Sersic fit to the bulge, which can be interpreted as a nuclear cluster, as shown by previous studies. We provide zero-order estimates for the magnitude of these components. We discuss the correlations among the structural galaxy parameters and with other relevant quantities (abridged).Comment: 28 pages, 12 figures and 7 tables. Accepted for publication in MNRAS. Higher resolution version available at http://www.astro.rug.nl/~peletier/ganda2009.pd