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The field of Artificial Intelligence (AI) has always faced two major challenges. The first is that data is kept scattered and cannot be collected for more efficiently use. The second is that data privacy and security need to be continuously strengthened. Based on these two points, federated learning is proposed as an emerging machine learning scheme. The idea of federated learning is to collaboratively train neural networks on servers. Each user receives the current weights of the network and then sequentially sends parameter updates (gradients) based on their own data. Because the input data remains on-device and only the parameter gradients are shared, this scheme is considered to be effective in preserving data privacy. Some previous attacks also provide a false sense of security since they only succeed in contrived settings, even for a single image. Our research mainly focus on attacks on shared gradients, showing experimentally that private training data can be obtained from publicly shared gradients. We do experiments on both linear-based and convolutional-based deep networks, whose results show that our attack is capable of creating a threat to data privacy, and this threat is independent of the specific structure of neural networks. The method presented in this paper is only to illustrate that it is feasible to recover user data from shared gradients, and cannot be used as an attack to obtain privacy in large quantities. The goal is to spark further research on federated learning, especially gradient security. We also make some brief discussion on possible strategies against our attack methods of privacy. Different methods have their own advantages and disadvantages in terms of privacy protection. Therefore, data pre-processing and network structure adjustment may need to be further researched, so that the process of training the models can achieve better privacy protection while maintaining high precision. / Området artificiell intelligens har alltid stått inför två stora utmaningar. Den första är att data hålls utspridda och inte kan samlas in för mer effektiv användning. Det andra är att datasekretess och säkerhet behöver stärkas kontinuerligt. Baserat på dessa två punkter föreslås federerat lärande som ett framväxande angreppssätt inom maskininlärning. Tanken med federerat lärande är att tillsammans träna neurala nätverk på servrar. Varje användare får nätverkets aktuella vikter och skickar sedan parameteruppdateringar (gradienter) sekventiellt baserat på sina egna data. Eftersom indata förblir på enheten och endast parametergradienterna delas, anses detta schema vara effektivt för att bevara datasekretessen. Vissa tidigare attacker ger också en falsk känsla av säkerhet eftersom de bara lyckas i konstruerade inställningar, även för en enda bild. Vår forskning fokuserar främst på attacker på delade gradienter, och visar experimentellt att privat träningsdata kan erhållas från offentligt delade gradienter. Vi gör experiment på både linjärbaserade och faltningsbaserade djupa nätverk, vars resultat visar att vår attack kan skapa ett hot mot dataintegriteten, och detta hot är oberoende av den specifika strukturen hos djupa nätverk. Metoden som presenteras i denna rapport är endast för att illustrera att det är möjligt att rekonstruera användardata från delade gradienter, och kan inte användas som en attack för att erhålla integritet i stora mängder. Målet är att få igång ytterligare forskning om federerat lärande, särskilt gradientsäkerhet. Vi gör också en kort diskussion om möjliga strategier mot våra attackmetoder för integritet. Olika metoder har sina egna fördelar och nackdelar när det gäller integritetsskydd. Därför kan förbearbetning av data och justering av nätverksstruktur behöva undersökas ytterligare, så att processen med att träna modellerna kan uppnå bättre integritetsskydd samtidigt som hög precision bibehålls.

Background: Novel intraoperative imaging techniques, namely, hyperspectral (HSI) and fluorescence imaging (FI), are promising with respect to reducing severe postoperative complications, thus increasing patient safety. Both tools have already been used to evaluate perfusion of the gastric conduit after esophagectomy and before anastomosis. To our knowledge, this is the first study evaluating both modalities simultaneously during esophagectomy. Methods: In our pilot study, 13 patients, who underwent Ivor Lewis esophagectomy and gastric conduit reconstruction, were analyzed prospectively. HSI and FI were recorded before establishing the anastomosis in order to determine its optimum position. Results: No anastomotic leak occurred during this pilot study. In five patients, the imaging methods resulted in a more peripheral adaptation of the anastomosis. There were no significant differences between the two imaging tools, and no adverse events due to the imaging methods or indocyanine green (ICG) injection occurred. Conclusions: Simultaneous intraoperative application of both modalities was feasible and not time consuming. They are complementary with regard to the ideal anastomotic position and may contribute to better surgical outcomes. The impact of their simultaneous application will be proven in consecutive prospective trials with a large patient cohort.

Simple Summary Good oxygenation of both bowel ends is an important prerequisite to promote anastomotic healing after colorectal resections. Bowel oxygenation is usually assessed clinically. Hyperspectral imaging is a contactless and contrast-free tool that allows quantifying tissue oxygen intraoperatively. In this study, the results of 105 colorectal resections with hyperspectral imaging are reported. Abstract Background: A perfusion deficit is a well-defined and intraoperatively influenceable cause of anastomotic leak (AL). Current intraoperative perfusion assessment methods do not provide objective and quantitative results. In this study, the ability of hyperspectral imaging (HSI) to quantify tissue oxygenation intraoperatively was assessed. Methods: 115 patients undergoing colorectal resections were included in the final analysis. Before anastomotic formation, the bowel was extracted and the resection line was outlined and imaged using a compact HSI camera, in order to provide instantaneously quantitative perfusion assessment. Results: In 105 patients, a clear demarcation line was visible with HSI one minute after marginal artery transection, reaching a plateau after 3 min. In 58 (55.2%) patients, the clinically determined transection line matched with HSI. In 23 (21.9%) patients, the clinically established resection margin was entirely within the less perfused area. In 24 patients (22.8%), the HSI transection line had an irregular course and crossed the clinically established resection line. In four cases, HSI disclosed a clinically undetected lesion of the marginal artery. Conclusions: Intraoperative HSI is safe, well reproducible, and does not disrupt the surgical workflow. It also quantifies bowel surface perfusion. HSI might become an intraoperative guidance tool, potentially preventing postoperative complications.

Esophagectomy often presents anastomotic leaks (AL), due to tenuous perfusion of gastric conduit fundus (GCF). Hybrid (endovascular/surgical) ischemic gastric preconditioning (IGP), might improve GCF perfusion. Sixteen pigs undergoing IGP were randomized: (1) Max-IGP (n = 6): embolization of left gastric artery (LGA), right gastric artery (RGA), left gastroepiploic artery (LGEA), and laparoscopic division (LapD) of short gastric arteries (SGA); (2) Min-IGP (n = 5): LGA-embolization, SGA-LapD; (3) Sham (n = 5): angiography, laparoscopy. At day 21 gastric tubulation occurred and GCF perfusion was assessed as: (A) Serosal-tissue-oxygenation (StO2) by hyperspectral-imaging; (B) Serosal time-to-peak (TTP) by fluorescence-imaging; (C) Mucosal functional-capillary-density-area (FCD-A) index by confocal-laser-endomicroscopy. Local capillary lactates (LCL) were sampled. Neovascularization was assessed (histology/immunohistochemistry). Sham presented lower StO2 and FCD-A index (41 ± 10.6%; 0.03 ± 0.03 respectively) than min-IGP (66.2 ± 10.2%, p-value = 0.004; 0.22 ± 0.02, p-value < 0.0001 respectively) and max-IGP (63.8 ± 9.4%, p-value = 0.006; 0.2 ± 0.02, p-value < 0.0001 respectively). Sham had higher LCL (9.6 ± 4.8 mL/mol) than min-IGP (4 ± 3.1, p-value = 0.04) and max-IGP (3.4 ± 1.5, p-value = 0.02). For StO2, FCD-A, LCL, max- and min-IGP did not differ. Sham had higher TTP (24.4 ± 4.9 s) than max-IGP (10 ± 1.5 s, p-value = 0.0008) and min-IGP (14 ± 1.7 s, non-significant). Max- and min-IGP did not differ. Neovascularization was confirmed in both IGP groups. Hybrid IGP improves GCF perfusion, potentially reducing post-esophagectomy AL.

Le cancer colorectal (CCR) est le 3ème plus diagnostiqué au Canada. Son traitement implique une résection chirurgicale du côlon ou du rectum, et une reconnexion des deux bouts intestinaux pour rétablir la continuité gastrointestinale. Cette reconnexion, appelée « anastomose », peut ne pas bien guérir chez jusqu’à 30% des patients, ce qui mène à une complication morbide et mortelle appelée « fuite anastomotique ». En plus de diminuer la survie et la qualité de vie, la fuite est possiblement associée à une récidive accrue du cancer pour des raisons qui demeurent obscures. Malgré des progrès techniques importants dans les dernières décennies, les taux de fuite n’ont pas significativement diminué, et sa survenue demeure hautement imprévisible. Des données récentes ont suggéré que le microbiote intestinal, ou la collection de microorganismes dans l’intestin, peut influencer le processus de guérison après la chirurgie, mais l’évidence sur cette relation reste faible. Les études suivantes visaient donc à évaluer le lien causal entre le microbiote, la fuite anastomotique le CCR. En utilisant des échantillons de selles collectés avant la chirurgie de 18 patients avec CCR (9 avec fuite et 9 sans fuite), on a évalué le rôle causal du microbiote humain chez des souris assujetties à une greffe de microbiote fécal (GMF) puis une chirurgie colique. On a trouvé que la GMF avec des échantillons de patients avec fuite a entrainé chez la souris une mauvaise guérison anastomotique, un affaiblissement de la matrice extracellulaire dans la plaie colique, et une inflammation accrue localement. On a identifié 2 souches bactériennes, Parabacteroides goldsteinii kh35 et Alistipes onderdonkii kh33, qui influençaient la guérison anastomotique, la 1ère positivement et la 2ème négativement. Ces souches modulaient l’inflammation dans la muqueuse colique, avec P. goldsteinii exerçant un effet anti-inflammatoire et A. onderdonkii un effet pro-inflammatoire. En utilisant des échantillons de muqueuses collectés de patients avant la complétion de l’anastomose, on a trouvé avec une analyse multiplex que les patients présentant une fuite avaient des niveaux basaux plus élevés des macrophage inflammatory protein-1 alpha, monocyte chemoattractant protein-1, macrophage inflammatory protein 2 et interleukin-17A/F, et que le microbiote de ces patients entraine une augmentation similaire de ces cytokines pro-inflammatoires dans l’intestin des souris. Pour corroborer l’hypothèse que les patients présentant une fuite après la chirurgie avaient des niveaux basaux plus élevés d’inflammation intestinale de bas-grade induite par le microbiote, on a quantifié 9 cytokines dans la muqueuse colorectale de 77 patients avec CCR, pami lesquels 13 ont présenté une fuite après la chirurgie. Les 9 cytokines étaient plus élevées chez les patients ayant développé une fuite. On a exploré des marqueurs inflammatoires potentiels dans les selles, et qui peuvent être utilisés comme des biomarqueurs de dépistage avant la chirurgie, et avons identifié la calprotectine et la lipocaline-2 comme étant significativement différentes entre les patients présentant, ou pas, une fuite anastomotique. Ensuite, on a exploré si des métabolites bactériens peuvent être utilisés pour améliorer la guérison anastomotique. Les acides-gras à courte chaine (AGCCs) sont produits dans le côlon après la fermentation bactérienne de fibres alimentaires. On a ainsi testé si une supplémentation chez la souris avec de l’inuline ou des galacto-oligosaccharides (GOS), deux oligosaccharides fermentables, peut améliorer la guérison. On a trouvé que l’inuline et le GOS ont augmenté les niveaux du bénéfique AGCC butyrate, amélioré la guérison anastomotique, favorisé la réparation épithéliale, la déposition du collagène et la barrière intestinale. Enfin, puisque le butyrate est connu pour son effet anticancérigène via une activation peroxysome proliferator-activated receptor gamma (PPAR-γ), on a investigué la relation entre l’amélioration de la guérison intestinale postopératoire avec l’inuline et le 5-aminosalicylate (5-ASA), un activateur de PPAR-γ, et la récidive du CCR. Une revue de la survie postopératoire de patients avec CCR ayant, ou pas, présenté une fuite a été effectuée. L’effet d’une supplémentation alimentaire avec de l’inuline ou du 5-ASA sur les tumeurs anastomotiques a été évalué chez des souris subissant une chirurgie colique. L’inuline et le 5-ASA ont été aussi évalués dans un modèle murin de métastases hépatiques où les cellules de CCR étaient inoculées chirurgicalement dans la rate. Les patients présentant une fuite présentaient une survie globale et oncologique moindre que les patients sans fuite. Une mauvaise guérison anastomotique chez la souris a entrainé des tumeurs anastomotiques et péritonéales plus volumineuses. L’inuline et le 5-ASA ont renforcé la barrière intestinale et prévenu les tumeurs anastomotiques et dissémination métastatique chez la souris. Ces trouvailles renforcent l’hypothèse que prévenir la fuite améliore les issues oncologiques des patients avec CCR, et ouvre la voie à des essais cliniques où des interventions modifiant le microbiote seraient utilisées pour favoriser la guérison et diminuer la récidive du cancer. En résumé, on a démontré pour la première fois le lien causal entre le microbiote intestinal préopératoire et la guérison anastomotique chez les patients avec CCR. On a aussi identifié des biomarqueurs potentiels qui peuvent être utilisés en pratique pour détecter l’inflammation subclinique de bas-grade induite par le microbiote pour prédire la guérison avant la chirurgie. On a aussi démontré que le microbiote et PPAR-γ peuvent être modulés avec des oligosaccharides fermentables pour améliorer la guérison, renforcer la barrière intestinale et prévenir la récidive du cancer. / Colorectal cancer (CRC) is the third most diagnosed cancer in Canada. Its treatment involves a surgical resection of the colon or rectum, and a reconnection of the remaining bowel segments to re-establish gastrointestinal continuity. This reconnection, termed “anastomosis”, may fail to heal and leak in up to 30% of patients, which leads to a morbid and mortal complication called “anastomotic leak” (AL). In addition to decreasing survival and quality of life, AL may be linked to higher cancer recurrence for reasons that remain unclear. Despite significant technical progress over the last decades, the rates of AL have not significantly decreased, and its occurrence remains highly unpredictable. Recent data have suggested that the gut microbiota, or the collection of microorganisms in the gut, may influence the healing process after surgery, but evidence on this relation remains weak. The following studies aimed therefore at assessing the causal link between the gut microbiota, AL, and CRC in patients undergoing surgery. Using fecal samples collected before surgery from 18 patients with CRC (9 with AL and 9 without AL), we assessed the causal role of the human microbiota in mice subjected to fecal microbiota transplantation (FMT) then colonic surgery. We found that FMT from AL patients led to poor anastomotic healing, a weakened extracellular matrix in the colonic wound, and heightened inflammation locally. We identified 2 bacterial strains, Parabacteroides goldsteinii kh35 and Alistipes onderdonkii kh33, that were found to influence anastomotic healing, the first one positively and the second one negatively. These strains were found to modulate inflammation in the colonic mucosa, with P. goldsteinii exerting an anti-inflammatory effect and A. onderdonkii a pro-inflammatory effect. Using mucosal samples collected from patients before the completion of the anastomosis, we found with a multiplex assay that patients experiencing AL harbor higher basal levels of macrophage inflammatory protein- 1 alpha, monocyte chemoattractant protein-1, macrophage Inflammatory Protein 2 and interleukin-17A/F, and that the microbiota of these patients lead to the same increase in pro-inflammatory cytokines in mice. To corroborate the hypothesis that patients experiencing AL after surgery harbor higher basal levels of microbiota-driven low-grade inflammation in the gut, we quantified 9 cytokines in the colorectal mucosa of 77 patients with CRC, among whom 13 experienced AL after surgery. All 9 cytokines were found to be increased in patients developing AL. We explored potential fecal inflammatory markers that could be used as screening biomarkers before surgery, and identified calprotectin and lipocalin-2 as being significantly different between patients that subsequently developed, or not, AL. 4 Next we explored whether bacterial metabolites may be used to improve anastomotic healing. Short-chain fatty acids are produced in the gut upon bacterial fermentation of dietary fibers. We therefore tested in mice whether dietary supplementation with inulin or galacto-oligosaccharides (GOS), two fermentable oligosaccharides, could improve healing. We found that inulin and GOS increased the levels of the beneficial SCFA butyrate, improved anastomotic healing, promoted epithelial repair, collagen deposition and the gut barrier function. Finally, as butyrate is known to exert anticarcinogenic effect by stimulating the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-γ), we further investigated the relationship between promotion of postoperative intestinal healing using inulin and 5-aminosalicylate (5-ASA), a PPAR-γ activator, and CRC recurrence. A review of postoperative survival of CRC patients with and without AL was performed. The effect of dietary supplementation with inulin and 5-ASA on local anastomotic tumors was assessed in mice undergoing colonic surgery. Inulin and 5- ASA were also assessed in a mouse model of liver metastasis where CRC cells are surgically inoculated into the spleen. Patients experiencing AL displayed significantly lower overall and oncological survival than non-AL patients. Poor anastomotic healing in mice led to larger anastomotic and peritoneal tumors. Inulin and 5-ASA reinforced the gut barrier and prevented anastomotic tumors and metastatic spread in mice. These findings reinforce the hypothesis that preventing AL improves oncological outcomes in patients with CRC, and pave the way towards clinical trials in which microbiotatargeted interventions may be used to enhance healing and diminish cancer recurrence. In summary, we demonstrated for the first time the causal link between the preoperative gut microbiota and anastomotic healing in patients with CRC. We also identified potential biomarkers that could be used in practice to detect microbiota-driven subclinical inflammation and predict healing before surgery. We also showed that the gut microbiota and PPAR-g could be modulated using fermentable oligosaccharides to improve healing, reinforce the gut barrier and prevent cancer recurrence.

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Drones have become an integral part of the digital transformation currently sweeping the mining industry; particularly in surface operations, where they allow operators to model the terrain quickly and effortlessly with GPS localization and advanced mission planning software. Recently, the usage of drones has expanded to underground mines, with advancements in drone autonomy in GPS-denied environments. Developments in lidar technology and Simultaneous Localization and Mapping (SLAM) algorithms are enabling UAVs to function safely underground where they can be used to map workings and digitally reconstruct them into 3D point clouds for a wide variety of applications. Underground mines can be expansive with inaccessible and dangerous areas preventing safe access for traditional inspections, mapping and monitoring. In addition, abandoned mines and historic mines being reopened may lack reliable maps of sufficient detail. The underground mine environment presents a multitude of unique challenges that must be addressed for reliable drone flights. This work covers the development of drones for GPS-denied underground mines, in addition to several case studies where drone-based lidar and photogrammetry were used to capture 3D point clouds of underground mines, and the associated applications of mine digitization, such as geotechnical analysis and pillar strength analysis. This research also features an applied use case of custom drones built to detect methane leaks at natural gas production and distribution sites. / Doctor of Philosophy / Drones have become an integral part of the digital transformation currently sweeping the mining industry; particularly in surface operations, where they allow operators to model the terrain quickly and effortlessly. Recently, the usage of drones has expanded to underground mines, with advancements in drone autonomy. New developments are enabling UAVs to function safely underground where they can be used to digitally reconstruct workings for a wide variety of applications. Underground mines can be expansive with inaccessible and dangerous areas preventing safe access for traditional inspections, mapping and monitoring. In addition, abandoned mines and historic mines being reopened may lack reliable maps of sufficient detail. The underground mine environment presents a multitude of unique challenges that must be addressed for reliable drone flights. This work covers the development of drones for GPS-denied underground mines, in addition to several case studies where drones were used to create 3D models of mines, and the associated applications of mine digitization. This research also features an applied use case of custom drones built to detect methane leaks at natural gas production and distribution sites.