The Dirichlet problem for elliptic and degenerate elliptic equations, and related results

Abstract from public.pdf file.Dissertation supervisor: Dr. Steve Hoffmann.Includes vita.In this thesis, we first prove the solvability of Dirichlet problem with Lp data on the boundary for degenerate elliptic equations. Second, We obtain Lp bounds semi-groups and their gradients, and then we get Lp bounds for Riesz transform and square functions associated to a degenerate elliptic operator in divergence form. Finally, we show that for a uniformly elliptic divergence form operator defined in an open set with Ahlfors-David regular boundary, BMO- solvability implies scale invariant quantitative absolute continuity of elliptic-harmonic measure with respect to surface measure.Includes bibliographical references

FedDRL: Deep Reinforcement Learning-based Adaptive Aggregation for Non-IID Data in Federated Learning

The uneven distribution of local data across different edge devices (clients) results in slow model training and accuracy reduction in federated learning. Naive federated learning (FL) strategy and most alternative solutions attempted to achieve more fairness by weighted aggregating deep learning models across clients. This work introduces a novel non-IID type encountered in real-world datasets, namely cluster-skew, in which groups of clients have local data with similar distributions, causing the global model to converge to an over-fitted solution. To deal with non-IID data, particularly the cluster-skewed data, we propose FedDRL, a novel FL model that employs deep reinforcement learning to adaptively determine each client's impact factor (which will be used as the weights in the aggregation process). Extensive experiments on a suite of federated datasets confirm that the proposed FedDRL improves favorably against FedAvg and FedProx methods, e.g., up to 4.05% and 2.17% on average for the CIFAR-100 dataset, respectively.Comment: Accepted for presentation at the 51st International Conference on Parallel Processin

ISOLATION AND SELECTION OF LIPASE-PRODUCING BACTERIA IN VIETNAM

Joint Research on Environmental Science and Technology for the Eart

Screening yeast strains for alcohol fermentation from the dried traditional yeast

Methods to produce rice alcohol by dried traditional yeast are unstable because the yeast system in dried traditional yeast has depended on nature and not been controlled. In this study, a total of 15 different kinds of dried traditional yeast were prepared and screened. Each yeast strain was evaluated by analyzing its fermentation property and alcohol tolerance. There are 19 yeast strains were isolated and their growth conditions and ethanol producing properties were examined. Results showed that three strains S1, BT, BL3 grew and produced ethanol at temperature 28-30oC, and pH 5-5.5. Especially, high concentration ethanol tolerance ability of the three strains was at 8-18%. Our results showed that these strains were valuable microorganisms and could be utilized as a basis for further study of dried traditional yeast in traditional alcoholic beverages

Towards a Visual-Language Foundation Model for Computational Pathology

The accelerated adoption of digital pathology and advances in deep learning have enabled the development of powerful models for various pathology tasks across a diverse array of diseases and patient cohorts. However, model training is often difficult due to label scarcity in the medical domain and the model's usage is limited by the specific task and disease for which it is trained. Additionally, most models in histopathology leverage only image data, a stark contrast to how humans teach each other and reason about histopathologic entities. We introduce CONtrastive learning from Captions for Histopathology (CONCH), a visual-language foundation model developed using diverse sources of histopathology images, biomedical text, and notably over 1.17 million image-caption pairs via task-agnostic pretraining. Evaluated on a suite of 13 diverse benchmarks, CONCH can be transferred to a wide range of downstream tasks involving either or both histopathology images and text, achieving state-of-the-art performance on histology image classification, segmentation, captioning, text-to-image and image-to-text retrieval. CONCH represents a substantial leap over concurrent visual-language pretrained systems for histopathology, with the potential to directly facilitate a wide array of machine learning-based workflows requiring minimal or no further supervised fine-tuning

Apocrine-Eccrine Carcinomas: Molecular and Immunohistochemical Analyses

Apocrine-eccrine carcinomas are rare and associated with poor prognosis. Currently there is no uniform treatment guideline. Chemotherapeutic drugs that selectively target cancer-promoting pathways may complement conventional therapeutic approaches. However, studies on genetic alterations and EGFR and Her2 status of apocrine-eccrine carcinomas are few in number. In addition, hormonal studies have not been comprehensive and performed only on certain subsets of apocrine-eccrine carcinomas. To investigate whether apocrine-eccrine carcinomas express hormonal receptors or possess activation of oncogenic pathways that can be targeted by available chemotherapeutic agent we performed immunohistochemistry for AR, PR, ER, EGFR, and HER2 expression; fluorescence in situ hybridization (FISH) for EGFR and ERBB2 gene amplification; and molecular analyses for recurrent mutations in 15 cancer genes including AKT-1, EGFR, PIK3CA, and TP53 on 54 cases of apocrine-eccrine carcinomas. They include 10 apocrine carcinomas, 7 eccrine carcinomas, 9 aggressive digital papillary adenocarcinomas, 10 hidradenocarcinomas, 11 porocarcinomas, 1 adenoid cystic carcinoma, 4 malignant chondroid syringomas, 1 malignant spiradenoma, and 1 malignant cylindroma. AR, ER, PR, EGFR and HER2 expression was seen in 36% (19/53), 27% (14/51), 16% (8/51), 85% (44/52) and 12% (6/52), respectively. Polysomy or trisomy of EGFR was detected by FISH in 30% (14/46). Mutations of AKT-1, PIK3CA, and TP53 were detected in 1, 3, and 7 cases, respectively (11/47, 23%). Additional investigation regarding the potential treatment of rare cases of apocrine-eccrine carcinomas with PI3K/Akt/mTOR pathway inhibitors, currently in clinical testing, may be of clinical interest

Clinicopathologic and Molecular Profiles of Microsatellite Unstable Barrett Esophagus-associated Adenocarcinoma

Microsatellite instability (MSI) has been reported in various tumors, with colon cancer as the prototype. However, little is known about MSI in Barrett esophagus (BE)-associated adenocarcinoma. Thus, the aim of this study was to compare the clinicopathologic and molecular features of BE-associated adenocarcinomas with and without MSI. The study cohort consisted of 76 patients with BE-associated adenocarcinomas (66 male, 10 female), with a mean age of 65.1 years. Immunohistochemistry (IHC) for MLH1, MSH2, MSH6, PMS2, and CD3 and in situ hybridization for Epstein-Barr virus-encoded RNA were performed. MLH1 and PMS2 expression was lost by IHC in 5 cases (6.6%); of these, 5 showed high-level MSI (MSI-H) by polymerase chain reaction assay, and 4 showed hMLH1 promoter methylation. Histologically, tumors with MSI-H were heterogenous and included conventional adenocarcinomas with tumor-infiltrating lymphocytes (n=1), medullary carcinoma (n=2), signet ring cells (n=1), and signet ring cell and mucinous components (n=1). Compared with tumors negative for MSI by IHC, BE-associated adenocarcinomas with MSI-H were associated with older patient age (P=0.0060), lymphovascular invasion (P=0.027), and significantly larger numbers of tumor-infiltrating lymphocytes (P<0.0001). However, there was no statistical difference in overall survival between the 2 groups (P=0.285). In conclusion, MSI-H is uncommon in BE-associated adenocarcinomas, but is associated with clinicopathologic features fairly similar to sporadic microsatellite unstable colorectal cancers. Given the growing evidence that indicates lack of benefits from adjuvant therapy with fluorouracil in the colonic counterpart, it may be important to identify MSI-H in BE-associated adenocarcinomas

Papillary thyroid carcinoma with tall cell features is as aggressive as tall cell variant: a meta-analysis

There are still ongoing debates as to which cut-off percentage of tall cell (TC) should be used to define tall cell variant (TCV) papillary thyroid carcinoma (PTC). In this meta-analysis, we aimed to investigate the clinicopathological significance of PTC with tall cell features (PTC-TCF, PTC with 10–50% of TCs) in comparison with classical PTC and TCVPTC (PTC with more than 50% of TCs) to clarify the controversial issue. Four electronic databases including PubMed, Web of Science, Scopus and Virtual Health Library were accessed to search for relevant articles. We extracted data from published studies and pooled into odds ratio (OR) and its corresponding 95% confidence intervals (CIs) using random-effect modeling. Nine studies comprising 403 TCVPTCs, 325 PTC-TCFs and 3552 classical PTCs were included for meta-analyses. Overall, the clinicopathological profiles of PTC-TCF including multifocality, extrathyroidal extension, lymph node metastasis, distant metastasis and patient mortality were not statistically different from those of TCVPTC. Additionally, PTC-TCF and TCVPTC were both associated with an increased risk for aggressive clinical courses as compared to classical PTC. The prevalence of BRAF mutation in PTC-TCF and TCVPTC was comparable and both were significantly higher than that in classical PTC. The present meta-analysis demonstrated that even a PTC comprising only 10% of TCs might be associated with a poor clinical outcome. Therefore, the proportions of PTC in PTC should be carefully estimated and reported even when the TC component is as little as 10%

EZH2 Codon 641 Mutations are Common in BCL2-Rearranged Germinal Center B Cell Lymphomas

Mutations at codon 641 of EZH2 are recurrent in germinal center B cell lymphomas, and the most common variants lead to altered EZH2 enzymatic activity and enhanced tri-methylation of histone H3 at lysine 27, a repressive chromatin modification. As an initial step toward screening patients for cancer genotype-directed therapy, we developed a screening assay for EZH2 codon 641 mutations amenable for testing formalin-fixed clinical specimens, based on the sensitive SNaPshot single nucleotide extension technology. We detected EZH2 mutations in 12/55 (22%) follicular lymphomas (FL), 5/35 (14%) diffuse large B cell lymphomas with a germinal center immunophenotype (GCB-DLBCL), and 2/11 (18%) high grade B cell lymphomas with concurrent rearrangements of BCL2 and MYC. No EZH2 mutations were detected in cases of Burkitt lymphoma (0/23). EZH2 mutations were frequently associated with the presence of BCL2 rearrangement (BCL2-R) in both the FL (28% of BCL-R cases versus 0% of BCL2-WT cases, p<0.05) and GCB-DLBCL groups (33% of BCL2-R cases versus 4% of BCL2-WT cases, p<0.04), and across all lymphoma types excluding BL (27% of BCL2-R cases versus 3% of BCL2-WT cases, p<0.003). We confirmed gain-of-function activity for all previously reported EZH2 codon 641 mutation variants. Our findings suggest that EZH2 mutations constitute an additional genetic “hit” in many BCL2-rearranged germinal center B cell lymphomas. Our work may be helpful in the selection of lymphoma patients for future trials of pharmacologic agents targeting EZH2 and EZH2-regulated pathways