On Decentralized Cloud Storage Security and an Efficient Post-Quantum Encryption Scheme

In this thesis, we address three main security problems related to cryptography andcloud storage. To tackle the challenge posed by a quantum computer, we needencryption that is resistant to quantum computers. This category of cryptographyis called post-quantum cryptography. In the first paper, we solve a challengein one of the lattice-based cryptographic protocols called Nth-degree Truncatedpolynomial Ring Unit (NTRU) namely how to reduce the key size while keepingthe desired security level. We propose a solution that reduces the key size significantly.Our proposed solution allows a practical implementation of NTRU withfast polynomial multiplications.Next, we move to solve a long-standing problem arising in any cloud storagenamely the reduction of storage cost of redundant data and maintaining securityand privacy at the same time. Data deduplication is considered to be a tool thatcan be used to eliminate redundant data and store only one of its copies. Butdata deduplication also means that the file cannot go through client-side encryptionwhich opens up new possibilities of adversarial threats. In order to tackle thischallenge, we propose a new architecture where we perform client-side deduplicationalong with dynamic erasure protection by introducing a third-party assistant.We also performed an erasure analysis to quantitatively analyze the probability ofloss of a file when a large number of replicas are deleted at random.Finally, we shift our interest to Decentralized Cloud Storage (DCS). DCSsolutions like Filecoin, Storj, and Arweave are gaining more popularity in the Web 3.0 ecosystem. But they are not without challenges. The robustness of the DCSprotocols remains a challenging ground. Since the file in a DCS protocol is storedin a decentralized manner among different nodes, a Distributed Denial of Service(DDoS) attack would render the system vulnerable to data loss. Therefore, it isimportant to analyze the robustness of decentralized architecture against DDoSattacks. In our last paper, we perform a similar erasure analysis to that of thesecond paper but in a decentralized setup, where the adversary aims to disruptthe system by deleting a file from the network. Storj is one of the leading playersin the DCS space. We have created an adversarial model capturing the real Storjnetwork scenario and simulated our model using real-time data obtained from theStorj network. We obtain resource budget figures for DDoS on Storj using ourmodel. Also, we propose a better parametric value for the erasure piece distributionin Storj which suits well when there is a large portion of so-called unvetted nodesin the network

Testing models of dental development in the earliest bony vertebrates, Andreolepis and Lophosteus

Theories on the development and evolution of teeth have long been biased by the fallacy that chondrichthyans reflect the ancestral condition for jawed vertebrates. However, correctly resolving the nature of the primitive vertebrate dentition is challenged by a dearth of evidence on dental development in primitive osteichthyans. Jaw elements from the Silurian–Devonian stem-osteichthyans Lophosteus and Andreolepis have been described to bear a dentition arranged in longitudinal rows and vertical files, reminiscent of a pattern of successional development. We tested this inference, using synchrotron radiation X-ray tomographic microscopy (SRXTM) to reveal the pattern of skeletal development preserved in the sclerochronology of the mineralized tissues. The tooth-like tubercles represent focal elaborations of dentine within otherwise continuous sheets of the dermal skeleton, present in at least three stacked generations. Thus, the tubercles are not discrete modular teeth and their arrangement into rows and files is a feature of the dermal ornamentation that does not reflect a polarity of development or linear succession. These fossil remains have no bearing on the nature of the dentition in osteichthyans and, indeed, our results raise questions concerning the homologies of these bones and the phylogenetic classification of Andreolepis and Lophosteus

Ecthyma gangrenosum with a coinfection of methicillin-sensitive staphylococcus aureus and streptococcus pyogenes: a case report

Introduction: Ecthyma gangrenosum (EG) is a cutaneous infection characterized by gangrenous ulcers with erythematous borders seen in immunocompromised as well as immunocompetent individuals. Although Pseudomonas aeruginosa is the commonest pathogen isolated, several other bacteria and fungi contribute to the pathogenesis of EG. Identification of the microorganism is very essential to initiate early empirical antimicrobial therapy. Case presentation: We present a case report of a 13-year-old boy with multiple recurrent ulcerative lesions in both lower extremities for the past 1 year. His blood parameters showed signs of inflammation but was negative for aerobic blood culture, suggesting absence of underlying bacteraemia. There were no features of immunosuppression. On examination of pus sample, Methicillin Sensitive Staphylococcus aureus and Streptococcus pyogenes were isolated from the ulcerative lesions. Amoxicillin- Clavulanate and Doxycycline was advised for 2 weeks along with surgical debridement of the lesion followed by aseptic dressing. Patient showed complete resolution after 2 weeks. Discussion: Staphylococcus aureus and Streptococcus pyogenes were the causative agents in this case, suggesting a polymicrobial association of EG besides Pseudomonas aeruginosa. Underlying bacteraemia or any other immunodeficiency is usually seen in a case of EG, however there are cases reported where cutaneous manifestations show predominance. Conclusion: A prompt diagnosis of EG is essential because there are instances when it has proven to be fatal. Ruling out any immunodeficiency disorders and underlying bacteraemia is of vital importance. Administration of proper antibiotic coverage (gram positive or gram negative) along with debridement and regular dressing can help in limiting the spread of infections and thus improving patient outcome

Early Gnathostome Phylogeny Revisited: Multiple Method Consensus

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.A series of recent studies recovered consistent phylogenetic scenarios of jawed vertebrates, such as the paraphyly of placoderms with respect to crown gnathostomes, and antiarchs as the sister group of all other jawed vertebrates. However, some of the hylogenetic relationships within the group have remained controversial, such as the positions of Entelognathus, ptyctodontids, and the Guiyu-lineage that comprises Guiyu, Psarolepis and Achoania. The revision of the dataset in a recent study reveals a modified phylogenetic hypothesis, which shows that some of these phylogenetic conflicts were sourced from a few inadvertent miscodings. The interrelationships of early gnathostomes are addressed based on a combined new dataset with 103 taxa and 335 characters, which is the most comprehensive morphological dataset constructed to date. This dataset is investigated in a phylogenetic context using maximum parsimony (MP), Bayesian inference (BI) and maximum likelihood (ML) approaches in an attempt to explore the consensus and incongruence between the hypotheses of early gnathostome interrelationships recovered from different methods. Our findings consistently corroborate the paraphyly of placoderms, all `acanthodians' as a paraphyletic stem group of chondrichthyans, Entelognathus as a stem gnathostome, and the Guiyu-lineage as stem sarcopterygians. The incongruence using different methods is less significant than the consensus, and mainly relates to the positions of the placoderm Wuttagoonaspis, the stem chondrichthyan Ramirosuarezia, and the stem osteichthyan LophosteusÐthe taxa that are either poorly known or highly specialized in character complement. Given that the different performances of each phylogenetic approach, our study provides an empirical case that the multiple phylogenetic analyses of morphological data are mutually complementary rather than redundant

Enlarged Memory T-Cell Pool and Enhanced Th1-Type Responses in Chronic Myeloid Leukemia Patients Who Have Successfully Discontinued IFN-alpha Monotherapy

Peer reviewe

Imatinib Treatment Induces CD5+ B Lymphocytes and IgM Natural Antibodies with Anti-Leukemic Reactivity in Patients with Chronic Myelogenous Leukemia

Imatinib mesylate is a first line treatment of Chronic Myelogenous Leukemia and of a rare form of gastrointestinal stromal cancer, where the response to the drug is also linked to the immune system activation with production of antineoplastic cytokines. In this study, forty patients in the chronic phase of disease, treated with imatinib mesylate, were analyzed. Bone marrow aspirates were drawn at diagnosis, after 3, 6, 12, 18 months for haematological, cytofluorimetric, cytogenetic, biomolecular evaluation and cytokine measurement. Responder and non responder patients were defined according to the European LeukemiaNet recommendations. In responder patients (n = 32), the percentage of bone marrow CD20+CD5+sIgM+ lymphocytes, and the plasma levels of IgM, were significantly higher, at 3 months and up to 9 months, than in non responders. These IgM reacted with O-linked sugars expressed by leukemic cells and could induce tumor cell apoptosis. In responeìder patients the stromal-derived factor-1 and the B-lymphocyte-activating factor of the tumor necrosis factor family significantly raised in the bone marrow after imatinib administration, together with the bone morphogenetic proteins-2 and −7. All patients with high number of CD20+CD5+sIgM+ cells and high stromal-derived factor-1 and B lymphocyte activating factor levels, underwent complete cytogenetic and/or molecular remission by 12 months. We propose that CD20+CD5+sIgM+ lymphocytes producing anti-carbohydrate antibodies with anti-tumor activity, might contribute to the response to imatinib treatment. As in multivariate analysis bone marrow CD20+CD5+sIgM+ cells and stromal-derived factor-1 and B-lymphocyte-activating factor levels were significantly related to cytogenetical and molecular changes, they might contribute to the definition of the pharmacological response

The mesencephalic root of the fifth nerve. A comparative anatomical study

No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49899/1/900460202_ftp.pd

Chronic Myeloid Leukemia Patients in Prolonged Remission following Interferon-alpha Monotherapy Have Distinct Cytokine and Oligoclonal Lymphocyte Profile

Peer reviewe