Combinatorial Bounds and Characterizations of Splitting Authentication Codes

We present several generalizations of results for splitting authentication codes by studying the aspect of multi-fold security. As the two primary results, we prove a combinatorial lower bound on the number of encoding rules and a combinatorial characterization of optimal splitting authentication codes that are multi-fold secure against spoofing attacks. The characterization is based on a new type of combinatorial designs, which we introduce and for which basic necessary conditions are given regarding their existence.Comment: 13 pages; to appear in "Cryptography and Communications

Gap Opening in Double-Sided Highly Hydrogenated Free-Standing Graphene

Conversion of free-standing graphene into pure graphane-where each C atom is sp3bound to a hydrogen atom-has not been achieved so far, in spite of numerous experimental attempts. Here, we obtain an unprecedented level of hydrogenation (≈90% of sp3bonds) by exposing fully free-standing nanoporous samples-constituted by a single to a few veils of smoothly rippled graphene-to atomic hydrogen in ultrahigh vacuum. Such a controlled hydrogenation of high-quality and high-specific-area samples converts the original conductive graphene into a wide gap semiconductor, with the valence band maximum (VBM) ∼3.5 eV below the Fermi level, as monitored by photoemission spectromicroscopy and confirmed by theoretical predictions. In fact, the calculated band structure unequivocally identifies the achievement of a stable, double-sided fully hydrogenated configuration, with gap opening and no trace of πstates, in excellent agreement with the experimental results

Retained PTEN Expression Preferentially Identifies Mismatch Repair-Proficient Breast Cancers

Introduction/ Background Loss of phosphatase and tensin homolog (PTEN) expression and alterations in mismatch repair (MMR) genes are regarded as early oncogenic events in breast cancer. It has recently been hypothesized that the polyadenosine tract in PTEN might be a target for mutation in MMR-deficient endometrial tumors. However, the frequency and significance of MMR alterations in breast cancer is debated, and their relationship with PTEN status has not been investigated in the breast. Aims In this study, we sought to explore the relationships between PTEN expression and MMR alterations and to define whether PTEN immunohistochemistry is a predictor of MMR status in breast cancer. Methods 309 cases, including 261 invasive ductal carcinomas, no special type, 32 invasive lobular carcinomas, and 16 invasive ductal carcinomas, mixed types, carefully characterized from clinical and pathological standpoints, were reviewed and used to construct 11 tissue microarrays (TMAs). For each case, a mean of 4.5 tumor tissue cores (range 3 to 6 cores) was sampled, incorporating distinct topographic areas of the tumor, as well as matched non-neoplastic breast tissue, and, when present, associated in situ carcinoma. Taken together, 1381 spots were generated. Each TMA was subjected to immunohistochemical analysis of PTEN and the DNA MMR proteins MLH1, MSH2, MSH6 and PMS2. In order to allow a quick navigation within each TMA, and to minimize human-related biases, each stained slide was digitalized and blindly analyzed by two pathologists using a dedicated software able to segment TMA cores. The pattern of expression was therefore annotated manually on a digital database using a specific add-on module. Results According to clinicopathologic surrogate definition of intrinsic subtypes, PTEN protein loss was more frequent in luminal A-like and triple negative groups compared to luminal B-like carcinomas, as recently observed in other studies. MMR status in Luminal B-like tumors did not differ significantly between PTEN-retained and PTEN-loss groups, regardless HER2 amplification. In particular, retained PTEN expression was a predictor of MMR proficiency in approximately 35% of cases for this group. However, in luminal A-like and triple negative breast cancer groups, retained positive expression of MMR proteins was observed in 100% of cases showing PTEN wild-type immunohistochemical expression. Discussion: The present study is the first to investigate PTEN protein loss in a large set of breast carcinomas based on DNA MMR status by immunohistochemistry. Our findings broaden the understanding of the biology underpinning breast cancer, suggesting that MMR alterations are likely to be independent of PTEN status in the majority of luminal B-like breast cancers and that, in a way akin to endometrial carcinoma, MMR deficiency could play a part in the development of PTEN alterations in luminal A-like and triple negative breast cancers. The integration of traditional pathology with cutting-edge digital tools allowed a rapid quantification of immunohistochemistry and effective data organization in this wide cohort multi-variable study. Conclusion: PTEN immunohistochemistry is a useful adjunct in the clinical evaluation of breast cancer patients, being able to capture all MMR-proficient luminal A-like and triple negative tumors

Security and Privacy Issues in Wireless Mesh Networks: A Survey

This book chapter identifies various security threats in wireless mesh network (WMN). Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different layers of the communication protocol stack for WMNs and their corresponding defense mechanisms. First, it identifies the security vulnerabilities in the physical, link, network, transport, application layers. Furthermore, various possible attacks on the key management protocols, user authentication and access control protocols, and user privacy preservation protocols are presented. After enumerating various possible attacks, the chapter provides a detailed discussion on various existing security mechanisms and protocols to defend against and wherever possible prevent the possible attacks. Comparative analyses are also presented on the security schemes with regards to the cryptographic schemes used, key management strategies deployed, use of any trusted third party, computation and communication overhead involved etc. The chapter then presents a brief discussion on various trust management approaches for WMNs since trust and reputation-based schemes are increasingly becoming popular for enforcing security in wireless networks. A number of open problems in security and privacy issues for WMNs are subsequently discussed before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the author's previous submission in arXiv submission: arXiv:1102.1226. There are some text overlaps with the previous submissio

Breast Cancer Systemic Treatments and Upper Limb Lymphedema: A Risk-Assessment Platform Encompassing Tumor-Specific Pathological Features Reveals the Potential Role of Trastuzumab

Breast cancer related lymphedema (BCRL) is frequent but strategies for an individualized risk assessment are lacking. We aimed to define whether tumor-specific pathological features, coupled with clinical and therapeutic data, could help identify patients at risk. Data from 368 patients with node-positive breast cancers were retrospectively collected, including 75 patients with BCRL (0.4\u207b25.6 years follow-up). BCRL was assessed during the standard follow-up oncology visits using the circumferential measurement. Clinicopathologic and therapeutic factors associated with BCRL were integrated into a Cox proportional hazards regression model. Lymphovascular invasion (LVI) was more common in BCRL patients (n = 33, 44% vs. n = 85, 29%, p = 0.01), akin extra nodal extension (ENE) of the metastasis (n = 57, 76% vs. n = 180, 61%, p = 0.02). Sentinel lymph node excision without axillary dissection and extra-axillary radiotherapy were BCRL-unrelated. A higher number of BCRL-positive patients were treated with taxane-based chemotherapy with or without trastuzumab, compared to BCRL-negative patients (p < 0.01). Treatment with trastuzumab and/or taxanes, adjusted for systemic infections, laterality, therapy, and pathological features (i.e., LVI and ENE), had a significant impact in BCRL-free survival (p < 0.01). This work offers new insights on BCRL risk stratification, where the integration of clinical, therapeutic, and tumor-specific pathological data suggests a possible role of anti-human epidermal growth factor receptor 2 (HER2) therapy in BCRL pathogenesis

Mismatch Repair Protein Loss as a Prognostic and Predictive Biomarker in Breast Cancers Regardless of Microsatellite Instability

BackgroundBreast cancers that harbor mismatch-repair (MMR) deficiency and/or microsatellite instability (MSI) might be sensitive to immune checkpoint blockade, but there are currently no specific guidelines for assessing MMR status in breast cancer. Here, we sought to define the clinical value of MMR immunohistochemistry (IHC) and MSI analysis in breast cancers.MethodsWe subjected 444 breast cancers to MMR IHC and MSI analysis. Cases were classified as MMR-proficient (pMMR), MMR-deficient (dMMR), and MMR-heterogeneous (hMMR) based on the loss of immunoreactivity; MSI was defined by instability in the five indicators recommended by the National Cancer Institute for endometrial and colorectal cancers. Correlation of MMR status with patients\u2019 survival was assessed using the Kaplan-Meier estimator. Statistical tests were two-sided.ResultsLoss of MMR proteins was homogeneous (dMMR) in 75 patients (17%) and heterogeneous (hMMR) in 55 (12%). Among luminal breast cancers, there were similar frequencies of dMMR and hMMR tumors. Overall, the rate of discrepancy between IHC and MSI analysis was high (91%). Women with Luminal B-like dMMR carcinomas (n\u2009=\u200944) showed shorter overall survival (median\u2009=\u200977\u2009months, range\u2009=\u20090\u2013115\u2009months) than those with pMMR (n\u2009=\u2009205) or hMMR (n\u2009=\u200935) tumors (median\u2009=\u200984\u2009months, range\u2009=\u20090\u2013127\u2009months) (P\u2009=\u2009.008). On the contrary, patients with estrogen receptor-negative breast cancers treated with chemotherapy lived longer in cases of dMMR (n\u2009=\u20099) than pMMR (n\u2009=\u200933) or hMMR (n\u2009=\u20097) tumors, with 87\u2009months of median survival (range\u2009=\u200973\u2013123\u2009months) for the former compared with 79\u2009months (range\u2009=\u20098\u2013113\u2009months) for the latter two categories (P\u2009<\u2009.001).ConclusionsImmunohistochemistry and MSI are not interchangeable tests in breast carcinomas. MMR protein loss is a more common event than MSI and shows intra-tumor heterogeneity. MMR IHC allows the identification of clinically relevant subclasses of breast cancer patients, provided that multiple areas of the tumor are analyzed