Structure, mass and stability of galactic disks

In this review I concentrate on three areas related to structure of disks in spiral galaxies. First I will review the work on structure, kinematics and dynamics of stellar disks. Next I will review the progress in the area of flaring of HI layers. These subjects are relevant for the presence of dark matter and lead to the conclusion that disk are in general not `maximal', have lower M/L ratios than previously suspected and are locally stable w.r.t. Toomre's Q criterion for local stability. I will end with a few words on `truncations' in stellar disks.Comment: Invited review at "Galaxies and their Masks" for Ken Freeman's 70-th birthday, Sossusvlei, Namibia, April 2010. A version with high-res. figures is available at http://www.astro.rug.nl/~vdkruit/jea3/homepage/Namibiachapter.pd

Genetic interaction analysis among oncogenesis-related genes revealed novel genes and networks in lung cancer development

The development of cancer is driven by the accumulation of many oncogenesis-related genetic alterationsand tumorigenesis is triggered by complex networks of involved genes rather than independent actions. To explore the epistasis existing among oncogenesis-related genes in lung cancer development, we conducted pairwise genetic interaction analyses among 35,031 SNPs from 2027 oncogenesis-related genes. The genotypes from three independent genome-wide association studies including a total of 24,037 lung cancer patients and 20,401 healthy controls with Caucasian ancestry were analyzed in the study. Using a two-stage study design including discovery and replication studies, and stringent Bonferroni correction for multiple statistical analysis, we identified significant genetic interactions between SNPs in RGL1:RAD51B (OR=0.44, p value=3.27x10-11 in overall lung cancer and OR=0.41, p value=9.71x10-11 in non-small cell lung cancer), SYNE1:RNF43 (OR=0.73, p value=1.01x10-12 in adenocarcinoma) and FHIT:TSPAN8 (OR=1.82, p value=7.62x10-11 in squamous cell carcinoma) in our analysis. None of these genes have been identified from previous main effect association studies in lung cancer. Further eQTL gene expression analysis in lung tissues provided information supporting the functional role of the identified epistasis in lung tumorigenesis. Gene set enrichment analysis revealed potential pathways and gene networks underlying molecular mechanisms in overall lung cancer as well as histology subtypes development. Our results provide evidence that genetic interactions between oncogenesis-related genes play an important role in lung tumorigenesis and epistasis analysis, combined with functional annotation, provides a valuable tool for uncovering functional novel susceptibility genes that contribute to lung cancer development by interacting with other modifier genes

Secure Password-Based Authenticated Group Key Agreement for Data-Sharing Peer-to-Peer Networks

We explore authenticated group key agreement in data-sharing Peer-to-Peer networks. We first propose a novel password-based authenticated group key agreement protocol with key confirmation. We present a formal statement of its security in a variant of the Bresson et al. security model adapted for the password-based setting. A discussion of the limitations of our protocol in the case where the group size becomes large is then presented. We conclude the paper with an enhanced version of the protocol, using a CAPTCHA technique, designed to make it more robust against online password guessing attacks

A contextual privacy-aware access control model for network monitoring workflows: Work in progress

Abstract. Network monitoring activities are surrounded by serious privacy implications. The inherent leakage-proneness is harshened due to the increasing complexity of the monitoring procedures and infrastructures, that may include multiple traffic observation points, distributed mitigation mechanisms and even inter-operator cooperation. In this paper, we report a work in progress policy model that aims at addressing these concernes, by verifying access requests from network monitoring workflows, with privacy features already contained since their specification phase. We survey related work, outline some of their limitations, and describe an early version of our proposal