Forensic Analysis in Access Control: a Case-Study of a Cloud Application

We discuss a case-study we have conducted on forensic analysis in access control. The case-study is an application in the Amazon Web Services (AWS) cloud provider. Forensic analysis is the investigation and analysis of evidence of possible wrongdoing. Access control is used to regulate accesses to computing resources. Both forensic analysis and access control are recognized as important aspects of the security of a system. We first argue that posing the forensic analysis problem in the context of access control is meaningful and useful towards the security of a system. We then summarize results on the computational hardness of the forensic analysis problem for two access control schemes from the research literature. We point out that these results suggest that meaningful logging information can render forensic analysis tractable, even efficient. We then instantiate the forensic analysis in access control problem in the context of a cloud application. A cloud application is a software service that can be accessed over the Internet and uses computing resources provided by a cloud provider. A cloud provider provides computing tools and services that can be administered over the Internet. The cloud provider we have adopted is AWS, and the application is ``Hello Retail'', an image-sourcing application for online retailers. In addressing forensic analysis in this context, our particular focus is the manner in which logging information can be leveraged. We ask two kinds of questions: (i) is particular logging information from AWS necessary to answer forensics analysis questions of interest, and, (ii) is particular logging information sufficient? We observe that from the standpoint of (i), default AWS logs have considerable redundancy. We propose an algorithm to prune logs for efficient forensic analysis. From the standpoint of (ii), we observe that it is not possible to definitively answer "yes" or "no" to forensic analysis questions of interest given only the information AWS permits us to log. We identify additional logging information that, if available, would be sufficient. Together, (i) and (ii) provide us with "goal-directed logging". We conclude by reiterating the benefits of forensic analysis in access control, and with suggestions for goal-directed logging in cloud systems

A Critical Study of the Contradictory Role of Women’s Magazines

The role of women’s magazines is contradictory. The term contradictory refers to the way in which magazines provide a range of information about how to be a perfect woman, for women of all ages. However, no matter the role of women as portrayed by the magazines, or women’s duties for the family, society, or the understanding of the world, are contradictory in the text. This paper aims at analyzing the role of contemporary women’s magazines. It focuses on the group of young female magazine readers and emphasises question relating to physical appearance in the magazines. The motivation of this paper is to investigate how women’s magazines affect women’s attention in terms of their body image. Today, a slender and thinner body has been set as the standard of an ideal body. This achievement seems to be established as a goal for women not only in the West, but also in the East. It is not merely a beauty matter. What is the correlation between a notion of beauty and the global market

Whole-cell 3D STORM reveals interactions between cellular structures with nanometer-scale resolution.

The ability to directly visualize nanoscopic cellular structures and their spatial relationship in all three dimensions will greatly enhance our understanding of molecular processes in cells. Here we demonstrated multicolor three-dimensional (3D) stochastic optical reconstruction microscopy (STORM) as a tool to quantitatively probe cellular structures and their interactions. To facilitate STORM imaging, we generated photoswitchable probes in several distinct colors by covalently linking a photoswitchable cyanine reporter and an activator molecule to assist bioconjugation. We performed 3D localization in conjunction with focal plane scanning and correction for refractive index mismatch to obtain whole-cell images with a spatial resolution of 20-30 nm and 60-70 nm in the lateral and axial dimensions, respectively. Using this approach, we imaged the entire mitochondrial network in fixed monkey kidney BS-C-1 cells, and studied the spatial relationship between mitochondria and microtubules. The 3D STORM images resolved mitochondrial morphologies as well as mitochondria-microtubule contacts that were obscured in conventional fluorescence images

Stellar loci I. Metallicity dependence and intrinsic widths

Stellar loci are widely used for selection of interesting outliers, reddening determinations, and calibrations. However, hitherto the dependence of stellar loci on metallicity has not been fully explored and their intrinsic widths are unclear. In this paper, by combining the spectroscopic and re-calibrated imaging data of the SDSS Stripe 82, we have built a large, clean sample of dwarf stars with accurate colors and well determined metallicities to investigate the metallicity dependence and intrinsic widths of the SDSS stellar loci. Typically, one dex decrease in metallicity causes 0.20 and 0.02 mag decrease in colors u-g and g-r, and 0.02 and 0.02 mag increase in colors r-i and i-z, respectively. The variations are larger for metal-rich stars than for metal-poor ones, and for F/G/K stars than for A/M ones. Using the sample, we have performed two dimensional polynomial fitting to the u-g, g-r, r-i, and i-z colors as a function of color g-i and metallicity [Fe/H]. The residuals, at the level of 0.029, 0.008, 0.008 and 0.011 mag for the u-g, g-r, r-i, and i-z colors, respectively can be fully accounted for by the photometric errors and metallicity uncertainties, suggesting that the intrinsic widths of the loci are at maximum a few mmag. The residual distributions are asymmetric, revealing that a significant fraction of stars are binaries. In a companion paper, we will present an unbiased estimate of the binary fraction for field stars. Other potential applications of the metallicity dependent stellar loci are briefly discussed.Comment: 6 pages, 4 figures, 1 table, ApJ in pres

Stellar loci III: Photometric metallicities for half million FGK stars of Stripe 82

We develop a method to estimate photometric metallicities by simultaneously fitting the dereddened colors u-g, g-r, r-i and i-z from the SDSS with those predicted by the metallicity-dependent stellar loci. The method is tested with a spectroscopic sample of main-sequence stars in Stripe 82 selected from the SDSS DR9 and three open clusters. With 1 per cent photometry, the method is capable of delivering photometric metallicities precise to about 0.05, 0.12, and 0.18 dex at metallicities of 0.0, -1.0, and -2.0, respectively, comparable to the precision achievable with low-resolution spectroscopy at a signal-to-noise ratio of 10. We apply this method to the re-calibrated Stripe 82 catalog and derive metallicities for about 0.5 million stars of colors 0.3 < g-i < 1.6 mag and distances between 0.3 -- 18 kpc. Potential systematics in the metallicities thus derived, due to the contamination of giants and binaries, are investigated. Photometric distances are also calculated. About 91, 72, and 53 per cent of the sample stars are brighter than r = 20.5, 19.5, and 18.5 mag, respectively. The median metallicity errors are around 0.19, 0.16, 0.11, and 0.085 dex for the whole sample, and for stars brighter than r = 20.5, 19.5, and 18.5 mag, respectively. The median distance errors are 8.8, 8.4, 7.7, and 7.3 per cent for the aforementioned four groups of stars, respectively. The data are publicly available. Potential applications of the data in studies of the distribution, (sub)structure, and chemistry of the Galactic stellar populations, are briefly discussed. The results will be presented in future papers.Comment: 10 pages, 10 figures, ApJ accepte

The infrared spectra of ABC-stacking tri- and tetra-layer graphenes studied by first-principles calculations

The infrared absorption spectra of ABC-stacking tri- and tetra-layer graphenes are studied using the density functional theory. It is found that they exhibit very different characteristic peaks compared with those of AB-stacking ones, caused by the different stacking sequence and interlayer coupling. The anisotropy of the spectra with respect to the direction of the light electric field is significant. The spectra are more sensitive to the stacking number when the electric field is perpendicular to the graphene plane due to the interlayer polarization. The high sensitivities make it possible to identify the stacking sequence and stacking number of samples by comparing theory and experiment.Comment: 7 pages, 5 figure