15 research outputs found
Chemical abundance analysis of the Open Clusters Berkeley 32, NGC 752, Hyades and Praesepe
Context. Open clusters are ideal test particles to study the chemical
evolution of the Galactic disc. However the existing high-resolution abundance
determinations, not only of [Fe/H], but also of other key elements, is largely
insufficient at the moment. Aims. To increase the number of Galactic open
clusters with high quality abundance determinations, and to gather all the
literature determinations published so far. Methods. Using high-resolution
(R~30000), high-quality (S/N$>60 per pixel), we obtained spectra for twelve
stars in four open clusters with the fiber spectrograph FOCES, at the 2.2 Calar
Alto Telescope in Spain. We use the classical equivalent widths analysis to
obtain accurate abundances of sixteen elements: Al, Ba, Ca, Co, Cr, Fe, La, Mg,
Na, Nd, Ni, Sc, Si, Ti, V, Y. Oxygen abundances have been derived through
spectral synthesis of the 6300 A forbidden line. Results. We provide the first
determination of abundance ratios other than Fe for NGC 752 giants, and ratios
in agreement with the literature for the Hyades, Praesepe and Be 32. We use a
compilation of literature data to study Galactic trends of [Fe/H] and
[alpha/Fe] with Galactocentric radius, age, and height above the Galactic
plane. We find no significant trends, but some indication for a flattening of
[Fe/H] at large Rgc, and for younger ages in the inner disc. We also found a
possible decrease of [Fe/H] with |z| in the outer disc, and a weak increase of
[alpha/Fe] with Rgc.Comment: 21 pages, Accepted for publication in A&A, Updated Table 1
The transcriptional landscape of age in human peripheral blood
Disease incidences increase with age, but the molecular characteristics of ageing that lead to increased disease susceptibility remain inadequately understood. Here we perform a whole-blood gene expression meta-analysis in 14,983 individuals of European ancestry (including replication) and identify 1,497 genes that are differentially expressed with chronological age. The age-associated genes do not harbor more age-associated CpG-methylation sites than other genes, but are instead enriched for the presence of potentially functional CpG-methylation sites in enhancer and insulator regions that associate with both chronological age and gene expression levels. We further used the gene expression profiles to calculate the 'transcriptomic age' of an individual, and show that differences between transcriptomic age and chronological age are associated with biological features linked to ageing, such as blood pressure, cholesterol levels, fasting glucose, and body mass index. The transcriptomic prediction model adds biological relevance and complements existing epigenetic prediction models, and can be used by others to calculate transcriptomic age in external cohorts.Peer reviewe
Android inter-app communication threats and detection techniques
With the digital breakthrough, smart phones have become very essential
component. Mobile devices are very attractive attack surface for cyber thieves
as they hold personal details (accounts, locations, contacts, photos) and have
potential capabilities for eavesdropping (with cameras/microphone, wireless
connections). Android, being the most popular, is the target of malicious
hackers who are trying to use Android app as a tool to break into and control
device. Android malware authors use many anti-analysis techniques to hide from
analysis tools. Academic researchers and commercial anti-malware companies are
putting great effort to detect such malicious apps. They are making use of the
combinations of static, dynamic and behavior based analysis techniques. Despite
of all the security mechanisms provided by Android, apps can carry out
malicious actions through collusion. In collusion malicious functionality is
divided across multiple apps. Each participating app accomplish its part and
communicate information to another app through Inter Component Communication
(ICC). ICC do not require any special permissions. Also, there is no compulsion
to inform user about the communication. Each participating app needs to request
a minimal set of privileges, which may make it appear benign to current
state-of-the-art techniques that analyze one app at a time. There are many
surveys on app analysis techniques in Android; however they focus on single-app
analysis. This survey augments this through focusing only on collusion among
multiple-apps. In this paper, we present Android vulnerabilities that may be
exploited for a possible collusion attack. We cover the existing threat
analysis, scenarios, and a detailed comparison of tools for intra and inter-app
analysis. To the best of our knowledge this is the first survey on app
collusion and state-of-the-art detection tools in Android.Comment: 83 pages, 4 figures, This is a survey pape