From Large to Small Scales: Global Models of the ISM

We review large scale modelling of the ISM with emphasis on the importance to include the disk-halo-disk duty cycle and to use a dynamical refinement of the grid (in regions where steep variations of density and pressure occur) for a realistic modelling of the ISM. We also discuss the necessity of convergence of the simulation results by comparing 0.625, 1.25 and 2.5 pc resolution simulations and show that a minimum grid resolution of 1.25 pc is required for quantitatively reliable results, as there is a rapid convergence for Delta x \leq 1.1 pc.Comment: 10 pages, 8 figures that include 2 simulation images (in jpeg format) and 6 plots (4 in ps and 2 in jpeg formats), to appear in the proceedings of ``From Observations to Self-Consistent Modelling of the ISM in Galaxies'', Kluwe

A catalog of Kazarian galaxies

The entire Kazarian galaxies (KG) catalog is presented which combines extensive new measurements of their optical parameters with a literature and database search. The measurements were made using images extracted from the STScI Digitized Sky Survey (DSS) of Jpg(blue), Fpg(red) and Ipg(NIR) band photographic sky survey plates obtained by the Palomar and UK Schmidt telescopes. We provide accurate coordinates, morphological type, spectral and activity classes, blue apparent diameters, axial ratios, position angles, red, blue and NIR apparent magnitudes, as well as counts of neighboring objects in a circle of radius 50 kpc from centers of KG. Special attention was paid to the individual descriptions of the galaxies in the original Kazarian lists, which clarified many cases of misidentifications of the objects, particularly among interacting systems. The total number of individual Kazarian objects in the database is now 706. We also include the redshifts which are now available for 404 galaxies and the 2MASS infrared magnitudes for 598 KG. The database also includes extensive notes, which summarize information about the membership of KG in different systems of galaxies, and about revised activity classes and redshifts. An atlas of several interesting subclasses of KG is also presented.Comment: 15 pages, 5 figures, 1 table, Accepted in Astrophysics, Vol. 53, No. 1, 2010 (English translation of Astrofizika

Gathering realistic authentication performance data through field trials

Most evaluations of novel authentication mechanisms have been conducted under laboratory conditions. We argue that the results of short-term usage under laboratory conditions do not predict user performance “in the wild”, because there is insufficient time between enrolment and testing, the number of authentications is low, and authentication is presented as a primary task, rather then the secondary task as it is “in the wild”. User generated reports of performance on the other hand provide subjective data, so reports on frequency of use, time intervals, and success or failure of authentication are subject to the vagaries of users ’ memories. Studies on authentication that provide objective performance data under real-world conditions are rare. In this paper, we present our experiences with a study method that tries to control frequency and timing of authentication, and collects reliable performance data, while maintaining ecological validity of the authentication context at the same time. We describe the development of an authentication server called APET, which allows us to prompt users enrolled in trial cohorts to authenticate at controlled intervals, and report our initial experiences with trials. We conclude by discussing remaining challenges in obtaining reliable performance data through a field trial method such as this one

Analysing and attacking the 4-way handshake of IEEE 802.11i standard

The IEEE 802.11i standard has been designed to enhance security in wireless networks. In the 4-way handshake the supplicant and the authenticator use the pairwise master key (PMK) to derive a fresh pairwise transient key (PTK). The PMK is not used directly for security while assuming the supplicant and authenticator have the same PMK before running 4-way handshake. In this paper, the 4-way handshake phase has been analysed using Isabelle tool to identify a new Denial-of-Service (DoS) attack. The attack prevents the authenticator from receiving message 4 after the supplicant sends it out. This attack forces the authenticator to re-send the message 3 until time out and subsequently to de-authenticate supplicant. This paper has proposed improvements to the 4-way handshake to avoid the Denial-of-Service attack

Addressing Minority Health Disparities in Richmond: Results from a Health Needs Assessment of a Southside Community

Background: Evidence shows the effectiveness of integrating community health workers (CHWs) into care models serving high-risk patients to reduce emergency department (ED) use, increase primary care use, and address adverse social determinants of health (SDH). The Southwood Resource Center, part of a network of clinics established by Richmond City Health Department, utilizes CHWs to address disparities affecting underserved populations through primary care referrals and additional resource linkages. Local student-volunteers in partnership with CHWs conducted a community needs assessment to identify patient resource gaps, aid in design and implementation of SDH interventions, and examine the relationship between chronic disease management and ED use reductions. Methods: English and Spanish-language surveys were conducted during patient visits to the SRC, in addition to other settings to facilitate representative sampling. A total of 134 responses were received, with Blacks (34%) and Hispanic/Latinos (65%) well represented. Results: Significant social determinants identified by the needs assessment included housing stability, and transportation and food access. Respondents indicated need for support managing chronic conditions including heart disease, diabetes, mental health and asthma. 1 in 3 respondents (31%) reported using the ED for primary care, and nearly 2 in 3 (66%) reported not having a family doctor. Barriers to health care included cost (35.6%), insurance status (50.4%) and transportation access (29.6%). Conclusions: CHWs play an important role in identifying community strengths and resource gaps and linking patients to additional resources. Opportunities for service improvements include bilingual care coordination, chronic care management, health insurance navigation, food subsistence resources, and transportation support.https://scholarscompass.vcu.edu/gradposters/1104/thumbnail.jp

Hyperbolic character of the angular moment equations of radiative transfer and numerical methods

We study the mathematical character of the angular moment equations of radiative transfer in spherical symmetry and conclude that the system is hyperbolic for general forms of the closure relation found in the literature. Hyperbolicity and causality preservation lead to mathematical conditions allowing to establish a useful characterization of the closure relations. We apply numerical methods specifically designed to solve hyperbolic systems of conservation laws (the so-called Godunov-type methods), to calculate numerical solutions of the radiation transport equations in a static background. The feasibility of the method in any kind of regime, from diffusion to free-streaming, is demonstrated by a number of numerical tests and the effect of the choice of the closure relation on the results is discussed.Comment: 37 pags, 12 figures, accepted for publication in MNRA