Joint Hitting-Time Densities for Finite State Markov Processes

For a finite state Markov process and a finite collection $\{ \Gamma_k, k \in K \}$ of subsets of its state space, let $\tau_k$ be the first time the process visits the set $\Gamma_k$. We derive explicit/recursive formulas for the joint density and tail probabilities of the stopping times $\{ \tau_k, k \in K\}$. The formulas are natural generalizations of those associated with the jump times of a simple Poisson process. We give a numerical example and indicate the relevance of our results to credit risk modeling.Comment: 25 pages, 3 figure

Smoking among Nurses in Turkey: Comparison with Other Countries

The purpose of this study was to obtain baseline information on smoking among nurses. An attempt was made to contact, in person, all 301 nurses working for the university hospital in Sivas, Turkey, and when contacted they were asked to complete an anonymous questionnaire. Each unit of the hospital was visited three times, and 239 (79%) nurses were reached who all completed the questionnaire. Of the 239 respondents, 107 (45%) were current smokers, reflecting a substantially higher prevalence compared to that among the adult female population. The quit ratio was 22.5%. Of 127 ever-smoker nurses who responded to the related item, 90% started smoking during or after nursing education. This pattern of smoking initiation was different from the pattern in developed countries where nurses had already started smoking before beginning that training. Nurses with a high school education had a significantly higher prevalence of ever-smoking. Most respondents frequently or sometimes saw doctors smoking in rooms for nurses and in rooms for doctors in inpatient services. In-depth qualitative studies are needed to determine the reasons for the different smoking-initiation pattern

Recombining Plasma & Gamma-ray Emission in the Mixed-morphology Supernova Remnant 3C 400.2

3C 400.2 belongs to the mixed morphology supernova remnant class, showing center-filled X-ray and shell-like radio morphology. We present a study of 3C 400.2 with archival Suzaku and Fermi-LAT observations. We find recombining plasma (RP) in the Suzaku spectra of north-east and south-east regions. The spectra of these regions are well described by two-component thermal plasma models: The hard component is in RP, while the soft component is in collisional ionization equilibrium (CIE) conditions. The RP has enhanced abundances indicating that the X-ray emission has an ejecta origin, while the CIE has solar abundances associated with the interstellar material. The X-ray spectra of north-west and south-west regions are best fitted by a two-component thermal plasma model: an ionizing and a CIE plasma. We have detected GeV gamma-ray emission from 3C 400.2 at the level of $\sim$5$\sigma$ assuming a point-like source model with a power-law (PL) type spectrum. We have also detected a new GeV source at the level of $\sim$13$\sigma$ assuming a Gaussian extension model with a PL type spectrum in the neighborhood of the SNR. We report the analysis results of 3C 400.2 and the new extended gamma-ray source and discuss the nature of gamma-ray emission of 3C 400.2 in the context of existing NANTEN CO data, DRAO HI data, and the Suzaku X-ray analysis results.Comment: Accepted to be published in the Astrophysical Journa

On algebraic properties of general proper decentralized systems

The new concepts of the decentralized output feedback variable polynomial, the decentralized output feedback cycle index of general proper systems, and the geometric multiplicities of decentralized fixed modes are introduced. Their computational methods and some algebraic properties are presented. It is shown that the decentralized output feedback cycle index of a general proper system is equal to one when the system has no fixed modes or equal to the maximum of the geometric multiplicities of its decentralized fixed modes. It is also shown that almost all decentralized output feedback can be used to make the zeros of the decentralized variable polynomial distinct, and disjoint from any given finite set of points on the complex plane. © 1993

Optimization of a wifi wireless network that maximizes the level of satisfaction of users and allows the use of new technological trends in higher education institutions

The campus wireless networks have many users, who have different roles and network requirements, ranging from the use of educational platforms, informative consultations, emails, among others. Currently due to the inefficient use of network resources and little wireless planning, caused by the growth of the technological infrastructure (which is often due to daily worries, rather than to a lack of preparation by those in charge of managing the network), There are two essential factors that truncate the requirement of having a stable and robust net-work platform. First, the degradation of the quality of services perceived by users, and second, the congestion caused by the high demand for convergent traffic (video, voice, and data). Both factors imply great challenges on the part of the administrators of the network, which in many occasions are overwhelmed by per-manent incidences of instability, coverage, and congestion, as well as the diffi-culty of maintaining it economically. The present investigation seeks to propose a process of optimization of the infrastructure and parameters of the configuration of a wireless network, that allows maximizing the level of satisfaction of the users in Higher Education Institutions. In the first place, it is expected to determine an adequate methodology to estimate the level of satisfaction of the users (defining a mathematical criterion or algorithm based on the study variables [1], character-ize the environment in which the project will be developed, making a complete study of the wireless conditions and implement optimization strategies with soft-ware-defined networks (SDN). SDN is a concept in computer networks that al-lows network management to be carried out efficiently and flexibly, separating the control plane from the data plane into network devices. SDN architecture consists of an infrastructure layer which is a collection of network devices con-nected to the SDN Controller using protocol (OpenFlow) as a protocol [2]. Also, SDN will study traffic patterns on the network as a basis for optimizing network device usage [3]. The phases of the research will be carried out following the life cycle defined by the Cisco PPDIOO methodology (Prepare, Plan, Design, Imple-ment, Operate, Optimize) [4].Institución Universitaria ITSA, Corporación Universitaria Reformada CUR, Corporación Universitaria Latinoamericana CUL, Universidad de la Costa CUC, Universitaria Minuto de Dios UNIMINUTO, Universidad Libre

Optical Imaging and Spectroscopic Observation of the Galactic Supernova Remnant G85.9-0.6

Optical CCD imaging with H$\alpha$ and [SII] filters and spectroscopic observations of the galactic supernova remnant G85.9-0.6 have been performed for the first time. The CCD image data are taken with the 1.5m Russian-Turkish Telescope (RTT150) at TUBITAK National Observatory (TUG) and spectral data are taken with the Bok 2.3 m telescope on Kitt Peak, AZ. The images are taken with narrow-band interference filters H$\alpha$, [SII] and their continuum. [SII]/H$\alpha$ ratio image is performed. The ratio obtained from [SII]/H$\alpha$ is found to be $\sim$0.42, indicating that the remnant interacts with HII regions. G85.9-0.6 shows diffuse-shell morphology. [SII]$\lambda\lambda 6716/6731$ average flux ratio is calculated from the spectra, and the electron density $N_{e}$ is obtained to be 395 $cm^{-3}$. From [OIII]/H$\beta$ ratio, shock velocity has been estimated, pre-shock density of $n_{c}=14$ $cm^{-3}$, explosion energy of $E=9.2\times10^{50}$ ergs, interstellar extinction of $E(B-V)=0.28$, and neutral hydrogen column density of $N(HI)=1.53\times10^{21}$ $cm^{-2}$ are reported.Comment: 20 pages, 4 tables, 4 figures. Accepted for publication in Astrophysics & Space Scienc

MobiQ: A modular Android application for collecting social interaction, repeated survey, GPS and photographic data

The MobiQ app for Android smartphones is a feature-rich application enabling a novel approach to data collection for longitudinal surveys. It combines continuous automatic background data collection with user supplied data. It can prompt users to complete questionnaires at regular intervals, and allows users to upload photographs for social research projects. The app has the capability to collect GPS location data, and calls and text frequency (excluding content) unobtrusively. The app transmits data to a secure cloud rather than storing research data on the phone, but can also store data temporarily if a data connection is unavailable; hence, MobiQ offers data security advantages over text- or web-based surveys using phones. MobiQ has been pilot tested in the field in a social science research project and is able to collect longitudinal social research data. Due to its modular and flexible design, MobiQ can easily be adapted to suit different research questions. Furthermore, its core design approach which allows for long-term power efficient data collection can be re-used outside the social sciences domain for other kinds of smartphone-based data-driven projects. Projects that have a requirement for communications-based, sensors-based, user-based data collection or any combination of these may find our code and design approach beneficial. For example, MobiQ code and architecture has been successfully adapted to build an app for a project investigating smartphone-based implicit authentication for mobile access control

The effect of trepanning speed of laser drilled acute angled cooling holes on the high temperature low cycle corrosion fatigue performance of CMSX-4 at 850 °C

The effect of laser trepanning speed and, as a result, recast layer thickness on the high temperature corrosion fatigue behaviour of CMSX-4 superalloy acute angled holes was investigated. The experimental test results show that an increasing laser drilling speed caused a reduction in corrosion fatigue life by 35–50% at 850 °C, under low cycle fatigue regime. This reduction was found to correlate directly with the recast layer thickness and surface anomalies within the recast layer produced during the laser drilling process. Corrosion had a smaller effect on the overall life of the laser drilled specimens under the conditions tested. The results presented show that laser trepanning speed is influential in limiting the life performance of laser drilled components in service

Density functional theory studies of MTSL nitroxide side chain conformations attached to an activation loop

A quantum-mechanical (QM) method rooted on density functional theory (DFT) linked to the Stochastic Liouville equation (SLE) in the Fokker Planck (FP) form has been employed for the first time to sample the methane-thiosulfonate spin label (MTSL) conformational space attached to the Aurora-A kinase activation loop and to calculate the EPR spectrum. The features of the calculated energy surface allowed us to describe the system in a limited number of rotamers stabilized by interactions of the MTSL side chain and neighbouring residues. The relevant magnetic parameters and the electron paramagnetic resonance (EPR) spectrum were subsequently calculated from the trajectories of the spin probe in the protein environment. The comparison between theoretical and experimental continuous wave (CW) EPR spectra revealed some small differences in the EPR line shape which arises from the combinations of g- and A-values obtained from the conformations selected. The theoretical approach adopted in this work can be used to recognise the contribution of MTSL rotamers to the EPR spectrum in order to help extract structural/dynamics properties of protein from the experimental data