The Outer Limits of Galaxy Clusters: Observations to the Virial Radius with Suzaku, XMM, and Chandra

The outskirts of galaxy clusters, near the virial radius, remain relatively unexplored territory and yet are vital to our understanding of cluster growth, structure, and mass. In this presentation, we show the first results from a program to constrain the state of the outer intracluster medium (ICM) in a large sample of galaxy clusters, exploiting the strengths of three complementary X-ray observatories: Suzaku (low, stable background), XMM-Newton (high sensitivity), and Chandra (good spatial resolution). By carefully combining observations from the cluster core to beyond r_200, we are able to identify and reduce systematic uncertainties that would impede our spatial and spectral analysis using a single telescope. Our sample comprises nine clusters at z ~ 0.1-0.2 fully covered in azimuth to beyond r_200, and our analysis indicates that the ICM is not in hydrostatic equilibrium in the cluster outskirts, where we see clear azimuthal variations in temperature and surface brightness. In one of the clusters, we are able to measure the diffuse X-ray emission well beyond r_200, and we find that the entropy profile and the gas fraction are consistent with expectations from theory and numerical simulations. These results stand in contrast to recent studies which point to gas clumping in the outskirts; the extent to which differences of cluster environment or instrumental effects factor in this difference remains unclear. From a broader perspective, this project will produce a sizeable fiducial data set for detailed comparison with high-resolution numerical simulations.Comment: 8 pages, 6 figures. To appear in the proceedings of the Suzaku 2011 Conference, "Exploring the X-ray Universe: Suzaku and Beyond.

Effects of UV light and moisture absorption on the impact resistance of three different carbon fiber-reinforced composites

Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical EngineeringCarbon fiber is extensively used in aircraft components and structures, where its superior strength-to weight ratio far exceeds that of any metal. Thirty percent of all carbon fiber is used in the aerospace industry. The purpose of this research was to determine the influence of material properties on the impact response of a laminate, whereby specimens were fabricated and cured under a vacuum and high temperature using three types of pre-impregnated (prepreg), carbon fibers, namely unidirectional fiber, plain weave woven fiber, and non-crimp fiber. Each carbon fiber panel, usually known for its low-impact properties, with respective type of prepregs, of 16 plies underwent impact testing using a low-velocity impactor and visual damage inspection by C-scan in order to measure the damage area and depth, before and after impact testing. These panels were treated with UV exposure and moisture conditioning for 20 days each. Water contact angles were taken into consideration to determine the hydrophobicity and hydrophillicity of the respective prepreg material. Experimental results and damage analysis show that UV exposure and moisture conditioning showcased the variation in impact response and behavior, such as load-carrying capacity, absorbed energy, and impact energy of the carbon fiber panels. This study illustrates that non-crimp carbon fiber laminates were far more superior relative to load capacity than woven and unidirectional laminates, with the NCF-AS laminate exhibiting the highest load capacity of 17,244 lb/in (pre-UV) with only 0.89% decrease after UV exposure. This same laminate also had a 1.54% decrease in sustaining impact and 31.4% increase in wettability of the panel. Moreover, the study shows how symmetric and asymmetric stacking sequences affect the impact behavior of non-crimp fiber laminates. These results may be useful for expanding the capacity of carbon fiber, lowering costs, and growing new markets, thus turning carbon fiber into a viable commercial product

A Comprehensive Study of the Outskirts of Galaxy Clusters Using Suzaku

Galaxy clusters, which contain up to tens of thousands of galaxies and which are the largest virialized structures in the universe, serve as unique probes of cosmology. Most of their baryonic mass is in the form of hot gas that emits X-rays via thermal bremsstrahlung radiation. The study of this emission from the outer, least-relaxed portions of clusters yields valuable information about the hierarchical assembly of large scale structure. In this thesis, we report on our X-ray analysis of the outskirts of four clusters. For this purpose, we Suzaku data, which is well-suited to the study of the outsides of clusters. Accurate parameter estimates require reliable data and proper analysis, so we focus on the 0.7--7.0 keV range because other studies have shown that energies below or above this range are less reliable. A key component of our analysis is our careful modeling of the background emission as a thermal component plus a power law contribution. Our power law model uses a fixed slope of 1.4, which is consistent with other clusters. We constrain our thermal background component by fitting it to ROSAT data over the energy range 0.3--2.0~keV. Using this method, we extract the temperature, density, and surface brightness from the Suzaku data. These parameters are somewhat different from the values obtained using XMM-Newton data but are consistent with other measurements using Suzaku. We then deprojected these quantities to estimate the total mass, entropy, pressure, and baryonic fraction. We find an entropy that is consistent with the previously suggested `universal' entropy profile, but our pressure deviates from the `universal' profile. We discuss some possible reasons for this discrepancy. Consistent with previous observations but in contrast to what is expected from simulations, we infer that the outer parts of the clusters we study have baryon fractions in excess of the cosmic fraction. We suggest some explanations for this, focusing on clumping as a possibility. We then finish by discussing the role of our observations in cluster physics studies and by enumerating other avenues of exploration to attain a more complete picture of galaxy clusters

Conceptual design and simulation study of an autonomous indoor medical waste collection robot

Solid waste management is one of the critical challenges seen everywhere, and the coronavirus disease (COVID-19) pandemic has only worsened the problems in the safe disposal of infectious waste. This paper outlines a design for a mobile robot that will intelligently identify, grasp, and collect a group of medical waste items using a six-degree of freedom (DoF) arm, You Only Look Once (YOLO) neural network, and a grasping algorithm. Various designs are generated before running simulations on the selected virtual model using Robot Operating System (ROS) and Gazebo simulator. A lidar sensor is also used to map the robot's surroundings and navigate autonomously. The robot has good scope for waste collection in medical facilities, where it can help create a safer environment

Early onset schizophrenia with an underlying epileptiform disorder-a case report

We report the case of a 15 year old girl presenting with negative symptoms of schizophrenia, with an underlying epileptiform disorder that was masked. Though many cases of epilepsy who subsequently develop a psychotic disorder have been well documented, only a few cases of primary psychotic disorder with epilepsy have been described. This case report highlights the overlap between both these disorders and the need for a clinician to be cognizant of both