Department of Physics
Graduate Seminar Announcement for Monday, March 24
Mar 21, 2014
PHYS 600, Monday, March 24, 4:00 pm
Currens Hall 205
All physics faculty and students are invited.
Speaker: Li Ean Lee
Graduate Student, Physics Department, WIU
Title: Pilot Survey for Microwave Molecular Lines Toward Massive Star Forming Regions
Molecular spectral lines are key to characterize the medium where massive stars form. Therefore, to learn more about the star formation process, a pilot survey for microwave molecular lines (between 6 and 8 GHz) was conducted toward 12 massive star forming regions with the 305m Arecibo Radio Telescope. We detected 6.67 GHz CH3OH toward 9 sources and 6.035 GHz OH toward four sources. We also detected the radio recombination line H99± toward four regions, which indicates significant ionization by young massive stars. A particularly interesting result is the detection of a 6.67 GHz CH3OH maser flare toward G45.12+0.13, where an emission line was present on 2008 October 14 and completely disappeared by 2008 October 27. We detected an unusual molecular line, 6.28 GHz H2CS toward G34.26+0.15, which is the second ever detection of this transition after it was discovered by MacLeod & Doherty (1975) toward Sgr B2. In addition, we report three tentative detections toward the massive star forming region IRAS 18566+0408: 6.85 GHz CH3OH, 7.28 GHz CH3OH, and 7.35 GHz CH. Even though the lines have low signal to noise ratios, the velocity of the lines is consistent with other molecular transitions detected in IRAS18566+0408. We submitted a proposal to the Arecibo Telescope to confirm the tentative detections; our proposal was approved and follow up observations will be conducted this year. If verified, we would have discovered three new astrophysical maser transitions.
Speaker: Saleh Alzahrani
Graduate Student, Physics Department, WIU
Title: Medical Imaging
The practice of modern medicine depends effectively on a significant number of techniques, tools and physical principles. The urgent need for accuracy in methods of diagnosis and treatment have led to the continuous development of techniques and physical tools, which finally led to the formation of medical imaging. The term medical imaging refers to the techniques and processes used to obtain images of the human body or parts thereof in order to diagnose, monitor, or treat medical conditions. The principal objective of this talk is to discuss different types of medical imaging techniques; each type differs in terms of characteristics and the physical principle utilized. Various techniques give different information about the area of the body being examined or treated. Amongst the techniques used in medical imaging are nuclear medicine and ultrasound imaging. Nuclear medicine is the use of radioactive isotopes and the energetic particles emitted from a radioactive material to produce an image of different parts of the body. These isotopes emit gamma rays. The diagnostic tests involve the formation of an image using a gamma camera. A gamma camera uses crystals of sodium iodide to detect gamma photons. When a gamma ray ionizes an iodine atom in the crystal, a faint flash of light is produced. The physical principle for the phenomena of the excited electron is similar to the photoelectric effect. One of the most important types of nuclear imaging is single-photon emission computed tomography. The concept of ultrasound differ from other medical imaging modalities in the fact that it is operated by the transmission and receipt of sound waves. In other words, ultrasound is the use of high frequency sound waves to create an image of some part of the inside of the body. The reflection of ultrasound pulses by structures within the body is the interaction that creates the ultrasound image. This reflection is what gives the ultrasound image its features. When ultrasound is used to image the heart it is referred to as an echocardiogram, therefore, we can define it as the use of the sound waves to create moving pictures to the heart. As a result, the medical imaging is the accurate technology to diagnose the medical conditions.