The Department of Physics at American University of Sharjah has offered its high-quality seminar series for many years. The Physics Seminar Series is part of the department's efforts to enhance the learning and research environment for faculty and students alike by providing a platform for prominent physicists from the region and abroad to present the latest "frontiers" developments in the various dynamic fields of physics, and their relevance to many applications in various academic, government and industry sectors. The series provides ample opportunity to have debates on rising research issues in physics, astrophysics, and space and materials science, and to promote regional and international collaborations.

 

Speaker: Dr. Alaa Ibrahim

Affiliation: American University of Cairo

Date: Wednesday, October 22, 2014

Title: The New Universe Revealed by Space Observatories

Abstract: Since Galileo started to explore the sky with his telescope nearly four hundred years ago, a revolution in astronomy (and a parallel one in science) started to unfold. The Earth-centered universe that prevailed for two thousand years was rectified, new planets and members of our solar system were discovered, more galaxies than our Milky Way were found, and the universe was discovered to be expanding. Astronomy advanced in these ~ 300 years more than it did since its inception as one of mankind’s first science disciplines. Yet, another revolution was awaiting when telescopes and light detectors were placed in space. The universe was seen for the first time to be vibrant at invisible wavelengths to the human eye, such as x-rays and gamma-rays, revealing a host of new cosmic objects, regions, and phenomena that are otherwise absent in the optical spectrum, and also shedding new insights in the optical band. These include observing the exotic activity of black holes and neutron stars, detecting the remnant radiation from the Big Bang, determining the age of the universe, constraining dark matter and dark energy, discovering the accelerating expansion of the universe, and detecting other planets and solar systems in and outside our Milky Way galaxy. The availability and abundance of the observations from these space telescopes via online data archives creates rich opportunities worldwide in research and education (including experiential, project-based learning and undergraduate research) among students and researchers, not only in physics and astronomy but also in computer science, mathematics, and astro-biology.

 

Speaker: T.C. Sabari Girisun

Affiliation: Bharathidasan University, India

Date: Monday, October 27, 2014

Topic: Laser Risks and Optical Limiters

Abstract: Physics would be dull and life most unfilling, if all physical phenomena around us were linear. Fortunately we are living in a nonlinear world. The laser is a source of light with unrivalled purity and intensity not found in any of the previously known sources of electromagnetic radiation has made the field of optics, nonlinear. At present the laser industry is surging briskly and it is estimated that its global market will be around 20 billion dollars by 2017. However it is worthwhile to be mentioned that sudden exposure to intense laser beam can cause damage of humans and photosensitive optical components. Recent reports shows that, the laser accidents has increased by 13 times in the period of 2000-2012. In particular the risk of handling green lasers is very higher as its visual hazard distance is 2 times the red (24%) and 5.3 times the blue (3%) lasers. So the need has rapidly arisen for optical limiting devices that protect the photosensitive components from intense optical radiation. In this discussion, an introduction on the laser interactions, possible laser risks as a function of wavelength and time, various nonlinear optical phenomena will be presented in detail. Also the fundamentals of optical limiting mechanisms and the current scenario of achieving efficient optical limiters will also be elaborated.

 

Speaker: Professor Philip Kaaret

Affiliation: University of Iowa, USA

Date: Monday, November 24, 2014

Title: Intermediate -Mass Black Holes and Ultra-Luminous X-Ray Sources

Abstract: Black holes are an essential piece of our current scientific description of the Universe. They come in two sizes: stellar-mass black holes, weighing about as much as a star, and supermassive black holes, weighing as much as millions or billions of stars and found at the centers of galaxies. It has been suggested that bright X-ray sources in nearby galaxies might represent a third type of "intermediate mass" black hole.

 

Speaker: Dr Rana M. Tamim

Affiliation: Zayed University, United Arab Emirates

Date: Wednesday, November 26, 2014

Topic: Technology for Teaching and Learning: Making use of the Big Picture for the benefit of University Students

Abstract: Seldom has educational research witnessed a faster growing and changing area of focus than technology integration. Regardless of research findings, the ongoing progression of technological innovation, coupled with the affordability and thus widespread use of personal digital tools and mobile devices, is forcing academics to realize the futility of the “use or not use technology” question. Rather, the more pressing concern is how to best use technology for teaching and learning, especially that the naïve assumption that mere introduction of computers will lead to higher levels of interactivity and constructive learning has been refuted. As such, university professors find themselves under the pressure of finding successful ways to utilize technological devices for supporting and enhancing the student’s learning experience. The current presentation will offer an overview of major findings from meta-analyses addressing the impact of technology on students’ achievement in face-to-face, blended, and distance learning contexts. More importantly, implications and recommendations for best practices will be provided while suggesting specific approaches for using technology for more active learning and student engagement.

 

Speaker: Professor Usama Al Khawaja

Affiliation: United Arab Emirates University, UAE

Date: Wednesday, March 11, 2015

Title: Soliton Diode

Abstract: We study the flow of bright solitons through two asymmetric potential wells. The scattering of a soliton by certain type of single potential wells, e.g., Gaussian or Rosen-Morse, is distinguished by a critical velocity above which solitons can transmit almost completely and below which solitons can reflect nearly perfectly. For two such wells in series with certain parameter combinations, we find that there is an appreciable velocity range for which solitons can propagate in one direction only. Our study shows that this directional propagation or diode behavior is due to a combined effect of the sharp transition in the transport coefficients at the critical velocity and a slight reduction in the center-of-mass speed of the soliton while it travels across a potential well.

 

Speaker: Dr. Raid M Suleiman

Affiliation: Harvard-Smithsonian Center for Astrophysics, USA

Date: Sunday, March 15, 2015

Topic: Measurements of Atmospheric Trace Gases from Space

Abstract: Space borne observations of the atmosphere provide significant knowledge about key components of the Earth's troposphere and stratosphere. Knowledge gained from observations of the Earth spectra can be used to provide more insights into the spectra of an Exoplanet. The spectra of a technologically advanced planet will be explained and the concept applied to an Exoplanet.

The bromine monoxide (BrO) product retrieved from observations by the Ozone Monitoring Instrument (OMI) onboard AURA will be discussed. A detailed description of the physics of the retrieval algorithm for the OMI operational BrO product will be presented. The algorithm is based on direct fitting of radiances from 319.0-347.5 nm, within the UV-2 channel of OMI. Radiances are modeled from the solar irradiance, attenuated by contributions from the target gas and interfering gases, rotational Raman scattering, additive and multiplicative closure polynomials and a common mode spectrum. The BrO retrieval uses albedo- and wavelength-dependent air mass factors (AMFs), which have been pre-computed using climatological BrO profiles. The wavelength-dependent AMF is applied pre-fit to the BrO cross-sections so that vertical column densities are retrieved directly.

Finally, I will discuss Tropospheric Emissions: Monitoring of Pollution (TEMPO) as the next instrument to advance atmospheric research. TEMPO was selected in 2012 by NASA as the first Earth Venture Instrument, for launch no earlier than November 2018. It will measure atmospheric pollution for greater North America from space using ultraviolet and visible spectroscopy. TEMPO measures from Mexico City to the Canadian oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution (~2 km N/S × 4.5 km E/W at 36.5°N, 100°W). The case will be made for a future TEMPO-like Middle East instrument.

 

Speaker: Dr. Abdel Isakovic

Affiliation: Khalifa University, UAE

Date: Wednesday, March 25, 2015

Title: Nano Engineering of Interfacial Geometries for Minimal Energy Electronic Systems

Abstract: A significant portion of research, development and post baccalaureate training of students in modern information processing and storage fields is dedicated to the design and nanofabrication of novel minimal energy electronic systems (MEES). This is an imperative both within more-Moore and more-than-Moore paradigms. In this seminar talk, I will discuss two systems that fall in the above categories – design, nanofabrication and characterization of nanocontacts to nanowires, and the novel approach to designing magnetic tunnel junctions (MTJs), so that both systems satisfy the MEES criteria. End and side contacts geometry is a subject of research efforts because of its potential to alter and augment nanoscale transport of electric charge. I will also revisit elementary, tri-layer design of MTJs in order to demonstrate how MTJs’ functionality could be preserved while decreasing the overall energy of their operation, which opens a path towards novel nanomagnetic memory elements, switches and sensors. Just like in the case of nanocontacts to nanowires, this modification of the MTJs is driven by the nanoengineering of interfacial geometry.

 

Speaker: Dr. Salah Nasri

Affiliation: United Arab Emirates University, UAE

Date: Wednesday, May 13, 2015

Topic: Naturalness and New Physics

Abstract: In this talk I will discuss the fine tuning of some of the physical parameters of nature which beg for explanations. Based on examples from the past, I will argue that naturalness criterion might be used as a guiding principle in the search for new Physics. I will also present counter examples where it seems that accidental cancellations and coincidences can be reasonable explanations for the fine tuning.

 

Speaker: Dr. Abdel Isakovic

Affiliation: Khalifa University, UAE

Date: Wednesday, March 25, 2015

Title: Nano engineering of Interfacial Geometries for Minimal Energy Electronic Systems

Abstract: A significant portion of research, development and post baccalaureate training of students in modern information processing and storage fields is dedicated to the design and nanofabrication of novel minimal energy electronic systems (MEES). This is an imperative both within more-Moore and more-than-Moore paradigms. In this seminar talk, I will discuss two systems that fall in the above categories – design, nanofabrication and characterization of nanocontacts to nanowires, and the novel approach to designing magnetic tunnel junctions (MTJs), so that both systems satisfy the MEES criteria. End and side contacts geometry is a subject of research efforts because of its potential to alter and augment nanoscale transport of electric charge. I will also revisit elementary, tri-layer design of MTJs in order to demonstrate how MTJs’ functionality could be preserved while decreasing the overall energy of their operation, which opens a path towards novel nanomagnetic memory elements, switches and sensors. Just like in the case of nanocontacts to nanowires, this modification of the MTJs is driven by the nanoengineering of interfacial geometry.

 

Speaker: Dr. Salah Nasri

Affiliation: United Arab Emirates University, UAE

Date: Wednesday, May 13, 2015

Topic: Naturalness and New Physics

Abstract: In this talk I will discuss the fine tuning of some of the physical parameters of nature which beg for explanations. Based on examples from the past, I will argue that naturalness criterion might be used as a guiding principle in the search for new Physics. I will also present counter examples where it seems that accidental cancellations and coincidences can be reasonable explanations for the fine tuning.

 

Speaker: Prof. Pascal Chardonnet

Affiliation: University of Savoie, France

Date: Tuesday, May 19, 2015

Title: Is Dark Matter Made of Small-Mass Black Holes?

Abstract: Dark matter is an essential constituent of the universe and currently represents a great mystery in astrophysics. The most favored explanation is that dark matter is made of neutral massive elementary particles. However, despite many efforts and much research using accelerators and underground experiments, such particles have yet to be detected, and dark matter remains elusive. Another possibility could be to explain dark matter with small, primordial black holes.

In this seminar, the second scenario will be developed and the evidence for this possibility will be presented. The consequences of this scenario in astrophysics and cosmology will also be reviewed.

 

Speaker: David Brain

Affiliation: University of Colorado, USA

Date: Wednesday, October 21, 2015

Topic: Evolution of the Martian Atmosphere

Abstract: Of all solar system planets, the one most similar to Earth is Mars. The planets share a number of physical resemblances, including canyons, polar caps, and sand dunes, but are enough different that life is thought to be unlikely to be present at the Martian surface today. The atmosphere of Mars, in particular, is thin and cold today, so that water cannot exist as a liquid at the surface for more than a few minutes or hours at a time in select locations. Yet the Martian surface exhibits abundant evidence that liquid water once flowed freely over the surface for long periods of time, implying that the atmosphere must have been substantially thicker billions of years ago. Thus, the Martian atmosphere has evolved over long time scales. On shorter timescales, the atmosphere transports particles and energy around the planet in ways that are poorly understood but that are likely to be quite different from Earth due to the small size of the planet and the different atmospheric composition. This presentation will provide a brief overview of Mars as a planet, and discuss how the atmosphere changes on both short and long timescales. Efforts to understand these changes using spacecraft measurements from NASA’s MAVEN and UAE’s Al Amal missions will be described.

 

Speaker: Dr. Mahmoud Said Rasras

Affiliation: Masdar Institute of Science and technology (MI), UAE

Date: Monday, March 28, 2016

Title: Optical Signal Processing in CMOS-Compatible Silicon Nano-Photonics

Abstract: Developing CMOS silicon-based photonics holds the promise of disruptively creating new signal processing and transport solutions through the monolithic integration of electronic and photonic functions. Furthermore, integrating photonic components in a CMOS platform provides the benefits of a significant reduction in power consumption, cost, and size. In addition, there is a great potential in creating new functions from incorporating photonics and electronics on the same silicon chip. In this talk, implementation and integration challenges of such components in CMOS-compatible silicon will be presented. The focus will be placed on optical interconnects and sensing applications.

 

Speaker: Dr. George Shubeita

Affiliation: New York University Abu Dhabi-NYUAD, UAE

Date: Wednesday, April 20, 2016

Topic: Molecular Motors: from Mechanics to Disease

Abstract: Much like a city, living cells are organized, and maintaining their organization is essential for their proper functioning. To position micrometer-sized vesicles and organelles inside the cell at the right place and in a timely fashion the cell shuttles these cargoes along a network of intracellular roads (microtubules and actin filaments) using a set of molecular motor proteins (kinesin, dynein and myosin). These motor proteins use the energy released by ATP hydrolysis to generate the force they need to haul the cargoes; thus, measuring that force amounts to directly probing their function. Measuring the piconewoton forces that motors exert in their native cellular environment enabled us to count the number of motors hauling individual cargoes, and to test physical models of intracellular transport. Given the ubiquity of molecular motors, failure in regulating their function can result in disease. Neurodegenerative diseases such as Alzheimer’s, Huntington and Amyotrophic Lateral Sclerosis, for example, have been linked to motor malfunction. Using a combination of genetic, biochemical and biophysical tools in a fruit fly model of Alzheimer’s disease, we established the mechanism by which the motor regulator GSK-3 alters transport when present in the elevated levels found in Alzheimer’s patients. Our findings have implications on the development Alzheimer’s drugs targeting GSK-3.

 

Speaker: Professor Goong Chen

Affiliation: Texas A&M University, USA

Date: Wednesday, October 12, 2016

Topic: Modeling and Simulation of Pulverizing Aircraft Crashes

Abstract: Do you know how an airplane crash causes the breakup of the aircraft? Speaker, Professor Goong Chen of Texas A&M University, uses computational physics and applied mathematics to build a model of airplane, the Airbus A320, and let it be run on a supercomputer to simulate the collision into different terrains of land or mountain to see what damage a crash may cause. There are many videos showing the processes and outcomes of crashes. The talk aim aims at explaining a forensic investigation and making assessments of how the German wings Flight 9525 “pulverized" when the airplane crashed into the French Alps in March 2015. The study is based on mathematical modeling, supercomputing and visualization using the numerical modeling tool LS-DYNA. The method was developed by hybridizing two primary methods: the Finite Element Analysis (FEA) and the Smoothed Particle Hydrodynamics (SPH), and the methodology was validated against an experimental crash test of an F4 Phantom II fighter jet into a wall. The study has a potential of being made into real-time flight crash simulators to help the study of crash worthiness and survivability for future aviation safety. The talk is intended for a general audience and does not require strong technical background in order to understand.