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2014 Seminars

  • The Higgs (Amplitude) Mode in Ferromagnetic Metals

    Dec. 5, 2014, 1:15pm-2:30pm, OE 134

    Dr. Kevin Bedell John H. Rourke Professor of Physics Physics Department,Boston College

    Abstract:

    The emergence of new modes in systems with spontaneously broken continuous symmetries plays an important role in our fundamental understanding of nature. Two of the fundamental particles that can be present in the field theory descriptions of these spontaneously broken symmetries are: massless Nambu-Goldstone bosons (phase modes) and massive Higgs bosons (amplitude modes). These two modes can be understood as following from fluctuations in the order parameter describing the spontaneously broken symmetry: φ(x) = ρ(x)eiθ(x). The massless mode, arises from fluctuations of the phase of the order parameter, θ(x), and the massive mode, comes from fluctuations of the amplitude of the order parameter, ρ(x). The Higgs amplitude mode can exist in a variety of condensed matter systems with broken continuous symmetry including, antiferromagnets, fermionic superfluids, and charge density waves, to name a few. In a ferromagnetic metal the existence of the phase mode (magnon /spin wave) is well know but the Higgs mode was not expected. In (2001) Bedell and Blagoev showed that the Ferromagnetic Fermi Liquid (FFL) theory predicted the existence of a gaped collective excitation in a ferromagnetic metal. Recently Yi, Farinas and Bedell (2013) identified this mode as the Higgs amplitude mode. Using existing measurements of some of the parameters needed in the FFL theory we predicted that there is a well-defined propagating Higgs amplitude mode in MnSi. From the calculation of the spin density response function we can estimate the relative intensity of the Higgs amplitude mode in neutron scattering experiments on MnSi and we expect that it should be observable. A recent experiment searching for the Higgs in MnSi was carried out at ORNL; currently the data is being analyzed and there is nothing to report now. If you want an update on the experiment you will have to come to my talk!

    Biography:

    Dr. Kevin Bedell received his B.S. in Physics from Dowling College, Oakdale NY in 1971, M.S. in Applied Mathematics and Ph.D. in Physics from SUNY Stony Brook, NY in 1972 and 1979, respectively. Dr. Bedell was a research associate at University of Illinois at Urbana-Champagne from 1979 to 1982, a research fellow, at ITP, SUNY Stony Brook from 1982 to 1985, and a visiting professor at Kamerling Onnes Laboratory at Leiden from 1985 to 1986. Dr. Bedell worked at Los Alamos National Laboratory, T-11 from 1986-1996. He was the director of Program in Correlated Electron Theory from 1991 to 1995 and the co-director of Many-Body Theory Program from 1996 to 2002. Dr. Bedell was the chair of Physics Department, Boston College from 1996 to 2006 and the Vice Provost for Research at Boston College from 2006 to 2010. He became the Rourke Professor of Physics at Boston College in 1999. Dr. Bedell is an APS fellow and also the editor for Advances in Physics since 1995.

  • C-MEMS/NEMS for Energy Storage and Biosensing Applications

    Nov. 21, 2014, 1:15pm-2:30pm, OE 134

    Dr. Chunlei (Peggy) Wang Mechanical and Materials Engineering FIU

    Abstract

    Carbon microelectromechanical systems (C-MEMS) and carbon nanoelectromechanical systems (C-NEMS) have received much attention because of their various potential applications, such as: microbatteries and DNA arrays. Microfabrication of carbon structures using current processing technology, including focused ion beam (FIB) and reactive ion etching (RIE), is time consuming and expensive. Low feature resolution, and poor repeatability of the carbon composition as well as widely varying properties of the resulting devices limits the use of scree printing of commercial carbon inks for C-MEMS. Our newly developed 3D C-MEMS/NEMS microfabrication technique is based on the pyrolysis of photo patterned resists at high temperatures in an oxygen free environment. It is possible to use the C-MEMS/NEMS technique to create various complex 3D carbon structures, such as: high aspect ratio carbon post arrays and suspended carbon nano wires. They can have a wide variety of shapes, resistivities and mechanical properties. We demonstrate that C-MEMS/NEMS with sizes ranging from the millimeter to the micrometer and even nanometer is very possible to provide solutions, alone or in combination with silicon and other organic, inorganic, and biological materials, in miniaturized power systems (Li-ion batteries, ultracapacitors, biofuel cells) and biosensors (such as: glucose sensors and aptamer sensors).

    Biography:

    Chunlei (Peggy) Wang is an associate professor in the Mechanical and Materials Engineering Department at Florida International University. She received her MS (1993) and PhD (1997) in Solid State Physics from Jilin University (China). Before joining FIU, she held various research positions at Osaka University (1995-2001) and University of California Irvine (2001-2006). At FIU, her group focuses on the development of micro and nanofabrication methods for building novel micro and nanostructures and synthesizing nanomaterials that have unique structures and useful properties for energy and biological applications. She published in 5 book chapters, 90 peer reviewed journal publications, and 10 patent. She is a recipient of FIU faculty award in research and creative activities (2013), FIU Kauffman Professor Award (2009), and DARPA Young Faculty Award (2008). She was a co-founder of Carbon Microbattery Corporation (now: Enevate Corp), a consultant at Intel Lab, and a guest scientist at Max Planck Institute.

  • Do Ideas, Products, Messages, and Behaviors Really Spread Just Like Viruses?

    Nov. 14, 2014, 1:30-2:30pm, OE 134

    Dr. Julia Poncela-Casasnovas Departament d'Enginyeria Informàtica i Matemàtiques (Computer Science & Mathematics) Universitat Rovira i Virgili (Spain)

    Abstract:

    Adoption of innovations, whether new ideas, technologies, or products, is crucially important in knowledge societies. Studies of adoption of innovations have generally focused on products with little societal impact (such as online apps) and, even if large-scale and real-world based, on heterogeneous populations. These limitations have so far hindered the development and testing of a mechanistic understanding of the adoption process. In this work, we experimentally study the adoption by critical care physicians of a medical innovation that complements current protocols for the diagnosis of life-threatening bacterial infections. We show through computational modeling of the experiment that infection spreading models – which have been formalized as generalized contagion processes – are not consistent with the experimental data. Instead, we find that a “persuasion” model inspired by opinion models is better able to reproduce the empirical data, providing insight into the mechanism of innovation adoption within this homogeneous population of highly-trained professionals. Using our model, we also propose an intervention scheme and show its possible impact on increasing the rate and robustness of innovation adoption in the real-world.

    Biography:

    Dr. Julia Poncela-Casasnovas obtained her PhD in Physics at University of Zaragoza (Spain). Her dissertation was on Evolutionary Game Theory on Complex Networks, where she analyzed the interface between cooperative dynamics and the underlying structure of a given population. Her current research interests are in Complex Systems and big data in general, and more specifically, the study of different processes on top of complex topologies, such as social networks, using computer simulations and statistical analysis. Dr. Poncela-Casasnovas joined the Amaral Lab at Northwestern University as a postdoc for three and a half years, where she worked on analyzing social systems using computational and statistical methods. One project was about understanding the way ideas propagate within a professional network. Another one was a study of an online community for people that want to control their weight, where she worked to understand the correlations between network topology and individual’s behaviors. She recently moved back to Spain to work with Dr. Alex Arenas on multiplex networks (or multilayered networks). She is also currently starting new collaborations to apply network analysis tools to health and social problems and serving on the advisory board for the FIU Project, “Network Analysis of Student Retention and Persistence.”

  • Stochastic optical beams: from mathematical modeling to applications

    Nov. 7, 2014, 1:15pm-2:30pm, OE 134

    Dr. Olga Korotkova Physics Department, University of Miami

    Abstract:

    Recently several new classes of random stationary beams having different shapes of correlation functions were introduced theoretically and realized experimentally. Unlike conventional random beams with Gaussian correlations, whose intensity profiles remain Gaussian on free-space propagation, the novel beams can change the shape of their intensity to a prescribed one in the far zone, from any profile in the source plane. Among important average intensity profiles are flat-tops, rings, frames and cages. The most convenient ways of synthesizing the sources of such random beams is with the help of the spatial light modulators. Potential applications are envisioned for distant material surface processing and particle manipulation, as well as communications, imaging and sensing in random media. Preliminary computer simulations and experiments show that the new beams exhibit robust features on propagating in random media, such as atmosphere, ocean waters and bio-tissues in terms of both their average intensity and scintillations. In the electromagnetic generalization the possibility of full control of the far-field polarization properties from the source plane is also a possibility.

    Biography:

    Dr. Olga Korotkova graduated from the Samara State University, Russia, with BS in mathematics in 1999, the University of Central Florida with MS in 2002, and with PhD in 2003, both in applied mathematics. She worked at the University of Rochester as a postdoc of Prof. Emil Wolf from 2004 to 2007. In 2007 she accepted the position of the Assistant professor at the Physics Department, University of Miami and was promoted to the Associate Professor in 2012. Olga Korotkova has published two books and about 120 peer-reviewed papers in the area of statistical optics, both theoretical and experimental. She is a Topical Editor for Optics Letters since 2009 and is a chair of the "Atmospheric and Oceanic Propagation of EM waves" conference at the SPIE "Photonics West" meetings held annually.

  • Understanding Complex Systems: Network and Dynamics

    Oct. 31, 2014, 1:15pm-2:30pm, OE 134

    Dr.Chaoming Song Department of Physics, Miami University

    Abstract:

    Fueled by a wealth of data supplied by a wide range of high-throughput tools and technologies, the study of complex systems is currently reshaping a number of research fields from social science to computer science and biology. This data-rich reality calls for new approaches and techniques to harvest the hidden information and devise new models to explain the underlying principles of various complex systems. While from a functional standpoint different systems may appear to be distinct from one another, there is an increasing realization that they often share similar structural and dynamic properties. Such similarities offer new perspectives and unique opportunities for physicists to apply their methodologies on a much broader set of phenomena. In this talk, I will first present a macroscopic study of large-scale network structures observed in diverse datasets, and next focus on understanding social activities such as communication and traveling pattern at the each individual level. In the end, I will show a series of relationships that link the quantities characterizing social networks and human dynamics, and demonstrate their generality across a wide range of systems, from mobile calls to tweets.

    Biography:

    Dr. Dr. Chaoming Song is an Assistant Professor in physics at University of Miami. He received the B.S. degree from the Fudan University in China in 2001 and the Ph.D. degree in physics from the City University of New York (CUNY) in 2008. Between 2008 and 2013, he worked with Laszlo Barabasi at the Northeastern University and Harvard Medical School as a postdoctoral fellow. Since August 2013 he joined in the Physics Department of University of Miami. Song’s research interests lie in the intersection of statistical physics, network science, biological science and computational social science, broadly exploring patterns behind petabytes of data. One of his recent activities in this area is aiming to understand the fundamental properties of human mobility and interactions at various scales. He is also actively contributing to the network science area − an interdisciplinary field studying complex interactions that aims to connect phenomena emerged in different fields into a universal description. Currently Song is serving as an editorial board member of Nature: Scientific Reports.

  • Dynamics of Molecular Transformers in Silico

    Oct. 24, 2014, 1:15pm-2:30pm, OE 134

    Dr. Prem Chapagain Physics Department, FIU

    Abstract:

    Proteins are the molecular machines responsible for maintaining the biological self-organization in living cells. However, in order to perform their molecular functions, protein molecules themselves must fold into highly specific 3-dimensional shapes known as the native states. The information to fold to a functional native state of a protein is encoded in its one-dimensional string of amino acids, the primary sequence. However, structural conversion from the native state is a frequently observed process such as in the aggregation and fibrilization of amyloidogenic proteins, which is thought to be a critical process in the development of a variety of neurodegenerative diseases such as Alzheimer’s, Parkinson, Huntington, and prion diseases. A new class of proteins known as transformer proteins has recently emerged. The transformer proteins can undergo structural transformations that allow them to perform multiple functions, and they are re-defining the general perspective of sequence-structure-function relationship. In this talk, I will discuss the computer simulations of some model protein systems that shed light on the protein folding dynamics, including structural transitions in amyloidogenic proteins as well as the alpha helix to beta barrel structural transformation of the C-terminal domain of the transcription factor RfaH.

    Biography:

    Dr. Chapagain is an Associate Professor of Physics at Florida International University. Dr. Prem Chapagain received his Master’s degree from Tribhuvan University, Nepal in 1998 and his PhD in Physics from Florida International University in 2005. He worked as a post-doctoral research fellow at Cornell University before joining the department of physics at Florida International University as an Assistant Professor. Dr. Chapagain’s research interests lie in the area of biological physics. His research focus is on the protein dynamics and protein aggregation which involve applying computational and statistical mechanical techniques to understand the molecular level details of protein structural transitions. His research interests also include topics in broadly related fields such as mathematical modeling of the dynamics of infectious diseases, self-organization and complexity

  • Magnetic Resonance in Psychiatry

    Sept. 26, 2014, 1:30pm-2:30pm, OE 134

    Dr. Alayar Kangarlu Department of Psychiatry, Columbia University and New York State Psychiatric Institute

    Abstract:

    Magnetic resonance (MR) imaging has made a splash in characterization of psychiatric disorders. MR technologies such as voxel based morphometry (VBM), functional MRI (fMRI) and magnetic resonance spectroscopy MRS, and diffusion imaging (DTI) have shown to be capable of visualizing neural abnormalities and characterize their expression. MRI provides exquisite in vivo examination of neuroanatomy with potential to differentiate among psychiatric and healthy subject groups. Finding the neural substrates of some psychiatric disorders is now within the reach of structural MRI. In addition, structural MRI is more potent when combined with functional and spectroscopic (MRS) studies. Role of two metabolites, GABA and glutamate have been found to be prevalent in the schizophrenia. Contrary to the early use of MRS, today’s scanners are capable of resolving glutamate-glutamine levels which sheds light on glutametergic biosynthetic pathway in schizophrenia. The great potential of fMRI lies in its ability to detect the BOLD signal in specific brain regions to identify differences of activity between brains of clinical, subclinical and healthy subjects. Arterial Spin Labeling (ALS) has shown promise in revealing subtle brain perfusion changes occurring in psychiatric illnesses. DTI has visualized abnormalities in structural connectivity of the brain regions which in their comparison with functional connectivity maps make a great tool for assessment of the etiology of psychiatric disorders. A brief discussion will also be made about ultra high field (UHF) MRI applications and their associated perils and payoffs in the clinical settings. In this context, the challenges in the development of the precursor of UHF MRI scanners, i.e. the whole body 8T MR imager, which produced its first images fifteen years ago, will be presented along with some of its contributions in the study of multiple sclerosis, stroke, and brain tumors. Potentials of UHF MRI in providing new insight into the etiology and pathophysiology of psychiatric disorders will also be discussed.

    Biography:

    Dr. Alayar Kangarlu is currently an associate professor of neurobiology at the department of Psychiatry and a senior physicist with the New York State Psychiatric Institute (NYSPI). Alayar was trained in experimental physics with keen interest in theory. His interests in NMR led him to department of Radiology at Ohio State University in 1995 where he was a member of the team who built the 8 Tesla human MRI scanner and initiated the ensuing flurry of activities in ultra high field MRI. For the past 10 years, Alayar has been leading the Physics and Engineering developments on a GE 3T/94cm MR scanner at NYSPI. His interests include development of specialized RF coils and pulse sequences for high field applications in neurosciences. He is presently collaborating with the leading group of neuroscientists in the world within NYSPI and Columbia University and collectively they are improving the imaging tools for brain research to further expand potentials of NMR in unraveling the inner working of the human brain and mechanism of neuropsychiatric disorders.

  • TBA

    Sept. 19, 2014, 1:30pm-2:30pm, Venue TBA

    Dr. Nils Diaz

  • Mediator All-Solid-State Supercapacitor and Self-sustained Electrochemical Catalysts

    Sept. 12, 2014, 1:15pm-2:30pm, OE 134

    Dr. Xiangyang Zhou Department of Mechanical and Aerospace Engineering University of Miami

    Abstract:

    Supercapacitor (SC) as an alternative to the Li-ion battery possesses a very high charge rate, output power density, and cycleability. Development of all-solid-state electrolyte supercapacitors is encouraged by their appealing features for a number of important applications. However, it is hindered by relatively low ionic conductivity and low ionic accessibility of the polymer electrolytes to active phases. In this talk, why and how the concepts of mediator all-solid-state supercapacitors were conceived will be given. Experimental evidence will be presented to demonstrate the validity of these concepts for several polymer electrolyte systems. Increasing the performance/cost ratio of catalysts reflects a long-term passion in the area of chemical engineering. Usually, the presence of precious metals in the catalyst systems is required to enable a satisfactory performance and to maintain an acceptable stability/durability. However, our study demonstrates that for certain oxidation/reduction reactions, we can utilize a microscopic electrochemical process to sustain the promotion of the active phases to a high performance level in the absence of any precious metal. It has been demonstrated that this concept works effectively in hydrocarbon reforming/hydrogen production and recombination of carbon dioxide which are two key processes of the clean energy technology.

    Bio:

    Dr. Xiangyang Zhou is an associate professor at Department of Mechanical and Aerospace Engineering, University of Miami. He received his BS in physics from Wuhan University, China, MS in Institute of Metal Research, Chinese Academy of Sciences, and PhD in materials scince and engineering from University of Newcastle upon Tyne, England. His team is actively working in areas of electrochemical energy storage, catalytic hydrocarbon reforming/hydrogen production, electrochemical sensor, fuel cells, and electrochemistry/corrosion in high temperature water. His research has been supported by NSF, ONR, AFOSR, FAA, and industrial sponsors. Dr. Zhou has published 46 peer-reviewed papers and has been invited to give several talks in international conferences.

  • Mixed-Valent Octanuclear Iron Oxide Complexes and a Fresh Look at the “Verwey Transition”

    Aug. 29, 2014, 1:15pm-2:30pm, OE 134

    Dr. Raphael Raptis Department of Chemistry and biochemistry Florida International University

    Abstract:

    We will present structural, electrochemical and spectroscopic studies of a family of octanuclear complexes, [Fe8(µ4-O)4(µ-4-R-pz)12X4]—R = H, Cl, Br, Me, Et, Ph; X = Cl, Br, NCS, N3, OAr—containing a Fe4O4-cubane core, which can be reversibly reduced in four consecutive steps from an all-ferric, [Fe8], to four mixed-valence ferric/ferrous states, [Fe8]–2–3–/4– . The iron-oxide, Fe8(µ4-O)4-core of these complexes is a structural model of the repeat unit of the minerals magnetite, maghemite and ferrihydrite.

    The [Fe8] species are antiferromagnetically coupled with a diamagnetic ground state. Spectroscopic (electronic, vibrational, Mössbauer, XPS) analysis of mixed-valent [Fe8]– species indicates partial charge delocalization over the four Fe4O4-cubane Fe- sites. The magnetic susceptibility data of [Fe8]– complexes have been modeled with the help of magnetization measurements at pulsed magnetic fields of 65 T and 100 T, allowing an estimation of their double-exchange parameters.

    The twice reduced [Fe8]2– species with X = Cl, containing an iron-oxo core isoelectronic to magnetite (Fe3O4, an inverse spinel) shows upon cooling a transition from a delocalized to localized valence, over a temperature range overlapping with that of the “Verwey transition” of magnetite. In contrast the isoelectronic X = NCS species is valence-trapped with an electronic structure corresponding to a normal spinel. The spectroscopic and magnetic analysis of this species places the 100-year old issue of the Verwey transition of bulk magnetite into a new, molecular level perspective.

    Biography:

    Dr. Raphael Raptis received his B.S. in Chemistry from Aristotle Univ. of Thessaloniki, Greece and Ph.D. in Inorganic Chemistry from Texas A&M Univ., College Station. Dr. Raptis was a faculty at the Chem. Dept. of Univ. of Crete, Greece from 1993-1997, a visiting professor at the Chem. Dept. of Univ. of Texas at El Paso, TX from 1997-1998 and an Assistant, Associate and Full Professor at Chem. Dept. of Univ. of Puerto Rico, San Juan from 1998-2013. He joined the Department of Chemistry and Biochemistry at Florida International University in 2013. Dr. Raptis has authored over 100 peer-reviewed scientific publications and review articles and holds 3 patents. His research interests include synthetic and structural Inorganic Chemistry, polynuclear transition metal complexes, relationships between structure and redox properties, MRI contrast agents, X-ray crystallography.

  • Solution processed solar cell as an emerging solar energy conversion technique

    April 18, 2014, 1:30pm-2:30pm, AHC3 205

    Dr. Mengjin Yang Department of Physics Florida International University

    Abstract:

    High efficient and cost-effective solar cells are of paramount importance to harvest abundant and clean solar energy. Among various techniques, solution processed solar cells have emerged as the promising candidates for the next generation of solar cells. In this talk, three types of solution processed solar cells, inorganic (quantum dot sensitized solar cells, copper zinc tin sulfide solar cells), organic (polymer, small molecule), and hybrid (dye sensitized solar cells, perovskite solar cell), will be discussed for their architectures and working principles. The management of the discrepancy between optical absorption scale (micrometer) and charge transport scale (nanometer) are crucial for the device efficiency. Common approaches adopted to address this problem through rational interface engineering will be delineated. At the last part of the talk, solar cells research carried out in FIU will be presented.

    Biography:

    Dr. Mengjin Yang obtained his bachelor degree at Chongqing University (China) in 2005, master degree at Tsinghua University (China) in 2008, and Ph.D in materials science from University of Pittsburgh in 2012. Since 2012, he works as a postdoc research associate at Florida International University. Research interest: 1-D/2-D nanostructure materials for optoelectronics, solution processed solar cell, functional oxide materials and carbon materials.

  • A Time-traveller’s Guide to Protein Space

    April 11, 2014, 1:30pm-2:30pm, AHC3 205

    Dr. Jessica Liberles Assistant Professor Department of Biological Science Florida International University

    Abstract:

    Proteins are flexible in structure and function. Conformationally flexible regions are found to different extent in most proteins, ranging from fully structurally disorder proteins to proteins with almost no conformational flexibility. Embedded in these regions are post-translational modification sites and numerous functional motifs that commonly act as on/off switches of various biomolecular interactions and functions, in response to external and internal stimuli. Aiming to elucidate how these regions evolve, we are studying the evolutionary dynamics of various structural and functional properties in these intricate regions. This talk will focus on protein evolution and in particular some of our previous work on a comparative whole genome approach studying flaviviruses, our current large-scale endeavors in Metazoa, and future perspectives.

    Biography:

    Dr. Siltberg-Liberles obtained her M.S. degree in 2003 from Stockholm Bioinformatics Center, Stockholm University, Sweden. In 2008, Dr. Siltberg-Liberles attained her Ph.D. degree from the Department of Biomedicine at University of Bergen, Norway. Her Ph.D. thesis focused on evolution of protein structure and function with an emphasis on regulation. After a short postdoc in protein engineering, Dr. Siltberg-Liberles was the director of the Bioinformatics Service Core at University of Wyoming until Aug 2013 when she started her current position as an Assistant Professor in Biological Sciences at FIU.

  • Gradients of Transmembrane Voltage Potential Across Tissues Control Anatomy

    April 4, 2014, 1:30pm-2:30pm, AHC3 205

    Dr. Vaibhav P. Pai Center for Regenerative and Developmental Biology Tufts University

    Abstract:

    Tufts University’s Center for Regenerative and Developmental Biology (TCRDB) integrates molecular physiology, cell biology, developmental genetics, biophysics, computer science, and engineering to understand the storage and processing of information in living tissues. The research focuses on the study of bioelectrical signals that make up part of the language used by cells to fulfill complex patterning and organizational needs of the host organism. These natural voltage gradients exist in all cells and we use a convergence of variety of genetic, biophysical and molecular physiology to develop new tools to track and manipulate these bioelectric conversations between cells and tissues. This knowledge will help us in understanding how to apply this bioelectric information processing modality in regenerating such organ systems for treatment of birth defects, injuries and diseases.

    Biography:

    Dr. Vaibhav Pai obtained his B.S. in Microbiology from University of Mumbai (Bombay), India in 2001; M.S. in Biophysics from University of Mumbai (Bombay), India in 2003; Ph.D. in Systems Biology and Physiology from University of Cincinnati, Ohio in 2009. Currently, he is working as a Research Associate at Tufts University’s Center for Regenerative and Developmental Biology (TCRDB) under the leadership of Dr. Michael Levin.

  • Exploring Doctoral Admissions Practices in Physics

    March 28, 2014, 1:30pm-2:30pm, AHC3 205

    Dr. Geoff Potvin Assistant Professor STEM Transformation Institute Florida International University

    Abstract:

    Sustaining or improving the best graduate programs as well as increasing the diversity of the physics community requires us to better understand the critical gatekeeping role played by graduate admissions and the ways to make graduate education most effective in its preparation of future physicists. Admissions processes determine not only who is allowed to begin graduate study but can also influence who chooses to even consider applying. Recently, in concert with some of the activities of the APS Bridge Program, a survey was conducted of directors of graduate admissions and associated faculty in doctoral-granting departments about their admissions practices. Receiving responses from over 75% of departments in the U.S. that award physics PhDs, respondents were probed about their admissions decisions with special attention on the criteria used in admissions and their relative importance, and how student representation considerations are dealt with in the admissions process (if at all). Results indicate a number of important issues for future students, faculty, and administrators to consider including the importance placed on GRE scores. The results of this survey will be discussed in the context of prior research on success in graduate school and subsequent career productivity in science.

    Biography:

    Geoff Potvin completed his doctorate in theoretical physics at the University of Toronto before taking up a science education postdoctorate in the Curry School of Education at the University of Virginia. Prior to coming to FIU in January 2014, he spent five years as a faculty member in the Department of Engineering & Science Education at Clemson University. He is a member of the APS Forum on Education's Executive Committee and the American Association of Physics Teachers's Committee on Diversity. His research is focused on understanding diversity issues in the physical sciences and engineering at the undergraduate and graduate levels. Using an identity lens, he studies how educational practices and other experiences influence students' attitudes and career intentions, especially for those who are traditionally marginalized from STEM. He is working with the APS Bridge Program to understand how departmental admissions and retention practices can help to g

  • Scalable laser nano-engineered thin film processing

    March 21, 2014, 1:30pm-2:30pm, AHC3 205

    Professor Gary Cheng is an Associate Professor at School of Industrial Engineering and School of Mechanical Engineering, Purdue University.

    Abstract:

    Roll to roll processing of thin film has been one of the most promising and challenging technologies for industries, such as solar cells, LED, and TFT, optic-electric devices, etc. The primary barriers are cost and quality. One of the problems of the current thin film deposition is the crystal defects density, which is too high to have ideal physical property, such as conductivity, electron mobility, and quantum efficiency. In addition, scalable 2D/3D patterned thin film structures are needed for unique physical properties. For example, 3D thin film structures could be used as a strong light absorbent or concentrators. However, the current thin film processing is limited by high temperature, non-selective and high cost. There is a critical need for fast, selective, room temperature and low cost thin film processing techniques. This talk will discuss the process mechanisms of several new processes, which promise to solve most of these problems simultaneously, including laser crystallization, 3D shaping, and surface nanostructuring.

    Biography:

    Gary J. Cheng received a B.S. and M.S. in Materials Science from University of Science and Technology Beijing, China, and a Ph.D. from Columbia University in Mechanical Engineering in 2002. He is an Associate Professor at School of Industrial Engineering and School of Mechanical Engineering, Purdue University. His research focuses on laser materials processing, micro/nano manufacturing, bulk manufacturing of micro/nano 3D structures, mechanical/physical property enhancement of materials, renewable energy. He received the Young Investigator Award from the Office of Naval Research (ONR) in 2007 and the CAREER Award from the National Science Foundation (NSF) in 2006, Outstanding Young Manufacturing Engineer award from the Society of Manufacturing Engineer (SME) in 2007, ASME Chao & Trigger Young Investigator award. He has published 80 Journal articles and 14 US patents.

  • Doing Science with the Titan Supercomputer

    March 7, 2014, 1:30pm-2:30pm, AHC3 205

    Fernanda Foertter, Training Coordinator and HPC User Assistance Specialist, Oak Ridge Leadership Computing Facility

    Abstract

    The Oak Ridge Leadership Computing Facility (OLCF) was established at Oak Ridge National Laboratory in 2004 with the mission of standing up a supercomputer 100 times more powerful than the leading systems of the day. We continue delivering that promise with Titan, the fastest open science supercomputer in the United States. This hybrid system is delivering breakthrough scientific research in many areas, including materials science, astrophysics, climate, energy research and many other fields. This talk will give an overview of the science being done at OLCF and explore the future challenges and opportunities as we prepare for exascale. Specific information on how to apply for allocations of our computing resources will also be shared.

    Biography

    Ms. Fernanda obtained her B.S. in Physics from FIU in 2002. She obtained her M.S. in Materials Science and Engineering from UF in 2008. Currently, she is the Training Coordinator and HPC User Assistance Specialist at the Oak Ridge Leadership Computing Facility.

  • Heavy Gauge Boson Measurements in pp Collisions at 7 and 8 TeV Energies with the CMS Experiment

    Feb. 21, 2014, 1:30pm-2:30pm, AHC3 205

    Dr. Dimitri Bourilkov, University of Florida, Gainesville

    Abstract:

    With the Higgs discovery the LHC experiments at the CERN pp collider started the exploration of the last missing piece of the Standard Model of particle physics. To make this discovery the Higgs "needles" have to be separated from the huge stack of Standard Model backgrounds. In this talk I will concentrate on the production and decays of heavy gauge bosons at center-of-mass energies of 7 and 8 TeV, as measured by the CMS experiment. They enable a large variety of physics studies, in addition to being an integral part of the Higgs search. Measurements of inclusive W, Z and Drell Yan production cross sections with decays to electrons or muons are presented, based on data recorded by the CMS detector between 2010 and 2012. These results constrain the parton densities for valence and sea quarks in the protons, and put stringent limits on many popular extensions of the Standard Model. Precise measurements of di-boson production will be discussed next: WW, WZ and ZZ decaying to leptons, and WW+WZ pairs decaying semi-leptonically. We present first studies of exclusive and quasi-exclusive W+W- production in 7 TeV p-p collisions at the LHC, and studies of triple boson final states involving photons. The results are interpreted in terms of constraints on anomalous triple or quartic gauge boson couplings.

    Biography:

    Dimitri Bourilkov graduated from Sofia University, Bulgaria, in 1978, and completed his Ph.D. in particle physics in 1986 at the Institute for Nuclear Research in Sofia. During these years he was a member of the BIS2 collaboration at the Serpukhov accelerator in Russia, studying charm and strange hadron production in strong interactions. From 1988-2001 he worked in the Katholieke Universiteit Nijmegen, the Netherlands, and Swiss Federal Institute of Technology, Zurich, teams in the L3 experiment at the e+e- collider at CERN, studying the di-electron and di-muon channels and searching for new physics like contact interactions, large extra dimensions in low scale gravity models, Z' bosons, leptoquarks or supersymmetric neutrinos. In 1994 Dr. Bourilkov joined the CMS experiment, and is working full time on it since 2001 as Scientist at the University of Florida, USA. His current interests include the study of W, Z and Drell-Yan production, parton density functions, searches for contact interactions, extra dimensions and heavy gauge bosons Z', and grid/cloud computing.

  • Experiments with an ultracold Fermi gas -new prospective of tackling old condensed matter problems

    Feb. 14, 2014, 1:30pm-2:30pm, AHC3 205

    Dr. Yoav Sagi, Postdoctoral Research Associate JILA, University of Colorado and National Institute of Standards and Technology

    Abstract:

    The collective behavior of an ensemble of strongly interacting fermions is central to many physical systems, including high-Tc superconductors, heavy fermion materials, liquid 3He, quark-gluon plasma, neutron stars, and ultracold Fermi gases. Theoretical understanding of these systems is challenging due to the many-body nature of the problem and the lack of an obvious small parameter for a perturbative analysis. In this lecture I will introduce you to our experimental system, in which we use lasers to trap fermionic atoms (40K) in two internal spin states, and cool them down to ultralow temperatures while still maintaining their gaseous state. Similar to electrons in a metal, at low enough temperatures the spins pair and condense while creating a fermionic superfluid. This is an ideal model system to shed light on long-standing many-body problems, as it provides excellent controllability, reproducibility, and unique detection methods. I will describe several of these detection methods developed at JILA, which provide invaluable insight into the many-body state of the system. The talk will conclude with an overview of the open questions and future challenges we and others are facing.

    Biography:

    Dr. Yoav Sagi received his B.Sc. in physics and mathematics from the Hebrew University in Jerusalem in 1999, as part of the prestigious Talpiot excellence program. He received the Physics M.Sc. from the Technion, Israel Institute of Technology, in the field of quantum optics and quantum information. For his PhD, he moved into the field of ultracold atoms, joining Prof. Nir Davidson at the Weizmann Institute of Science. At 2010, Dr. Sagi joined Prof. Deborah Jin from JILA (Boulder, CO). His postdoctoral research is focused on extracting quantities of a homogeneous Fermi gas, in a system which is intrinsically inhomogeneous because of the confining potential. Dr. Yoav Sagi won several prizes and fellowships, including the John F. Kennedy Award (highest prize conferred by the Feinberg Graduate School at the Weizmann Institute of Science), the Rothschild postdoctoral fellowship, and the Fulbright fellowship (which I declined). His PhD work was published as a book in the Springer Theses series (“recognizing outstanding Ph.D. research“). Dr. Yoav Sagi will start a new experimental group this summer in the Physics department in the Technion, Israel.

  • Spin-selective Charge Recombination Dynamics in Organic Materials

    Feb. 7, 2014, 1:30pm-2:30pm, AHC3 205

    Dr. Amy M. Scott, Assistant Professor of Chemistry, Department of Chemistry, University of Miami

    Abstract:

    Artificial photosynthesis examines how sunlight is converted into different forms of usable energy, such as electricity and hydrogen (H2), in molecules that mimic the proteins in photosynthetic plants and bacteria. This is particularly relevant in renewable energies, where solar energy has the greatest potential as the most benign, universal resource for generating electricity. Just in the U.S. alone, approximately 2,200 TW is available on land and easily surpasses the 30 TW or more energy needed to meet the world’s energy needs by the year 2050, but harnessing that energy efficiently and converting it towards useful forms of power that are compatible with our current infrastructure remains a current challenge for researchers. My research efforts focus on understanding how to efficiently convert sunlight to electrical energy in new organic materials in two contexts: i) in model systems of covalently linked Donor-Bridge-Acceptor (DBA) systems that mimic the electron transport chain in photosynthetic reaction centers and ii) in photoactive liquid crystalline materials for organic photovoltaics (OPVs). We utilize ultrafast transient absorption spectroscopy to directly measure kinetic rates of photoinduced charge separation and recombination, and we study how electron spin dynamics control recombination pathways in organic materials.

    Biography:

    Dr. Amy M. Scott earned her ACS certified B.S. degree in chemistry at the University of Colorado, Colorado Springs and her Ph.D. in experimental physical chemistry at Northwestern University in 2009. She spent one year as a postdoctoral researcher at Argonne National Laboratory in Chicago, IL, and two years as a Dreyfus Environmental Postdoctoral Researcher at Columbia University in New York, NY working with Professors Colin Nuckolls and Nicholas Turro.

  • Breaking Barriers in “Understanding the Mind”

    Jan. 31, 2014, 1:30pm-2:30pm, AHC3 205

    Dr. Sakhrat Khizroev, Director, Center for Personalized Nanomedicine lab, Florida International University

    Abstract:

    Today, there is no practical way to directly map the electric field in response to the neural activity; nor is there a way to remotely stimulate the neural activity deep in the brain. A few years ago, we proposed to use energy-efficient magneto-electric nanoparticles (MENs) to bridge remote magnetic fields with the intrinsic electric fields deep in the brain and thus enable both electric-field mapping and remotely-controlled stimulation. Like the conventional magnetic nanoparticles (MNs), used as magnetic resonance imaging (MRI) contrast agents, the MENs have a non-zero magnetic moment and therefore their spatial distribution can be controlled remotely via an external magnetic field gradient. In addition, unlike the conventional MNs, MENs display an entirely new property, which is non-zero magneto-electric (ME) effect. This ME coupling can be used to enable remote stimulation of selective regions in the brain as well as sensing the local electric field induced by the neural activity in the brain. To use MENs for electric-field mapping, the new nanoparticles must be used together with an existing magnetic imaging technique such as MRI or the recently emerged magnetic nanoparticle imaging (MNI). In this case, MENs modulate the typical structural image obtained by MRI with the local electric field. Moreover, when used with MNI, MENs can be used for field mapping in real time (with a temporal resolution in the microsecond range). The potential applications span from the prevention and treatment of neurological disorders to opening a pathway to fundamental understanding of the brain. Further, MNI in conjunction with MENs is suitable for real-time studies of the neural activity field dynamics deep in the brain to understand less known intrinsic processes. This talk will summarize the current findings of our in-vitro and in-vivo studies.

    Biography:

    Dr. Sakhrat Khizroev received a B.S/M.S. degree in Physics from Moscow Institute of Physics and Technology in 1992/1994 and a PhD degree in Electrical and Computer Engineering from Carnegie Mellon University in 1999. After graduation, Dr. Khizroev spent almost four years as a Research Staff Member with Seagate Research (1999-2003). From 2003-2005, he was an Associate Professor of Electrical Engineering at FIU. From 2005-2011, Dr. Khizroev was a faculty at the Department of Electrical Engineering of the University of California, Riverside (UCR). At 2011, Dr. Khizroev re-joined FIU to lead the university-wide multi-disciplinary research effort in personalized nanomedicine. Dr. Sakhrat Khizroev is an inventor with an expertise in nanomagnetic/spintronic devices. Khizroev was named a Fellow of National Academy of Inventors (2012). He holds over 30 granted US patents plus many international patents. He has authored over 120 refereed papers. His background is in physics and electrical engineering. His group’s current research focus is at the intersection of nanoengineering with medicine. Though he is a tenured professor at the College of Engineering, today his main lab is at the College of Medicine where his team works hand-in-hand with leading medical researchers and clinicians to advance the state of the art in areas of Oncology, HIV/AIDs, Neurodegenerative Diseases, Ophthalmology, and others.

  • Lux et Lex: Optical Traps for β decay studies

    Jan. 17, 2014, 1:30pm-2:30pm, AHC3 205

    Dr. Guy Ron Racah Institute of Physics Hebrew University of Jerusalem

    Abstract

    Trapped radioactive atoms and ions have become a standard tool of the trade for precision studies of beyond SM physics. β decay studies, in particular, offer the possibility of detecting deviations from standard model predictions of the weak interaction which signal new physics. These 'precision frontier' searches are complementary to the high energy searches performed by the LHC and other high energy/high luminosity facilities. I will present a general overview of magnetooptical and optical traps and their use for weak interaction studies. I will further present both the Berkeley 21Na trapping experiment and the new Hebrew University 17-25Ne trapping program, recent experimental results, and future plans.

    Biography

    Guy Ron graduated 2009 from Tel Aviv University working with Prof. Eli Piasetzky on high precision measurements of proton form factor ratios at the Thomas Jefferson National Accelerator Facility CEBAF Accelerator. After a short postdoc at the Weizmann Institute jointly with Prof. Micha Hass and Prof. Nir Davidson he moved in Mid- 2009 to the Lawrence Berkeley National Lab to work with the late Prof. Stuart Freedman on high precision measurements of the beta decay of trapped atoms and ions. In 2011 Dr. Ron took up a position as an assistant professor at the Hebrew University of Jerusalem. His current research interest include: high precision measurements of the beta decay of trapped neon and helium isotopes, accelerator based measurements of nucleon charge and magnetization densities and radii, and positron annihilation spectroscopy as a probe of material and surface structure.