Materials by Design: Accelerating Discovery and Innovation Through Computational Simulations3365 Thomas Gosnell Hall
Materials by Design: Accelerating Discovery and Innovation Through Computational SimulationsWednesday, September 27, 2017
The need to discover and design materials with precise functionalities is key to modern technology. The functionality requirement in new materials make atomic and nanoscale design a necessity. However, at the nanoscale, synthesis of every new material via a trial and error approach is not only arduous, but also expensive. Recent advancements in theoretical methods along with ever-increasing computational resources have altered the interplay between computation and experiment. In this context, I will elucidate the concept of Materials by Design. Complex oxides are indispensable materials in renewable energy technologies such as fuel cells, batteries, energy storage, etc. I will elaborate on our use of computational tools based on density functional theory, molecular dynamics, and kinetic Monte Carlo methods to identify the underlying mechanisms that govern the properties of nanostructured complex oxides. Fundamental understanding of these mechanisms assists in designing nanomaterials with tailored properties. Potential research opportunities for students interested in utilizing computational physics and materials science for next-generation technology development will be discussed.
Physics Colloquium: Bailey3365 Thomas Gosnell Hall
Physics Colloquium: BaileyWednesday, October 11, 2017
Physics Colloquium3365 Thomas Gosnell Hall
Physics ColloquiumWednesday, October 25, 2017
Physics Colloquium: Robinson3365 Thomas Gosnell Hall
Physics Colloquium: RobinsonWednesday, November 1, 2017
Physics Colloquium: Loucks3365 Thomas Gosnell Hall
Physics Colloquium: LoucksWednesday, November 8, 2017
Science Policy and You (Yes, You!)1275 Carlson Building
Science Policy and You (Yes, You!)Monday, October 2, 2017
As science educators, researchers, communicators, and/or supporters, we cannot deny the connection between science and government. The ability to send missions to Mars, to study star formation in a galaxy, and to model the early universe primarily depends on both government -- i.e., taxpayer -- money and public -- i.e., not just scientist -- support. Scientists can and do engage in work to determine the direction of our field and how society prioritizes science. In this talk, I will focus on ways that policy impacts science, how you, as an individual, can influence policy, and how the American Astronomical Society (AAS) advocates for the astronomical sciences in Washington.
AST Colloquium: Charlie Qi1275 Carlson Building
AST Colloquium: Charlie QiMonday, October 16, 2017
AST Colloquium: Sivanandam1275 Carlson Building
AST Colloquium: SivanandamMonday, October 30, 2017
AST Colloquium: Lauranne Lanz1275 Carlson Building
AST Colloquium: Lauranne LanzMonday, November 13, 2017
AST Colloquium: Erik Shirokoff1275 Carlson Building
AST Colloquium: Erik ShirokoffMonday, November 27, 2017
AST Colloquium: Chris Belczynski1275 Carlson Building
AST Colloquium: Chris BelczynskiMonday, December 11, 2017
Conference for Undergraduate Women in Physics (CUWiP)
Conference for Undergraduate Women in Physics (CUWiP)Friday, January 12, 2018
Welcome Reception will be held on Friday January 12th. More information will be posted soon.
The Conference will run from January 12th to January 14th
Highlights of the High Energy Universe from HAWC
Highlights of the High Energy Universe from HAWCMonday, September 18, 2017
During the past decade, the observation of teraelectronvolt (TeV) cosmic rays and gamma rays has opened a new frontier in the study of astrophysical particle accelerators such as super nova remnants, pulsars, microquasars, and active galactic nuclei. This energetic radiation can also be used to explore physics beyond the Standard Model, such as the particle nature of dark matter. Since 2015 the High Altitude Water Cherenkov (HAWC) Observatory has recorded TeV gamma rays and cosmic rays from 2/3 of the sky each day. I will report on recent results from HAWC, including the discovery of nearly 20 new gamma ray sources and high-statistics observations of cosmic rays.
TARdYS an upcoming exoplanet hunter for the southern hemisphere
TARdYS an upcoming exoplanet hunter for the southern hemisphereMonday, July 10, 2017
The relatively close habitable zone to the host stars of the very common cool-low mass stars makes M dwarfs attractive for finding habitable planets. Up to date only a few of these stars can be observed by visible high resolution spectrographs since M dwarfs emit the peak of its energy at λ>900 nm in the near infrared region. We optimized a spectrograph for the observation of cool stars in the southern hemisphere where only a few high resolution near infrared spectrographs are available. TARdYS is a high resolution echelle spectrograph to be installed at the Tokyo Atacama Observatory TAO 6.5 m telescope. This spectrograph is a dual fiber fed, white pupil Echelle, which can yield R>50,000 within the spectral range of 0.843-1.117 μm covers Y band. We adopt an echelle R6, 13.33 lines/mm and a VPH 333 lines/mm grating as cross disperser. A Teledyne H1RG detector will be operated in a cryogenic environment cooled to 80K. Our optimization using computer-aided simulation programs results in excellent resolution performance within the diffraction limit even when taking realistic manufacturing and alignment tolerances into account. We will discuss challenges and design decisions of an upcoming exoplanet hunter in the southern hemisphere. The overall instrument system design and ongoing development of TARdYS will be presented.
Quanta Image Sensor: Every Photon Counts
Quanta Image Sensor: Every Photon CountsMonday, April 24, 2017
The Quanta Image Sensor (QIS) is a possible paradigm shift in solid-state image sensors. Conceptually, the QIS counts photons one at a time using small pixels with low full-well capacity and single-photoelectron sensitivity. This binary data is collected and transformed into gray scale images by post-acquisition digital image processing. In recent years, the QIS has moved from concept to experimental devices. A 1Mpixel QIS has been designed and fabricated in a commercial stacked, backside-illuminated CMOS image sensor 65/45nm node process. The device, with 1.1um shared-readout pixel pitch, has been shown to have read noise as low as 0.172e- rms at room temperature without the use of avalanche multiplication, and is successfully readout at 1040fps using a cluster-parallel readout architecture. Each binary bit represents the detection or absence of a photoelectron.
The QIS technology is evolved from the CMOS image sensor currently incorporated into billions of cameras each year. In a preamble to the QIS part of the talk, the invention and development of the CMOS image sensor technology at the NASA Jet Propulsion Laboratory at Caltech, and by the spinoff company Photobit will be discussed.
The Intricate Role of Cold Gas and Dust in Galaxy Evolution at Early Cosmic Epochs
The Intricate Role of Cold Gas and Dust in Galaxy Evolution at Early Cosmic EpochsMonday, April 10, 2017
Dusty starburst galaxies at very high redshift represent an important phase in the early evolution of massive galaxies. They typically represent large-scale, gas-rich major mergers that trigger intense, short-lived bursts of star formation, which consume most of the available gas and drive the morphological transition to spheroids. At early cosmic epochs, these hyper-luminous galaxies commonly trace regions of high galaxy overdensity, and may be directly related to the formation of galaxy clusters and their giant central ellipticals. Molecular and atomic gas plays a central role in our understanding of the nature of these often heavily obscured distant systems. It represents the material that stars form out of, and its mass, distribution, excitation, and dynamics provide crucial insight into the physical processes that support the ongoing star formation and stellar mass buildup. I will discuss the most recent progress in studies of the cold gas content of dusty starburst galaxies at high redshift, back to the first billion years of cosmic time using CARMA, the Jansky Very Large Array, the Plateau de Bure interferometer, and the Atacama Large (sub)Millimeter Array (ALMA). I will also highlight our recent successful first detections of the interstellar medium in "normal" (~L*) galaxies at z>5 with ALMA, and discuss the impact of our findings on future studies back to even earlier epochs.
New Approaches to Dark Matter
New Approaches to Dark MatterMonday, March 27, 2017
In this talk I will discuss a novel theory of superfluid dark matter. The scenario matches the predictions of the Lambda-Cold-Dark-Matter (LambdaCDM) model on cosmological scales while simultaneously reproducing the MOdified Newtonian Dynamics (MOND) empirical success on galactic scales. The dark matter and MOND components have a common origin, as different phases of a single underlying substance. This is achieved through the rich and well-studied physics of superfluidity. The framework naturally distinguishes between galaxies (where MOND is successful) and galaxy clusters (where MOND is not): due to the higher velocity dispersion in clusters, and correspondingly higher temperature, the dark matter in clusters is either in a mixture of superfluid and normal phases, or fully in the normal phase. The model makes various observational predictions that distinguishes it from both LambdaCDM and standard MOND. In the last part of the talk, I will discuss an on-going attempt at explaining cosmic acceleration as yet another manifestation of dark matter superfluidity.
Unveiling Black Hole Growth Over Cosmic Time
Unveiling Black Hole Growth Over Cosmic TimeMonday, February 27, 2017
Supermassive black holes, millions to billions of times the mass of our Sun, live in the center of every massive galaxy. When they grow via the process of accretion, they are observed as Active Galactic Nuclei (AGN). In addition to being among the most energetic sources in the Universe, AGN seemed to be intrinsically linked to the galaxies in which they reside. By surveying regions of the sky, we can discover AGN from early cosmic times to the present day, thereby learning about supermassive black hole growth and evolution and the role they may play in shaping their host galaxies. Currently, we are missing an important piece of the puzzle in AGN evolution - luminous obscured black hole growth. To this end, I am leading a wide area X-ray survey: by probing a large volume of the Universe, a representative sample of rare objects are detected, and X-rays pierce through dust that obscures optical light, recovering AGN missed by optical surveys. By executing this survey in the Stripe 82 region of the Sloan Digital Sky Survey which contains rich multi-wavelength coverage, we have the ancillary data necessary to characterize the AGN and their host galaxies. In this talk, I will give an overview of this “Stripe 82X" survey, summarize the properties of the objects we have detected thus far, discuss what we are planning to learn from this dataset in the coming years, and how we can these data to develop best-effort practices to push into new discovery space with upcoming missions like JWST, WFIRST, LSST, and eROSITA. I will highlight a peculiar source I discovered in this survey which has now become a burgeoning subfield in AGN physics, providing unique insight into AGN lifetimes and black hole fueling.
Modeling Baryonic Physics in Galaxy Clusters
Modeling Baryonic Physics in Galaxy ClustersMonday, February 13, 2017
A Galaxy-Scale Fountain of Cold Molecular Gas Pumped by a Black Hole
A Galaxy-Scale Fountain of Cold Molecular Gas Pumped by a Black HoleMonday, January 30, 2017
A new ALMA observation of the cool core brightest cluster galaxy in Abell 2597 reveals that a supermassive black hole can act much like a mechanical pump in a water fountain, driving a convective flow of molecular gas that drains into the black hole accretion reservoir, only to be pushed outward again in a jet-driven outflow that then rains back toward the galaxy center from which it came. The ALMA data reveal "shadows" cast by giant molecular clouds falling on ballistic trajectories towards the black hole in the innermost hundred parsecs of the galaxy, manifesting as deep redshifted continuum absorption features. The black hole accretion reservoir, fueled by these infalling cold clouds, powers an AGN that drives a jet-driven molecular outflow in the form of a 10 kpc-scale, billion solar mass expanding molecular bubble. HST reveals that the molecular shell is permeated with young stars, perhaps triggered in situ by the jet. Buoyant X-ray cavities excavated by the propagating radio source may further uplift the molecular filaments, which are observed to fall inward toward the center of the galaxy from which they came, presumably keeping the fountain long-lived. I will discuss this specific result in the larger context of galaxies as a whole, as the results show that cold molecular gas can couple to black hole growth via both feedback and feeding, in alignment with "cold chaotic accretion" models for the regulation of star formation in galaxies.
Opening the gravitational wave universe: the physics behind a new type of astronomy
Opening the gravitational wave universe: the physics behind a new type of astronomyMonday, December 12, 2016
Hosted by the School of Physics & Astronomy and the Center for Computational Relativity and Gravitation
With the first direct detection of gravitational waves, the LIGO detectors have opened a new field of astrophysics, discovered a new class of massive stellar mass black holes, and enabled tests of general relativity. To make these discoveries, we built the most sensitive displacement meters yet, measuring displacements of one thousandth of a proton diameter over a 4 kilometer baseline. This talk will focus on the physics of the ground breaking detectors, and the possibilities for extending their reach. One of the most promising techniques for improving the sensitivity is the use of squeezed states to reduce quantum noise. l will describe a test of squeezing in the LIGO interferometers, and implications for the permanent application of squeezing in Advanced LIGO over the next few years. Because gravitational wave detectors measure amplitude rather than power, improvements in sensitivity from squeezing, cryogenic operation and new optical materials have the potential to dramatically increase the volume of the universe which can be surveyed. In a new and larger facility, LIGO style detectors could observe compact object binaries from the earliest periods of star formation, making complete surveys at distances difficult to observe with optical telescopes.
The Future of Gravitational Wave Interferometers
The Future of Gravitational Wave InterferometersMonday, December 5, 2016
Hosted by the School of Physics & Astronomy and the Center for Computational Relativity and Gravitation
The recent detection of gravitational waves from binary black hole mergers marks the beginning of the field of gravitational wave astronomy. New and more sensitive techniques will be required to continue expanding our understanding of the universe through gravitational waves. Current research and development efforts range from surpassing the standard quantum limit using squeezed states, to improving thermal noise at the frontiers of the material science of optical coatings, to the conceptual design of new interferometer topologies. These noise reduction efforts will increase the sensitivity of the detectors, allowing the measurement of smaller effects and extending our reach to cosmological scales.
The radial acceleration relation: linking baryons and dark matter in galaxies
The radial acceleration relation: linking baryons and dark matter in galaxiesMonday, November 21, 2016
The flat rotation curves of spiral galaxies provided clear evidence for mass discrepancies in galactic systems, but the nature of dark matter (DM) still remains elusive. I will describe recent results from the Spitzer Photometry and Accurate Rotation Curves (SPARC) dataset: the largest collection of HI rotation curves currently available for late-type galaxies (spirals and irregulars). New Spitzer photometry at 3.6 um provides the closest proxy to the stellar mass, allowing precise estimates of the baryonic gravitational field at every radii (g_bar). We find that the observed acceleration correlates with g_bar over 4 dex, implying a close link between baryons and DM in galaxies. This radial acceleration relation coincides with unity (no DM) at high g_bar but systematically deviates below a critical acceleration scale. The observed scatter is remarkably small, even when DM dominates at low g_bar. Early-type galaxies (ellipticals, lenticulars, and dwarf spheroidals) follow the same relation as late-type galaxies. The radial acceleration relation is tantamount to a "Kepler Law" for galactic systems: when the baryonic contribution is measured, the rotation curve follows, and vice versa. I will discuss possible interpretations within the standard LCDM cosmology as well as alternative theories.
Studying planet formation processes with molecular spectroscopy
Studying planet formation processes with molecular spectroscopyMonday, November 7, 2016
As our understanding of the solar system and exoplanetary systems continues to grow, our view of planet formation processes must expand to accommodate the incredibly diversity of formation outcomes. I will focus this talk on my favorite technique for studying planet formation processes in action - molecular spectroscopy. I will review the techniques of molecular spectroscopy and discuss how they can be used to tackle key questions about planet formation, including: Where does water freeze, and does this correspond with giant planet formation? Are there spectroscopic signatures of disk evolution, or the presence of planets? What factors determine the final chemical make-up of a planet? I will highlight some of the incredible progress that has been made on answering these questions in recent years, and provide updates on ongoing projects, including several involving undergraduate students.
Illuminating the Black Hole – Galaxy Connection with CANDELS
Illuminating the Black Hole – Galaxy Connection with CANDELSMonday, October 24, 2016
Supermassive black holes, and the active galactic nuclei (AGN) that they power, are thought to play an integral role in the evolution of galaxies by acting to regulate, and eventually suppress, the star formation activity of their host galaxies. I will discuss recent efforts to test this proposed connection by studying the demographics of galaxies undergoing active black hole growth. In particular, I will highlight recent results from the CANDELS survey, whose panchromatic Hubble ACS and WFC3 imaging is now allowing us to characterize the morphologies and stellar populations of thousands of AGN hosts out to z=2, the era when star formation activity and black hole growth in the Universe are at their peak. I will discuss what CANDELS is currently revealing about the mechanisms that fuel AGN activity at this epoch and the connection between black hole growth and the emergence of the first generation of passive galaxies in the Universe.
Glimpses of futuristic cosmology: relativistic effects and spectral maps
Glimpses of futuristic cosmology: relativistic effects and spectral mapsMonday, October 10, 2016
Bridging interferometry and astrophysics: noise and the future of gravitational wave astronomy
Bridging interferometry and astrophysics: noise and the future of gravitational wave astronomyMonday, September 26, 2016
Inside-Out Planet Formation
Inside-Out Planet FormationMonday, May 9, 2016
Unveiling the dark side of the Universe
Unveiling the dark side of the UniverseMonday, May 2, 2016
Dusty UniverseMonday, April 25, 2016
Dr. Cooray will summarize the scientific case for studying the universe and Far-Infrared and sub-millimeter wavelengths. She will present results from Herschel, summarize on going plans for ground-based instruments, and outline the ongoing Far-Infared Surveyor study facilitated by NASA for 2020 Decadal Surveyor.
Galaxy Mergers on FIRE: Mapping Star Formation
Galaxy Mergers on FIRE: Mapping Star FormationMonday, March 21, 2016
Galaxy mergers and interactions are responsible for generating bursts of star formation, for changing galactic morphology in dramatic ways, and for triggering single and dual active galactic nuclei. In this talk, I will unveil the very first results from a novel suite of high-resolution galaxy merger simulations, based on the “Feedback In Realistic Environments” (FIRE) model. This model treats energy and momentum-driven feedback from young stars and SN explosions explicitly, which acts directly on resolved star-forming clouds within the ISM. Moreover, this framework relies on a new meshless Lagrangian hydro code, GIZMO, which solves many problems associated with older solvers. Our first work focuses on the spatial localization of star formation. In particular, we confirm results from previous work: galaxy-galaxy interactions enhance nuclear star formation, and suppress it at large galacto-centric radii (Moreno et al. 2015). However, two major differences are found. First, star-formation enhancement and suppression are not as dramatic as in older models. Secondly, the interaction-induced nuclear starburst has a larger spatial extent. These differences are a reflection of the fact that, in our new models, non-axisymmetric gravitational torques are not as effective at driving fuel into the central regions as in older sub-grid based models. This suite of merger simulations is ideal for making predictions for, and interpreting results from, observations by new-generation integral field spectroscopic surveys, such as CALIFA, MaNGA and HECTOR.
New astronomical projects from Japan: TAO and the Tomo-e Gozen Camera
New astronomical projects from Japan: TAO and the Tomo-e Gozen CameraMonday, March 7, 2016
The Biggest Blowhards: Windy Supermassive Black Holes
The Biggest Blowhards: Windy Supermassive Black HolesMonday, February 29, 2016
Cosmological Simulations of Galaxy Formation and Evolution
Cosmological Simulations of Galaxy Formation and EvolutionMonday, December 7, 2015
A predictive theory of galaxy formation remains elusive, even after more than 50 years of dedicated effort by many renowned astrophysicists. The problem of galaxy formation is made difficult by the large range in scales involved and the many non-linear physical processes at work. In this talk, I describe a new generation of numerical models designed to overcome these difficulties based on novel schemes for solving the fluid equations on a moving mesh. Initial results from this study provide insight into many aspects of galaxy assembly and the relationship between galaxies and cosmologically-distributed baryons.
Dark Energy Spectroscopic Instrument
Dark Energy Spectroscopic InstrumentMonday, November 23, 2015
Successes and failures of LambdaCDM and its alternatives
Successes and failures of LambdaCDM and its alternativesMonday, October 19, 2015
Exoplanet Climatology: The Next Era of Habitable-planet Hunting
Exoplanet Climatology: The Next Era of Habitable-planet HuntingMonday, October 12, 2015
Star Formation in the Midst of Upheaval - Goings On in the Centers of Rich Clusters of Galaxies
Star Formation in the Midst of Upheaval - Goings On in the Centers of Rich Clusters of GalaxiesMonday, October 5, 2015
How and where does star formation occur in elliptical galaxies sitting at the centers of rich clusters of galaxies in the midst of cooling cores of hot-xray gas, mergers of galaxies, and powerful outflowing jets emanating from a central black hole? Recent ALMA (millimeter), HST (ultraviolet) and Ground Based (Optical) observations reveal more detailed information on the interplay of energetics, activity and star formation in these unique environments.
RIT Observatory: Open House
RIT Observatory: Open HouseSunday, September 27, 2015
Rings and Radial Waves in the Milky Way's Stellar Disk
Rings and Radial Waves in the Milky Way's Stellar DiskMonday, September 21, 2015
Abstract: I will show that there is an asymmetry in the main sequence star counts on either side of the Galactic plane, as one looks towards the Galactic anticenter. This can be explained if the disk of the Milky Way oscillates up and down. This oscillation could provide an explanation for the Monoceros Ring, and also for the TriAndromeda Stream (or Ring). The implication is that the stellar disk extends out to at least 25 kpc from the Galactic center - much farther than the canonical 15 kpc that is typically quoted. The oscillations are aligned with the spiral arms of the Milky Way, and are plausibly consistent with previous predictions for disk ringing due to a Sagittarius dwarf-sized galaxy plunging through the disk.
What neutrinos and magnetic turbulence do to nuclear-density toroidal stars and disks: some numerical relativity models
What neutrinos and magnetic turbulence do to nuclear-density toroidal stars and disks: some numerical relativity modelsMonday, May 11, 2015
RR Lyrae Stars in M31, M32 and M33
RR Lyrae Stars in M31, M32 and M33Monday, May 4, 2015
Gas in Local Dwarf Galaxies
Gas in Local Dwarf GalaxiesMonday, April 27, 2015
Scrutinizing the Relationship Between Galaxies and Supermassive Black Holes
Scrutinizing the Relationship Between Galaxies and Supermassive Black HolesMonday, April 20, 2015
[Re]Exploring the Universe with [NEO]WISE
[Re]Exploring the Universe with [NEO]WISEMonday, April 13, 2015
Observable Signatures of Neutron Star Mergers
Observable Signatures of Neutron Star MergersFriday, March 20, 2015
Bose-Einstein Condensate Axion Dark Matter
Bose-Einstein Condensate Axion Dark MatterMonday, March 16, 2015
"Tension" in the Extragalactic Distance Scale and "New Physics": Ending the Debate over the Hubble Constant
"Tension" in the Extragalactic Distance Scale and "New Physics": Ending the Debate over the Hubble ConstantMonday, December 1, 2014
Determining the Cause of Cosmological Acceleration with Large Astronomical Surveys
Determining the Cause of Cosmological Acceleration with Large Astronomical SurveysMonday, November 24, 2014
Are exoplanets really tidally synchronized?
Are exoplanets really tidally synchronized?Friday, November 21, 2014
Where's the Matter? : Tails form the Milky Way's Past
Where's the Matter? : Tails form the Milky Way's PastMonday, October 27, 2014
The Physics of Evolved Stars
The Physics of Evolved StarsMonday, October 6, 2014
Novel Materials and Nanostructures for Photovoltaic Energy Conversion
Photons After Dark
Novel Materials and Nanostructures for Photovoltaic Energy ConversionWednesday, September 13, 2017
Polarized Vision for Astronomers and Other Humans
Photons After Dark
Polarized Vision for Astronomers and Other HumansWednesday, April 26, 2017
Humans have long benefitted from our ability to distinguish light of different frequency based on its color. Sadly, our eyes are not sensitive to the polarization of light. As a result, we are far less familiar with the utility of polarimetric measurement. Devices to measure polarization are relatively rare and expertise in polarimetry even more so. Polarization sensors based on micropolarizer arrays appear to be the first devices capable of bringing polarimetric capability to a wide range of applications. Based on a combination of theoretical models and lab-based measurements, I conclude that the current generation of these devices can measure fractional polarization as small as 0.5%, across the visible and near-infrared spectrum, with potential for further improvement. I will present some astronomical observations acquired with the RIT Polarization Imaging Camera and end with a discussion of applications outside of astronomy that are well-positioned to benefit from these sensors.
Making a go of it with licensed technology – Low Coherence Interferometry from Kodak and Shack-Hartmann from AMO-Abbott
Photons After Dark
Making a go of it with licensed technology – Low Coherence Interferometry from Kodak and Shack-Hartmann from AMO-AbbottWednesday, March 8, 2017
Formed in March 2003 Lumetrics grew from 3 employees to 20 originally on the strength of the LCI product and in 2012 adding the Shack-Hartmann line. Lumetrics is a “Photonics” company serving a diverse customer base including medical, industrial, electronics, automotive, food packaging, glass, adhesives markets. Lumetrics one main optics market is the intraocular & contact lens ophthalmic industry, an industry known for making purposefully “bad” optics.
Manufacturing High Precision Optics using MRF and SSI Technologies
Photons After Dark
Manufacturing High Precision Optics using MRF and SSI TechnologiesWednesday, February 8, 2017
QED Technologies was founded about 20 years ago, leveraging Magnetorheological Finishing (MRF) and Subaperture Stitching Interferometry (SSI) technologies that were developed at the University of Rochester. These two technologies for polishing and metrology provide a deterministic method for manufacturing high precision spheres, aspheres and freeform optics. In this seminar we will discuss the theory behind MRF and SSI technologies as well as how they are used in the optical manufacturing industry.
Advances in Manufacturing and Metrology of Optical Freeform Surfaces
Photons After Dark
Advances in Manufacturing and Metrology of Optical Freeform SurfacesThursday, November 17, 2016
Designing optical systems using freeform optical components can provide many advantages to the optical designer such as fewer optical components and less distortion. Techniques for manufacturing these complex geometries are advancing very quickly with increasing demand. Additionally, the metrology of freeform optics has progressed enabling higher precision surfaces to be made. We will explain the ongoing research efforts at Optimax that enable us to be at the forefront of optical manufacturing capability.
Measuring the Largest Structures in the Universe with the Smallest Telescopes in Space
Photons After Dark
Measuring the Largest Structures in the Universe with the Smallest Telescopes in SpaceWednesday, September 14, 2016
Observational astrophysics has always been driven by the race to build telescopes with larger and larger apertures. However, telescopes with very small apertures can perform cosmological measurements as important as their larger siblings. In this talk, I will present several examples of small aperture, space-based experiments providing unique views on the large scale structure of the universe. My discussion will include The Cosmic Infrared Background Experiment (CIBER) that has successfully measured the amplitude of the near-IR background fluctuations on arcminute scales; SPHEREx, a spectrometric instrument designed to probe the inflationary history of the universe and the evolution of galaxies; and work using the Long Range Reconnaissance Imager (LORRI) on New Horizons to measure the cosmic optical background.
Field Eect Electro-Absorption Modulator Based on Conductive Oxide
Photons After Dark
Field Eect Electro-Absorption Modulator Based on Conductive OxideThursday, April 21, 2016
The lack of ultracompact, high speed, broadband electro-optical (EO) modulators impedes the wide applications of integrated photonic circuits. Novel approaches and materials need to be explored to overcome the technical barrier. In this talk, I will present an EO mod-ulator, more specically electro-absorption (EA) modulator, based on a novel yet inexpensive active material, conductive oxide (COx), which exhibits moderate carrier concentration for tele-com application. Light modulation is realized through the eld eect in a metal-insulator-COx(MIC) structure. Dielectric constant epsilon-near-zero (ENZ) state is observed. Furthermore, we investigate an MICIM plasmonic EA modulator with a waveguide length of only 800 nm. The modulator can potentially operate at high speed.
Quantum Integrated Photonics: A source of spectrally indistinguishable photons
Photons After Dark
Quantum Integrated Photonics: A source of spectrally indistinguishable photonsTuesday, March 15, 2016
Quantum information science relies on the property of quantum interference, where the interference quality correlates to the indistinguishability of the interacting particles. The creation of these indistinguishable particles, photons in this case, has conventionally been accomplished with nonlinear crystals and optical filters to remove spectral distinguishability, albeit sacrificing the number of photons. This research describes the use of an integrated silicon microring resonator circuit to selectively generate photon pairs at the narrow cavity transmissions, thereby producing spectrally indistinguishable photons, and then entangle the resulting photon pair.
Designing a spatial mode sorting interferometer
Photons After Dark
Designing a spatial mode sorting interferometerWednesday, February 17, 2016
The ability to decompose an optical beam/scene into a specific modal basis is desirable in a wide array of optical technologies. By generalizing the delay line in a conventional Michelson interferometer to an arbitrary unitary transformation, it becomes possible to unlock the full mode sorting ability of the interferometer. Specifically, the eigenfunctions of the generalized delay line are the basis in which beam modal analysis is possible. In the following we describe an approach to arbitrary spatial mode sorting based on two-path interferometry. Our proof-of-principle mode sorting demonstration is based on the fractional Fourier transform (fFT). When replacing the conventional temporal delay line in the interferometer with an optical implementation of the fFT, the interferometer is able to decompose an input optical beam in terms of its constituent HG modes which are the fFT eigenmodes.
State transfer based on classical nonseparability
Photons After Dark
State transfer based on classical nonseparabilityWednesday, November 18, 2015
We discuss recent interest in appearance of entanglement in classical physics. We demonstrate a protocol that utilizes nonseparability between different degrees of freedom of a beam of light to transfer an arbitrary and a priori unknown, state of two different OAM modes onto the polarization, in a fashion that is analogous to teleportation using quantum entanglement.
Exotic Effects in Optical Coherence
Photons After Dark
Exotic Effects in Optical CoherenceTuesday, October 13, 2015
In this talk I will describe our recent contributions to the field of exotic effects in optical coherence. I will start by describing how the chaotic fluctuations of light can give rise to the formation of correlations in the orbital angular momentum (OAM) components and angular positions of pseudothermal light. The presence of these correlations is manifested through a new family of exotic interference structures in the OAM distribution of random light. In addition, it has been recently predicted that the finite probability of a photon to follow looped paths in a three-slit interferometer produces an apparent deviation from the most conventional form of the superposition principle. However, the probability of observing these exotic paths is very small and thus extremely hard to be measured. I will discuss how we have increased the probability of photons to follow such looped trajectories and measured its contributions to the formation of interference fringes.
Photons After Dark: Robin Sharma
Photons After Dark
Photons After Dark: Robin SharmaWednesday, September 16, 2015
Twisting starlight to directly image exoplanets
Photons After Dark
Twisting starlight to directly image exoplanetsWednesday, April 15, 2015
A physicist in the woods: closing the fire energy budget
Photons After Dark
A physicist in the woods: closing the fire energy budgetWednesday, March 18, 2015
Measuring Photons with a "Light" touch
Photons After Dark
Measuring Photons with a "Light" touchWednesday, November 19, 2014
How much information can a photon hold?
Photons After Dark
How much information can a photon hold?Wednesday, October 22, 2014
Physics ColloquiumWednesday, September 6, 2017
Rethinking Introductory Physics Lab Courses
Rethinking Introductory Physics Lab CoursesWednesday, May 3, 2017
In physics education research, we are taking a scientific approach to understanding and improving how we teach physics. This starts with figuring out what it is we are trying to teach (what are our goals?), and then how we can accurately measure it. The goals of lab courses have been highly debated for decades with not much research to back up any position. In this talk, I will describe new research into the goals of lab courses, how we are measuring student progress towards those goals, and the efficacy of different approaches for achieving them. I will draw comparisons to student experiences in undergraduate research, question the role of authenticity in developing an understanding of science, and discuss finding the balance between structure and autonomy.
Electronic Engines - The Principles and Practice of Solar Power Conversion
Electronic Engines - The Principles and Practice of Solar Power ConversionFriday, April 28, 2017
Civilizations throughout history have sought to harness the power of the sun, a process that nature established ~3400 million years ago trough the evolution of photosynthesis. A consequence of the semiconductor technology revolution has been our ability to manufacture affordable solar cells that convert sunlight into electricity at an efficiency of up to 20%. However, the thermodynamic limit for solar power conversion sits at 87%, suggesting there is considerable scope for improvement. Using a multi-junction architecture, photovoltaic solar cell efficiencies in excess of 40% have been demonstrated and it looks likely that a 50% efficient solar cell will be achieved within the next decade. In the longer term it may be possible to develop materials that can support sequential optical transitions leading to the so called intermediate band solar cell or extract power from a hot electron distribution.
Mechanical Quantum Systems
Mechanical Quantum SystemsWednesday, April 19, 2017
The field of mechanical quantum systems has made important strides in the past 10 years developing the technology to elicit and study quantum properties of motion with systems that are normally well described as behaving classically. Such systems have promise as new components for burgeoning applications in quantum information and quantum-assisted sensing, and they offer the potential for explorations of fundamental topics in quantum mechanics like the quantum-to-classical divide. In my talk, I will first give an overview of this growing field. Then I will highlight ongoing work in my group to develop a particular type of mechanical quantum system - a quantum electromechanical system (QEMS) - that is composed of integrated superconducting circuity and nanomechanical elements. It is expected that such QEMS should enable the production and measurement of a variety of non-classical states of nanostructures, making these systems a potentially versatile new element for quantum processing architectures and for pursuing fundamental studies.
Optical beams with spatially variable polarization
Optical beams with spatially variable polarizationWednesday, April 12, 2017
When we think of the polarization of optical beams, the oscillation of the field vectors, we usually imagine every point in the beam having the same polarization. In our work we prepare and study optical beams where the polarization varies from point to point. They can be prepared via superpositions (interference) of two beams with orthogonal polarization and distinct spatial mode, with at least one mode carrying a phase singularity or vortex. We have observed the polarization of the light contorting in many ways within a beam, including in 3-dimensions, twisting and forming Mobius strips around the singularity.
iOLabs and smartphones: New technologies for doing labs inside and outside of class
iOLabs and smartphones: New technologies for doing labs inside and outside of classWednesday, March 29, 2017
The ubiquity of smartphones that are chock-full of sensors has inspired new educational technologies for labs, such as the iOLab Wireless Lab System, the Pocket Lab, and physics-focused smartphone apps (e.g., Vieyra Software Physics Toolbox Apps, https://www.vieyrasoftware.net/). These tools provide students with more autonomy collecting their own data and designing their own experiments. During the first half of the talk, I will overview my experiences using the iOLab in Fall 2016 in University Physics 1. I will describe modified UP1 labs, demos, and "real world" outside-of-class labs that utilize the iOLab, and reflect on the pros and cons of the iOLab. The second half will be an opportunity to try out the iOLab yourself! All you need to do is (1) bring your own laptop and (2) install the free iOLab application software from http://www.iolab.science/ . I'll bring about 40 iOLabs so there should be enough for everyone. The class set of iOLabs was funded by an RIT Provost's Learning Innovations Grant.
The iOLab was developed by physicist Mats Selen and the physics education research group at the University of Illinois to improve large enrollment introductory physics lab courses. The iOLab is a bundle of physics sensors (accelerometer, wheel, gyroscope, magnetic field, voltage, etc.) that interfaces wirelessly with a laptop via a free software interface.
Ultrafast Lasers for Photonics/Optics Fabrication and Optical Differentiation Wavefront Sensing for Astronomy and Freeform Metrology
Ultrafast Lasers for Photonics/Optics Fabrication and Optical Differentiation Wavefront Sensing for Astronomy and Freeform MetrologyWednesday, March 22, 2017
The research on next-generation, laser-based manufacturing technologies is highly interdisciplinary, intersecting physics, novel ultrafast laser technology, metrology, precision controls, materials, and the associated laser-material interaction processes. The first part of the talk presents novel systems and physical mechanisms, processes using ultrafast lasers for the fabrication of photonic devices and micro- optics. The second part of the talk presents a new optical differentiation wavefront sensing technique based on measurements of wavefront slopes obtained by far-field spatial modulation with a binary pixelated filter inducing a linear amplitude transmission. This sensor is expected to offer phase measurement with higher spatial resolution, higher dynamic range and higher signal-to-noise ratio for freeform metrology lasers, vison, and astronomy applications.
How I Became an Expert
How I Became an ExpertWednesday, March 8, 2017
When I was a kid, I loved building my own radios and destroying radios of my grandparents. I wanted to keep tinkering through the rest of my life. A physics professor told me that I should become a physicist, because physicists are tinkering more than anyone else. So I became a research physicist. About fifteen years ago I started designing electronic instruments, hoping that my kid's experience will somehow be useful in my professional life. After a while I became an expert in developing research electronics. I started a small high-tech company specialized in such instruments with many potential research applications. I will describe a particular example, where our instruments are helping uncover the nature of Dark Matter, which is holding the galaxies together. Our instruments are also used on campuses by physics faculty and students. I will end the talk by describing how you can become an expert in any activity, which you consider joyful and inspiring.
Milestones toward topological quantum computing
Milestones toward topological quantum computingFriday, March 3, 2017
Ordinarily, exchanging two identical quantum mechanical particles results in at most a sign change of the many-body wavefunction (+1 for bosons, -1 for fermions). However, certain low-dimensional topological phases of matter host quasiparticles which exhibit *non-Abelian* statistics: exchanging two such particles gives rise to a nontrivial unitary (matrix) rotation. Such particles — termed non-Abelian anyons — form the building blocks of a type of quantum computer which is fundamentally immune to noise at the hardware level: the topological quantum computer. In this talk, I will discuss our recent theoretical work which aims to bring the topological quantum computer closer to experimental reality by proposing a series of relatively short-term “milestone” experiments on 1D quantum wires believed to harbor *Majorana zero modes*, exotic quasiparticles which give rise to non-Abelian statistics (as well as obey the famous Majorana commutation relations). I will conclude by discussing other past, present, and future research on various problems involving exotic many-body phenomena pertinent to present day experiments on quantum condensed matter systems.
Computational materials design of next-generation nanostructured ceramic oxides
Computational materials design of next-generation nanostructured ceramic oxidesFriday, February 24, 2017
Recent advancements in theoretical methods along with ever-increasing computational resources have altered the interplay between computation and experiment. Computational materials design offers the possibility of predicting fundamental physical and chemical attributes of existing and new materials, and thereby facilitating design of advanced materials with tunable properties before actual synthesis in a laboratory. Nanostructured complex ceramic oxides are pervasive in diverse technologies and have wide-ranging applications. I will elaborate on our recent work that entails investigation of fundamental structure-property relationships at heterointerfaces, grain boundaries, surfaces, and solids of ceramic oxides. The complementary nature of different atomistic simulation methods such as first-principles density functional theory, molecular dynamics, and kinetic Monte Carlo will be discussed. I will further demonstrate how these different simulation methods assist in elucidating the underlying mechanisms that control the properties of ceramic oxides, and lead to nanoscale design of ceramic oxides for renewable energy applications. I will briefly address how our theory-experiment collaboration has served as an effective strategy to accelerate materials discovery and design. Finally, I will give an outlook regarding the promise of computational materials design and offer a glimpse of my future research direction.
First-principles Simulation of Electron Localization in Real Materials
First-principles Simulation of Electron Localization in Real MaterialsWednesday, February 22, 2017
There is a long history of theoretical research into electron localization. The majority of this work focuses on either disorder-induced localization or localization caused by electron interactions. These limiting cases were predicted by Philip Anderson and Nevill Francis Mott and are nowadays known as Anderson and Mott localization, respectively. We also know that both disorder and electron interactions can be substantial in real materials, especially in low-dimensional materials where electronic polarization is less effective in reducing the long-range electron interactions. Alongside experiment and theory, computation has become an essential part of the development of an understanding of many properties in real pristine solids. Despite the need, first-principles-based computer simulations of electron localization in real materials that ``properly’’ characterizes electron localization have been elusive because both disorder and electron interactions break two of the fundamental assumptions in band theory, material homogeneity, and independent particles. In this talk, I will present a new computational approach overcoming these roadblocks by combining first-principles density functional theory, the Anderson-Hubbard model, and the typical medium dynamical cluster approximation within the dynamical mean-field theory. The computer simulations enabled by this method are expected to reveal new critical insight, e.g., simulations of monolayer hexagonal boron nitride predict that both disorder and electron interactions are essential for the material to undergo an insulator-to-metal transition.
Flowing, squeezing, clogging, and jamming of oil droplets
Flowing, squeezing, clogging, and jamming of oil dropletsTuesday, February 7, 2017
We use quasi-two-dimensional emulsions as experimental models to study the flow of jammed materials. Our emulsions are oil droplets in water and are compressed between two parallel glass plates so that the droplets are deformed into pancake-like disks. We use microscopy to observe these droplets as they flow. From the deformed outlines of the droplets, we can measure all of the inter-droplet forces to within 10%. In this way, we study the relationship between the local stresses in the system and the rearrangements as the sample is sheared. The simplest rearrangement involves four droplets (a ‘T1 event’) and we confirm theoretical predictions for the quadrupolar spatial pattern of the stress redistribution around the T1 events. We also study gravity-driven flow in hoppers and investigate the probability of clogging as a function of the hopper exit size. Here, experiments and simulations show that the softness of the particles is important, as soft particles form less stable arches and thus reduce the probability of clogging.
Symmetry in Theoretical Physics: From Newton to the Standard Model to GUTs to SUSY and Beyond
Symmetry in Theoretical Physics: From Newton to the Standard Model to GUTs to SUSY and BeyondWednesday, December 7, 2016
Classical physics includes many important conservation laws which were established through experiment. Looking back these conservation laws can be explained as the consequence of symmetry. For the advancement of Modern Physics in the early Twentieth Century, theory, including applications of symmetry, played a vital role in the understanding of relativity, particle spin and anti-matter. Theoretical considerations of symmetries and broken symmetry led the development of the Standard Model of Elementary Particles, and these same considerations provide tantalizing clues to what may yet be discovered. This discussion will provide a high-level overview of these concepts without all of the mathematics and technical complications.
How might Physics Education Research facilitate the coming computational revolution?
How might Physics Education Research facilitate the coming computational revolution?Wednesday, November 16, 2016
Computation has revolutionized how modern science is done. Modern scientists use computational techniques to reduce mountains of data, to simulate impossible experiments, and to develop intuition about the behavior of complex systems. Much of the research completed by modern scientists would be impossible without the use of computation. And yet, while computation is a crucial tool of practicing scientists, most modern science curricula do not reflect its importance and utility. In this talk, I will discuss the urgent need to construct such curricula in physics and present research that investigates the challenges at a variety of all scales -- from the largest (institutional structures) to the smallest (student understanding of a concept). I will discuss how the results of this research can be leveraged to facilitate the computational revolution. This research will help us understand and develop institutional/departmental incentives, effective teaching practices, evidence-based course activities, and valid assessment tools.
Cell Mechanics: How Cells Regulate Force Generation
Cell Mechanics: How Cells Regulate Force GenerationWednesday, November 2, 2016
: In the absence of mechanical interactions, cells would mostly be just round spheres, unable to engineer even the most rudimentary shape changes that are necessary in physiological processes like migration. The cell’s ability to alter its shape is built upon the capacity to coordinate processes like adhesion, polymerization and contraction events in both space and time. In particular, while we know significant amounts about the biochemical interactions that allow cells to generate forces, we have surprisingly little knowledge of how these molecular interactions are integrated to produce contractile behavior at the scale of the cell. In this talk I will discuss how we can use approaches from physics to describe the cell cytoskeleton as a material with dynamic properties that help to regulate this contractile behavior in adherent cells.
A Physicist's Perspective on Closed Traumatic Brain Injury and its Mitigation
A Physicist's Perspective on Closed Traumatic Brain Injury and its MitigationWednesday, October 26, 2016
Brain injury without skull fracture, called "closed traumatic brain injury” (TBI), is a large public health problem that affects soldiers and civilians of all ages. Blast waves and head Impacts are sources of brain injury in military contexts while impacts are dominant in civilian contexts.
In sports, impact-induced TBI results from both concussive and repeated sub-concussive head impacts, the latter only manifesting as long term brain damage with present diagnostics. I will first highlight the history of evidence for TBI in both military and sports contexts. I will then discuss progress and challenges in understanding mechanisms of how the brain is injured. I will explain why current helmets are deficient from a physics perspective and offer some simple recommendations for both improving helmets, along with strategies for interdisciplinary research in both helmet protection and connecting physics to physiology. Physics training is essential for tackling some frontier aspects of this enterprise.
Raman Spectroscopy: Using Light to Speed Up Medical Diagnosis
Raman Spectroscopy: Using Light to Speed Up Medical DiagnosisFriday, October 21, 2016
Among women, breast cancer is the second most common type of cancer after skin cancer. The tumor is often removed through surgery. For many patients, this surgery can remove the tumor and preserve much of the surrounding tissue. However, over 20% of these patients must undergo a second surgery to remove residual cancer tissue. This high re-excision rate is largely due to the inherently slow process of evaluating the tumor margins of the removed tissue.
Raman spectroscopy may provide a solution to this problem. Raman spectroscopy is an optical method that non-invasively measures chemical concentrations. This spectral fingerprint can be used to diagnose biological tissues and cells. This talk will discuss the creation of a diagnostic model based on Raman spectroscopy. The measurement procedure can be accelerated through the use of multi-modal imaging, image processing, and multifocal spectroscopy. Spatially-offset Raman spectroscopy (SORS) could also allow future systems to probe deeper into tissues. The talk will also discuss the integration of this system into current clinical practice as well as the opportunities and challenges of collaborating with medical professionals.
Thinking about round cows: Introductory Physics for Life Science Students
Thinking about round cows: Introductory Physics for Life Science StudentsWednesday, October 19, 2016
The introductory physics course for life science majors (IPLS) has been the focus of reform over the last 10 years. I will talk about the challenges and successes in teaching this course, and why it should not be just an algebra-based version of the course for engineers. I will also talk about our focus on developing and assessing tutorials on static and moving fluids, and how we used the resources framework to inform our development and recognize productive student work.
Ab-Initio Study of Electron Localization in Low-Dimensional Materials
Ab-Initio Study of Electron Localization in Low-Dimensional MaterialsFriday, September 30, 2016
Plasma, Fusion and PPPL: The Quest for Making a Star on Earth and info on Princeton Conference on UG Women in Physics
Plasma, Fusion and PPPL: The Quest for Making a Star on Earth and info on Princeton Conference on UG Women in PhysicsWednesday, September 21, 2016
The challenge of developing sustainable, safe, environmentally friendly sources of energy is one of the most important scientific endeavors of the modern world. At the Princeton Plasma Physics Laboratory, research is being conducted on various fields of plasma physics, including the primary mission of the lab, the development of fusion energy as an alternative energy source. This presentation will discuss the physics of fusion plasmas, the challenges towards the goal of a fusion future, and the opportunities available at PPPL for research, including undergraduate internships.
Student Summer Research Experiences
Student Summer Research ExperiencesWednesday, September 7, 2016
Spintronics: Fundamentals and Applications
Spintronics: Fundamentals and ApplicationsTuesday, April 19, 2016
Rational design of electrode materials for energy storage
Rational design of electrode materials for energy storageThursday, April 14, 2016
For over 20 years, Li-ion batteries have enabled the rise of portable electronics, dominating the battery market. Current Li-ion batteries use layered oxides as cathode materials, specially LiCoO2, organic liquid electrolytes and graphite as anode. However, Co layered oxides and organic liquid electrolytes suffer from certain instability at high operational temperatures and flammability, respectively. In this colloquium, using first principles density-functional theory, I will examine the main characteristics of the most promising alternatives for electrode and solid-electrolyte materials, suggesting suitable pathways to improve their conceptual design and performance, thus serving as design principles for future discovery of electrode materials.
Spontaneous parametric down conversion with a depleted pump as an analogue for black hole evaporation/particle production
Spontaneous parametric down conversion with a depleted pump as an analogue for black hole evaporation/particle productionWednesday, April 13, 2016
In this talk, I argue that black hole evaporation/particle production has a very close analogy to the laboratory process of spontaneous parametric down conversion, when the laser pump source is allowed to deplete. I will first present an overview of the essential features of the Unruh and Hawking effect and its analogy to the quantum optical process of spontaneous parametric down conversion widely used in the field of quantum information science as a source of photon-based qubits. In the previous case, the pump is considered a constant (i.e. non-depleted). I will next discuss the case when the black hole is treated as a finite `pump' source which is allowed to deplete, hence modeling the processes of black hole evaporation and Hawking radiation production. This model reproduces essential features of the Page Information curves (conjectured by D. Page, 1993) which are widely believe to describe the rate at which information escapes from the black hole as it evaporates, as the Hawking radiation deviates at late times from the pure thermal spectrum characterized by early black hole evolution times. Further details of this work can be found in (i) P.M. Alsing: Class. & Quant. Grav. 32, 075010, (2015); (arXiv:1408.4491), and (ii) P.M. Alsing & M.L. Fanto: Class. & Quant. Grav. 33, 015005 (2016), (arXiv:1507.00429).
First-principles theory-driven materials design and innovation in all-solid-state batteries
First-principles theory-driven materials design and innovation in all-solid-state batteriesWednesday, April 6, 2016
Thin-film Electronics by Spatial ALD: Achieving High Performance with Low Process Complexity
Thin-film Electronics by Spatial ALD: Achieving High Performance with Low Process ComplexityWednesday, March 9, 2016
Patterning thin-film transistors for “printed electronics” applications can be challenging both for resolution and for alignment accuracy. This is particularly true for high-performance devices with submicron channel lengths, and for diverse and deformable substrates. Printing organic-based devices has additional issues such as printing dynamics, and orthogonality of solvents. In this talk, I will describe alternative approaches to scalable thin-film electronics based on spatial atomic layer deposition (SALD) of metal oxides. Using the relatively high deposition speed of SALD, the conformality of the deposited layers, and the surface-sensitivity of the technique, we have explored both print-compatible high-performance vertical transistors, and patterned-by-printing circuitry. A reliable ZnO mobility above 10 cm2/Vs, on-off ratio above 107, and uniform threshold voltage values across the substrate give these approaches promise for large-area applications.
The Dawn of Gravitational Wave Astronomy
The Dawn of Gravitational Wave AstronomyWednesday, February 24, 2016
The benefits of low permeability in articular cartilage
The benefits of low permeability in articular cartilageWednesday, December 2, 2015
Abstract: Articular cartilage is a durable, load-bearing, poroelastic tissue that coats bones in joints and protects them from damage over several decades. Unfortunately, trauma-induced cartilage cell (chondrocyte) death can initiate a cascade of degradative alterations in the joint. In this talk, I will discuss how a key property of articular cartilage – its hydraulic permeability – mediates its ability to withstand extreme forces in two distinct ways. First, since exudation of fluid facilitates tissue compression, low permeability delays tissue deformation and allows chondrocytes to survive brief periods under extreme loads that would otherwise be fatal. Second, because permeability is low in articular cartilage and further decreased when the tissue is compressed, harmful intracellular contents that are released in areas where cell death occurs always flow towards the point of contact rather than towards healthy, uninjured cells. This protective feature could prevent the spread of cell death and contribute to the durability of articular cartilage. Finally, I will discuss a separate phenomenon related to cartilage longevity that our experiments have recently revealed: the ability of chondrocytes to adapt to recently imposed physical forces and thereby become less susceptible to subsequent mechanical injury.
Unexpected ordered phases in active systems
Unexpected ordered phases in active systemsWednesday, November 4, 2015
Active matter describes systems whose constituent elements consume energy to generate motion or forces. Since these systems are intrinsically nonequilibrium, they can exhibit collective behaviors unlike anything possible in a traditional equilibrium material. In this talk I will describe computer simulations of two recently developed model active matter systems, self-propelled colloidal particles and extensile active nematics, and unexpected ordered phases that arise as a consequence of activity in these systems.
When colloidal particles are asymmetrically coated with a catalyst and placed in the presence of a fuel, they undergo directed motion. An idealized model for such particles, self-propelled spheres with repulsive interactions and no aligning interactions, has become an intensely studied theoretical and computational model system. We and others have recently shown that this system undergoes a continuous phase transition analogous to that of equilibrium systems with attractive interactions. Particles in the dense phase form ‘active crystals’ with hexatic or crystalline order but efficient transport properties. I will discuss some new features of this system; then, I will show that when these particles are confined they undergo another transition, in which the particles become confined to the boundary, with a density that depends on the local curvature radius of the boundary. A theory describing this behavior allows designing boundary shapes that lead to a wide variety of particle density distributions.
Active nematics are liquid crystals which are driven out of equilibrium by energy-dissipating active stresses. The ordered nematic state is unstable in these materials, due to the spontaneous generation of topological defects, which undergo birth, streaming dynamics, and annihilation to yield a complex, seemingly chaotic dynamical steady-state. In this talk, I will show that order emerges from this chaos, in the form of heretofore unknown broken-symmetry phases in which the topological defects themselves undergo orientational ordering. I will describe the appearance of these phases into realizations of an active nematic: (1) an experimental system containing extensile bundled microtubules and molecular motor proteins studied by the Dogic lab at Brandeis, and (2) a computational model of extending hard rods. I will describe the defect-stabilized phase that manifests in each system and our current understanding of their origins. Such phases may be a general feature of extensile active nematics.
Pentaquarks: Quark Model Revisited
Pentaquarks: Quark Model RevisitedWednesday, October 14, 2015
Shearing While Looking at Nonlinear Soft Materials
Shearing While Looking at Nonlinear Soft MaterialsWednesday, September 30, 2015
Physics Colloquium: Summer REUs
Physics Colloquium: Summer REUsWednesday, September 9, 2015
Breaking The Myth of the "Non-Traditional" Physicist: The Real Story About Employment for Physics Graduates
Breaking The Myth of the "Non-Traditional" Physicist: The Real Story About Employment for Physics GraduatesWednesday, April 15, 2015
Characterizing Exoplanet Atmospheres through Our Own
Characterizing Exoplanet Atmospheres through Our OwnMonday, March 2, 2015
Galactic Ecology: Where Have All the Baryons Gone?
Women in Science
Galactic Ecology: Where Have All the Baryons Gone?Thursday, December 1, 2016
Galaxies are surprisingly deficient in normal matter. Compared to the universe as a whole, the ratio of normal matter to dark matter is low in galaxies. Recent work strongly suggests that these missing baryons reside in a diffuse gas surrounding galaxies. Professor Martin will describe why astrophysicists believe this halo gas is very dynamic. She will present the latest results on measurements of gas flows between galaxies and this circumgalactic medium. The results have important implications for how the star formation rate in galaxies is regulated as well as the enrichment history of interstellar and intergalactic gas.
From Career Pathways to Physics/Astronomy Trivia
From Career Pathways to Physics/Astronomy TriviaWednesday, October 19, 2016
Come learn about physics and astronomy career options, topics such as how to fail an interview, why networking is so important, and compete in physics trivia with the Director of the Society of Physics Students and Sigma Pi Sigma! Alum Dr. Brad R. Conrad will discuss how to make the most of your time at RIT and teach a few skills that can help you along the way.
Bio: Dr. Brad R. Conrad is the Director of the Society of Physics Students (SPS) and Sigma Pi Sigma (ΣΠΣ), the physics honors society, at the American Institute of Physics (AIP) in College Park, MD. In addition to leading SPS National initiatives, he works to support and promote undergraduate Physics and Astronomy majors and their mentors. Before becoming director, Dr. Conrad was an Associate Professor of Physics and Astronomy at Appalachian State University, an NRC postdoctoral fellow at the National Institute of Standards, earned his Ph.D. in Physics at the University of Maryland, College Park MD, in the area of condensed matter/surface physics, and earned his Bachelor’s degree from Rochester Institute of Technology in Physics.
From Exoplanets to Exoworlds
From Exoplanets to ExoworldsWednesday, May 6, 2015
How Cosmic Collisions Shape the Universe
How Cosmic Collisions Shape the UniverseFriday, May 1, 2015
From Exoplanets to Exoworlds
From Exoplanets to ExoworldsWednesday, April 29, 2015
Assessment: The silent killer of learning
Assessment: The silent killer of learningMonday, October 17, 2016
Why is it that stellar students sometimes fail in the workplace while dropouts succeed? One reason is that most, if not all, of our current assessment practices are inauthentic. Just as the lecture focuses on the delivery of information to students, so does assessment often focus on having students regurgitate that same information back to the instructor. Consequently, assessment fails to focus on the skills that are relevant in life in the 21st century. Assessment has been called the "hidden curriculum" as it is an important driver of students' study habits. Unless we rethink our approach to assessment, it will be very difficult to produce a meaningful change in education.
Vibrations from the Big Bang
Vibrations from the Big BangMonday, December 7, 2015
Moments after the Big Bang, our observable universe underwent a violent growth spurt called inflation. The inflationary expansion flung apart the observable universe from a causally-connected sub-atomic volume, and established a primordial spectrum of scalar perturbations that led to the temperature anisotropies observed in the cosmic microwave background. Dr. Bock's team has been making precise degree-scale polarization measurements of the CMB from the south pole with the BICEP/Keck series of experiments in search of a distinctive ‘B-mode’ pattern, a hallmark of tensor perturbations associated with a background of gravitational waves generated by inflation. Dr. Bock will present our latest results that incorporate multi-band information from the Planck satellite and new Keck Array data at 95 and 150 GHz. He will also discuss prospects from new data and improved measurements coming in the near future.
Supported by the John Wiley Jones Science Endowment Fund
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Observation of Gravitational Waves from a Binary Black Hole Merger
Observation of Gravitational Waves from a Binary Black Hole MergerFriday, February 12, 2016
LIGO has just reported three discoveries: the first direct detection of gravitational waves; the discovery of a binary black hole; and the observation of gravitational waves from this binary's coalescence, in excellent agreement with Einstein's theory of gravity. In a presentation and panel discussion, RIT scientists John Whelan, Richard O'Shaughnessy, Carlos Lousto, and Manuella Campanelli -- all members of RIT's Center for Computational Relativity and Gravitation -- discuss the significance of these findings.
Listening for Deep Understanding of Energy
Listening for Deep Understanding of EnergyFriday, September 11, 2015
How do people understand energy? In studying teaching and learning in physics, researchers have primarily used two methods to understand content understanding: individual interviews or large-class surveys. Sometimes it's not possible to do either, given constraints on the population being interviewed, or a small enough population that the statistics from surveys won't tell us much. In the Maine Physical Sciences Partnership, we have addressed this problem in two ways when working with the population of middle school physical science teachers. We have asked them survey questions on an annual basis and can use the changes in their responses to investigate their thinking about energy. We have also observed and analyzed their interactions in large-group discussion during professional development activities. By listening differently, we're able to learn about their knowledge of the deep structure of the physics.