Past talks
More about global warming
John Parejko 2010-04-30 12pm, Disque 919
Many of you saw my talk in May 2008 describing the main reason that I'm personally scared out of my wits about anthropogenic climate change. I'll be talking more about global warming this Friday.
Dll Injection and Windows Function Detouring
Frank Jones 2010-04-23 12pm, Disque 919
Dll injection is a method of running your own code inside another process giving access to the target's memory space and function calls. Function hooking allows a user to redefine the actions of a function call. This will be done specifically for Windows using Function Detours. Instructions and applications of both processes will be shown.
Fencing and Thinking Tactically
Donna Yosmanovich 2010-03-19 1pm, Disque 919
How do you beat Ben Coy in heads up poker? Why shouldn’t you sacrifice all your pawns in Chess? What does deception have to do with warfare? How the heck will I relate all these ideas to fencing? If you want answers, then come to Disque 919 this Friday at 1pm for some food and sword fighting.
Intellectual Hedonism: Irrelevant Topics in Physics V
Travis Hoppe 2010-03-12 12pm, Disque 919
As is customary with these talks, I invite you to partake in some intellectual excursions from our everyday works. On Fridays talk I will be covering Random Matrix Theory (RMT), which may be the theory I've encountered with the absolute least set of assumptions. I'll try then to do something that Pathria wouldn't dare, extended temperatures onto the complex plane. Finally I'll encourage you to make some noise - just the right amount - so I can cover the topic of Stochastic Resonance.
Software life-cycles and alphabet soup
Trevor King 2009-10-23 1pm, Disque 919.
I'll talk about iterative and incremental design (IID), from plan-do-study-act (PDSA) to test-driven development (TDD) and extreme programming (XP), even the non-acronym SCRUM (which people sometimes capitalize so it fits in with the other acronyms :p). We'll peer into the history of IID, and consider the large role played by the International Business Machines Corporation (IBM) and the Department of Defence (DoD, and probably the source for the acronym affinity). Finally, I'll discuss What IID Can Do For Us as physicists, pointing out some useful software and going over some example workflows.
The “everyone talk about research event”
Everybody Talks 2009-09-25 1pm, Disque 919.
Every group (if not more folks), should have a slide and a 2 minute talk about what they do.
Black-Holes Influence Galaxies? OMG Neutrinos Everywhere!!! Imagine pulled muscles. Qubit superconductor graphene. And so much more...
Too Much Information
Sam Kennerly 2009-09-08 1pm, Disque 919.
What exactly is "quantum information theory," and why should I care? In this talk, I'll attempt to answer both questions. Along the way, we will see how QuIT and the mathematics it's based on can help us:
- improve our email passwords
- debunk misuses of the 2nd Law of Thermodynamics
- beat John von Neumann at poker
- solve Alice vs. Bob quals problems
- pass Stat Phys II on the first try
- make Erwin Schroedinger very, very angry
- and win... a shiny new car! (*see footnote)
I will also attempt to prove that, contrary to popular belief, I actually do research work when nobody's looking.
(* 2/3 of the time. The other 1/3 of the time you win a goat.)
From Quantum Mechanics to Maxwell's Equations (The Work of Dr. Jairzinho Ramos)
Dan Cross 2009-07-24 noon, Disque 919
Both classical and quantum mechanics possess relativistic field theories. In quantum mechanics a field is an arbitrary superposition of basis states in a Hilbert space, while in classical mechanics a field is a manifestly covariant object (vector, tensor,...) obeying a partial differential equation. Jairzinho Ramos (PhD Drexel, 2006) used group theory to demonstrate how Maxwell's and Einstein's (weak field) equations arise as suppressants of unphysical states in the classical field. In this talk we will follow Ramos' approach and derive Maxwell's equations from quantum mechanics using group theory.
We grow sickle hemoglobin polymers in laser-carved cavities
Zenghui Liu 2009-07-10 noon, Disque 919
Sickle hemoglobin (HbS) will polymerize at concentrations above solubility. The individual HbS fiber's diameter is only 20 nm, which precludes direct optical visualization. Our method is to project optical patterns to a COHbS sample, which creates deoxyHbS that can polymerize only in the illuminated area. After this, polymers form in an incubation circle. From the circle, a line of deoxyHbS is optically generated along which fibers can grow. Finally, a detection circle is illuminated and the connecting line is extinguished. If a polymer has entered the detection circle, thanks to heterogeneous nucleation it will fill the circle with easily observed polymers, otherwise the detection circle remains monomeric. Thus we can measure the elongation of a fiber too small to detect optically.
Rock Climbing
Hanbing Lin 2009-05-08 Noon, Disque 919
I call it 123s of rock climbing, there will be videos of different types of climbing (bouldering, sport & trad), hopefully the videos work. I'll talk a little about fall factors and anchors, plus a brief introduction to indoor climbing (I have to use our pics and videos somewhere :D)
Irrelevant Topics in Physics Part IV
Travis Hoppe 2009-05-01 < IN (!( AT !@:))PM>
Today's installment of ITIP consists of two exciting topics. In the first half we explore the world of Esolang, or esoteric computer languages. If you think regular coding is hard wait until you've examined the likes of Befunge or Brainf*ck. The idea of an algorithm and computation will be carefully taken apart, dissected and reassembled until the fundamental ideas themselves are challenged. Shannon did this for information theory years ago. Humbly in his footsteps we will continue. In the second part of qthe talk we will conduct an in depth analysis of the timeless classic children's game: Chutes and Ladders. Don't miss it!
Useful Programming Languages
Ernie Mamikonyan 2009-04-24 Noon, Disque 919.
There are many different types of tacos: flour tortillas (soft shell), corn tortillas (hard shell or soft shell), hand made (typically, but not always, corn, and full of deliciousness), soy tortillas (generally only found in hippie places like San Francisco), tortilla de patatas (actually more like an omelet, but it has the name), etc. But building dinners that work well between these different styles of tortilla is a big challenge. And there are additional constraints imposed by regional cuisine and individual salsa preferences (mild, medium, hot, or "gringo killing!"). One must be careful when mixing flavors!
It is the job of the language developers to allow cross-compiling between these different flavors, and they must do so in a way that is usable by programmers who are not familiar with the nuances of the language. Such as physicists, like us. But it is still difficult for a non-specialist to navigate these complex issues.
Tomorrow, Ernest Mamikonyan (or Travis, if Ernie can't get back in time from jury duty), will guide us through several different types of compilers and their associated languages. If you always wondered why C uses [0] to index arrays and Fortran uses [1], he just might tell you.
There will also be tacos.
P.s. This is what happens if you fail to promptly send me [John Parejko] an abstract about your talk. ;-)
Cameras
Vish Kasliwal 2009-04-17 Noon, Disque 919.
The goal of photographic equipment design is permit the photographer to transform a photograph concept into a final image. Numerous technical improvements in photographic equipment have been made since the photograph was created 184 years ago. I present an overview of history of photography covering basic concepts such as the various photographic formats, the exposure system and the major engineering strides that permit the existence of the modern digital camera.
PMT Installation at Chooz
Ned Damon 2009-04-10 Noon, Disque 919
Ever wonder what the neutrino group is doing when they go to France for months at a time? Interested in what awaits you in the wonderful world of experimental physics? Many people will give you the run-down of the experiment they're working on, but only one man is willing to Ned up and provide an audio-visual extravaganza detailing his time spent working on the Double Chooz experiment. And by time spent, he means the parts of experimental work that no-one talks about, along with the stuff you wish he'd shut up about. An afternoon of entertainment and horror awaits!
Neutrino Physics with the KamLAND Detector
Tanya Miletic 2009-04-03 noon, Disque 919
This is the historic era in neutrino physics. I will first review the properties of neutrinos and discuss why neutrino masses are interesting probes to physics beyond the Standard Model. I will describe KamLAND detector and discuss very exciting results produced in 5 years of data taking. Finally, I will talk about research I did and plans to graduate from Drexel.
Biophysical Meeting in a Nutshell
Donna Yosmanovich 2009-03-13 noon, Disque 919
I will talk about the glamor of attending the largest meeting of biophysicists in the world. There will be dancing, mysteries and important life lessons! Learn about what your colleagues are supposedly researching! I will also talk about why what you do while in grad school really does matter!
Double Chooz @ Drexel
Erica Caden 2009-02-20 noon, Disque 919
Yours truly will be giving her FOURTH talk for PGSA.
Interestingly enough, it is the first time I'll be talking about my own research. My alma mater has invited me back to entice their current crop to join our rank as graduate students. I'll be giving a talk on my own work for the Double Chooz Experiment, including a brief introduction on why the heck we even care about neutrinos in the first place. You all can hear me talk about what I do all day in 715/611, critiquing me as you see fit on content and clarity, while you scarf down sammiches.
The Real World
Alf Whitehead 2009-02-06 2pm, Disque 919
I'll describe briefly my experience of taking my physics degree to the software job market. In particular, I'll focus on the hiring/recruitment process and strategies specific to physics folks looking for a (dis-)honest job in the corporate world. Mostly, this should be a fairly informal show-and-tell about how one can successfully carve out a career in a field without the formal training usually required.
Milli-Kelvin fridge design
Zech Thrailkill 2009-01-23 noon, Disque 919
Ever wonder what goes on down in the low temperature physics lab? Miss my oral quall and want to know about Josephson Junctions? This Friday I will be giving a presentation that will rehash the theory of the devices we hope to experiment on in the helium dilution refrigerator. As well as introduce a few new ideas that we are thinking about attempting. I will also discuss the method with which we cool the sample down and communicate with it. These connections have to be made without exposing the sample to noise from the surrounding 300K environment which can cause decoherence. There are also factors on and directly around the chip sample itself that contribute to noise. I will be giving a general overview of all of this, so if there is anything in particular that interests you I can go into further detail.
Demonstrating Definitive Evidence of the Quantum Mechanical Nature of Light Using Correlated Pairs of Down-Converted Photons
Joey Lambert 2008-11-12 noon, Disque 919
When we want cite evidence of the particle nature of light, i.e. the photon, we usually use the photoelectric effect. It is possible though to explain the photoelectric effect by interaction of continuous classical EM waves with matter possessing quantized energy states. For definitive evidence of the photon, a simple quantum optics experiment can be done. With recent advancements in photon detection and nonlinear optics, this experiment has been done at the undergraduate level. For my senior project, I worked on recreating this experiment as first steps in developing an undergraduate quantum optics lab at Willamette University. I will present this experiment, my work, and a few other interesting quantum mechanics experiments that can be done with similar apparatus. Cool animations included.
How astrophysicists have been wrong about giant molecular clouds (GMC's) for the past 20 years and did not know it!
Coleman Krawczyk 2008-10-10 1pm, Disque 919
The properties of Galactic molecular clouds tabulated by Solomon etal(1987) (SRBY) are re-examined using the Boston University-FCRAO Galactic Ring Survey of 13CO J=1-0 emission. These new data provide a lower opacity tracer of molecular clouds and improved angular and spectral resolution than previous surveys of molecular line emission along the Galactic Plane. We calculate GMC masses within the SRBY cloud boundaries assuming LTE conditions throughout the cloud and a constant H2 to CO abundance, while accounting for the variation of the 12C/13C with Galacto-centric radius. The LTE derived masses are typically five times smaller than the SRBY virial masses. The corresponding median mass surface density of molecular hydrogen for this sample is 42 Msun/pc^2, which is significantly lower than the value derived by SRBY (median 206 Msun/pc^2) that has been widely adopted by most models of cloud evolution and star formation. This discrepancy arises from both the extrapolation by S RBY of velocity dispersion, size, and CO luminosity to the 1K antenna temperature isophote that likely overestimates the GMC masses and our assumption of constant CO abundance over the projected area of each cloud. The true surface density of clouds likely falls within the range 80-120 Msun/pc^2. From velocity dispersions derived from the 13CO data, we find that the coefficient of the cloud structure functions, vo=sigma_v/R^{1/2}, is not constant, as required to satisfy Larson's scaling laws, but rather systematically varies with the surface density of the cloud as Sigma^{0.5} as predicted for magnetically supported molecular clouds (Mouschovias 1987).
This is from a paper that he has out, available at http://adsabs.harvard.edu/abs/2008arXiv0809.1397H.
“The Science of Sound” OR “How Your MP3 Player Can Help You Pass Math Phys, Part 1”
Sam Kennerly 2008-09-26 1pm, Disque 919
We discuss the mechanisms of sound production, recording and reproduction using acoustic and electronic equipment, explain the relationship between Eddie Van Halen and eigenstates of the square- well Hamiltonian, and demonstrate the utility of the convolution theorem in producing epic arena-trance anthems.
Irrelevant Topics in Physics III
Travis Hoppe 2008-09-05 noon, Disque 919 (date approximate)
I've always enjoyed slacking. As a perfectionist doing nothing has never been an option. Far from it, I've worked hard studying and mastering all the non-essential skills one needs in academia. The culmination of these efforts by my colleges and I have brought forth the third talk in a series of Irrelevant Topic in Physics.
In the last talk we studied very large numbers (cf. Irrelevant Topics in Physics II), today we are going to look at the largest of them all, infinity. Or rather, we are going to classify your infinity from my infinity and try to settle such schoolyard threats as infinity plus one. Next we are going to take a brief diversion into negative probabilities. Finally, time permitting, I'd like to share a formula I derived that may answer the question on graph isomorphism (via the method of train-hopping hobo's).
Lindau Meeting
Erica Caden 2008-07-25 noon, Disque 919
I'll be speaking about my trip to the 58th Meeting of Nobel Laureates and Students in Lindau, Germany. I'll be discussing everything that I learned, in and outside of the lecture hall. I'll also go over fun things to do in Bavaria! There will be lots and lots of pictures, and a reasonable amount of science as well.
The Very Large Array
Rachael Kratzer 2008-07-11 noon, Disque 919
If you've ever seen the movie "Contact," you may have wondered to yourself, "How did Jodie Foster feel while she was trying to make contact with extra-terrestrial beings at the Very Large Array in New Mexico?" Unfortunately, Jodie Foster is unable to give our graduate student lunch talk this week, so I'll have to do my best to be her surrogate. I'm no actress, nor have I fictionally tried to make contact with aliens, but I have been to Socorro, NM. I will tell you what it's like to spend 8+ days in the middle of the desert with only a bunch of radio astronomers and locals to communicate with (totally bitching!), show sweet pictures of the Very Large Array facilities, and touch upon why there are 27 very large radio antennas in the middle of the New Mexican desert. I'll discuss the different configurations of the array, it's basics components, the physics behind why it works, and future plans for other arrays around the world.
Locks and Light
Trevor King 2008-06-27 noon, Disque 919
Have you ever forgotten the combination for your combination lock. Fear not! All it needs is a little ‘persuasion’… We'll discuss the basics of combination lock operation, manipulation, and forcing. Since that won't take to long, I'll also talk about a visual Python ray tracer I wrote after Tim's talk, demonstrating the link between visual Python and POV-Ray. I'll introduce Stokes vectors and Mueller matricies, since no talk is complete without a little basic theory.
Beyond gnuplot: Povray is a free and easy-to-use ray-tracer
Tim Jones 2008-05-30 noon, Disque 919
Abstract: Visualization of data can be useful. In this very brief talk I will give a minor introduction to using Povray, which is an open source ray tracing program. I will show examples of figures I have made for various projects using Povray, and end by showing a 15 minute film compilation (with music) of simulations I've made using Povray for my research. Since it is a cliché for documentary producers to use a Philip Glass score, I will do so sardonically for this film.
Why I'm worried about global climate change
John Parejko 2008-05-23 noon, Disque 919
Earth's climate is warming. Human produced CO2 is the cause of the majority of that warming. These two facts are by now solidly established. I will briefly run through (as if with a sword) the standard objections. What is not so well established is just what the climate sensitivity to higher CO2 concentrations really is. I will discuss recent research that attempts to provide both upper and lower bounds on “CO2 climate forcing” and show some of the papers that got me, personally, most worried about climate change.
Also, Jeff Blomquist will give a short introduction. His talk is one I've been waiting a while to hear, so don't be late!
Fishing proteins with AFM
Marisa Roman 2008-05-18 noon, Disque 919
Protein folding has been studied for quite a long time using chemical denaturants to accelerate the process. These bulk techniques measure the ensemble average on the sample of molecules, usually big. Some questions still remain unanswered on the behavior of each single molecule. Atomic force microscopy can be used to address some of theses questions. In this case, the force replaces the usual chemical denaturants used in the experiments. This technique offers an alternative way of exploring the folding nature of individual proteins.
Physicists Play Nice with Others
Brad Hubartt 2008-05-02 noon, Disque 919
We all got into physics to make money, right? Turns out, using the same modeling techniques used in physics you actually get paid. The field of econophysics is growing, lots of physicists are getting hired by investment firms, banks, and the like...and getting paid well for it. The whole idea is to parlay our training in describing complex systems to describe and understand the economy. I’ll be talking about a couple of these ideas. One will be options pricing through Black-Scholes (which a lot of you probably know of, you at least know the equation) and a slightly modified version of it. The other will have to do with individual stocks and their daily fluctuations. We’ll play a little guessing game to see who can spot the real stock chart vs ones I’ve generated, with disclosure as to how they were made after you guess. Warning: this may make you lose faith in your broker.
Paradoxical Twins: Beyond an Introduction
Dan Cross 2008-04-25 noon, Disque 919
We're all (too) familiar with the standard twin paradox. But what if the twins could reunite without acceleration? I will explore two situations in which this can occur, giving special attention to a “flat-space” version of the paradox. Symmetries, and the lack thereof, will be stressed.
Note: stomaches may not attend without their respective bodies. No exceptions, no matter how hungry said stomach may be. Violators will be shot off in a sandwichless spacecraft…
Superior Senses of Familiar Fauna
Mike Kaczmarczik 2008-04-04 noon, Disque 919
We will look at a variety of local fauna with exceptional senses. Special emphasis will be placed on the physics that allows these unique adaptations to function so successfully. Although nearly all the specimens we will examine can be found in or around the city, we will stray a bit to discuss topics such as the use of electric and magnetic fields as a means of navigation and detection. However, it should be noted that above all else, there will be FREE FOOD.
Irrelevant Topics in Physics (part deux)
Travis Hoppe 2008-03-07 2pm, Disque 919
As always these talks seek to answer the question, “Why are you putting your incredible brainpower, expertise and finely honed reasoning skills to good use?”. Clearly I haven't been and as a result I create these exciting, yet irrelevant topics accessible only to those at the top of the academic food chain. Come tomorrow to learn about really, really, really (I mean really) big numbers. After that we will explore the mystery and allure of Venn Diagrams. If I have any time left I might even throw in some nibblets of knowledge that I've created myself!
Discussion of “The Mathematical Universe” by cosmologist Max Tegmark
Ernie Mamikonyan 2008-02-15 2pm, Disque 919
Tim sent out a link earlier, but as repetition is the spice of life, here it is again:
http://arxiv.org/abs/0704.0646
Try and read at least some of it before 2pm, so that we can all argue with our mouths full of pizza. If you absolutely don't have time to look at the full thing, there is a “directors cut” version here:
Supernova Neutrinos
Erica Caden 2008-02-08 noon, Disque 919
Being here at Drexel, you (presumably) know all about the neutrinos that we study from reactors. I can't count how many talks I've heard about the KamLAND and DoubleChooz experiments. On Friday, I'll be telling you about Supernova neutrinos. How they are created, why they matter, and what they can tell us about supernovas that light can't. Take that astronomers!!
The Science of Fencing
Donna Yosmanovich 2007-12-07 1pm, Disque 919
Fencing has, and continues to benefit from the application of science. From being able to tell who scored a hit, to the safety of the equipment used, and just being able to describe why certain actions are the most efficient, science has improved the sport greatly. I will talk about these three topics in brief, and give a short demonstration, for which I will need volunteers.
Solubility of sickle hemoglobin with dextran as crowding agent
Zenghui Liu 2007-11-30 2pm, Disque 109
Fundamental to the analysis of protein polymerization is the free energy of association, typically determined from solubility. It has been previously shown that the solubility of sickle hemoglobin with concentrated 70kD dextran could be measured by centrifuge method, and I will explain how we measured it with the photolysis method.
Space Shuttle Debris Environment and Why the Hubble Repair Mission is in Jeopardy
Ryan Lee 2007-11-02 1pm, Disque 919
In February 2003, the orbiter Columbia disintegrated upon reentering the atmosphere, killing all 7 astronauts aboard. An investigation showed that the cause was debris striking the wing, producing a large hole in the thermal protection systems. The aerodynamic heating at the weak location led to a catastrohpic failure of the vehicle. Since that time, Boeing and NASA developed tools to predict the capability of the thermal protection systems to withstand the debris environment, which led to a reduction in the debris environment. Eventually, the probability of failure was deemed “low enough” to resume flying in 2005. The aging vehicle now has about 10 missions left to complete the space station construction, and one mission to repair the Hubble telescope, however this mission is under intense scrutany because the debris problem and the safety of the crew. Come Friday to get an overview of the debris problems, how the problems are handled, and why the Hubble mission may or may not actually occur.
Physics for Physicists for Artists
Edward Damon 2007-10-19 1pm, Disque 919
Physics is Phun! However, it's often hard to get some things across to well-meaning family members and acquaintances who may ask you things about popular science columns in the newspaper, some fact they heard on the radio, or, worst of all, questions about your own research. You have the Scylla of being incomprehensible and the Charybdis of being dull, meaning that only the most experienced grad students can escape through unscathed.
The solution to this little trouble is Physics for Physicists for Art People: topics pre-selected to have the unique traits of sounding cool, being easy to explain, and having interesting consequences/applications. This time, the particular nugget of amusement is the thermodynamics of black holes.
Irrelevant topics in physics (Volume I)
Travis Hoppe 2007-10-05
To often it seems we have become regimented in our studies post-quals. The idea of studying one topic (research) often distances you from the rest. So in the ultimate act of procrastination of research duties I present the first of a series of Irrelevant Topics in Physics. Topics which may have no immediate, or practical value, but are have that intrinsic cool factor. I will be presenting three topics: Dissipative Hamiltonians, Superformula, and why you shouldn't get drunk in 3D. I am an expert in none of these topics, I would however like to share them and see where the discussion leads.
The Great Job (and Lunch) Extravaganza!
Tony Abi-Salloum 2007-09-11
Tony is currently an Assistant Professor of Physics at Widener University. Impressive, no? With his (soon to be) patented N-step plan, you too can gain a tenure-track faculty position at an accredited university! Also, he will be selling and autographing copies of his book, "What the Heck Should I do With This Physics Degree?" for $99.99 per copy (it's cheaper than Jackson!). I'll be on hand to take your order, but you can pre-pay to secure one today.
Sandwich enough stars together, and what do you get?
Ernest Mamikonyan 2007-08-27
I'll talk a little bit about the hybrid N-body code Steve and I have developed to look at the evolution of star clusters in arbitrary potential fields, e.g., the host galaxy, very accurately. At the end, I'll mention some exciting new technologies that are being used to do massively parallel (vector) scientific calculations.
The codes he uses require hefty computing power, and there have been a variety of dedicated (i.e. expensive) solutions. But the computing landscape is changing, and hardware that some of us use for more mundane tasks (i.e. World of Warcraft) turns out to be useful for more realistic simulations, as well. For some examples, follow these intertube links:
Weighing Clusters with Gravitational Lensing: A new technique
Sanghamitra Deb 2007-08-03
Combining weak and strong lensing is becoming an important tool in mass measurements of galaxy clusters. The difference in scale between weak and strong lensing is traditionally dealt by either finely gridding the field and using regularization or by using multiresolution grids. The first method is computationally expensive while the second compromises on the accuracy. As an alternative to gridding, we use a Smooth Particle Hydrodynamics (SPH) like method where the potential (or the mass) is reconstructed at the positions of available data (lensed galaxies). The local density of the data at each point contributes to the potential and determines the accuracy of the method. Also, the present techniques do not use all possible strong lensing information. Typically weak lensing ellipticities are combined with strong lensing positions. No attention has been given toflux ratios and ellipticity differences of multiple images. We intend to incorporate these information in our technique.
The Strange Case of Tidal Dissipation
Chris Coughenour 2007-07-20
One of the central problems in classical physics was an explanation of the mechanisms responsible for the genesis of Earth's solid body and oceanic tides. Newton, Laplace, Kelvin and others made significant contributions to this end, providing a theoretical basis for future studies and facilitating more accurate prediction of tides. The delineation of processes inducing tidal dissipation, however, has remained elusive. Far from being the closed problem many predicted with the realization of fast electronic computers, a variety of semi-empirical numerical models have failed to yield a consensus as to the correct dissipative agent. The analysis of the geologic record of tidal deposits may prove useful in addressing this problem. Through the preservation of fortnightly neap-spring cycles in coastal sediments, researchers have been afforded a glimpse into the evolution of the lunar orbit. The use of Kepler's third law and the postulate of conservation of momentum of the Earth-Moon system allows computation of past lunar orbital distances. This temporally controlled distance is a direct function of the rate of tidal dissipation on Earth and, thus, may permit further examination of potential dissipative agents in a more constrained context.
The Shape of the Universe
Danny Pan 2007-06-29
The shape and structure of voids in the Universe is predicted to be filamentary by Lambda-CDM models. I employ ShapeFinder, a method of determining the shape and structure of any arbitrary object, to determine the statistics of voids in the Universe. ShapeFinder uses basic statistics of an object (Volume, Surface Area, Curvature) to determine its general shape. By looking at voids and void galaxies, it is possible to assess shapes to the mass distribution within voids. This mass distribution is then checked with Lambda-CDM models to determine their viability as predictors to the evolution of the Universe. The method for determining the final results of shapes and structures has not yet been solved and I hope to employ everyone in discussing how to resolve this issue at the luncheon.
Kohler Illumination for Spectral Optical Microscopy
Mikhail Zakharov 2007-06-01
Conventional white light microscopy has been used for years. Much work has been done to enhance magnification, resolution, light transfer efficiency and other parameters of regular microscopes. In some cases, in addition to fine spatial resolution, it is important to get spectral resolution of the substances being studied. The illumination systems of most conventional light microscopes follow Kohler (1893) and Dempster (1944). This type of illumination gives maximum lateral resolution as well as maximum vertical resolution. In our laboratory we developed a spectral imaging approach where the specimen is illuminated by a monochromatic light of constantly changing wavelength.
The problem is: how does one illuminate the specimen using the output slit of the monochromator as a source, following the principles of Kohler illumination? The other criterion here is to achieve maximum energy transfer efficiency, so that the maximum possible amount of light reaches the specimen. Surprisingly enough, no solution to this problem has been published yet. By working in the centered optical system approximation, a matrix approach was utilized to calculate the light propagation. Software was created to solve the matrix equations, visualize solutions and help select the right one. Common solutions will be shown. Maximizing energy transfer and minimizing aberrations will be discussed.
Topological Invariants and Degree of Freedoms of Embeddings of Low-dimensional Strange Attractors
Nicola Romanazzi 2007-05-17
When a low dimensional chaotic attractor is embedded in 3-d its topological properties are embedding-dependent. The topological properties that depend on the embeddings are parity, global torsion, and knot type. The mechanism that is responsible for creating the attractor in invariant independent.
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