Theory of disorder-induced multiple coherent scattering in photonic crystal waveguides

We introduce a theoretical formalism to describe disorder-induced extrinsic scattering in slow-light photonic crystal waveguides. This work details and extends the optical scattering theory used in a recent \emph{Physical Review Letter} [M. Patterson \emph{et al.}, \emph{Phys. Rev. Lett.} \textbf{102}, 103901 (2009)] to describe coherent scattering phenomena and successfully explain complex experimental measurements. Our presented theory, that combines Green function and coupled mode methods, allows one to self-consistently account for arbitrary multiple scattering for the propagating electric field and recover experimental features such as resonances near the band edge. The technique is fully three-dimensional and can calculate the effects of disorder on the propagating field over thousands of unit cells. As an application of this theory, we explore various sample lengths and disordered instances, and demonstrate the profound effect of multiple scattering in the waveguide transmission. The spectra yield rich features associated with disorder-induced localization and multiple scattering, which are shown to be exasperated in the slow light propagation regime

Residential Docks and Piers: Inventory of laws, regulations, and policies for the Southeastern United States

While the homes threatened by erosion and the developer illegally filling in marshlands are the projects that make the headlines, for many state regulatory programs, it’s the residential docks and piers that take up the most time. When is a dock too long? What about crossing extended property lines? And at what point does a creek have too many docks? There are no easy answers to any of the dock and pier related questions. Each state has to craft the laws and policies that are best for its natural resources and its political and legal environment. At the same time, mistakes in judgment can be costly for the organization, the homeowner, and the natural resources. At the request of the Georgia Coastal Management Program, the National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center compiled an inventory of dock information for four states—Georgia, Florida, North Carolina, and South Carolina. Federal laws, state laws and regulations, permitting policies, and contact information are included in a tabular format that is easy to use. (PDF contaions 18 pages

On Learning and Unlearning

I remember passing our lunch lady–the nice one with a big bleach-blond afro. She was perched on an elementary-school-sized desk, eyes fixated to the television. I glanced at the screen on the way into my classroom while my teacher hesitated in the hallway, whispering to the other adults. She reentered the room a few minutes later to explain. In the following months, my television provided me with one of the most formative, practical and comprehensive educational experiences of my life. First it was vocabulary building, with the words like “hi-jacker,” and “terrorist.” Then it was physics, learning that inertia is the reason for absolute devastation when your plane crashes into a building. Soon, “Al-Qaeda,” “the Taliban,” and “Osama bin Laden” became part of my reality, as I watched a broadcast of young men in the “Middle East” (I was learning geography too!) burning American flags. [excerpt

I Don\u27t Want to Save Your Children

A few weeks ago, the moment that I’ve been dreaming of for almost half of a year finally arrived. I started the Heston Summer Experience as an intern in Gettysburg. An embarrassing amount of my winter break was devoted to writing and rewriting my applications. After receiving an invitation for an interview, I convened my roommates to help me choose an outfit and ask me practice questions, which is not something I do…ever. Getting my acceptance letter in the mail was the ultimate highlight of a long and difficult year. When I was home for the first few weeks of summer and people were asking me about my plans, I was initially really excited to share. (Who wouldn’t be?) The more time I spent explaining the internship to my friends and family though, the more embarrassed I became. [excerpt

An Equal Opportunity Rejection

Let’s talk about applications. We’ve all been there. You write your application, work on draft after draft and then you send it all off to the college or job of your dreams. And you wait…and wait…and wait. You wait for some sort of letter or phone call that says something along the lines of, “We love you! You’re awesome, and smart and special, and we think you’d be a great asset!” And maybe you’re lucky and you do get that letter, but let’s be real - that doesn’t always happen. It can be frustrating to receive a rejection letter (or nothing at all), because in all honesty, who wants to be told that they’re “not good enough”? Not me. [excerpt

Sexism - LMFAO

So I have a confession to make, one that I’m really not proud of, but part of being a mature person is acknowledging, accepting, and learning from your past mistakes. Here it is: I told a sexist joke. [excerpt

Performance characteristics of ring-cusp thrusters with xenon propellant

The performance characteristics and operating envelope of several 30-cm ring-cusp ion thrusters with xenon propellant were investigated. Results indicate a strong performance dependence on the discharge chamber boundary magnetic fields and resultant distribution of electron currents. Significant improvements in discharge performance over J-series divergent-field thrusters were achieved for large throttling ranges, which translate into reduced cathode emission currents and reduced power dissipation which should be of significant benefit for operation at thruster power levels in excess of 10 kW. Mass spectrometry of the ion beam was documented for both the ring-cusp and J-series thrusters with xenon propellant for determination of overall thruster efficiency, and lifetime. Based on the lower centerline values of doubly charged ions in the ion beam and the lower operating discharge voltage, the screen grid erosion rate of the ring-cusp thruster is expected to be lower than the divergent-field J-series thruster by a factor of 2

Slow, Continuous Beams of Large Gas Phase Molecules

Cold, continuous, high flux beams of benzonitrile, fluorobenzine, and anisole have been created. Buffer-gas cooling with a cryogenic gas provides the cooling and slow forward beam velocities. The beam of benzonitrile was measured to have a forward velocity peaked at 67 $\pm 5$ m s$^{-1}$, and a continuous flux of $10^{15}$ molecules s$^{-1}$. These beams provide a continuous source for high resolution spectroscopy, and provide an attractive starting point for further spatial manipulation of such molecules, including eventual trapping

Duty to Warn and Intervention with HIV-Positive Clients

Complex ethical and legal issues are involved when an HIV-positive client presents a danger to others as a result of engaging in unprotected sex or needle sharing. This article presents a detailed assessment-and-intervention model that is based on the integration of ethical and legal principles with information about the level of risk associated with a client\u27s behavior, the HIV status of the client, and the sexual or needle-sharing partner\u27s awareness of the client\u27s HIV status. Appropriate interventions, including the duty to warn, are identified for each of the risk levels