Particle production from marginally trapped surfaces of general spacetimes

We provide a general formalism that allows to analyze the phenomenon of tunneling in arbitrary spacetimes. We show that a flux of particles produced by tunneling through general marginally trapped surfaces may be perceived by some privileged observers. We discuss how this particle perception can be related to Hawking/Unruh radiation in specific cases. Our approach naturally leads to an expression for the effective surface gravity of marginally trapped surfaces. The procedure is applicable to general astrophysical and cosmological dynamical situations. Some practical examples for known and new cases are provided.Comment: 24 pages, 2 figures. Section 4.2, concerning the analysis of the Kerr-Vaidya solution, has been rewritten, correcting mistakes in previous versions. The corrected calculations do support our claims. A corrigendum has also been sent to CQG. New references added. Some of the mistakes in previous versions are actually common and spread in the literature on the Kerr-Vaidya solutio

Exchange rate dynamics in crawling-band systems

In this note we show that an exchange rate crawling-band system can borrow a portion of those aspects of a target zone that lead to its stabilizing effects on the exchange rate, depending on the relationship between the crawl rate and the drift of the fundamentals process. If the crawl rate is sufficiently high (with respect to the drift), the crawling-band is similar to a free float regime. As the crawl rate decreases, the crawling-band system collapses to a standard target zone.crawling band

Personal Reflections / 3.1.18

Even with the distance created by time between the shooting in Parkland, Florida and today, I still choke up when I consider the loss of life that happened at the Marjory Stoneman Douglas High School on February 14, Valentine’s Day, two weeks ago. Ponder their lives, their unfulfilled potential and their unrealized dreams. Consider how we should live in this society. Determine what action you can take

Personal Reflections / 12.20.18

Today as our IMSA students depart from their IMSA home to spend winter break at their other home, I want to wish them and their families a very joy-filled winter break. I know that our staff, including myself and the faculty, look forward to enjoying the holidays with our respective families. Last Friday, our students, led ably by our Music Faculty Mary Beth McCarthy and Emily Cooley, put on a spectacular music program, Sleigh Ride Around the World . Many family members who joined us can attest to the quality and variety of the performance. I was so impressed with the diversity of songs, composers, and instruments represented in the program. This diversity reminded me that I have not yet focused on Equity and Excellence in these Personal Reflections. As you might recall, I am using each issue of this year\u27s Personal Reflections to focus on one IMSA Priority. Today, I want to focus on our Equity and Excellence priority

Personal Reflections / 4.30.18

We are now in the home stretch just several weeks before the end of the school year. Final papers and projects, exams, Advanced Placement examinations and college decisions are now the only thing between us and commencement. Of course, we can’t forget senior prom, senior banquet, senior recognition and transition day! Before we wrap up the school year, I wanted to provide you with a brief update on our budget hearings. We just had an amazing week in Springfield

Personal Reflections / 11.18.16

It’s been an eventful time since the Cubs won the World Series! It was amazing to see 5 million people celebrate the Cub’s victory. Hopefully we won’t have to wait another 108 years to relive the experience. Last week we had a historic election and now, our country will transition power from President Obama to President-elect Trump. Heightened discourse followed this historic election and rising tensions and fears are being experienced, especially by minorities, immigrants, refugees and others groups. IMSA will remain the safe and welcoming place that it’s always been for 30 years. Our counselors are available for our students, and our faculty and staff are alerted that students might want to talk about the election results. We’ve seen national election results give rise to heightened concerns about America’s future. I’d like to share some reassuring thoughts about thi