Thomas-forbidden particle capture

At high energies, in particle-capture processes between ions and atoms, classical kinematic requirements show that generally double collision Thomas processes dominate. However, for certain mass-ratios these processes are kinematically forbidden. This paper explores the possibility of capture for such processes by triple or higher order collision processes.Comment: 34 pages and three figure

Statistical inference of the generation probability of T-cell receptors from sequence repertoires

Stochastic rearrangement of germline DNA by VDJ recombination is at the origin of immune system diversity. This process is implemented via a series of stochastic molecular events involving gene choices and random nucleotide insertions between, and deletions from, genes. We use large sequence repertoires of the variable CDR3 region of human CD4+ T-cell receptor beta chains to infer the statistical properties of these basic biochemical events. Since any given CDR3 sequence can be produced in multiple ways, the probability distribution of hidden recombination events cannot be inferred directly from the observed sequences; we therefore develop a maximum likelihood inference method to achieve this end. To separate the properties of the molecular rearrangement mechanism from the effects of selection, we focus on non-productive CDR3 sequences in T-cell DNA. We infer the joint distribution of the various generative events that occur when a new T-cell receptor gene is created. We find a rich picture of correlation (and absence thereof), providing insight into the molecular mechanisms involved. The generative event statistics are consistent between individuals, suggesting a universal biochemical process. Our distribution predicts the generation probability of any specific CDR3 sequence by the primitive recombination process, allowing us to quantify the potential diversity of the T-cell repertoire and to understand why some sequences are shared between individuals. We argue that the use of formal statistical inference methods, of the kind presented in this paper, will be essential for quantitative understanding of the generation and evolution of diversity in the adaptive immune system.Comment: 20 pages, including Appendi

Lessons Learned: Kieran J. Fallon

Presently the senior deputy general counsel for regulation and government affairs at PNC Fi-nancial Services Group, Kieran Fallon completed a 16-year tenure in the legal division of the Board of Governors of the Federal Reserve System in 2011. As associate general counsel dur-ing the Global Financial Crisis (GFC), he helped design the Federal Reserve’s Commercial Pa-per Funding Facility, restructure American International Group (AIG), and implement the Dodd-Frank Act. Relatedly, Fallon also served as general counsel for the Financial Stability Oversight Board from 2008 to 2011. This Lessons Learned is based on an interview conducted with Fallon on August 13, 2020

Lessons Learned: Mark Van Der Weide

With more than two decades of continuing service at the Federal Reserve Board, Mark Van Der Weide brings a unique insider perspective on central bank policymaking before, during, and after the Global Financial Crisis (GFC), including the Fed’s response to the COVID-19 pandemic in 2020. From 1998 to 2009, Van Der Weide served in the Fed’s legal division. De-tailed to the Treasury Department in 2009, he helped draft the Dodd-Frank Wall Street Re-form and Consumer Protection Act of 2010. Back at the Fed in 2010, Van Der Weide served for eight years in the Division of Supervision and Regulation, where he was made deputy direc-tor, helping to implement the Dodd-Frank Act and the Basel III accord, among other policies. The Board of Governors appointed him general counsel in 2017. This “Lessons Learned” is based on an interview with Mr. Van Der Weide in September 2020

Lessons Learned: Susan McLaughlin

A veteran staff member of the Federal Reserve Bank of New York (FRBNY), Susan McLaughlin served as head of the discount window and chief operating officer of the FRBNY’s Markets Trading Desk during the Global Financial Crisis. She was centrally involved in the Fed’s policy response to the disruptions to secured and unsecured funding markets during 2007–2008. Following the crisis, McLaughlin coordinated an effective Fed initiative to reform the triparty repurchase agreement (repo) market’s settlement infrastructure. The Fed’s reform efforts, engaging the financial industry under FRBNY president Bill Dudley, were instrumental in im-proving the stability of the funding market. This Lesson Learned is based on an interview conducted with McLaughlin on December 2, 2020

Lessons Learned: Raghuram Rajan

Raghuram Rajan, a University of Chicago professor of economics and finance, served as director of research at the International Monetary Fund (IMF) from 2003 to 2006. In 2005, Rajan warned very publicly of the risks of a financial crisis. Following his tenure at the IMF, Rajan served as chief economic adviser to India’s Finance Ministry and governor of the Reserve Bank of India. An expert on financial institutions and their effects on economic growth and development across countries, Rajan was recognized as a fellow of the American Academy of Arts and Sciences in 2009. He is co-author of Saving Capitalism from the Capitalists (2003) and author of The Third Pillar (2019), about community organization. This Lessons Learned is based on an interview with Rajan conducted on December 16, 2020

Lessons Learned: Frederic Mishkin

Rick Mishkin served as a member of the Board of Governors of the Federal Reserve System from 2006 to 2008 and as director of research at the Federal Reserve Bank of New York from 1994 to 1997. A leading expert on monetary economics and financial markets and a professor at Columbia University’s School of Business since 1983, Mishkin has written 20 books, including the textbook The Economics of Money, Banking, and Financial Markets. This Lessons Learned is based on an interview with Mishkin conducted on October 20, 2020

Lessons Learned: Steven H. Kasoff

Steve Kasoff was employed at Elliott Management Corporation from 2003 until 2020. His responsibilities centered on developing the structured products and real estate groups at Elliott. He was made senior portfolio manager, a member of the firm’s management committee, and equity partner. Kasoff has extensive experience in the origination, trading, and management of structured products such as collateralized debt obligations (CDOs) and mortgage-backed securities, including earlier posts at Deutsche Bank, Merrill Lynch, and Lehman Brothers. He earned his BA in economics from Yale College and his MBA in finance from the Wharton School of the University of Pennsylvania. In 2016, Kasoff joined the advisory board of the International Center for Finance at the Yale School of Management. After retiring from Elliott in 2020, he began to work with the Yale Program on Financial Stability (YPFS). This Lessons Learned summary is based on two interviews of Kasoff by YPFS and is part of an investigation he spearheaded into the subprime securitization boom before the financial crisis—the Inside the CDO Machine project—which includes interviews with financial industry practitioners. The complete Inside the CDO Machine project materials can be accessed on the YPFS Lessons Learned website: https://som.yale.edu/centers/program-on-financial-stability/lessons-learned-oral-history-project

Lessons Learned: Kevin Warsh

As senior deputy director of the Division of Supervision and Consumer Protection at the Federal Deposit Insurance Corporation (FDIC), Spoth led examinations, enforcement actions, problem bank remediations, and failure resolutions, among a range of responsibilities. During the Global Financial Crisis, he was on the front lines of fast-moving policy discussions and actions to help stabilize the financial system, and he oversaw the closure and restructuring of some of the nation’s largest banks. This abstract is based on an interview with Spoth on February 4, 2021