Evaluating the Effectiveness of Child Safety Seats and Seat Belts in Protecting Children from Injury

Young children are required to use child safety seats, and the age threshold at which children can legally graduate to seat belts has steadily increased. This paper tests the relative effectiveness of child safety seats, lap-and-shoulder seat belts, and lap belts in preventing injuries among motor vehicle passengers aged 2-6. We analyze three large, representative samples of crashes reported to police, as well as linked hospital data. We find no apparent difference in the two most serious injury categories for children in child safety seats versus lap-and-shoulder belts. Child safety seats provide a statistically significant 25% reduction in the least serious injury category. Lap belts are somewhat less effective than the two other types of restraints, but far superior to riding unrestrained.

Measurement Error, Legalized Abortion, and the Decline in Crime: A Response to Foote and Goetz (2005)

Donohue and Levitt (2001) argue that the legalization of abortion in the United States in the 1970s played an important role in explaining the observed decline in crime approximately two decades later. Foote and Goetz (2005) challenge the results presented in one of the tables in that original paper. In this reply, we regretfully acknowledge the omission of state-year interactions in the published version of that table, but show that their inclusion does not alter the qualitative results (or their statistical significance), although it does reduce the magnitude of the estimates. When one uses a more carefully constructed measure of abortion (e.g. one that takes into account cross-state mobility, or doing a better job of matching dates of birth to abortion exposure), however, the evidence in support of the abortion-crime hypothesis is as strong or stronger than suggested in our original work.

Further Evidence that Legalized Abortion Lowered Crime: A Reply to Joyce

Donohue and Levitt (2001) present a number of analyses that suggest a causal link between legalized abortion and reductions in crime almost two decades later when the cohorts exposed to legalized abortion reach their peak crime years. Joyce (2003) challenges that finding. In this paper, we demonstrate that Joyce's failure to uncover a negative relationship between abortion and crime is a direct consequence of his decision to focus exclusively on the six-year period 1985-90 without including adequate controls for the crack epidemic. We provide empirical evidence that crack hit the high-abortion early legalizing states harder and earlier. We then demonstrate that using precisely the same treatment and control groups as Joyce, but extending the data analysis to encompass the lifetime criminal experiences (as opposed to an arbitrary six-year window), the evidence strongly supports the hypothesis that legalized abortion reduces crime. We also show that our original results are robust to focusing on only the cohorts born immediately before or after Roe v. Wade. The data suggest that ease of access to abortion, rather than simply de jure legalization, is a critical determinant of the extent of the crime reduction.

Magic composite pulses

I describe composite pulses during which the average dipolar interactions within a spin ensemble are controlled while realizing a global rotation. The construction method used is based on the average Hamiltonian theory and rely on the geometrical properties of the spin-spin dipolar interaction only. I present several such composite pulses robust against standard experimental defects in NRM: static or radio-frequency field miscalibration, fields inhomogeneities. Numerical simulations show that the magic sandwich pulse sequence, a pulse sequence that reverse the average dipolar field while applied, is plagued by defects originating from its short initial and final \pi/2 radio-frequency pulses. Using the magic composite pulses instead of \pi/2 pulses improves the magic sandwich effect. A numerical test using a classical description of NMR allows to check the validity of the magic composite pulses and estimate their efficiency.Comment: 22 pages, 6 figure

Pulse Sequences for NMR Quantum Computers: How to Manipulate Nuclear Spins While Freezing the Motion of Coupled Neighbours

We show how to divide a coupled multi-spin system into a small subset of ``active'' spins that evolve under chemical shift or scalar coupling operators, and a larger subset of ``spectator'' spins which are returned to their initial states, as if their motion had been temporarily frozen. This allows us to implement basic one-qubit and two-qubit operations from which general operations on $N$-qubits can be constructed, suitable for quantum computation. The principles are illustrated by experiments on the three coupled protons of 2,3-dibromopropanoic acid, but the method is applicable to any spin-1/2 nuclei and to systems containing arbitrary numbers of coupled spins.Comment: 11 pages, 5 fig

Proposal for a Penn Bookstore Internship Program in Events and Marketing

The purpose of this thesis is to propose the creation of an events/marketing internship program at the Penn Bookstore. I begin with a review of common terms and definitions used to describe student-learning experiences. Penn has multiple resources available to undergraduate students looking for an internship. Based on a review of internship programs offered through Penn and at a variety of local organizations, I identify and describe common and unique program categories. In addition, I examine three internship program models from the perspective of academic, non-profit and corporate/for-profit organizational settings. Based on this review, I propose my vision for an internship program model for the Penn Bookstore. I conclude by relating the benefits of the proposed internship program to the Bookstore, the undergraduate student community at Penn, and the University

Doctors, Lawyers, & Leadership: Two Coaching Cases and Perspectives on the Future

Both physicians and attorneys complete highly rigorous academic regimens in order to prepare to practice in their respective fields. Rarely does the training in law school or medical school prepare them to manage either staff or departments. Leadership coaching for physicians and attorneys is a newer field, which is slowly beginning to gain traction in medical and legal fields. Through coaching, professionals gain insights into how they are viewed by their supervisor, peers, and direct reports and use this knowledge to formulate coaching goals, which are facilitated by an Executive Coach. Coaching approaches are based on theoretical knowledge, which provides coaches with a framework for their client work. This framework when balanced with the coach’s insights through observation, the use of assessments and instruments, and other data provides a comprehensive method for client intervention. This paper focuses on two case studies of coaching engagements, which were a part of the Organizational Consulting and Executive Coaching Concentration requirements: a Practicum with a retina surgeon, and an Executive Coaching Internship with a litigation department chair. The application of theory as well as a review of selected articles related to the training and coaching of physicians and attorneys is included to provide an understanding of the past, present, and future of coaching in these fields. This paper is written in first person to create a connection between the author and reader and offer an introspective viewpoint beyond the academic nature of the topics. The case studies, though not originally connected, offer a glimpse into two portraits of successful professionals striving to better understand both management and themselves