A Study of the Dark Core in A520 with Hubble Space Telescope: The Mystery Deepens

We present a Hubble Space Telescope/Wide Field Planetary Camera 2 weak-lensing study of A520, where a previous analysis of ground-based data suggested the presence of a dark mass concentration. We map the complex mass structure in much greater detail leveraging more than a factor of three increase in the number density of source galaxies available for lensing analysis. The "dark core" that is coincident with the X-ray gas peak, but not with any stellar luminosity peak is now detected with more than 10 sigma significance. The ~1.5 Mpc filamentary structure elongated in the NE-SW direction is also clearly visible. Taken at face value, the comparison among the centroids of dark matter, intracluster medium, and galaxy luminosity is at odds with what has been observed in other merging clusters with a similar geometric configuration. To date, the most remarkable counter-example might be the Bullet Cluster, which shows a distinct bow-shock feature as in A520, but no significant weak-lensing mass concentration around the X-ray gas. With the most up-to-date data, we consider several possible explanations that might lead to the detection of this peculiar feature in A520. However, we conclude that none of these scenarios can be singled out yet as the definite explanation for this puzzle.Comment: Published in ApJ. Figures are slightly degraded to meet the size limi

Diversity Means Justice: Growing Grassroots Library Staff Diversity Leaders

Paper presented at the ACRL (Association of College & Research Libraries) 2015 Conference in Portland, Oregon.UT Librarie

Sustaining Free Trade with Imperfect Private Information about Non-Tariff Barriers

This paper examines the issue of sustaining free trade when countries receive imperfect private information about each other’s non-tariff barriers. Because the countries can misrepresent their private belief about other countries’ protection levels, the punishment scheme to deter deviations from free trade should provide right incentives for the countries to elicit the true private information. This incentive constraint (ICP) restricts the length of punishment phases. If the private information is almost perfect, the ICP is not a binding constraint for symmetric countries in sustaining symmetric cooperation. However, the ICP does become a binding constraint if there exists a large enough asymmetry in the countries’ incentives to deviate from free trade, or if there exists a large enough asymmetry in the transparency of countries’ trade policies. Then, a mechanism that publicizes the information about non-tariff barriers, like Trade Policy Review Mechanism (TPRM) of WTO, can play a positive role in restoring cooperation by relaxing the ICP.International Economic Order, Non-tariff Barriers, Imperfect Private Information, Noncooperative Game

Enforcing International Trade Agreements with Imperfect Private Monitoring: Private Trigger Strategies and a Possible Role for the WTO

International trade disputes often involve the WTO as a third party that generates impartial opinions of potential violations when countries receive imperfect and private signals of violations. To identify the role that the WTO plays in enforcing trade agreements, this paper first characterizes what countries can achieve alone in a repeated bilateral trade relationship in which they can secretly raise their protection levels through concealed trade barriers. In particular, countries adopt gprivate trigger strategies (PTS)h under which each country triggers a punishment phase by imposing an explicit tariff based on its privately observed imperfect signals of such barriers. This paper identifies the condition under which countries can restrain the use of concealed barriers based on simple PTS, where each country imposes its static optimal tariff in all periods under any punishment phase: The sensitivity of private signals rises in response to an increase in concealed protection. Any equilibrium payoff under almost strongly symmetric PTS will be identical to the one under simple PTS, as long as the initial punishment is triggered by a static optimal tariff, justifying the paper's focus on simple PTS. With countries maximizing their expected payoffs under the optimal PTS, they will not push down the cooperative protection level to its minimum attainable level, thus not setting it to the free trade level even when it is attainable. To analyze a possible role of the WTO, this paper considers gthird-party trigger strategies (TTS)h under which the WTO allows each country to initiate a punishment phase based on the WTO's judgment (signals) about potential violations. The WTO changes the nature of punishment-triggering signals from private into public, enabling countries to use punishment phases of any length under TTS, which in turn facilitates a better cooperative equilibrium. The optimal TTS will involve an asymmetric and minimum punishment if the probability of a punishment phase being triggered is low enough, but it will entail punishments involving a permanent Nash tariff war if the probability of a punishment being triggered is high enough. A numerical comparison of the optimal TTS and optimal PTS indicates that the contribution of the WTO is likely to be significant when the signals of potential violations are relatively accurate. The WTO enables countries to adopt a more efficient punishment, such as the asymmetric and minimum punishment, which in turn enables countries to be less tolerant of potential violations and attain a higher level of cooperation as a result.

Transforming Technical Services: Evolving Functions in Large Research University Libraries

Technical services functions in academic libraries have evolved in response to fiscal pressures and advances in technology. In this study the author investigates how technical services in large research university libraries are adapting to support the changing roles of academic libraries. The author conducted hour-long phone interviews in early 2014 with the representatives from nineteen out of the twenty-five university libraries in the Technical Services Directors Large Research Libraries Interest Group. This paper presents the results and discussion based on the interview data: use of the name, Technical Services; new and emerging functions of technical services; organizational structure of technical services units; change drivers that are affecting technical services now, and those that will soon; and challenges in managing technical services. Five models of a technical services organizational structure were developed from participants’ organizational charts and interview data. This research also highlights the skills needed among technical services personnel.UT Librarie

Robust statistical methods for automated outlier detection

The computational challenge of automating outlier, or blunder point, detection in radio metric data requires the use of nonstandard statistical methods because the outliers have a deleterious effect on standard least squares methods. The particular nonstandard methods most applicable to the task are the robust statistical techniques that have undergone intense development since the 1960s. These new methods are by design more resistant to the effects of outliers than standard methods. Because the topic may be unfamiliar, a brief introduction to the philosophy and methods of robust statistics is presented. Then the application of these methods to the automated outlier detection problem is detailed for some specific examples encountered in practice

Emergency Department: Effectiveness of a Referral Intervention for High Utilizers

This research examined the impact of a referral intervention for patients with high utilization of the Emergency Department (ED) for non-­‐emergent care. The referral intervention was offered by the ED provider who provided the patient with feedback regarding their utilization along with a referral to outpatient services including: primary care physicians, mental health services, and brochure of available resources in the local area. This study used archival retrospective data, and compared frequency of ED visits pre-­‐ intervention and referral to post-­‐intervention frequency of visits and length of time between intervention and next visit. Following the intervention, the participants were classified as either responders or non-­‐responders based on their recidivism. An independent sample t-­‐test showed that the responder group had a significant decrease in number of visits to the ED during the post-­‐intervention period. Additionally, the responders had a significantly longer lag time before they returned to the ED as compared to the non-­‐responders. The referral did not significantly increase patients’ visits to their primary care physician/behavioral health consultant. Therefore brief-­‐ED based intervention may be useful in reducing recidivism in the ED