Constraints on OH Megamaser Excitation from a Survey of OH Satellite Lines

We report the results of a full-Stokes survey of all four 18 cm OH lines in 77 OH megamasers (OHMs) using the Arecibo Observatory. This is the first survey of OHMs that included observations of the OH satellite lines; only 4 of the 77 OHMs have existing satellite line observations in the literature. In 5 sources, satellite line emission is detected, with 3 of the 5 sources re-detections of previously published sources. The 2 sources with new detections of satellite line emission are IRAS F10173+0829, which was detected at 1720 MHz, and IRAS F15107+0724, for which both the 1612 MHz and 1720 MHz lines were detected. In IRAS F15107+0724, the satellite lines are partially conjugate, as 1720 MHz absorption and 1612 MHz emission have the same structure at some velocities within the source, along with additional broader 1612 MHz emission. This is the first observed example of conjugate satellite lines in an OHM. In the remaining sources, no satellite line emission is observed. The detections and upper limits are generally consistent with models of OHM emission in which all of the 18 cm OH lines have the same excitation temperature. There is no evidence for a significant population of strong satellite line emitters among OHMs.Comment: 9 pages, accepted to Ap

Robust and Fast 3D Scan Alignment using Mutual Information

This paper presents a mutual information (MI) based algorithm for the estimation of full 6-degree-of-freedom (DOF) rigid body transformation between two overlapping point clouds. We first divide the scene into a 3D voxel grid and define simple to compute features for each voxel in the scan. The two scans that need to be aligned are considered as a collection of these features and the MI between these voxelized features is maximized to obtain the correct alignment of scans. We have implemented our method with various simple point cloud features (such as number of points in voxel, variance of z-height in voxel) and compared the performance of the proposed method with existing point-to-point and point-to- distribution registration methods. We show that our approach has an efficient and fast parallel implementation on GPU, and evaluate the robustness and speed of the proposed algorithm on two real-world datasets which have variety of dynamic scenes from different environments

"Almost-stable" matchings in the Hospitals / Residents problem with Couples

The Hospitals / Residents problem with Couples (hrc) models the allocation of intending junior doctors to hospitals where couples are allowed to submit joint preference lists over pairs of (typically geographically close) hospitals. It is known that a stable matching need not exist, so we consider min bp hrc, the problem of finding a matching that admits the minimum number of blocking pairs (i.e., is “as stable as possible”). We show that this problem is NP-hard and difficult to approximate even in the highly restricted case that each couple finds only one hospital pair acceptable. However if we further assume that the preference list of each single resident and hospital is of length at most 2, we give a polynomial-time algorithm for this case. We then present the first Integer Programming (IP) and Constraint Programming (CP) models for min bp hrc. Finally, we discuss an empirical evaluation of these models applied to randomly-generated instances of min bp hrc. We find that on average, the CP model is about 1.15 times faster than the IP model, and when presolving is applied to the CP model, it is on average 8.14 times faster. We further observe that the number of blocking pairs admitted by a solution is very small, i.e., usually at most 1, and never more than 2, for the (28,000) instances considered

The Transformation of U.S. Livestock Agriculture: Scale, Efficiency, and Risks

U.S. livestock production has shifted to much larger and more specialized farms, and the various stages of input provision, farm production, and processing are now much more tightly coordinated through formal contracts and shared ownership of assets. Important financial advantages have driven these structural changes, which in turn have boosted productivity growth in the livestock sector. But structural changes can also generate environmental and health risks for society, as industrialization concentrates animals and animal wastes in localized areas. This report relies on farm-level data to detail the nature, causes, and effects of structural changes in livestock production.Livestock, dairy, broilers, hogs, fed cattle, farm structure, scale economies, contract agriculture, CAFOs, growth-promoting antibiotics, Farm Management, Livestock Production/Industries,

The 2016 Irish general election: the parties and the polling

Ireland is expected to hold its next general election in either February or March. Ahead of the election, James McBride assesses developments since the last contest in 2011, where Fianna Fáil saw its vote share substantially reduced in the aftermath of the financial crisis. He writes that present polling suggests Fine Gael will retain its status as the largest party, but that it is unclear who the party would be able to go into coalition with to form a new government if the Labour Party experiences a drop in support

Design and Assessment of an Interactive Digital Tutorial for Undergraduate-Level Sandstone Petrology

This study describes the goals, features and effectiveness of a digital interactive tutorial which was created to provide undergraduates a 'virtual microscope' resource for learning sandstone petrology. The goal of the tutorial is to provide students exposure to the highly visual subject matter of petrography outside the confines of organized laboratory exercises. The hope is that widespread use of such digital interactive formats will allow students to gain high levels of expertise with description and interpretation of earth materials despite the reduced amounts of hands-on laboratory practice that are allowed by modern curricula. Educational levels: Graduate or professional

Reformation in Practices and Policies Regarding Public School Safety

Among the many sections of Dallas, SMU\u27s campus is definitely one of the safest. Many contributing reasons for this include the active police force and campus security. Besides the manpower, the campus has a safe feel due to the many other precautions that the school has taken. An example of these precautions is the emergency text messaging and email system, which allows for the quick spread of vital information. In the wake of the tragic Virginia Tech shooting, SMU took a strong step toward protecting its students and faculty with this system. The effect of this system could be felt at local Dallas high schools where danger is still quite a possibility. Most high school students have or have access to cell phones and computers during the day. During an emergency situation they could be alerted of a threat quickly and silently. While the full details of the current system used by SMU are not known to us, we believe that high schools would be able to go through the same process of registering numbers and emails to allow the messages the broadest reach possible. These alerts could also be used to provide information during dangerous weather or other such situations