systemfit: A Package for Estimating Systems of Simultaneous Equations in R

Many statistical analyses (e.g., in econometrics, biostatistics and experimental design) are based on models containing systems of structurally related equations. The systemfit package provides the capability to estimate systems of linear equations within the R programming environment. For instance, this package can be used for "ordinary least squares" (OLS), "seemingly unrelated regression" (SUR), and the instrumental variable (IV) methods "two-stage least squares" (2SLS) and "three-stage least squares" (3SLS), where SUR and 3SLS estimations can optionally be iterated. Furthermore, the systemfit package provides tools for several statistical tests. It has been tested on a variety of datasets and its reliability is demonstrated.

Econometric Analysis of the Effects of Subsidies on Farm Production in Case of Endogenous Input Quantities

The effect of subsidies on farm production has been a major topic in agricultural economics for several decades. We present a new approach for analyzing the effects of different types of coupled and decoupled subsidies on farm production with econometric methods. In contrast to most previous studies, our approach is entirely based on a theoretical microeconomic model, explicitly allows subsidies to have an impact on input use, and takes linkages between the farm and the farm household into account.Agricultural and Food Policy, Productivity Analysis,

Econometric Analysis of the Effects of Subsidies on Farm Production in Case of Endogenous Input Quantities

Replaced with revised version of paper 07/29/09.panel data, subsidies, household model, endogeneity, Norwegian grain farming, Agricultural and Food Policy, Consumer/Household Economics, Production Economics,

systemfit: A Package for Estimating Systems of Simultaneous Equations in R

Many statistical analyses (e.g., in econometrics, biostatistics and experimental design) are based on models containing systems of structurally related equations. The systemfit package provides the capability to estimate systems of linear equations within the R programming environment. For instance, this package can be used for "ordinary least squares" (OLS), "seemingly unrelated regression" (SUR), and the instrumental variable (IV) methods "two-stage least squares" (2SLS) and "three-stage least squares" (3SLS), where SUR and 3SLS estimations can optionally be iterated. Furthermore, the systemfit package provides tools for several statistical tests. It has been tested on a variety of datasets and its reliability is demonstrated

Predictors of Comforting Communication in Romantic Relationships

The ability to provide adequate comforting is valued in close relationships. As a valued commodity, the quality of the comforting that a person provides may be used to maintain equitable relationships or to balance rewards and costs in close relationships. We examined whether perceptions of equity in dating relationships predicts the quality of comforting communication. One hundred and fifteen college students reported their perceptions of equity in their relationships. In addition, they estimated the effort they would expend on comforting their partner in different situations and reported the verbal messages they would use to comfort their partners in a particular scenario. Although molecular measures of equity were significant predictors of comforting behavior, global measures were not. Support was found for the use of comforting communication as a maintenance and as a balancing mechanism. In addition, the effort that participants reported they would expend in comforting their partner did not mediate the association between equity and comforting quality

Fault-controlled asymmetric landscapes and low-relief surfaces on Vestvågøya, Lofoten, North Norway: inherited Mesozoic rift-margin structures?

Source at https://dx.doi.org/10.17850/njg98-3-06The Lofoten Ridge is an integral basement horst of the hyperextended continental rift-margin off northern Norway. It is a key area for studying onshore–offshore rift-related faults, and for evaluating tectonic control on landscape development along the North Atlantic margin. This paper combines onshore geomorphological relief/aspect data and fault/fracture analysis with offshore bathymetric and seismic data, to demonstrate linkage of landscapes and Mesozoic rift-margin structures. At Leknes on Vestvågøya, an erosional remnant of a down-faulted Caledonian thrust nappe (Leknes Group) is preserved in a complex surface depression that extends across the entire Lofoten Ridge. This depression is bounded by opposing asymmetric mountains comprising fault-bounded steep scarps and gently dipping, partly incised lowrelief surfaces. Similar features and boundary faults of Palaeozoic–Mesozoic age are present on the offshore margin surrounding the Lofoten Ridge. The offshore margin is underlain by a crystalline, Permo–Triassic to Early Jurassic, peneplained basement surface that was successively truncated by normal faults, down-dropped and variably rotated into asymmetric fault blocks and basins in the Mesozoic, and the basins were subsequently filled by Late Jurassic to Early Cretaceous sedimentary strata. Comparison of the onshore asymmetric landscapes and offshore tectonic architecture supports the idea that disrupted low-relief surfaces, bounding steep scarps, ridges and depressions onshore the Lofoten Ridge, represent tectonic inheritance of a tilted basement-cover surface, rotated fault blocks and half-graben basins from Mesozoic rifting of the margin. In the Cenozoic, Mesozoic faults controlled the landscape by tilting and reactivated footwall uplift, followed by exhumation of the Mesozoic–Cenozoic cover sediments. Glacial erosion during the Pleistocene partly incised and modified these tectonic features, which nevertheless remain as distinct elements in the landscape

Radiographic Measurements Correlate to Isolated Posterolateral Corner (PLC) Injury in a Novel Cadaveric Model

Introduction: Injury to the posterolateral corner (PLC) of the knee often requires surgical reconstruction. There remains no consensus on treatment for PLC injury, and, therefore, it is imperative to have a reproducible injury model to improve the general knowledge of PLC injuries. A novel cadaveric model of isolated PLC injury is proposed and evaluated using radiographic parameters as well as gross dissection. Material and methods: All protocols were reviewed by the Human Investigation and Research Committee of the home institution and were approved. Translational force in a defined posterior and lateral direction was applied to cadaveric native knees to induce PLC injury. Varus and recurvatum stress fluoroscopic imaging was obtained of each specimen before and after the injury model. Lateral joint distance and recurvatum angle after stress was measured on each image via picture archiving and communication software (PACS) imaging software. After the injury model, injured structures were assessed via saline loading and gross dissection. Any specimens found to be fractured were excluded from the analysis of stress radiography. Results: A total of 12 knees underwent testing and 6/12 successfully induced PLC injury without fracture. The lateral capsule was torn in every specimen. The popliteofibular ligament (PFL) was torn in 83% of specimens and the fibular collateral ligament (FCL) in 66.7% of specimens. The median lateral gapping after injury under varus stress radiography was 5.39 mm and the median recurvatum angle after injury was 14.25°. Radiographic parameters had a direct relationship with a number of structures injured. Conclusions: This is the first successful cadaver model of PLC injury. The lateral capsule was injured in every specimen emphasizing the importance of this structure to the PLC

Effects of Ohio Opioid Prescribing Policy on Postsurgical Prescriptions Following Sports Procedures

Background: Prescribed opioid medication after orthopedic sports surgery has been shown to exceed patient requirements. In 2017, as a response to the opioid epidemic, Ohio passed Opioid Prescribing Guidelines (OPG) limiting narcotic prescriptions for acute pain. This study sought to evaluate the effects of the OPG on prescribing behavior of orthopedists following knee arthroscopy (KA), shoulder arthroscopy (SA), and anterior cruciate ligament reconstruction (ACLR). Methods: An institutional database was queried to calculate morphine equivalent dose (MED) prescribed at discharge, acute follow-up (\u3c90 days), and chronic follow-up (\u3e90 days) and compare MED pre- and post-OPG. Cases were identified over a 2-year period starting 1 year prior to OPG implementation. Individual surgeon data were tracked to control for inter-surgeon variability. Results: A total of 1663 patients were included in the analysis. Demographic variables were similar pre- and post-OPG for each procedure group. With all surgeons included, average discharge MED decreased significantly for all procedures from pre- to post-OPG. Surgeons qualified for individual analysis if they had at least 10 surgeries pre- and post-OPG. Of qualifying providers, 80% of KA, 25% of SA, and 0% of ACLR surgeons reduced discharge MED prescribed post-OPG. MED prescribed during follow-up was largely unaffected by implementation of the OPG. Conclusion: Average discharge morphine equivalent dose (MED) prescribed after SA, KA, and ACLR decreased following the implementation of the OPG. The MED reduction effect of the OPG was the greatest in magnitude after SA, and SA was the only surgery that showed MED reductions that persisted during acute follow up. Opioid prescriptions beyond 90 days postoperatively were unchanged by the OPG for all surgeries. Policy that restricts postoperative opioid prescriptions can be an effective, but incomplete method to address the opioid crisis

Adaptive Management of Winter Elk Feedgrounds in Western Wyoming as a Long-Term Strategy for Reducing Brucellosis in Elk While Maintaining Separation from Cattle: A Work in Progress

Brucellosis is of large economic and management concern in the Greater Yellowstone Ecosystem (GYE) where wildlife remain the last reservoir of the disease in the United States. Wyoming Game and Fish Department (WGFD) management of brucellosis has focused on separation of elk (Cervus elaphus) and cattle (Bos taurus) through operation of 22 winter feedgrounds, which originated to prevent elk starvation and elk damage. Although feedgrounds perpetuate the spread of brucellosis among elk, they are largely maintained to prevent disease spillover to cattle. Despite efforts, recent brucellosis occurrences in Wyoming cattle during 2004-2008 were linked to feedground elk. Therefore, numerous research projects conducted during 2006-2008 were aimed at developing feedground management strategies that lead to long-term brucellosis reductions in elk. Major research results lead the WGFD to development of the Target Feedground Project, which manipulates feeding management to reduce brucellosis in elk. This project was first implemented in winter 2007-08 and is conducted exclusively at target feedgrounds, where perceived elk-cattle commingling risk is low and there is a high potential for elk to free range in late winter/early spring. The first objective is to reduce elk densities while on feedgrounds by using low-density feeding. The second objective is to reduce duration of high elk concentration by manipulating end-feeding season date through systematic reductions in hay rations in late winter and early spring, with the goal of ending an average of 3-4 weeks earlier than long-term means. Advantages of this project, if successful, are sustainable reductions in elk brucellosis and decreased risk to cattle, lower elk feeding costs, and continued operation of feedgrounds to minimize elk-cattle commingling, elk damage, and sustain elk numbers that meet public expectation. Disadvantages are that the project is not suitable for all feedgrounds and elk on target feedgrounds remain susceptible to new diseases that may arise