Bidentate N,O-prolinate ruthenium benzylidene catalyst highly active in RCM of disubstituted dienes

The synthesis of a bidentate N,O-prolinate ruthenium benzylidene from commercially available starting materials and its activity in ring-closing metathesis of functionalized disubstituted dienes at 30 °C is disclosed

Proceedings of the African Diaspora Conference on Sustainable Development

The authors urge the Western donor organizations to facilitate and support the take up of such more sustainable models

Market Structure, Strike Activity, and Union Wage Settlements

We attempt a synthesis of the industrial relations market structure hypothesis with the modern asymmetric information theory of wage and strike outcomes The industrial relations literature contains a variety of arguments indicating that wage settlements should be positively related to the degree of product market sales concentration and the degree of product market coverage by the union. An asymmetric information bargaining model is specified that relates these same variables to strike probabilities as well as wage settlements. Our empirical analysis is conducted for :he periods from 1970-1380 (strikes) and 1976-1980 (wages). We find that the relation between trade-adjusted sales concentration and wage settlements is positive at low levels of concentration but negative at high levels of concentration. The relation is always negative for strike probabilities. We also find that the relation between the trade-adjusted percent of the product market covered by the same union and the percentage covered by other union are positively related to both wage settlements and strike probabilities. Our empirical analysis includes a rich set of controls including unrestricted time and industry effects, which do not affect the major conclusions.

Trauma and acute care surgeons report prescribing less opioids over time.

IntroductionConfronted with the opioid epidemic, surgeons must play a larger role to reduce risk of opioid abuse while managing acute pain. Having a better understanding of the beliefs and practices of trauma and acute care surgeons regarding discharge pain management may offer potential targets for interventions beyond fixed legal mandates.MethodsAn Institutional Review Board-approved electronic survey was sent to trauma and acute care surgeons who are members of the American Association for the Surgery of Trauma, and trauma and acute care surgeons and nurse practitioners at a Level 1 trauma center in February 2018. The survey included four case-based scenarios and questions about discharge prescription practices and beliefs.ResultsOf 66 respondents, most (88.1%) were at academic institutions. Mean number of opioid tablets prescribed was 20-30 (range 5-90), with the fewest tablets prescribed for elective laparoscopic cholecystectomy and the most for rib fractures. Few prescribed both opioid and non-opioid medications (22.4% to 31.4 %). Most would not change the number/strength of medications (69.2%), dose (53.9%), or number of tablets of opioids (83.1%) prescribed if patients used opioids regularly prior to their operation. The most common factors that made providers more likely to prescribe opioids were high inpatient opioid use (32.4%), history of opioid use/abuse (24.5%), and if the patient lives far from the hospital (12.9%). Most providers in practice >5 years reported a decrease in opioids (71.9%) prescribed at discharge.ConclusionTrauma and acute care surgeons and nurse practitioners reported decreasing the number/amount of opioids prescribed over time. Patients with high opioid use in the hospital, history of opioid use/abuse, or who live far from the provider may be prescribed more opioids at discharge.Level of evidenceLevel IV

An Algorithmic Study of Manufacturing Paperclips and Other Folded Structures

We study algorithmic aspects of bending wires and sheet metal into a specified structure. Problems of this type are closely related to the question of deciding whether a simple non-self-intersecting wire structure (a carpenter's ruler) can be straightened, a problem that was open for several years and has only recently been solved in the affirmative. If we impose some of the constraints that are imposed by the manufacturing process, we obtain quite different results. In particular, we study the variant of the carpenter's ruler problem in which there is a restriction that only one joint can be modified at a time. For a linkage that does not self-intersect or self-touch, the recent results of Connelly et al. and Streinu imply that it can always be straightened, modifying one joint at a time. However, we show that for a linkage with even a single vertex degeneracy, it becomes NP-hard to decide if it can be straightened while altering only one joint at a time. If we add the restriction that each joint can be altered at most once, we show that the problem is NP-complete even without vertex degeneracies. In the special case, arising in wire forming manufacturing, that each joint can be altered at most once, and must be done sequentially from one or both ends of the linkage, we give an efficient algorithm to determine if a linkage can be straightened.Comment: 28 pages, 14 figures, Latex, to appear in Computational Geometry - Theory and Application

A Simple Kinetic Analysis of Syngas During Steam Hydrogasification of Biomass Using a Novel Inverted Batch Reactor with Instant High Pressure Feeding

A newly designed inverted batch reactor equipped with a pressure-driven feeding system was built for investigating the kinetics of syngas during the steam hydrogasification (SHR) of biomass. The system could instantly load the feedstock into the reactor at high temperature and pressure, which simulated the way to transport the feedstock into a hot and pressurized gasifier. Experiments were conducted from 600 °C to 700 °C. The inverted reactor showed very high heating rate by enhancing the carbon conversion and syngas production. The kinetic study showed that the rates of CH4, CO and CO2 formation during SHR were increased when the gasification temperature went up. SHR had comparatively lower activation energy for CH4 production. The activation energies of CH4, CO and CO2 during SHR were 42.8, 51.8 and 14 kJ/mol, respectively

Thermodynamic Analysis of Interacting Nucleic Acid Strands

Motivated by the analysis of natural and engineered DNA and RNA systems, we present the first algorithm for calculating the partition function of an unpseudoknotted complex of multiple interacting nucleic acid strands. This dynamic program is based on a rigorous extension of secondary structure models to the multistranded case, addressing representation and distinguishability issues that do not arise for single-stranded structures. We then derive the form of the partition function for a fixed volume containing a dilute solution of nucleic acid complexes. This expression can be evaluated explicitly for small numbers of strands, allowing the calculation of the equilibrium population distribution for each species of complex. Alternatively, for large systems (e.g., a test tube), we show that the unique complex concentrations corresponding to thermodynamic equilibrium can be obtained by solving a convex programming problem. Partition function and concentration information can then be used to calculate equilibrium base-pairing observables. The underlying physics and mathematical formulation of these problems lead to an interesting blend of approaches, including ideas from graph theory, group theory, dynamic programming, combinatorics, convex optimization, and Lagrange duality

STS-36 Space Shuttle mission report

The STS-36 Space Shuttle Program Mission Report contains a summary of the vehicle subsystem activities on this thirty-fourth flight of the Space Shuttle and the sixth flight of the OV-104 Orbiter vehicle, Atlantis. In addition to the Atlantis vehicle, the flight vehicle consisted of an External Tank (ET) (designated as ET-33/LWT-26), three Space Shuttle main engines (SSME's) (serial numbers 2019, 2030, and 2029), and two Solid Rocket Boosters (SRB's) (designated as BI-036). The STS-36 mission was a classified Department of Defense mission, and as such, the classified portions of the mission are not discussed. The unclassified sequence of events for this mission is shown in tabular form. Summarized are the significant problems that occurred in the Orbiter subsystems during the mission. The official problem tracking list is presented. In addition, each of the Orbiter problems is cited in the subsystem discussion