SOME IMPLICATIONS OF THE TWO-CONSTRAINT JOINT RECREATIONAL CHOICE DEMAND MODEL

This paper explores the implications of applying a two-constraint joint recreational demand framework to estimate the demand for recreation at an Alaskan sportfishery. The demand for total days on-site and total trips per season are jointly estimated and used to parametrically define average on-site time and obtain consumer's surplus values.Resource /Energy Economics and Policy,

Valuing a Beach Day with a Repeated Nested Logit Model of Participation, Site Choice, and Stochastic Time Value

Beach recreation values are often needed by policy-makers and resource managers to efficiently manage coastal resources, especially in popular coastal areas like Southern California. This article presents welfare values derived from random utility maximization-based recreation demand models that explain an individual’s decisions about whether or not to visit a beach and which beach to visit. The models utilize labor market decisions to reveal each individual’s opportunity cost of recreation time. The value of having access to the beach in San Diego County is estimated to be between $21 and$23 per day.Recreation demand, repeated nested logit, labor supply, opportunity cost of leisure, time, beach recreation., Demand and Price Analysis, Environmental Economics and Policy, Institutional and Behavioral Economics, Q26, J22, Q51.,

ESTIMATING THE OPPORTUNITY COST OF RECREATION TIME IN AN INTEGRABLE 2-CONSTRAINT COUNT DEMAND MODEL

How researchers treat the opportunity cost of time substantially influences recreation demand parameter and welfare estimates. This paper presents a utility-theoretic and implementable approach, estimating the shadow value of time jointly with recreation demands for coastal activities, using a generalization of the semilog demand system in a two-constraint model.Consumer/Household Economics, Demand and Price Analysis,

An automated system for global atmospheric sampling using B-747 airliners

The global air sampling program utilizes commercial aircrafts in scheduled service to measure atmospheric constituents. A fully automated system designed for the 747 aircraft is described. Airline operational constraints and data and control subsystems are treated. The overall program management, system monitoring, and data retrieval from four aircraft in global service is described

Few-Shot Bayesian Imitation Learning with Logical Program Policies

Humans can learn many novel tasks from a very small number (1--5) of demonstrations, in stark contrast to the data requirements of nearly tabula rasa deep learning methods. We propose an expressive class of policies, a strong but general prior, and a learning algorithm that, together, can learn interesting policies from very few examples. We represent policies as logical combinations of programs drawn from a domain-specific language (DSL), define a prior over policies with a probabilistic grammar, and derive an approximate Bayesian inference algorithm to learn policies from demonstrations. In experiments, we study five strategy games played on a 2D grid with one shared DSL. After a few demonstrations of each game, the inferred policies generalize to new game instances that differ substantially from the demonstrations. Our policy learning is 20--1,000x more data efficient than convolutional and fully convolutional policy learning and many orders of magnitude more computationally efficient than vanilla program induction. We argue that the proposed method is an apt choice for tasks that have scarce training data and feature significant, structured variation between task instances.Comment: AAAI 202

Dynamic Behavior of Precast Concrete Beam-Column Sub-Assemblages with High Performance Connections Subjected to Sudden Column Removal Scenario

Unbonded posttensioned precast concrete (UPPC) structure has shown its excellent aseismic performance in laboratory tests and earthquake investigation. However, the progressive collapse behavior of UPPC subjected to column removal scenario is still unclear. To fill this knowledge gap, two 1/2 scaled UPPC beam-column sub-assemblages were tested under a penultimate column removal scenario. The dynamic test results indicated that UPPC sub-assemblages have desirable load redistribution capacity to mitigate progressive collapse. The failure modes of the sub-assemblages observed in dynamic test were quite similar to that in static counterparts

Clinical use of topical thrombin as a surgical hemostat

When surgical ligation of bleeding fails, or is not possible, surgeons rely on a number of hemostatic aids, including thrombin. This review discusses the history, pharmacology and clinical application of thrombin as a surgical hemostat. The initial thrombin was bovine in origin, but its use has been complicated by the formation of antibodies that cross react with human coagulation factors. This has been associated with life threatening bleeding and in some circumstances anaphylaxis and death. Human thrombin, isolated from pooled plasma of donors, has been developed in an effort to minimize these risks, but its downside is the potential of transmitting blood-borne pathogens and limited availability. Recently a recombinant thrombin has been developed and approved for use by the FDA. It has the advantage of being minimally antigenic and devoid of the risk if viral transmission. Thrombin is often used in conjunction with other hemostatic aids, including absorbable agents (like gelfoam, collagen, and cellulose), and with fibrinogen in fibrin glues. The last part of this review will discuss these agents in detail, and review their clinical applications