Discrete choice modelling incorporating attribute thresholds of perception

In this paper we formulate a discrete choice model that incorporates thresholds in the perception of attribute changes. The model considers multiple options and allows changes in several attributes. We postulate that if thresholds exist they could be random, differ between individuals, and even be a function of socio-economic characteristics and choice conditions. Our formulation allows estimation of the parameters of the threshold probability distribution starting from information about choices. The model is applied to synthetic data and also to real data from a stated preference survey. We found that where perception thresholds exist in the population, the use of models without them leads to errors in estimation and prediction. Clearly, the effect is more relevant when the typical size of change in the attribute value is comparable with the threshold, and when the contribution of this attribute in the utility function is substantial. Finally, we discuss the implications of the threshold model for estimation of the benefits of transport investments, and show that where thresholds exist, models that do not represent them can overestimate benefits substantially

Biodiversity study of Southern Biscayne Bay and Card Sound 1968-1973

A multi-disciplinary investigation was conducted in southern Biscayne Bay and Card Sound from 1968 to 1973. The purpose of the investigation was to conduct an integrated study of the ecology of southern Biscayne Bay with special emphasis on the effects of the heated effluent from the Turkey Point fossil fuel power plant, and to predict the impact of additional effluent from the planned conversion of the plant to nuclear fuel. The results of this investigation have been discussed in numerous publications. This report contains the unpublished biology data that resulted from the investigation. (PDF contains 44 pages

Resource survey of Looe Key National Marine Sanctuary, 1983

Forward: Looe Key National Marine Sanctuary (LKNMS) was designated in 1981 to protect and promote the study, teaching, and wise use of the resources of Looe Key Sanctuary (Plate A). In order to wisely manage this valuable resource, a quantitative resource inventory was funded by the Sanctuary Programs Division (SPD), Office of Ocean and Coastal Resource Management, National Oceanic and Atmospheric Administration (NOAA) in cooperation with the Southeast Fisheries Center, National Marine Fisheries Service, NOAA; the Cooperative Institute for Marine and Atmospheric Studies (CIMAS), University of Miami; the Fisher Island Laboratory, United States Geological Survey; and the St. Petersburg Laboratory, State of Florida Department of Natural Resources. This report is the result of this cooperative effort. The objective of this study was to quantitatively inventory selected resources of LKNMS in order to allow future monitoring of changes in the Sanctuary as a result of human or natural processes. This study, referred to as Phase I, gives a brief summary of past and present uses of the Sanctuary (Chapter 2); and describes general habitat types (Chapter 3), geology and sediment distribution (Chapter 4), coral abundance and distribution (Chapter 5), the growth history of the coral Montastraea annularis (Chapter 6), reef fish abundance and distribution (Chapter 7), and status of selected resources (Chapter 8). An interpretation of the results of the survey are provided for management consideration (Chapter 9). The results are expected to provide fundamental information for applied management, natural history interpretation, and scientific research. Numerous photographs and illustrations were used to supplement the report to make the material presented easier to comprehend (Plate B). We anticipate the information provided will be used by managers, naturalists, and the general public in addition to scientists. Unless otherwise indicated, all photographs were taken at Looe Key Reef by Dr. James A. Bohnsack. The top photograph in Plate 7.8 was taken by Michael C. Schmale. Illustrations were done by Jack Javech, NMFS. Field work was initiated in May 1983 and completed for the most part by October 1983 thanks to the cooperation of numerous people and organizations. In addition to the participating agencies and organizations we thank the Newfound Harbor Marine Institute and the Division of Parks and Recreation, State of Florida Department of Natural Resources for their logistical support. Special thanks goes to Billy Causey, the Sanctuary Manager, for his help, information, and comments. We thank in alphabetical order: Scott Bannerot, Margie Bastian, Bill Becker, Barbara Bohnsack, Grant Beardsley, John Halas, Raymond Hixon, Irene Hooper, Eric Lindblad, and Mike Schmale. We dedicate this effort to the memory of Ray Hixon who participated in the study and who loved Looe Key. (PDF contains 43 pages

Results of a fish health survey of North Biscayne Bay, June 1976-June 1977

Fish were collected weekly in Biscayne Bay using a monofilament gill net set from a small skiff during 20-30 minute intervals. Although weekly sampling took place for 2.5 years, only the data from samples collected from June 1976 to June 1977 were used in this document. Abnormal external conditions of fins and body were observed on each fish and recorded. Fish were returned immediately to their habitats. Fish collected in the time period for this study numbered 3,765 and included 32 species. Of these, 16 species, totaling 3,556 fish, were caught in sufficient numbers (20 or more) to warrant data analysis. Only 3 of the 16 species could be considered relatively unafflicted: Aetobatus narinari (spotted eagle ray), Diodon hystrix (porcupinefish), and Selene vomer (lookdown). More than 80% of the examined specimens of these three species were unaffected. Less than 20% of the specimens of Diapterus plumieri (striped mojarra), Micropogonias undulatus (Atlantic croaker), and Pogonias cromis (black drum) displayed normal conditions. The three most afflicted species were Diapterus plumieri, striped mojarra; Micropogonias undulatus, Atlantic croaker; and Pogonias cromis, black drum. Only 7, 3, and 7% respectively showed no external evidence of disease. Data described in this document were originally tabulated in the mid-1970s, remained unpublished, and are no longer available. This document was based on archived unpublished text, a data summary table, and figures. Most of the text and cited references were the ones used in the original manuscript and no attempt was made to update them. (PDF contains 44 pages

An environmental assessment of the John Pennekamp Coral Reef State Park and the Key Largo Coral Reef Marine Sanctuary (Unpublished 1983 Report)

The Pennekamp Coral Reef State Park was established in 1960 and the Key Largo National Marine Sanctuary in 1975. Field studies, funded by NOAA, were conducted in 1980 - 1981 to determine the state of the coral reefs and surrounding areas in relation to changing environmental conditions and resource management that had occurred over the intervening years. Ten reef sites within the Sanctuary and seven shallow grass and hardbottom sites within the Park were chosen for qualitative and quantitative studies. At each site, three parallel transects not less than 400 m long were run perpendicular to the reef or shore, each 300 m apart. Observations, data collecting and sampling were done by two teams of divers. Approximately 75 percent of the bottom within the 18-m isobath was covered by marine grasses, predominantly turtle grass. The general health of the seagrasses appeared good but a few areas showed signs of stress. The inner hardbottom of the Park was studied at the two entrances to Largo Sound. Though at the time of the study the North Channel hardbottom was subjected to only moderate boat traffic, marked changes had taken place over the past years, the most obvious of which was the loss of the extensive beds of Sargassum weed, one of the most extensive beds of this alga in the Keys. Only at this site was the green alga Enteromorpha encountered. This alga, often considered a pollution indicator, may denote the effects of shore run off. The hardbottom at South Channel and the surrounding grass beds showed signs of stress. This area bears the heaviest boat traffic within the Park waters causing continuous turbidity from boat wakes with resulting siltation. The offshore hardbottom and rubble areas in the Sanctuary appeared to be in good health and showed no visible indications of deterioration. Damage by boat groundings and anchors was negligible in the areas surveyed. The outer reefs in general appear to be healthy. Corals have a surprising resiliency to detrimental factors and, when conditions again become favorable, recover quickly from even severe damage. It is, therefore, a cause for concern that Grecian Rocks, which sits somewhat inshore of the outer reef line, has yet to recover from die-off in 1978. The slow recovery, if occurring, may be due to the lower quality of the inshore waters. The patch reefs, more adapted to inshore waters, do not show obvious stress signs, at least those surveyed in this study. It is apparent that water quality was changing in the keys. Water clarity over much of the reef tract was observed to be much reduced from former years and undoubtedly plays an important part in the stresses seen today over the Sanctuary and Park. (PDF contains 119 pages

Analysing a license plate-based vehicle restriction policy with optional exemption charge: The case in Cali, Colombia

Several cities have restricted the use of private vehicles based on the last digit of a vehicle's license plate to reduce traffic congestion and pollution. However, the effectiveness of this measure has been questioned. In 2017, a hybrid scheme, License Plate Restriction Charging (LPRC), was implemented in Cali, Colombia. With this scheme, drivers can pay a charge (monthly, quarterly, or yearly) to circumvent the restriction, while the revenue is used to subsidise the BRT System. Cali was the first city in Latin America to implement such a scheme, while Colombia's capital, Bogota, adopted a similar policy in 2020. This article analyses the evolution of the measure using official information. In addition, we conducted a stated preferences survey and estimated a choice model to evaluate the behaviour of car owners to policy variables. Results show that LPRC price is the most relevant attribute in decision-making. Increasing the number of days with traffic restrictions and extending the hours of vehicle use restriction increases drivers' probability of paying for the LPRC. As currently implemented in Cali, the LPRC is a fixed cost that does not vary according to the car use level, encouraging users who pay for the exemption to use their car as much as possible to make the most out of the payment. Furthermore, the revenue from the charge contributes only marginally to financing the BRT. Finally, we propose several changes in the policy to improve its efficiency. Among them, consider a daily payment and hardening the current driving restriction. © 2023 The Author(s)APCs y acuerdos transformativos 2023, Elsevie

Engaging women into STEM in Latin America: W-STEM project

[EN]Significant progress has been made during the last decades to achieve gender equality, but there is still much work to do. In particular, the gender gap is pronounced in the science, technology, engineering, and mathematics (STEM) fields at all levels of education and labour market. In those areas, the women participation remains low, although there are differences from country to country. In the Latin American context, there is a need for carrying out studies to collect quality data about the actual situation of women in STEM. Although some available data show a high proportion of women in Latin American university education, they are a minority in STEM programs. Moreover, this problem is particularly severe in Latin America because of the biases or cultural norms that influence female behaviour. In this context, the W-STEM project seeks to improve strategies and mechanisms for attracting, accessing, and guiding women in Latin America in STEM higher education programs. This work aims to describe the main results to prepare a set of attraction campaigns in secondary schools in the Latin American countries involved in the project (Chile, Colombia, Costa Rica, Ecuador, Mexico). In particular, a self-assessment tool about gender equality in higher education institutions in Latin America, an interview protocol for female role models, and a mobile application to show those role models

Patógenos associados ao neem (Azadirachta indica A. Juss.) no estado do Ceará.

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Un enfoque de bajo costo para monitorear la salud estructural de los puentes peatonales

Changes in dynamic properties of structures, such as damping ratios and natural frequencies can be detected by periodic monitoring (e.g. one time by year). These changes are often indications of structural damage thereby, the maintenance or demolition of the structure can be doing in due time. In the case of pedestrian bridges, people’s movements may produce a resonance state, which leads to excessive deflection that accelerates the deterioration of these structures. Typically, these dynamic properties are detected by using high-cost vibration measurement equipment to achieve high levels of precision (i.e. a very low noise levels). This article studies the measurement of dynamic properties in pedestrian bridges using a tri-axial accelerometer integrated into a mobile phone as a low-cost and alternative practice. Accelerations were recorded on a steel pedestrian bridge (flexible) and on a post-tensioned concrete pedestrian bridge (rigid) located in Barranquilla City (Colombia). Vibrations were induced by a person (e.g., by jumping). Previous studies based on traditional measuring techniques show that two dominant frequencies in both types of bridges can be identified. However, in this study a reliable damping ratio could only be established for the steel bridge that it is associated with the flexibility and the low amplitude of the induced vibrations by a single pedestrian use

Impact of a basic mathematics course on the performance of college students in algebra subject

A common problem for universities is the lack of knowledge and mathematical skills of new students because this deficiency creates difficulties in their studies throughout their career, which can cause their dropout. The aim of this paper is to describe the impact of a basic mathematics course on the performance of college student in algebra subject. This is a 32-hour course which is developed in 16 sessions in parallel to the algebra classes and is mainly offered to students: a) identified with low performance on mathematics component of national highschool test, and b) remitted by the subject teacher. The main findings are: a) the pass rate for students who attended to more than half of the sessions of the course if 95%, and b) the average grade of the subject tends to increase as with the attendance level to the course of the students. Consequently, these results lead to the conclusion that the course has a positive effect on the students' performance