An analysis of short haul air passenger demand, volume 2

Several demand models for short haul air travel are proposed and calibrated on pooled data. The models are designed to predict demand and analyze some of the motivating phenomena behind demand generation. In particular, an attempt is made to include the effects of competing modes and of alternate destinations. The results support three conclusions: (1) the auto mode is the air mode's major competitor; (2) trip time is an overriding factor in intermodal competition, with air fare at its present level appearing unimportant to the typical short haul air traveler; and (3) distance appears to underly several demand generating phenomena, and therefore, must be considered very carefully to any intercity demand model. It may be the cause of the wide range of fare elasticities reported by researchers over the past 15 years. A behavioral demand model is proposed and calibrated. It combines the travel generating effects of income and population, the effects of modal split, the sensitivity of travel to price and time, and the effect of alternative destinations satisfying the trip purpose

New approaches for estimating risk from exposure to diethylstilbestrol.

A subgroup from a National Institute of Environmental Health Sciences, workshop concerned with characterizing the effects of endocrine disruptors on human health at environmental exposure levels considered the question, If diethylstilbestrol (DES) were introduced into the market for human use today and likely to result in low-dose exposure of the human fetus, what would be required to assess risk? On the basis of an analysis of the quality of data on human DES exposure, the critical times and doses for inducing genital tract malformations and cancer must be determined. This would be facilitated through analysis of the ontogeny of estrogen receptor expression in the developing human genital tract. Models of low-dose estrogenic effects will have to be developed for human and rodent genital tract development. Mouse models offer many advantages over other potential animal models because of the wealth of the earlier literature, the availability of sensitive end points, the availability of mutant lines, and the possibility of generating genetically engineered model systems. Through multidisciplinary approaches, it should be possible to elucidate the cellular and molecular mechanisms of endocrine disruption elicited by estrogens during development and facilitate an assessment of risk to humans

LONG-TERM TILLAGE EFFECTS ON CONTINUOUS CORN YIELDS

Long-term comparisons of alternative tillage systems are needed to evaluate their effect on corn (Zea mays L.) yield under the variable temperature and rainfall conditions of the Corn Belt. Our objective was to evaluate long-term effects of alternative tillage systems on corn growth and yield on low organic matter silt loam soils. The effect of no-tillage (NT), chisel plow (CP), and moldboard plow (MP) treatments on plant density and grain yield was measured from 1981 through 1990 on Palsgrove and Rozetta silt loam (fine-silty, mixed mesic Typic Hapludalfs) soils. Tillage treatments were randomly allocated to plots in 1981 and treatments were applied in subsequent years without rerandomization. Therefore, measurements over years on the same plot were treated as repeated measures. Grain yields for all tillage treatments were primarily affected by water stress, which varied with yearly weather conditions. Grain yield decreased approximately 0.3 Mg ha-1 per cm weighted water stress (WWS) for WWS \u3e8 cm. No statistically significant yield differences among tillage treatments, when averaged over the 10-year period covered by the experiment, were detected. A combined analysis indicated that yield differences among tillage treatments did not depend on whether water stress or non-stress conditions occurred. Over half the variation in yearly differences in grain yield between tilled and NT treatments was explained by differences in plant density. Years were classified as stress or non-stress years on the basis of observed water stress and yearly weather factors. Variability among years was partitioned into variability among years within stress years and non-stress years. The difference in mean yields between ending (1989-90) and beginning (1981-82) years were used to investigate cumUlative effects of tillage treatments

Band Gap Engineering with Ultralarge Biaxial Strains in Suspended Monolayer MoS2

We demonstrate the continuous and reversible tuning of the optical band gap of suspended monolayer MoS2 membranes by as much as 500 meV by applying very large biaxial strains. By using chemical vapor deposition (CVD) to grow crystals that are highly impermeable to gas, we are able to apply a pressure difference across suspended membranes to induce biaxial strains. We observe the effect of strain on the energy and intensity of the peaks in the photoluminescence (PL) spectrum, and find a linear tuning rate of the optical band gap of 99 meV/%. This method is then used to study the PL spectra of bilayer and trilayer devices under strain, and to find the shift rates and Gr\"uneisen parameters of two Raman modes in monolayer MoS2. Finally, we use this result to show that we can apply biaxial strains as large as 5.6% across micron sized areas, and report evidence for the strain tuning of higher level optical transitions.Comment: Nano Lett., Article ASA

The Dark Side of ROTSE-III Prompt GRB Observations

We present several cases of optical observations during gamma-ray bursts (GRBs) which resulted in prompt limits but no detection of optical emission. These limits constrain the prompt optical flux densities and the optical brightness relative to the gamma-ray emission. The derived constraints fall within the range of properties observed in GRBs with prompt optical detections, though at the faint end of optical/gamma flux ratios. The presently accessible prompt optical limits do not require a different set of intrinsic or environmental GRB properties, relative to the events with prompt optical detections.Comment: ApJ accepted. 20 pages in draft manuscript form, which includes 6 pages of tables and 2 figure

Status of the ROTSE-III telescope network

ROTSE-III is a homogeneous worldwide array of 4 robotic telescopes. They were designed to provide optical observations of γ-ray burst (GRB) afterglows as close as possible to the start of γ-ray emission. ROTSE-III is fulfilling its potential for GRB science, and provides optical observations for a variety of astrophysical sources in the interim between GRB events

The effects of stress management interventions among police officers and recruits

Law enforcement organizations began to take notice of officer stress during the late 1970s. Stress has been found to not only affect the officers’ job performance, but their personal lives and relationships as well. Because police officers are first responders to potentially stressful situations, their ability to successfully manage stress is critical not only to their own mental health but to the safety of society as a whole. Research has found that police officers who have difficulties coping with stress exhibit maladaptive behavior and personality traits such as aloofness, authoritarianism, cynicism, depersonalization, emotional detachment, suspiciousness, and excessive use of alcohol. High levels of stress can lead to serious physiological (headaches, stomachaches, backaches, ulcers, heart attacks) and psychological (anxiety, depression, flashbacks, and panic attacks) symptoms. Stress among police officers has also been connected to police misconduct and can also have a negative effect on the law enforcement organization due to lawsuits resulting from officers’ performance. Other organizational effects include impaired officer performance, lower productivity, poor morale, poor public relations, labor-management problems, tardiness and missed work, and officer turnover. Law enforcement organizations provide a wide variety of stress management interventions aimed at ameliorating officer stress. The objectives of this systematic review were to identify, retrieve, evaluate and synthesize the available evidence regarding outcomes of stress management interventions provided to veteran police officers and recruits. The review question is: What are the effects of officer stress management interventions on stress outcomes

Friction factor and heat transfer correlation for irradiated organic coolants

"September 1965."Series statement handwritten on cover"MIT-334-23 Chemistry."Also written as an M.S. theses written by the first author and advised by the second author, Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1966Includes bibliographical references (pages 163-165)M.I.T. DSR Project no. 9819Work performed for the Savannah River Operations Office, U.S. Atomic Energy Commission under contract no. AT(38-1)-33