880 research outputs found
Discriminating deceptive from truthful statements using the verifiability approach: A meta-analysis
Pricing of imperfect substitutes:The next flight is not the same flight
We investigate how airfares respond to changes in the fare of adjacent flights. Using a fixed effects regression on fares from Amsterdam to Geneva, we find flights that only differ in departure times to be weak substitutes. Fare-to-fare elasticities for imperfect substitute flights of different airlines are even smaller, implying weak competition between airlines on this specific route. If our findings hold for other routes as well, this will have implications for the analysis of price dispersion in civil aviation. It would imply that demand shocks for individual flights have small effects on prices of other flights. Demand volatility would then be likely to affect price dispersion on a route level and should be considered when analyzing price dispersion
Reply to: can a functional ecological model reliably reveal the nature of early plant management in southwest Asia?
History of the software industry: the challenge
Martin Campbell-Kelly opened a new field in the history of computing in his groundbreaking From airline reservation to Sonic the Hedgehog; a history of the software industry. The book is discussed by Adrienne van den Bogaard and Frank Veraart and by Gerard Alberts, followed by a reply by the author. Van den Bogaard and Veraart join great appreciation for the three-sector division Campbell-Kelly developed to describe the history of the software industry, to a slight criticism of his ad hoc-argumentation in explaining why in each sector some enterprises survive and others do not. Lacking, in their view, is a discussion of the dynamics of software itself in the context of emerging practices and businesses. Alberts overcomes his prima facie unease with th
Combining functional weed ecology and crop stable isotope ratios to identify cultivation intensity: a comparison of cereal production regimes in Haute Provence, France and Asturias, Spain
This investigation combines two independent
methods of identifying crop growing conditions and husbandry
practices—functional weed ecology and crop stable
carbon and nitrogen isotope analysis—in order to assess
their potential for inferring the intensity of past cereal
production systems using archaeobotanical assemblages.
Present-day organic cereal farming in Haute Provence,
France features crop varieties adapted to low-nutrient soils
managed through crop rotation, with little to no manuring.
Weed quadrat survey of 60 crop field transects in this region
revealed that floristic variation primarily reflects
geographical differences. Functional ecological weed data
clearly distinguish the Provence fields from those surveyed
in a previous study of intensively managed spelt wheat in
Asturias, north-western Spain: as expected, weed ecological
data reflect higher soil fertility and disturbance in
Asturias. Similarly, crop stable nitrogen isotope values
distinguish between intensive manuring in Asturias and
long-term cultivation with minimal manuring in Haute
Provence. The new model of cereal cultivation intensity
based on weed ecology and crop isotope values in Haute
Provence and Asturias was tested through application to
two other present-day regimes, successfully identifying a
high-intensity regime in the Sighisoara region, Romania,
and low-intensity production in Kastamonu, Turkey. Application
of this new model to Neolithic archaeobotanical
assemblages in central Europe suggests that early farming
tended to be intensive, and likely incorporated manuring,
but also exhibited considerable variation, providing a finer
grained understanding of cultivation intensity than previously
available
Melting of olive oil in immiscible surroundings: experiments and theory
We report on the melting dynamics of frozen olive oil in quiescent water for
Rayleigh numbers up to . The density difference results in an upward
buoyancy-driven flow of liquid oil forming a thin film around the frozen oil.
We experimentally investigate flat, cylindrical, and spherical shapes and we
derive theoretical expressions for the local film thickness, velocity, and the
local melt rate for these three canonical geometries. Our theoretical models
compare favourably with our experimental findings.Comment: 18 pages, 9 figures, to be submitte
Introduction to RISC-KIT: Resilience-increasing strategies for coasts
Recent and historic low-frequency, high-impact events have demonstrated the flood risks faced by exposed coastal areas in Europe and beyond. These coastal zone risks are likely to increase in the future which requires a re-evaluation of coastal disaster risk reduction (DRR) strategies and a new mix of PMP (prevention, e.g., dike protection; mitigation, e.g., limiting construction in flood-prone areas and eco-system based solutions; and preparedness, e.g., Early Warning Systems, EWS) measures.
In response to these challenges, the RISC-KIT project has delivered a set of open-source and openaccess methods, tools and management approaches to reduce risk and increase resilience to lowfrequency, high-impact hydro-meteorological events in the coastal zone (the “RISC-toolKIT”). These products enhance forecasting, prediction and early warning capabilities, improve the assessment of long-term coastal risk and optimise the mix of PMP-measures.
In this paper an introduction is provided to the objectives, products, applications and lessonslearned of the RISC-KIT project, which are the subjects of this Special Issue. Subsequent papers provide details on the tools and their application on 10 case study sites in Europe
Does phase 2 of the expiratory PCO2 versus volume curve have diagnostic value in emphysema patients?
It has been postulated that serial inhomogeneity of ventilation in the
peripheral airways in emphysema is represented by the shape of expiratory
carbon dioxide tension versus volume curve. We examined the diagnostic
value of this test in patients with various degrees of emphysema. The
volumes between 25-50% (V25-50) and 25-75% (V25-75) of the expiratory
carbon dioxide tension versus volume curve were determined in 29
emphysematous patients (20 severely obstructed and 9 moderately
obstructed), 12 asthma patients in exacerbation of symptoms, and 28
healthy controls. Discriminant analysis was used to examine whether these
diagnostic groups could be separated. With regard to phase 2 of the
expiratory CO2 versus volume curve (mixture of anatomic deadspace and
alveolar air), a plot of intercept versus slope of the relationships of
(V25-50) and (V25-75) versus inspiratory volume (VI) from functional
residual capacity (FRC), obtained during natural breathing frequency,
proved to be most discriminating in the separation between healthy
controls and severely obstructed emphysema patients. Separating healthy
controls and severely obstructed emphysema patients on the basis of the
discriminant line for V25-50, 9 of the 12 asthma patients in exacerbation
were classified as normal, and only 5 of the 9 moderately obstructed
emphysema patients as emphysematous. For V25-75 involvement of phase 3 of
the curve (alveolar plateau) in asthma patients in exacerbation caused a
marked overlap with the severely obstructed emphysema patients. In the
healthy controls, a fixed breathing frequency of 20 breaths.min-1 led to
an increase of both volumes.(ABSTRACT TRUNCATED AT 250 WORDS
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