35,708 research outputs found
Exploring the returns to scale in food preparation (baking penny buns at home)
We show that as household size increases, households substitute away from prepared foods and towards ingredients. They also devote more time to food preparation. These observations (1) are consistent with a simple model with home production, returns to scale in the time input to food preparation, and varieties of food that differ in the required time input; (2) support the idea that returns to scale in home production are an important source of returns to scale in consumption; and (3), mean that across household sizes, household market expenditures on food are not proportional to food consumption quantities. The latter may provide a partial explanation for a puzzle raised by Deaton and Paxson.Household returns to scale, home production, food preparation
The neutron charge form factor in helium-3
In order to measure the charge form factor of the neutron, , one
needs to use a neutron bound in a nuclear target. We calculate the change in
the form factor for a neutron bound in , with respect to the free case,
using several versions of the quark meson coupling model. It is found that the
form factor may be suppressed by as much as 12% at with
respect to that of the free neutron.Comment: 13 pages including 2 ps figure
Quantum fluctuations and isotope effects in ab initio descriptions of water
Nuclear quantum effects, such as zero-point energy and tunneling, cause
significant changes to the structure and dynamics of hydrogen bonded systems
such as liquid water. However, due to the current inability to simulate liquid
water using an exact description of its electronic structure, the interplay
between nuclear and electronic quantum effects remains unclear. Here we use
simulations that incorporate the quantum mechanical nature of both the nuclei
and electrons to provide a fully ab initio determination of the particle
quantum kinetic energies, free energy change upon exchanging hydrogen for
deuterium and the isotope fractionation ratio in water. These properties, which
selectively probe the quantum nature of the nuclear degrees of freedom, allow
us to make direct comparison to recent experiments and elucidate how electronic
exchange and correlation and nuclear quantum fluctuations determine the
structure of the hydrogen bond in water.Comment: 8 pages, 2 figures, 2 table
Exploring the Returns to Scale in Food Preparation (Baking Penny Buns at Home)
We show that as household size increases, households substitute away from prepared foods and towards ingredients. They also devote more time to food preparation. These observations (1) are consistent with a simple model with home production, returns to scale in the time input to food preparation, and varieties of food that differ in the required time input; (2) support the idea that returns to scale in home production are an important source of returns to scale in consumption; and (3), mean that across household sizes, household market expenditures on food are not proportional to food consumption quantities. The latter may provide a partial explanation for a puzzle raised by Deaton and Paxson.household returns to scale; home production; food preparation
Exploring the Returns-to-Scale in Food Preparation
We show that as household size increases, households substitute away from prepared foods and towards ingredients. They also devote more time to food preparation. These observations (1) are consistent with a simple model with home production, returns to scale in the time input to food preparation, and varieties of food that differ in the required time input; (2) support the idea that returns to scale in home production are an important source of returns to scale in consumption; and (3), mean that across household sizes, household market expenditures on food are not proportional to food consumption quantities. The latter may provide a partial explanation for a puzzle raised by Deaton and Paxson.
An MDL approach to the climate segmentation problem
This paper proposes an information theory approach to estimate the number of
changepoints and their locations in a climatic time series. A model is
introduced that has an unknown number of changepoints and allows for series
autocorrelations, periodic dynamics, and a mean shift at each changepoint time.
An objective function gauging the number of changepoints and their locations,
based on a minimum description length (MDL) information criterion, is derived.
A genetic algorithm is then developed to optimize the objective function. The
methods are applied in the analysis of a century of monthly temperatures from
Tuscaloosa, Alabama.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS289 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
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