708 research outputs found
The impact of income shocks on health: evidence from cohort data
We study the effect of permanent income innovations on health for a prime-aged population. Using information
on more than half a million individuals sampled over a twenty-five year period in three different cross-sectional
surveys we aggregate data by date-of-birth cohort to construct a ’synthetic cohort’ dataset with details of income, expenditure, socio-demographic factors, health outcomes and selected risk factors. We then exploit structural and arguably exogenous changes in cohort incomes over the eighties and nineties to uncover causal effects of
permanent income shocks on health. We find that such income innovations have little effects on health, but do
affect health behaviour and mortality
Career progression and formal versus on-the-job training
We develop a dynamic discrete choice model of training choice, employment and wage growth, allowing for job mobility, in a world where wages depend on firm-worker matches, as well as experience and tenure and jobs take time to locate. We estimate this model on a large administrative panel data set which traces labour market transitions, mobility across firms and wages from the end of statutory schooling. We use the model to evaluate the life-cycle return to apprenticeship training and find that on average the costs outweigh the benefits; however for those who choose to train the returns are positive. We then use our model to consider the long-term lifecycle effects of two reforms: One is the introduction of an Earned Income Tax Credit in Germany, and the other is a reform to Unemployment Insurance. In both reforms we find very significant impacts of the policy on training choices and on the value of realised matches, demonstrating the importance of considering such longer term implications
Career progression and formal versus on-the-job training
We model the choice of individuals to follow or not apprenticeship training and their subsequent career. We use German administrative data, which records education, labour market transitions and wages to estimate a dynamic discrete choice model of training choice, employment and wage growth. The model allows for returns to experience and tenure, match specific effects, job mobility and search frictions. We show how apprenticeship training affects labour market careers and we quantify its benefits, relative to the overall costs. We then use our model to show how two welfare reforms change life-cycle decisions and human capital accumulation: One is the introduction of an Earned Income Tax Credit in Germany, and the other is a reform to Unemployment Insurance. In both reforms we find very significant impacts of the policy on training choices and on the value of realized matches,
demonstrating the importance of considering such longer term implications
Seismic Radiation From Simple Models of Earthquakes
We review some basic features of shear wave generation and energy balance for a
2D anti plane rupture. We first study the energy balance for a flat fault, and for a fault
that contains a single localized kink. We determine an exact expression for the partition
between strain energy flow released from the elastic medium surrounding the
fault, radiated energy flow and energy release rate. This balance depends only on the
rupture speed and the residual stress intensity factor. When the fault contains a kink,
the energy available for fracture is reduced so that the rupture speed is reduced. When
rupture speed changes abruptly, the radiated energy flow also changes abruptly. As
rupture propagates across the kink, a shear wave is emitted that has a displacement
spectral content that decreases like ω^(-2) at high frequencies. We then use spectral elements
to model the propagation of an antiplane crack with a slip-weakening friction
law. Since the rupture front in this case has a finite length scale, the wave emitted by
the kink is smoothed at very high frequencies but its general behavior is similar to
that predicted by the simple sharp crack model. A model of a crack that has several kinks and wanders around a mean rupture directions, shows that kinks reduce the rupture speed along the average rupture direction of the fault. Contrary to flat fault models, a fault with kinks produces high frequency waves that are emitted every time the rupture front turns at a kink. Finally, we discuss the applicability of the present results to a 3D rupture model
Market regulation and firm performance: the case of smoking bans in the UK
This paper analyzes the effects of a ban on smoking in public places upon firms and
consumers. It presents a theoretical model and tests its predictions using unique data from
before and after the introduction of smoking bans in the UK. Cigarette smoke is a public bad,
and smokers and non-smokers differ in their valuation of smoke-free amenities. Consumer
heterogeneity implies that the market equilibrium may result in too much uniformity, whereas
social optimality requires a mix of smoking and non-smoking pubs (which can be
operationalized via licensing). If the market equilibrium has almost all pubs permitting
smoking (as is the case in the data) then a blanket ban reduces pub sales, profits, and
consumer welfare. We collect survey data from public houses and find that the Scottish
smoking ban (introduced in March 2006) reduced pub sales and harmed medium run
profitability. An event study analysis of the stock market performance of pub-holding
companies corroborates the negative effects of the smoking ban on firm performance
Theory of dynamic crack branching in brittle materials
The problem of dynamic symmetric branching of an initial single brittle crack
propagating at a given speed under plane loading conditions is studied within a
continuum mechanics approach. Griffith's energy criterion and the principle of
local symmetry are used to determine the cracks paths. The bifurcation is
predicted at a given critical speed and at a specific branching angle: both
correlated very well with experiments. The curvature of the subsequent branches
is also studied: the sign of , with being the non singular stress at the
initial crack tip, separates branches paths that diverge from or converge to
the initial path, a feature that may be tested in future experiments. The model
rests on a scenario of crack branching with some reasonable assumptions based
on general considerations and in exact dynamic results for anti-plane
branching. It is argued that it is possible to use a static analysis of the
crack bifurcation for plane loading as a good approximation to the dynamical
case. The results are interesting since they explain within a continuum
mechanics approach the main features of the branching instabilities of fast
cracks in brittle materials, i.e. critical speeds, branching angle and the
geometry of subsequent branches paths.Comment: 41 pages, 15 figures. Accepted to International Journal of Fractur
A Very Low Resource Language Speech Corpus for Computational Language Documentation Experiments
Most speech and language technologies are trained with massive amounts of
speech and text information. However, most of the world languages do not have
such resources or stable orthography. Systems constructed under these almost
zero resource conditions are not only promising for speech technology but also
for computational language documentation. The goal of computational language
documentation is to help field linguists to (semi-)automatically analyze and
annotate audio recordings of endangered and unwritten languages. Example tasks
are automatic phoneme discovery or lexicon discovery from the speech signal.
This paper presents a speech corpus collected during a realistic language
documentation process. It is made up of 5k speech utterances in Mboshi (Bantu
C25) aligned to French text translations. Speech transcriptions are also made
available: they correspond to a non-standard graphemic form close to the
language phonology. We present how the data was collected, cleaned and
processed and we illustrate its use through a zero-resource task: spoken term
discovery. The dataset is made available to the community for reproducible
computational language documentation experiments and their evaluation.Comment: accepted to LREC 201
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